Content uploaded by Tomáš Filipský
Author content
All content in this area was uploaded by Tomáš Filipský on Aug 30, 2015
Content may be subject to copyright.
Send Orders for Reprints to reprints@benthamscience.ae
Current Topics in Medicinal Chemistry, 2015, 15, 000-000 1
1568-0266/15 $58.00+.00 © 2015 Bentham Science Publishers
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity
Iveta Najmanová1a, Martin Doseděl1b, Radomír Hrdina1a, Pavel Anzenbacher2, Tomáš Filipský1a,
Michal Říha1a and Přemysl Mladěnka1a,*
1Charles University in Prague; Faculty of Pharmacy in Hradec Králové, Czech Republic: aDepartment of
Pharmacology and Toxicology and bDepartment of Social and Clinical Pharmacy; 2Department of
Pharmacology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Czech Republic
Abstract: Coumarins are a large group of substances, primarily of plant origin. Like their more intensively
examined congeners flavonoids, many of them are antioxidants. Although such properti es m ay be advanta-
geous in cardiovascular diseases, it has been shown that coumarins exhibit direct effects on the cardiovas-
cular system which are not based on antioxidant activity. The most common example is the well-known
drug warfarin, a synthetic compound derived from natural dicoumarol. Moreover, other coumarins have
been shown to possess antiplatelet and vasodilatory potential. Interestingly, the former effect may be mediated by the in-
hibition of various pathways leading to platelet aggregation, their differing effects on those pathways being due to struc-
tural differences betw een the various coumarins. Conversely, their vasodilatory potential is linked in the majority of cases
to the inhibition of increases in intracellular calcium concentration in vascular smooth muscle cells, and in several cou-
marins also to NO-mediated vasodilatation. Available data on both activities are summarized in this review. At the end of
this review, relevant data are provided from a few studies testing the in vivo effects of coumarins on major cardiovascular
diseases; the clinical use of warfarin and other coumarin anticoagulants, as well as the limited data on the clinical use of
coumarins in chronic venous insufficiency and the possible toxicological effects of coumarins.
Keywords: antioxidant, antiplatelet, cardiovascu lar, coumarin, vasodilation, warfarin.
INTRODUCTION
Coumarins (also known as 2H-1-benzopyran-2-ones or
less commonly as o-hydroxycinnamic acid-8-lactones) are a
large class of compounds with more than 1300 members
broadly distributed as secondary metabolites in the plant
kingdom, and in addition, their presence has also been de-
tected in fungi, bacteria and animals. In plants, coumarins
occur both as free compounds and glycosides, and, moreo-
ver, many other coumarins have been synthesized [1-4]. The
name is derived from Coumarouna odorata Aube (Dipterix
odorata), a plant from which the prototypical compound
coumarin was isolated in 1820 [2]. Based on an epidemiol-
ogical survey study, the average dietary coumarin intake for
a 60-kg consumer has been estimated to be 0.02 mg/kg/day.
From fragrance use in cosmetic products, coumarin exposure
has been estimated to be 0.04 mg/kg/day [4].
According to their chemical structure, coumarins can be
divided into several chemical subgroups including simple
coumarins, isocoumarins, furanocoumarins, pyranocoumar-
ins, biscoumarins, triscoumarins and coumarinolignans (Fig.
1) [2, 5]. Although a vast number of coumarins h ave been
isolated or synthesized, only a few substances have been
largely characterized in terms of their pharmacological or
*Address correspondence to this author at the Charles University in Prague,
Faculty of Pharmacy in Hradec Králové, Department of Pharmacology and
Toxicology, Heyrovského 1 203, 500 05 Hradec Králové, Czech Republic;
Tel: +420 495 067 295; Fax: +420 495 067 170;
E-mail: mladenkap@faf.cuni.cz
toxicological properties in human. These compounds include
warfarin and related anticoagulants, aflatoxins and psoralens
[3]. Aflatoxins, fungal metabolites from Aspergillus spp., are
potent hepatotoxins, cancerogens and can contaminate food
[3, 6]. Psoralens are photosensitizing agents and certain sub-
stances can be used in the treatment of inflammatory skin
disorders, such as psoriasis [3].
Many recent studies have documented the potentially
positive effect of coumarins in a variety of pathologic con-
ditions. These possible effects include antibacterial [7], anti-
inflammatory [8], anticancer [9], antiviral [10], antioxidant
[11], the above-mentioned anticoagulant activities and other
positive cardiovascular effects, which will be discussed in
this review. On the other hand, pro-carcinogenic activity
and hepatotoxicity were also observed [12, 13]. Positive
cardiovascular effects were found in several studies and
may be partly based on antioxidant activity. As the chemical
nature of coumarins is similar to flavonoids, these effects
were expected and documented in many studies. Their anti-
oxidant activity is based both on the direct scavenging of
reactive oxygen and nitrogen species and on transient metal
chelation and as well on the inhibition of free-radical-
forming enzymes such as xanthine ox idase [14-17]. Because
an analysis of the structure-antioxidant activity relationship
is the topic of another study in this issue, this rev iew is fo-
cused on the detailed analysis of the known cardiovascular
effects of coumarins, which are not based on antioxidant
activity, but on direct interaction with the cardiovascular
system. The most data are available on the vasorelaxant and
antiplatelet effect of coumarins. A short clinical overview of
2 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
Fig. (1). Basic coumarin types (a-d) and examp les of other rare coumarins (e-g): (a) simple coumarin, (b) isocoumarin, (c) furanocoumarin,
(d) pyranocoumarin, (e) an example of biscoumarin (dicoumarol), (f) an example of triscoumarins (Edgeworoside B) and (g) and an example
of coumarinolignans (daphnecin). Both furanocoumarins and pyran ocoumarins can be further b riefly divided into linear (c1, d1) and angular
(c2, d2) forms.
anticoagulant coumarins is presented at the end, as well as
the limited data on the use of coumarins in chronic venous
insufficiency.
VASORELAXANT PROPERTIES
Many coumarins have been shown to relax the contrac-
tions of vascular smooth muscle induced by various media-
tors, in particular by the sympathomimetics norepin ephrine
and phenylephrine or by high doses of potassium chloride
(KCl), as well as by endothelin-1 and an analogue of the
endop eroxide prostaglandin H2 named U-46619 [18]. De-
spite the vast differences in the chemical structure of cou-
marins, a mechanism of action based on influencing cal-
cium kinetics seems to be common for a majority of them.
Coumarins may exert influence on both endothelium-based
and endothelium-independent vasorelaxation. Because
some coumarins have influenced both mechanisms, they
are summarized altogether (a detailed analysis is given in
Table 1).
A large number of coumarins act predominantly via an
endothelium-independent mechanism. Those substances did
not influence the steady-state of vascular rings, but they were
able to relax contractions induced by the above-mentioned
inducers [18-20]. Coumarins act in a dose-dependent manner
and probably block calcium entry through both voltage-
dependent calcium channels (VDCC) and receptor-operated
calcium channels (ROCC) located in the membrane of vas-
cular smooth muscle cells, and/or by inhibiting calcium re-
lease from the sarcoplasmic reticulum [18-25]. Although
competitive antagonism at 5-HT receptors could also be par-
tially responsible, the main mechanism is to block the entry
of Ca2+ through the membrane channels and subsequent re-
lease from intracellular stores [18, 21, 26].
Imperatorin (Table 1 - C7), a furanocoumarin derivate, at
concentrations higher than 10 µM was able to inhibit Ca
2+-
influx through VDCC and ROCC and the subsequent release
of Ca2+ from intracellular stores by interfering with the inosi-
tol-1,4,5-trisphosphate pathway [18]. A similar conclusion
was also reached by Oliveira et al. (2001), who tested the
relaxant effect of scopoletin (Table 1 - C1). However, th e
above two studies differed in terms of the reported ability to
relax contraction evoked by caffeine: while imperatorin was
able to markedly suppress this contraction, scopoletin had no
effect [18, 21]. Muscarinic receptors apparently did not play
a role in the effects of imperatorin on blood vessels [27]. The
vasorelaxant activity of imperatorin can be improved by in-
creasing its solubility by incorporating the nitrogen atom into
the molecule. Such a compound, 8-(2-(azepan-1-
yl)ethoxy)psoralen (Table 1 - C6), is more effective than
imperatorin. The o ther changes such as incorporating a mor-
pholine ring, extending the length of the side chain or incor-
porating a hydrophobic benzene ring onto the nitrogen de-
crease its vasorelaxant activity. Neither the dimethyl group
nor the olefinic bond are essential for its activity [28]. On the
contrary, lengthening or changing the position of the side
chain decreases the vasodilatory activity when compared to
imperatorin [22, 28].
Some pyranocoumarins, e.g., pteryxin (Fig. 3 - C20), (+)-
praeruptorin A (Table 1 - C4) and (±)-praeruptorin A (Table
1 - C4 and C5), have a stronger relaxant effect against con-
striction evoked by KCl than by norepinephrine. These com-
pounds have a predominantly antagonistic effect on VDCC
[24]. Lee et al. (2008) reached a similar conclusion by test-
ing (+)-praeruptorin A relaxant abilities on rat aorta con-
tracted by phenylephrine. The addition of nifedipine, a
VDCC blocker, significantly attenuated the effect of (+)-
praeruptorin A [25]. Using various types of blood vessels
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 3
Table 1. Simplified overview of in vitro studies of coumarins and their va sorelaxant effect on vascular smooth muscle.
Ref.
Coumarin
Chemical Formula
KCl
Sympath-
omimetics
Serotonin
Others
[21]
scopoletin (7-hydroxy-6-
methoxycoumarin, C1)
1
1A
1
C
[26, 29]
scoparone (6,7-dimethoxycoumarin, C2)
4
1
D
[39]
6-guanidinocoumarin
1
[39]
6-(4,6-dimethylpyrimidin-2-
ylamino)coumarin
1
[31]
osthole (7-methoxy-8-
isopentenylcoumarin, C3)
4
[39]
7-methoxy-8-(3-(thiophen-2-
yl)acryloyl)coumarin
1
[39]
7-methoxy-8-(3-(4-
(trifluoromethyl)phenyl)acryloyl)coumarin
1
[40]
1,4-dihydropyridine derivatives of cou-
marin - the most active: 1,4-dihydro-4-(2-
oxo-2H-chromen-8-yl)2,6-
dimethylpyridine-3,5-dicarboxylate
5
[41]
coumarin-resveratrol hybrids - the most
active 6-hydroxy-3-(3´,5´-
dihydroxyphenyl)coumarin
3
[42]
6-halogen derivatives of 3-phenylcoumarin
the most active: 6-chloro-3-(2´-
hydroxy)phenylcoumarin
3
[25, 30]
(+)-praeruptorin A /(+)-cis-4´-acetyl-3´-
angeloylkhellactone, C4/
3-4B
3B
4 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
(Table 1) contd….
Ref.
Coumarin
Chemical Formula
KCl
Sympath-
omimetics
Serotonin
Others
[30]
(-)-praeruptorin A /(-)-cis-4´-acetyl-3´-
angeloylkhellactone, C5/
3A
3A
[28]
8-derivatives of psoralen - the most active:
8-(2-(azepan-1-yl)ethoxy)psoralen (C6)
5
[18-20,
22, 27,
28]
imperatorin/8-(3-methylbut-2-
enoxy)psoralen, C7/
3
3-4B
E
[22]
isoimperatorin/5-(3-methylbut-2-
enoxy)psoralen/
3
[24]
8-methoxypsoralen (C8)
0
0 - non significant vs. control, 1 - slight effect or the effect was observed at very high concentrations (more than 100 µM), 2 - intermediate effect - IC50 value 50-100 µM, 3 - good
effect - IC50 value 10-50 µM, 4 - excellent eff ect - IC50 value 1-10 µM, 5 - IC50 value below 1 µM.
A - IC50 was no t significantly affe cted after en dothelium removal
B - IC50 increased after end othelium r emoval
C - no effect on contr action induced by caffeine
D - a good effect again st contra ction caused by angioten sin II and slight effec t against con traction cau sed by histam ine
E - effective against caf feine induce d contractions
Sympathomim etics here mean nore pinephrine or pheny lephrine.
may explain some discrepancies among the studies because
of a different involvement of both Ca2+-channels, i.e., VDCC
and ROCC [29]. For example, scoparone (Table 1 - C2) did
not affect KCl-induced contraction in the rabbit thoracic
aorta, but if the contractions were induced by norepineph-
rine, they were markedly reduced. In contrast, scoparone
dilated both KCl- and norepinephrine-contracted rings of the
rabbit ear artery. The authors suggested that these differences
could be explained by the higher channel conductance of
VDCC in the rabbit ear artery than in the aorta [29]. On the
other hand, 8-methoxy-psoralen (Table 1 - C8) had the oppo-
site effect. This compound was able to relax constriction
caused by phenylephrine without effect on KCl-induced con-
traction. The explanation for this phenomenon is unknown,
but selective VDCC can be excluded [24].
It was found that the vasodilation induced by the tested
coumarins was not mediated by interaction with other recep-
tors such as β-adrenoreceptors, muscarinic receptors or ATP-
dependent potassium channels or the inwardly rectifying
potassium channel [18, 22, 25].
Several coumarins have exhibited endothelium-
dependent relaxation of vascular smooth muscle by increas-
ing NO production, which activates guanylyl cyclase. An
increase in cGMP concentration leads to a decrease in cyto-
solic Ca2+ concentration [30]. NO is synthesized by the oxi-
dation of L-arginin in the presence of endothelial NO syn-
thase (eNOS), activated by phosphatidylinositole 3-kinase
and protein kinase B (Akt). A more detailed examination of
mechanisms of action has shown that osthole (Table 1 - C3)
increased the phosphorylation of Akt on Ser-473 and eNOS
on Ser-1177. In addition, the inhibition of phosphatidylinosi-
tol 3-kinase decreased the effect of osthole, confirming the
mechanism of action [31].
There are even differences between individual enanti-
omers. (+)-Praeruptorin A was more potent in the induction
of relaxation after the administration of phenylephrine or
KCl than (-)-praeruptorin A (Table 1 - C5). Both enanti-
omers exhibited a concentration-dependent relaxation, how-
ever endothelium removal decreased the relaxant effect of
(+)-praeruptorin A but not that of (-)-praeruptorin A. The
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 5
same result was observed after the administration of an in-
hibitor of NO synthase L-NAME (Nω-nitro-L-arginine meth-
ylester hydrochloride). Moreover, an inhibition of guanylyl
cyclase decreased the vasorelaxant effect of (+)-praeruptorin
A, but an inhibition of cyclooxygenase, blockade of mus-
carinic receptors or non-selective blockade of potassium
channels had no such effect. Thus, the effect of (+)-
praeruptorin A is apparently endothelium/NO-dependent, in
contrast to its (-)-enantiomer [23, 25].
On the other hand, some coumarins, such as scopoletin,
imperatorin or (-)-praeruptorin A (Table 1 - C1, 7 and 5,
respectively), did not exhibit any significant decrease in re-
laxation after endothelium removal or the addition of L-
NAME. Therefore it can be concluded that the endothelium
did not play an important role in the relaxation induced by
those coumarins [21].
In vivo Studies
In a dose-dependent manner, coumarins by relaxation of
aorta and peripheral arteries decreased systolic and diastolic
blood pressure and vascular peripheral resistance. They were
also able to increase coronary blood flow by dilatation of the
coronary arteries [20, 23, 32, 33]. Osthole in a dose of 50
mg/kg was administered each day as part of a diet to stroke-
prone spontaneously hypertensive rats for four weeks. After
three weeks their systolic blood pressure was reduced by
about 10% [34]. The same substance administered in lower
doses, 10 mg/kg and 20 mg/kg, by gavage to rats with in-
duced renovascular hypertension, did not significantly re-
duce systolic blood pressure after four weeks of treatment
versus the control group. But at 2 and 4 weeks of the post-
treatment period, the systolic blood pressure decreased. With
20 mg/kg/day, the decrease was about 15% in the second
week and 19% in the fourth week, 10 mg/kg/day caused a
smaller decrease [35]. Imperatorin administered intragastri-
cally in a dose of 25 mg/kg to spontaneously hypertensive
rats (SHR) significantly decreased blood pressure after one
week, while lower doses (12.5 and 6.25 mg/kg) induced a
notable change 35 and 39 days after administration. After 13
weeks of treatment with 25 mg/kg, systolic blood pressure
was reduced by about 30 mmHg (18%) in comparison to the
placebo group [20]. Praeruptorin C (Fig. 3 - C21) in a dose
of 20 mg/kg decreased systolic blood pressure in spontane-
ously hypertensive rats by about 19% after eight weeks of
administration. Although the au thors have linked the effect
with the observed up-regulation of phospholamban mRNA,
other mechanisms are probably responsible for it [23]. (±)-
Praeruptorin A had a similar effect on the heart to diltiazem,
but diltiazem is ten times as potent, and while diltiazem
caused bradycardia, (±)-praeruptorin A did not inhibit the
action of sinus node and atrioventricular conduction but on
the contrary led to an incr ease in hear t rate [33]. Coumarin
glycosides isolated from Daucus carota administered in the
dose range 1 to 10 mg/kg lowered blood pressure, but the
heart rate decreased by about 10-15% at the highest dose of
10 mg/kg [36].
Campos-Toimil et al. (2002) showed during in vitro ex-
periments on rat aorta rings that carbocromen (3-β-
diethylaminoethyl-4- methyl-7-ethoxycarbonylmethoxy-
coumarin, sometimes also spelled carbochromen or car-
bocromene, Table 4 - C18) and simple coumarins, i.e., 7,8-
dihydroxy-4-hydroxymethylcoumarin and its bis(acetonyl)
derivate (Fig. 3 - C22 and 23), did not significantly modify
the contraction induced by norepinephrine or KCl. However,
during in vivo studies, vasorelaxant effects of carbocromen
on large coronary arteries were reported. Thus it seems that
carbocromen is selective for coronary arteries without affect-
ing systemic arterial blood pressure [37, 38]. This high selec-
tivity has also been proposed for cloricromen (also spelled
cloricromene by some authors or known as AD6, 8-chloro-3-
β-diethylaminoethyl-4-methyl-7-ethoxycarbonyl-
methoxycoumarin, Table 2 - C12), which caused stronger and
longer coronary vasorelaxation than carbocromen. Both cou-
marins increased the coronary blood flow via the above-
mentioned mechanism and had no effect on myocardial con-
tractility, the duration of systole and metabolic rate [38].
EFFECTS ON PLATELET FUNCTION
There are many articles analysing the antiplatelet activity
of coumarins, a simplified summary is given in Tables 2 and
3. Their comparison is not easy, because the concentrations
of the aggregation inducers and the tested compounds were
not identical. In many cases acetylsalicylic acid was used as
a comparator, but the concentration was not always the same
and acetylsalicylic acid was not able to block the aggregation
started by ADP or thrombin. Moreover, some researchers
tested only one or several concentrations, some plotted con-
centration-effect curves but only reported IC50. The effective
concentration should not be taken as an insurmountable fac-
tor, because generally the platelet inducer may be somehow
artificial, e.g., a stable agonist of thromboxane receptors U-
46619 or the extracellular administration of arachidonic acid
(AA). Thus the concentration needed to evoke an effect on a
human being might be lower. This can be demonstrated by
the fact that acetylsalicylic acid is clinically used in quite
low doses but the IC50 of acetylsalicylic acid on AA (50 µM)
induced aggregation w as quite high in rat platelet suspension
- 60 µM [43], while in another study 56 µM of acetylsali-
cylic acid was sufficient to completely block platelet aggre-
gation started by 100 µM of AA in a rabbit platelet suspen-
sion [44]. In both cases, the platelet concentration was al-
most identical. Thus the lowest effective concentration can-
not be easily established but, on the other hand, it may be
considered that since some coumarins only have an effect at
concentrations higher than 100 µM, they would very likely
have no pharmacological effect in clinical settings.
Based on their structure, coumarins are able to block the
platelet aggregation induced by various mediators. Many
compounds even reached the activity of the comparator and
appear to be suitable for future testing. Only a few articles
analysed the mechanism of action, which is again highly
variable, likely due to vast differences in their chemical
structures. In general, the antiplatelet activity of coumarins
seems to be reversible in most cases [45-47] but inhibitors of
phospholipase A2 may act as irreversible inhibitors [48].
Similarly to structurally related flavonoids, the blockade of
thromboxane production from AA may be one of their pos-
sible effects [14, 46, 47]. This effect may be mediated by
both the inhibition of cyclooxygenase and/or thromboxane
synthase. Our group has recently shown that 5,7-dihydroxy-
4-methylcoumarins (Table 2 - C11) did not influence throm-
boxane synthase but blocked cyclooxygenase-1 even at
6 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
Table 2. Simplified overview of in vitro studies with simple coumarins on inhibition of platelet aggregation activated by various
inducers. Th e table summarizes the best effect on platelet aggregation; where multiple compounds were tested, the result
shows the most activ e one.
Ref.
Coumarin(s)
Chemical Formula of the Most Active Com-
pound(s)
AA
Collagen
ADP
Thrombin
PAF
Ca-
ionophore
A23187
U-46619
[43]
coumarin (C9)
1
0
1
[47]
4-hydroxycoumarin
0
0
0
[44]
simple derivatives of 4-
hydroxycoumarin - the most active
was 4-[(oxiran-2-yl)methoxyl]-2H-
1-benzopyran-2-one
1
1
0
1
[44]
derivatives of 4-hydroxycoumarin
with α-methylene-γ-butyrolactone
(R = CH3, C6H5, 4-F-C6H4, 4-Cl-
C6H4, 4-CH3-C6H4 or 4-CH3O-C6H4)
4
1-4b
1-4b
4
[47, 50,
53]
7-hydroxycoumarin
(umbelliferone, C10)
1
1
0
0
0-
1
[47]
4-methyl-7-hydroxycoumarin
(4-methylumbelliferone)
0
0
0
[47]
7-hydroxy-6-methoxycoumarin
(scopoletin, R = H, partly active)
and its β-D-glycoside scopolin (R
= β-D-glycoside, inactive)
0-1
0-1
1
[53]
7-hydroxy-8-methoxycoumarin
(hydrangetin)
1
1
0
[50, 51]
derivatives of 7-hydroxycoumarin
with α-methylene-γ-butyrolactone
4
1-4b
1-4b
4c
[54]
8-(2´-O-β-D-glucopyranosyl-3´-
methyl-3´-hydroxybutyl-)-
umbelliferon
1d
0
0-1d
0
[53]
3,7,8-trimethoxycoumarin
(schinicoumarin)
1-4b
0
0
[55]
5,7,8-trimethoxycoumarin
1
1
0
1
[53]
7,8-derivatives of coumarin
3e
2
0
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 7
(Table 2) contd….
Ref.
Coumarin(s)
Chemical Formula of the Most Active Com-
pound(s)
AA
Collagen
ADP
Thrombin
PAF
Ca-
ionophore
A23187
U-46619
[55]
6-derivatives of 5,7-
dimethoxycoumarin
toddanol, toddanone (the most
active and shown in the figure)
and toddalolactone
1-2f
0
0
0
[56]
5,6,8-derivatives of 7-
methoxycoumarin/R =
CH2COCH(CH3)2 or
CH2CHOHC(CH3)=CH2/
2
2
0g
2
[47]
various derivatives of 4-
methylcoumarin - the most active
were 5,7-dihydroxy-4-
methylcoumarins (C11)
4
1
1
[46]
6,7-derivatives of coumarins -
suberosin (a) and aurapten (b)
2
1
1
0
1
1
[57]
8-derivatives of 7-
hydroxycoumarin
minumicroline acetonide (a) and
epimurpaniculol senecioate (b)
1
2-3
0g /1
1
[41]
3-arylcoumarins/6-hydroxy-3-
(3´,5´-dihydroxyphenyl)coumarins
was the most active/
3
[58-61]
4-(1-piperazinyl)-derivatives
R = 2-morpholinoethoxy or pyri-
din-3-ylmethoxy (Fig. 2)
4
4
4
4
[45, 62]
cloricromen (8-chloro-3-β-
diethylaminoethyl-4-methyl-7-
ethoxy-carbon ylmethoxy coumarin,
C12)
2-4
4
4
4
4
3-4h
3-
4h
[63]
11-O-β-D-glucopyranosyl thamno-
smonin
0i
0
0 i
0: non significant vs control, 1: slight effect or the effect was observed at very high concentrations (more than 100 µM), 2: intermediate effect - a significant effect observed at con-
centrations from 50 to 100 µM, 3: good effe ct - a significant eff ect in conce ntrations below 50 µM, 4 : excellen t effect - a significant effect at less than 10 µM
Data on warfarin (a simple coumarin) are shown in Table 3.
a althoug h it has little effect with common inducers, its IC50 on adrenaline-indu ced p latele t agg regat ion in the presen ce of collagen was 58 µM (that of ASA was 50 µM)
b the compound or some of the tested compou nd(s) completely abolish ed the aggr egation but t he concent rations were > 2 50 µM, n o additional data given
c IC50 of the mo st potent compound in the range 10-20 µM
d statistical analysis mis sing and tested co ncentratio ns approached 1 mM
e one com pound at a co ncentratio n of 61 µM caused more than 50% inh ibition
f the compound was p artly active at concen trations > 25 0 µM, no ad ditional data given
g interestin gly, rath er an opposit e effect (p roaggrega tion) was ob served instea d
h only re sults with 50 µM are sh own
i only co ncentrations of about 2 0 µM were tested and a n on-signific ant tendency was observed.
8 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
Table 3. Simplified overview of in vitro studies with complex coumarins on inhibition of platelet aggregation activated by various
inducers. Th e table summarizes the best effect on platelet aggregation; where multiple compounds were tested, the result
is for th e most active.
Ref.
Coumarin
Type
Coumarin(s)
Chemical Formula of the Most Active Com-
pound(s)
AA
Collagen
ADP
Thrombin
PAF
Ca-ionophore
A23187
U-46619
[63]
furano
12-O-β-D-
glucopyranosyl gosfe-
rol
0
0 a
0
[64]
furano
decurosides (R = sugar,
R´ = H or OH) and
nodakenin (R = sugar,
R´ = H)
2
[55]
furano
isopimpinellin
1-3b
0
0
0
[54]
furano
3 different structures
1-4c
1c
0-1c
0
[65]
furano
heraclenol (shown in
the figure, also tested
were its glycoside and
a dimer with a pyrano-
coumarin)
0
0
1
[46]
pyrano
poncitrin (R = OCH3, R´
= 2-methylbut-3-en-2-
yl), xanthyletin (R = R´
= H) and xanthoxyletin
(R = OCH3, R´ = H)
3-4d
1
1
0
2
1
[49]
pyrano
3´,4´-
diisovalerylkhellactone
diester (C13)
2
3
1
4
[55]
pyrano
braylin
1-4e
1-3f
1
[66]
pyrimidino
4-derivatives of 2-
methanesulfonyl-5H-
[1]benzopyrano[4,3-
d]pyrimidin-5-one
(R = morpholino,
piperidino, pyrrolidino)
4g
4g
4
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 9
(Table 3) contd….
Ref.
Coumarin
Type
Coumarin(s)
Chemical Formula of the Most Active Com-
pound(s)
AA
Collagen
ADP
Thrombin
PAF
Ca-ionophore
A23187
U-46619
[67]
simple/bis
warfarin (a), ethylbis-
coumacetate (b) and
biscoumacetic acid (b,
metabolite of the latter)
1h
[46]
bis
dicoumarol
1
1
0
0
0
0
0: non-significant vs control, 1: sl ight eff ect or the effect was observed at very high conce ntrations (more than 100 µM), 2: intermediate effect - a significant effect observed at con-
centrations from 50 to 100 µM, 3: good effect - a significant eff ect at concentrations below 50 µM, 4: excellent effect - a significan t effect at less than 10 µM
Data on 4-(1-piperazinyl)-derivatives of benzocoumarins are given in Table 2.
a only co ncentrations of about 2 0 µM was teste d and a n on-significant tendency was observed
b effectiv e at 200 µ M - reduction i n aggrega tion of 89 to 20%, but no additional data given
c statistical analysis mis sing and the tested concen trations appr oached 1 mM
d IC50 of xanth oxyletin was 30 µM, th e lowest eff ective con centration not shown
e the compound or some of the tested compou nd(s) completely abolish ed the aggr egation, but t he concent rations were > 2 50 µM, n o additional data g iven
f the compound was p artly active at concen trations > 25 0 µM, no additional data given
g IC50 of the mo st potent compound in the range 10-20 µM
h with warf arin, IC50 is not clinically relev ant - about 7 mM
lower con centrations than acetylsalicylic acid. In addition,
these coumarins also had a significant effect on another step
of aggregation: they probably acted as antagonists at throm-
boxane receptors [47]. Interestingly other coumarins, both
simple and pyrano, appeared to also act at the level of AA
transformation into thromboxane, in addition to acting on the
phosphoinositol pathway mediated by ADP and the platelet-
activating factor (PAF) [46]. In contrast, 3´,4´-
diisovalerylkhellactone diester (Table 3 - C13) probably
acted as an antagonist at PAF receptors without having
blocked cyclooxygenase-1 or thromboxane synthase [49].
The basic core of coumarins clearly has the potential to in-
fluence PAF and thrombin based pathways, since its re-
placement with naftalene, xanthrone or even flavone in com-
pounds bearing the active α-methylene-γ-butyrolactone moi-
ety substantially decreased the effect on both of the above-
mentioned pathways [44, 50-52]. A very interesting and less
common mechan ism of action includes the inhibition of
phospholipase A2 activation or enzymatic activity; and the
inhibition of phosphodiesterase 3. Data on these compounds
are more numerous and are summarized in the text below.
The group of Roma et al. rationally synthetized a large
series of coumarin derivatives with 1-piperazinyl at position
4. Some of their compounds, in particular 8-methyl-4-(1-
piperazinyl)-7-(3-pyridinylmethoxy)-2H-1-benzopyran-2-
one (Fig. 2a, C15) were remarkably efficient inhibitors of
various aggregation inducers (ADP, collagen, calcium iono-
phore A23187 and thrombin). The IC50 of the above-
mentioned compound was around 1-2 µM or even lower. Its
close analogue 8-methyl-7-(2-morpholinoethoxy)-4-(1-
piperazinyl)-2H-1-benzopyran-2-one (Fig. 2b, C16) was
slightly less potent on ADP and calcium ionophore-induced
aggregation, but its IC50 on collagen-induced aggregation
was 284 nM. The mechanism of action of the former was
examined in detail and included the inhibition of phosphodi-
esterase 3 with an IC50 of 37 nM, so an order of magnitude
lower than that of th e known inhibitors cilostazol and milri-
none. Phosphodiesterase inhibition leads to the accumulation
of cAMP, and this was probably associated with antiplatelet
activity on all the above-mentioned aggregation inducers.
Possible participation of the cyclooxygenase pathway can be
excluded, since preincubation with acetylsalicylic acid did
not significantly change the IC50 [58-61].
Fig. (2). The most efficient 1-piperazinyl derivatives of coumarins.
a: 8-methyl-4-(1-piperazinyl)-7-(3-pyridinylmethoxy)-2H-1-
benzopyran-2-one (C15), b: 8-methyl-7-(2-morpholinoethoxy)-4-
(1-piperazinyl)-2H-1-benzopyran-2-one (C16).
Cloricromen (Table 2 - C12) is also able to block the ag-
gregation induced by various inducers including adrenaline.
In rabbits it only partially inhibited ADP-induced aggrega-
tion, while its effect on collagen-induced aggregation was
more pronounced. In human platelet-rich plasma, clori-
cromen was markedly effective at inhibiting both ADP- and
10 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
collagen-induced aggregation, with a substantial effect at 10
µM and even some effect at 1 µM. Similarly, another study
found cloricromen to be highly effective on PAF-induced
aggregation at the µM level. The effect on the aggregation
pathway started by exogenously administered AA was much
lower and only substan tial at high concentrations. Moreover,
combination with acetylsalicylic acid may lead to a synergic
action. This is in agreement with the finding that this cou-
marin acts upstream of the inhibition of cyclooxygenase,
because it inhibited the release of AA from platelets stimu-
lated with thrombin. Thus a possible interference with phos-
pholipase A2 was likely, in particular because other coumar-
ins, umbelliferone (Table 2 - C10) and ethyl coumarin-3-
carboxylate (Fig. 3 - C24), are potent inhibitors of different
phospholipases A2, with IC50 in nM concentrations, and both
have antiplatelet effects. In contrast, the direct inhibition of
this enzyme by cloricromen was not documented. However,
it was shown that cloricromen likely interferes with the G
protein-mediated activation of phospholipase A2. Based on
these experimental results, the blockade of phospholipase C
and an increase in cAMP can be excluded as a mechanism of
cloricromen action. In agreement with these data, clori-
cromen was able to markedly inhibit the phospholipase A2-
dependent release of PAF from leucocytes stimulated with
Ca-ionophore A23187 [45, 48, 62, 68-72]. Thus the drug by
interference with ADP-, PAF-, thrombin- and collagen-based
pathways might be active inhibitor of the aggregation proc-
ess, where both collagen and the other above-mentioned
soluble agonists play a role [73]. Since cloricromen appears
to be a very safe compound (500 mM was tolerated well by
freshly isolated resident alveolar macrophages for 24 hours)
with additional positive activities (anti-inflammatory activity
due to inhibition of the NF-κB pathway, antioxid ant proper-
ties) [74, 75], its possible use in humans was tested. How-
ever, the result was disappointing, the drug was not able to
influence platelet aggregation 2, 4 or 6 hours after the ad-
ministration of 300 mg of cloricromen in healthy volunteers.
The reasons for this failure are not clear, but rapid metabo-
lism and/or reversibility of the antiplatelet activity may be
responsible [62, 69, 76].
Other data on in vivo models or clinical settings are
sparse. In addition to cloricromen’s failure to influence
platelet aggregation in volunteers, it also failed to improve
the condition of patients with intermittent claudication
treated with acetylsalicylic acid. There were only insignifi-
cant tendencies to improve their condition [77]. Similarly,
the pyranocoumarin seselin (Fig. 3 - C25) failed, in contrast
to acetylsalicylic acid, to provide protection against pulmo-
nary thromboembolism in mice [78].
A few studies confirmed that clinically used anticoagu-
lants have generally low or no direct antiplatelet potential.
However, some interactions based on pharmacokinetics were
found between clopidogrel and phenprocoumon (Table 5 -
C28), and a pro-aggregatory effect on platelet aggregation
with nicoumalone (acenocoumarol, Table 5 - C29) was ob-
served [79, 80]
EFFECTS ON MODELS OF ISCHAEMIC HEART
DISEASE, DYSRHYTHMIAS AND CHRONIC HEART
FAILURE
Few studies have tested the effects of coumarins on ex-
perimental major cardiovascular diseases, namely arterial
hypertension (summarized in the section VASORELAX-
ANT PROPERTIES), ischaemic heart disease, myocardial
infarction/damage, cardiac dysrhythmias and haemorrhagic
shock.
The tested coumarins exhibited mostly positive effects in
experimental models of serious diseases of the cardiovascu-
lar system, but also some negative. A deeper understanding
of the mechanisms of action of coumarins in these diseases
Fig. (3). Chemical structures of other mentioned coumarins. a: pteryxin (C20), b: praeruptorin C (C21), c: 7,8-dihydroxy-4-
hydroxymethylcoumarin (C22), d: bis(acetonyl) derivate of 7,8-dihydroxy-4-hydroxymethylcoumarin (C23), e: ethyl coum arin-3-
carboxylate (C24), f: seselin (C25), g: 3,3´-methylenbis(4-hydroxycoumarin) (C26).
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 11
requires further detailed studies. In summary, the principal
positive effects of coumarins mentioned in Table 4 are as
follows:
• an improvement in lipid metabolism and an increase in
glycolytic metabolism (osthole, Tables 1 or 4 - C3);
• a vasodilating effect caused by Ca2+-channel blockade or
by the elevation of cGMP (osthole);
• an antidysrhythmic activity accompanied by a prolonga-
tion of action potential duration and prolongation of the
refractory period (cloricromen, Tables 2 or 4 - C12);
• a membrane stabilizing effect and β-adrenoceptor block-
ing activity (bucumolol, Table 4 - C17);
• dilatation of coronary blood vessels (7-hydroxycoumarin
/Table 2 or Table 4 - C10/ and carbocromen /Table 4 -
C18/), better oxygen utilization by mitochondria (car-
bocromen);
• a positive effect on cardiac metabolism caused by an in-
crease in cAMP (carbocromen);
• reduction in the infarction size by inhibiting leucocytes
infiltration (cloricromen);
• anti-inflammatory and antioxidant effects, a decrease in
lipid peroxid ation (osthole);
• a decrease in myocardial damage induced by isoprotere-
nol by decreased lipid peroxidation (marmesinin, Table 4
- C19);
• a positive effect during haemorrhagic shock by reversing
myocardial failure (cloricromen).
A direct vasodilatory effect may not be purely beneficial,
because it could include vasodilation of shunt colaterals in
the heart, which may be deleterious due to the diversion of
blood from ischaemic parts (carbocromen).
Calcium channel blocking properties may be the basis for
the cardiodepressant activity of some coumarins. Scopoletin
(Table 1 - C1) had a negative chronotropic effect as well as a
negative inotropic effect on the atria from pigs. This effect
was not mediated by muscarinic receptors [81]. Similarly,
the introduction of a coumarin core at position 4 in dihydro-
pyridines led to a compound with vasorelaxant properties
and/or negative chronotropic and/or inotropic effects (on
atria). Moreover, several phenylcoumarin derivates exhibited
an inhibiting effect on contractility, while coumarin derivates
exhibited quite good negative chronotropic effects [40].
CLINICAL SUMMARY OF ORAL ANTICOAGU-
LANT THERAPY WITH COUMARINS
Coumarin derivatives are widely used oral anticoagulants
[93]. Their history began in the 1920s, when an unusual dis-
ease characterised by fatal bleeding, either spontaneously or
from minor injuries, was observed in cattle in the Northern
USA and Canada. Mouldy silage made from sweet clover
(Melilotus alba and Melilotus officinalis) was implicated,
and it was shown that it contained a haemorrhagic factor that
reduced the activity of prothrombin. It was not until the
1940s that it was discovered in Wisconsin that the anticoagu-
lant component of sweet clover was 3,3´-methylenbis(4-
hydroxycoumarin), Fig. 3 - C26. Further work led in 1948 to
the synthesis of warf arin (Table 5 - C27), which was initially
approved as a rodenticide in USA in 1952. It has been used
in humans since 1954. The name warfarin is derived from
WARF (Wisconsin Alumni Research Foundation) and the
suffix-ARIN, which identifies it as a coumarin [94]. Nowa-
days warfarin is the most widely used anticoagulant in the
world with annual prescriptions amounting to 0.5-1.5 % of
the population [95]. Warfarin is the first-choice coumarin
anticoagulant in the USA, Canada, the United K ingdom and
many other countries around the world. Apart from warfarin,
other coumarin derivatives are used as anticoagulants in
some countries. The most common are acenocoumarol and
phenprocoumon (Table 5 - C29 and C28), which are used in
some European countries (e.g., Germany, The Netherlands).
For example, more than 200,000 prescriptions for phenpro-
coumon and more than 1 million for acenocoumarol were
registered in 2008 in The Netherlands [93, 96, 97].
The anticoagulant effect of these substances is due to the
inhibition of vitamin K epoxide reductase (Fig. 4), which
leads to the depletion of several coagulation factors includ-
ing factors II, VII, IX and X, whose formation is dependent
on vitamin K (Fig. 4) [97, 98]. Warfarin has a single chiral
centre that gives rise to two different enantiomeric forms, of
which the S-form is approximately 2- to 5-fold more potent
than its R-counterpart. In clinical situations, a racemic 50:50
mixture of both enantiomers is administrated orally [97]. The
individual anticoagulants from the coumarins class differ in
their pharmacokinetic properties, of which the most impor-
tant is the elimination half-life. Acenocoumarol has the
shortest half-life (about 10 hours) followed by warfarin (36-
42 h) and then phenprocoumon (up to 140 h) [93]. A com-
parison of the selected pharmacokinetic parameters of vita-
min K antagonists is shown in Table 5.
The clinical effectiveness of coumarin anticoagulants
(most studies have been performed with warfarin) has been
established by well-designed clinical trials [98] and con-
firmed by meta-analysis of these trials. Coumarin anticoagu-
lants are effective in the treatment and prevention of arterial
and venous thrombosis [93]. Nowadays, the main clinical
use of coumarin anticoagulants is the prevention of stroke or
systemic embolism in patients with atrial fibrillation, which
is one of the most common cardiac disorders with a preva-
lence of around 1% of the population in the US, Canada and
the majority of European countries [99, 100]. Other current
uses are:
• the primary and secondary prevention of venous throm-
boembolism [98];
• the prevention of systemic embolism or stroke in patients
with prosthetic heart valves [101-104];
• the prevention of acute myocardial infarction in patients
with peripheral arterial disease [105];
• the treatment of antiphospholipid syndrome [106];
• the prevention of systemic embolism in high risk patients
with mitral stenosis and prevention of systemic embolism
in patients with presumed systemic embolism, either
cryptogenic or in association with a patent foramen ovale
(its effectiveness has not been proved by randomized
clinical trials) [98].
12 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
Table 4. Effects of selected coumarins on experimental major cardiovascular diseases.
Ref.
Coumarin
Chemical Formula
Pathological State
Experimental
Animal
Methods
Results
Cardiac hypertrophy caused by hypertension
[35]
osthole (C3)
Cardiac hypertro-
phy caused by
renovascular hy-
pertension.
rat ♂
Gavage, 10 or 20
mg/kg/d for 4
weeks.
The higher dose of
osthole reduced
heart/body weight
index (week 4), the
lower dose had no
significant effect.
Experimental dysrhythmias
[82]
cloricromen
(C12)
Experimental
dysrhythmias.
In vivo rat ♂
and cat, in
vitro guinea
pig isolated
cardiomyo-
cytes.
Aconitine in rats
(i.v. 0.25 µg/min
until VPB occur)
and adrenaline in
cats - 3 µg/kg i.v.
bolus, an increased
potential to induce
ventricular dys-
rhythmias. In vitro
functional refractory
periods in atrial and
ventricular muscle.
Cloricromen at i.v.
doses of 2.5-10
mg/kg antagonized
the dysrh yth-
mogenic potential
of aconitine and
adrenaline. In vitro
cloricromen (20-50
µM) prolonged
action potential
duration and func-
tional refractory
period.
[83]
6,7-dimethoxy-
coumarin
Experimental
dysrhythmia.
Rat (sex not
specified)
Aconitine i.v. 20
µg/kg; 6,7-
dimethoxy-
coumarin in doses
of 33-500 mg/kg ig,
procainamide 100-
800 mg/kg ig.
6,7-dimethoxy-
coumarin was
more potent at
reducing occur-
rence of VPB than
procainamide.
Experimental dysrhythmias
[84]
dl-bucumolol
(C17)
Experimental
dysrhythmias.
dog ♂♀
(mongrel)
Atrial dysrhythmia
produced by local
application of aco-
nitine onto atrial
surface in dogs.
Ventricular dys-
rhythmia produc ed by
ouabain (40 µg/kg
i.v.). Racemic bucu-
molol or its isomers
were given i.v. (0.5
mg/kg/min) until
antidysrhytmic effect
occurred.
In both trials,
effective doses of
bucumolol or its
stereoisomers
were in the range
of 2.8 to 6.2
mg/kg
Myocardial ischaemia/reperfusion (I/R)
[32]
7-
hydroxycoumarin
(umbelliferone,
C10)
Myocardial I/R
(isolated peru sed
rat heart).
rat ♂
30 min zero-flow
ischaemia followed
by 45 min of
reperfusion
(30I/45R).
10 min R: an
increase in coro-
nary blood flow (7-
hydroxycoumarin
10-4 M)
An increase in left
ventricular devel-
oped pressure after
reperfusion at a
concentration of
10-5 M.
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 13
(Table 4) contd….
Ref.
Coumarin
Chemical Formula
Pathological State
Experimental
Animal
Methods
Results
[85]
carbocromen
(C18)
A brief intermittent
myocardial
ischaemia.
dog ♂♀
(mongrel)
ST segment of the
epicardial ECG as a
parameter of inter-
mittent ischaemia.
Carbocromen
improved ischae-
mia.
[86]
Myocardial I/R in
vivo by occlusion
of the circumflex
coronary artery.
rabbit
(sex not speci-
fied)
A single dose of
cloricromen (0.25
mg/kg i.v.) for 4
days, 5th day occlu-
sion (50 min) with
infusion of clori-
cromen (6.4
µg/kg/min) fol-
lowed by 20 min of
reperfusion.
Cloricromen
caused a smaller
ST segment
elevation, de-
creased the num-
ber of ventricular
fibrillations, a
reduced necrotic
area compared to
the controls.
[87]
cloricromen
Myocardial I/R by
occlusion of left
coronary artery.
rabbit ♂
Infusion of clori-
cromen (30 or 300
µg/kg/min) 15 min
before I60/R120,
continued during
the experiment.
Cloricromen at
both rates of
infusion reduced
infarction size
and MPO activ-
ity.
Higher dose of
cloricromen also
reduced ST-
segment eleva-
tion during I.
Myocardial ischaemia/reperfusion (I/R)
[88]
osthole
Myocardial I/R
injury, LAD occlu-
sion.
rat ♂
I30/ R120 induced
by LAD occlusion.
Osthole was admin-
istered at doses of 1,
10, 50 mg/kg i.p.
upon initiation of I.
Osthole reduced
myocardial dam-
age and improved
haemodynamic
parameters after
I/R injury, in-
creased activities
antioxidant en-
zymes, decreased
products of lipid
peroxidation,
decreased proin-
flammatory cyto-
kines in most
cases in a dose-
dependent man-
ner.
[89]
carbocromen
Myocardial I/R
injury, in vivo,
open-chest, LAD
occlusion.
dog ♂♀
(mongrel)
I240/R90, Car-
bocromen for 8
weeks 2 x 20
mg/kg/d p.o., 15
min before occlu-
sion i.v. bolus of 4
mg/kg, 40
µg/kg/min during
occlusion and reper-
fusion.
Carbocromen
decreased infarc-
tion size, im-
proved coronary
collateral blood
flow.
14 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
(Table 4) contd….
Ref.
Coumarin
Chemical Formula
Pathological State
Experimental
Animal
Methods
Results
[90]
Myocardial I/R
injury, in vivo,
open-chest, LAD
occlusion
dog
(sex not speci-
fied)
i.v. dose of 3 mg/kg.
Carbocromen
increased blood
flow in normal
myocardium, but
decreased infarct
blood flow and
peripheral coro-
nary flow (2-3 h
after ligation).
Experimental myocardial injury, heamorrhagic shock
[91]
marmesinin
(linear furano-
coumarin,
(C19)
Myocardial dam-
age by isoprotere-
nol.
rat ♂
Isoproterenol (ISO)
150 mg/kg i.p. twice
at 24 h interval.
Two days prior and
during ISO admini-
stration marmesinin
administered in
doses 25-400 mg/kg
p.o.
Marmesinin at a
dose of 200
mg/kg p.o. ame-
liorated mo st
measured pa-
rameters of myo-
cardial damage
caused by ISO.
[92]
cloricromen
Haemorrhagic
shock.
rat ♂
Blood withdrawal
over 20 min until
MAP fell to 30 mm
Hg. Cloricromen
was administered in
doses of 0.5, 1.0 and
2 mg/kg i.v. after
the end of bleeding.
Haemorrhagic
shocked rats had
enhanced MDF,
TXB2 and 6-keto
PGF1α.
Higher doses of
cloricromen
increased sur-
vival rate, de-
creased MDF and
TXB2 and re-
versed ST seg-
ment elevation.
In contrast, clori-
cromen did not
affect the produc-
tion of PGI2.
4-HNE - 4-hydroxynonenal, 6-keto PGF1α - 6-ketoprostaglandin F1α, CAT - catalase, CK - creatine kinase, CK-MB - creatine kinase-MB, GPx - glutathione peroxidase, I/R - ischae-
mic/reperfusion, numerals indicate duration in min, IL-6, IL-10 - interleukines-6/-10, LAD - left anterior coronary descending artery, LDH - lactate dehydrogenase, MAP - mean
arterial pressure, MDA - malonyldialdehyde, MDF - myocardial depressant factor, MPO - myeloperoxidase, PGI2 - prostaglandin I2, SOD - superoxide dismutase, TNF-α - tumour
necrosis factor-α, TXB2 - thrombox ane B2, VPB - ven tricular p remature b eats.
Table 5. Selected pharmacokinetics parameters of vitamin K antagonists [93, 96, 97].
Warfarin (C27)
Phenprocoumon (C28)
Acenocoumarol (C29)
Chemical formula
Maintenance dosage (mg/day)
1.5-12
0.75-9
1-9
Volume of distribution (l/kg)
0.08-0.12
0.11-0.14
0.22-0.52
Protein binding
>99%
>99%
>98%
Half-life (h)
36-42
110-130
8-14
Elimination kinetics
first-order
first-order
biphasic
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 15
Fig. (4). The mechanism of action of warfarin. Vitamin K partici-
pates in the γ-carboxylation of several proteins (P) involved in the
coagulation cascade. Thi s carboxylation is responsible for the acti-
vation of those factors. The epoxide of vitamin K then has to be
regenerated by vitamin K (epoxide) reductase, which might be
blocked by warfarin, thus blocking the secondary activation of sev-
eral coagulation factors (II, V II, IX and X) and some n aturally oc-
curring anticoagulation factors, e.g., protein C and protein S.
On the one hand, coumarin derivatives are effective and
clinically used anticoagulants, on the other hand therapy
with these agents also brings with it significant complica-
tions and problems. In general, the major th erapeutic prob-
lem is the low therapeutic window, which is commonly
monitored by International Normalized Ratio (INR). INR is
more advantageous than direct drug level monitoring. In
particular due to the complicated pharmacokinetic and phar-
macodynamic profile of warfarin, maintaining INR in the
range 2-3 is not an easy task, as can be seen from a recent
analysis [106-109]. In high INR, bleeding represent the most
serious risk of the therapy. According to a meta-analysis o f
33 studies for patients who received anticoagulant therapy
for more than 3 months, the case-fatality rate of major bleed-
ing was 9.1% (CI, 2.5 % to 21.7 %), and the rate of intracra-
nial bleeding was 0.65 per 100 patient-years (CI, 0.63 to 0.68
per 100 patient-years) [110]. In contrast, a low INR is asso-
ciated with a higher risk of thromboembolism.
Despite the above-mentioned problems with anticoagu-
lant therapy in clinical practice, coumarin anticoagulants are
nowadays widely used, especially in the treatment of atrial
fibrillation or for the long-term treatment and prevention of
deep venous thrombosis or pulmonary embolism. In particu-
lar due to in teraction problems and the need to monitor INR,
novel oral anticoagulants may replace them in therapy. Such
anticoagulants include direct inhibitors of thrombin and fac-
tor Xa, but their structure is not based on the coumarin core
and thus they are not the subject of this review [111, 112].
Notwithstanding the clear advantages of those novel drugs,
warfarin remains the most frequently used oral anticoagulant
worldwide, especially due to its low price and large clinical
evidence and experience. The research of novel coumarin
anticoagulants has not stopped [113], but due to the advan-
tages of novel anticoagulants, their therapeutic use is ques-
tionable.
CHRONIC VENOUS INSUFFICIENCY
Non-substituted coumarin (Table 2 - C9) possesses
venoactive properties [114] and has been used for the ther-
apy of chronic venous insufficiency for decades [115]. Its
use has been more due to tradition than based on clinical
trials. The mode of action of coumarin on venous haemody-
namics is complex [116]. A beneficial effect has also been
observed when combining coumarin with the flavone trox-
erutin [116]. Moreover, troxerutin was able to protect the
liver from a possible lipid peroxidation caused by coumarin
[115].
PHARMACOKINETICS AND TOXICITY
Although the data presented here showed that coumarins,
apart from the known effects of warfarin and related antico-
agulants, might be very interesting compounds in the treat-
ment of cardiovascular diseases, there is still a long way to
go before possible clinical use. Firstly, coumarins which
were very active under in vitro conditions might not be so
promising in vivo or in humans. One such example is clori-
cromen, which failed in clinical settings. The reason is not
known, but pharmacokinetics may play a significant role
here. Pharmacokinetics is very important for two major rea-
sons in coumarins, firstly, the low bioavailability of the effi-
cient compound may hamper their effect and secondly, the
metabolites may be toxic. Last but not least, a possible inter-
action due to the inhibition of cytochrome P450 3A4 is well
known for some furanocoumarins from grapefruit juice, but
this is probably not a class effect for coumarins. In addition,
there is no clear evid ence whether any specific compound is
responsible for this effect or if this interaction arises from a
cumulative effect of compounds present in this fruit. Among
the furanocoumar ins thought to be responsible for the inhibi-
tion of CYP3A4, paradisins A and B (Fig. 5 - C30 and C31),
as well as 6´,7´-dihydroxybergamottin (Fig. 5 - 32) and its
dimer, are often cited in the literature [117, 118]. Furano-
coumarins seem to be particularly important for CYP inhibi-
tion, since the CYP2A6 enzyme is inhibited by two other
furanocoumarins. The better known one is methoxsalen (Fig.
5 - C33) [119] but recently, the furanocoumarin chalepensin
(Fig. 5 - C34) has been found to be a mechanism-based in-
hibitor of the same enzyme [120].
A particular problem with coumarins is that the pharma-
cokinetics have not been determined for the majority of
them, or the results are ambiguous. The most available data
are on the non-substituted basic coumarin. The coumarin
molecule itself can be hydroxylated at all the positions in
which such a reaction is possible, namely at positions 3, 4, 5,
6, 7 and 8. All such reactions were found in different species
16 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
Fig. (5). Chemical structures of suggested inhibitors of CYP3A4. a: paradisin A (C30), b: paradisin B (C31), c: 6´,7´-dihydroxybergamottin
(C32), d: methoxsalen (C33), e: chalepensin (C34).
and to a different extent [121]. However, in all the species
and samples of various tissues, two pathways were described
as the major ones, namely, 7-hydroxylation and formation of
the 3,4-epoxide. 7-Hydroxylation is the major pathway in
humans (about 75%), catalyzed by CYP2A6. This reaction is
commonly understood to be a detoxication. Formation of the
3,4-epoxide is achieved with help of other cytochromes
P450, of the CYP1A1, CYP1A2 and CYP2E1 enzymes with
the last one being the most important [121]. In rats, the situa-
tion is reversed with epoxidation being the major and 7-
hydroxylation the minor pathway of coumarin metabolism
[121, 122]. However, the coumarin 3,4-epoxide is unstable.
It may be either conjugated with glutathione (this detoxica-
tion reaction is catalysed by glutathione S-transferase, forms
α- or µ-, but not π- [123]) or, converted further to o-
hydroxyphenyl acetaldehyde. During this reaction, carbon
dioxide is lost and the o-hydroxyphenyl acetaldehyde, which
is considered to be the hepatotoxic intermediate, is formed
[4, 13, 121-125]. This compound may be detoxified by re-
duction to o-hydroxyphenyl ethanol or oxidation to o-
hydroxyphenylacetic acid [4, 123-125]. Interestingly, it has
been concluded that even in humans with a complete lack of
7-hydroxylation, the chance of forming the hepatotoxic o-
hydroxyphenyl acetaldehyde is lower than in rats when ex-
posed to a similar dose relative to body weight [125].
CONCLUSION
In addition to their known antioxidant effects, many
coumarins possess direct antiplatelet and vasorelaxant prop-
erties which are not associated with their interaction on the
level of reactive oxygen and nitrogen species. Antiplatelet
effects are based on various mechanisms depending on the
structure of a coumarin. In contrast, their vasorelaxant prop-
erties are based mainly on inhibition of Ca-entry inside vas-
cular smooth muscles cells. However, due to the lack of
pharmacokinetic studies, the path to their possible use in
clinical practice is very long with unpredictable outcomes.
LIST OF ABBR EVIATIONS
AA = arachidonic acid
PAF = platelet-activating factor
ROCC = receptor-operated calcium channels
VDCC = voltage-dependent calcium channels
CONFLICT OF INTEREST
The authors confirm that this article content has no con-
flict of interest.
ACKNOWLEDGEMENTS
This study was supported by grant of the Czech Science
Foundation project No. P303/12/G163. I.N. and M.Ř. would
like to thank Charles University (SVV 260 064).
REFERENCES
[1] Wu, L.; Wang, X.; Xu, W.; Farzaneh, F.; Xu, R. The structure and
pharmacological functions of coumarins and their derivatives.
Curr. Med. Chem., 2009, 16(32), 4236-4260.
[2] Borges, F.; Roleira, F.; Milhazes, N.; Santana, L.; Uriarte, E. Sim-
ple coumarins and analogues in medicinal chemistry: occurrence,
synthesis and biological activity. Curr. Med. Chem., 2005, 12(8),
887-916.
[3] Hoult, J.R.; Paya, M. Pharmacological and biochemical actions of
simple coumarins: natural products with therapeutic potential. Gen.
Pharmacol., 1996, 27(4), 713-722.
[4] Lake, B.G. Coumarin metabolism, toxicity and carcinogenicity:
relevance for human risk assessment. Food Chem. Toxicol., 1999,
37(4), 423-453.
[5] Rasool, M.A.; Khan, R.; Malik, A.; Bibi, N.; Kazmi, S.U. Struc-
tural determination of daphnecin, a new coumarinolignan from
Daphne mucronata. J. Asian Nat. Prod. Res., 2010, 12(4), 324-327.
[6] Hrdina, R.; Grossmann, V.; Nemeitová, M. [Sensitivity of biochemi-
cal indicators and the BSP-test in to xic liver da mage by aflatoxin B1].
Cas. Lek. Cesk., 1983, 122(30-31), 950-952 (article in Czech).
[7] Wang, S.F.; Yin, Y .; Qiao, F.; Wu, X.; Sha, S.; Zhang, L.; Zhu,
H.L. Synthesis, molecular docking and biological evaluation of
metronidazole derivatives containing piperazine skeleton as poten-
tial antibacterial agents. Bioorg. Med. Chem. Lett., 2014, 22(8),
2409-2415.
[8] Piller, N.B. A comparison of the effectiveness of some anti-
inflammatory drugs on thermal oedema. Br. J. Exp. Pathol., 1975,
56(6), 554-560.
[9] Musa, M.A.; Cooperwood, J.S.; Khan, M.O. A review of coumarin
derivatives in pharmacotherapy of breast cancer. Curr. Med.
Chem., 2008, 15(26), 2664-2679.
[10] Spino, C.; Dodier, M.; Sotheeswaran, S. Anti-HIV coumarins from
Calophyllum seed oil. Bioorg. Med. Chem. Lett., 1998, 8(24),
3475-3478.
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 17
[11] Basile, A.; Sorbo, S.; Spadaro, V.; Bruno, M.; Maggio, A.; Far-
aone, N.; Rosselli, S. Antimicrobial and Antioxidant Activities of
Coumarins from the Roots of Ferulago campestris (Apiaceae).
Molecu les, 2009, 14(3), 939-952.
[12] Venugopala, K.N.; Rashmi, V.; Odhav, B. Review on natural cou-
marin lead compounds for their pharmacological activity. BioMed
research international, 2013, 2013, 963248.
[13] Abraham, K.; Wohrlin, F.; Lindtner, O.; Heinemeyer, G.; Lampen,
A. Toxicology and risk assessment of coumarin: focus on human
data. Mol. Nutr. Food Res., 2010, 54(2), 228-239.
[14] Mladenka, P.; Zatlo ukalova, L.; Filipsky , T.; Hrdina, R. Cardiov as-
cular effects of flavonoids are not caused only by direct antioxidant
activity. Free Rad. Biol. Med., 2010, 49(6), 963-975.
[15] Mladěnka, P.; Macáková, K.; Zatloukalová, L.; Řeháková, Z.;
Singh, B.K.; Prasad, A.K.; Parmar, V.S.; Jahodář, L.; Hrdina, R.;
Saso, L. In vitro interactions of coumarins with iron. Biochimie,
2010, 92(9), 1108-1114.
[16] Kostova, I.; Bhatia, S.; Grigo rov, P.; Balkansky, S.; Parmar, V.S.;
Prasad, A.K.; Saso, L. Coumarins as antioxid ants. Curr. Med.
Chem., 2011, 18(25), 3929-3951.
[17] Lin, H.; Tsai, S.; Chen, C.; Chang, Y.; Lee, C.; Lai, Z.; Lin, C.
Structure-activity relationship of coumarin derivatives on xanthine
oxidase-inhibiting and free radical-scavenging activities. Biochem.
Pharmacol., 2008, 75(6), 1416-1425.
[18] He, J.Y.; Zhang, W.; He, L.C.; Cao, Y.X. Imperatorin induces
vasodilatation possibly via inhibiting voltage dependent calcium
channel and receptor-mediated Ca2+ influx and release. Eur. J.
Pharmacol., 2007, 573(1-3), 170-175.
[19] Zhang, Y.; Wang, Q.L.; Zhan, Y.Z.; Duan, H.J.; Cao, Y.J.; He,
L.C. Role of store-operated calcium entry in imperatorin-induced
vasodilatation of rat small mesenteric artery. Eur. J. Pharmacol.,
2010, 647(1-3), 126-131.
[20] Zhang, Y.; Cao, Y.; Wang, Q.; Zheng, L.; Zhang, J.; He, L. A
potential calcium antagonist and its antihypertensive effects. Fi-
toterapia, 2011, 82(7), 988 -996.
[21] Oliveira, E.J.; Romero, M.A.; Silva, M.S.; Silva, B.A.; Medeiros,
I.A. Intracellular calcium mobilization as a target for the spasmo-
lytic action of scopoletin. Planta Med., 2001, 67(7), 605-608.
[22] Nie, H.; Meng, L.Z.; Zhou, J.Y.; Fan, X.F.; Luo, Y.; Zhang, G.W.
Imperatorin is responsible for the vasodilatation activity of Angel-
ica Dahurica v ar. Formosana regulated by nitric oxide in an endo-
thelium-dependent manner. Chin. J. Integr. Med., 2009, 15(6), 442-
447.
[23] Wenjie, W.; Houqing, L.; Liming, S.; Ping, Z.; Gengyun, S. Effects
of praeruptorin C on blood pressure and expression of phospho-
lamban in spontaneously hypertensive rats. Phytomedicine, 2014,
21(3), 195-198.
[24] Zhao, N.C.; Jin, W.B.; Zhang, X.H.; Guan, F.L.; Sun, Y.B.; Ada-
chi, H.; Okuyama, T. Relaxant effects of pyranocoumarin com-
pounds isolated from a Chinese medical plant, Bai-Hua Qian-Hu,
on isolated rabbit tracheas and pulmonary arteries. Biol. Pharm.
Bull., 1999, 22(9), 984-987.
[25] Lee, J.W.; Roh, T.C.; Rho, M.C.; Kim, Y.K.; Lee, H.S. Mecha-
nisms of relaxant action of a pyranocoumarin from Peucedanum
japonicum in isolated rat thoracic aorta. Planta Med., 2002, 68(10),
891-895.
[26] Yamahara, J.; Kobayashi, G.; Matsuda, H.; Katayama, T.; Fuji-
mura, H. Vascular dilatory action of Artemisia capillaris bud ex-
tracts and their active constituent. J. Ethnopharmacol., 1989, 26(2),
129-136.
[27] Bertin, R.; Chen, Z.; Martinez-Vazquez, M.; Garcia-Argaez, A.;
Froldi, G. Vasodilation and radical-scavenging activity of impera-
torin and selected coumarinic and flavonoid compounds from ge-
nus Casimiroa. Phytomedicine, 2014, 21(5 ), 586 -594.
[28] Li, N.; He, J.; Zhan, Y.; Zhou, N.; Zhang, J. Design, synthesis and
preliminary evaluation of novel imperatorin derivatives as vasore-
laxant agents. Med. Chem., 2011, 7(1), 18-23.
[29] Yamahara, J.; Kobayashi, G.; Matsuda, H.; Iwamoto, M.; Fujimura,
H. Vascular dilatory action of the Chinese crude drug. II. Effects of
scoparone on calcium mobilization. Chem. Pharm. Bull. (Tokyo),
1989, 37(2), 485-489.
[30] Xu, Z.; Wang, X.; Dai, Y.; Kong, L.; Wang, F.; Xu, H.; Lu, D.;
Song, J.; Hou, Z. (+/-)-Praeruptorin A enantiomers exert distin ct re-
laxant effects on isolated rat aorta rings dependent on endothelium
and nitric oxide synthesis. Chem. Biol. Interact., 2010, 186(2), 239-
246.
[31] Yao, L.; Lu, P.; Li, Y.; Yang, L.; Feng, H.; Huang, Y.; Zhang, D.;
Chen, J.; Zhu, D. Osthole relaxes pulmonary arteries through endo-
thelial phosphatidylinositol 3-kinase/Akt-eNOS-NO signaling
pathway in rats. Eur. J. Pharmacol., 2013, 699(1-3), 23-32.
[32] Baccard, N.; Mechiche, H.; Nazeyrollas, P.; Manot, L.; Lamiable,
D.; Devillier, P.; Millart, H. Effects of 7-hydroxycoumarin (umbel-
liferone) on isolated perfused and ischemic-reperfused rat heart.
Arzneimittelforschung, 2000, 50(10), 89 0-896.
[33] Chang, T.H.; Adachi, H.; Mori, N.; Saito, I.; Okuyama, T. Effects
of a pyranocoumarin compound isolated from a Chinese medicinal
plant on ischemic myocardial dysfunction in anesthetized dogs.
Eur. J. Pharmacol., 1994, 258(1-2), 77-84.
[34] Ogawa, H.; Sasai, N.; Kamisako, T.; Baba, K. Effects of osthol on
blood pressure and lipid metabolism in stroke-prone spontaneously
hypertensive rats. J. Ethnopharmacol., 2007, 112(1), 26-31.
[35] Zhou, F.; Zhong, W.; Xue, J.; Gu, Z.L.; Xie, M.L. Reduction of rat
cardiac hypertrophy by osthol is related to regulation of cardiac
oxidative stress and lipid metabolism. Lipid s, 2012, 47(10), 987-
994.
[36] Gilani, A.H.; Shaheen, E.; Saeed, S.A.; Bibi, S.; Irfanullah; Sadiq,
M.; Faizi, S. Hypotensive action of coumarin glycosides from Dau-
cus carota. Phytomedicine, 2000, 7(5), 423-426.
[37] Campos-Toimil, M.; Orallo, F.; Santana, L.; Uriarte , E. Synthesis
and vasorelaxant activity of new coumarin and furocoumarin de-
rivatives. Bioorg. Med. Chem. Lett., 2002, 12(5), 783-786 .
[38] Aporti, F.; Finesso, M.; Granata, L. Effects of 8-mon ochloro-3-
beta-diethylaminoethyl-4-methyl-7-ethoxycarbonylmethoxy cou-
marin (AD6) on the coronary circulation in the dog. Pharmacol.
Res. Commun., 1978, 10(5), 469-477.
[39] Amin, K.M.; Awadalla, F.M.; Eissa, A.A.; Abou-Seri, S.M.; Has-
san, G.S. Design, synthesis and vasorelaxant evaluation of novel
coumarin-pyrimidine hybrids. Biorg. Med. Chem., 2011, 19(20),
6087-6097.
[40] Valenti, P.; Rampa, A.; Budriesi, R.; Bisi, A.; Chiarini, A. Couma-
rin 1,4-dihydropyridine derivatives. Biorg. Med. Chem., 1998, 6(6),
803-810.
[41] Vilar, S.; Quezada, E.; Santana, L.; Uriarte, E.; Yanez, M.; Fraiz,
N.; Alcaide, C.; Cano, E.; Orallo, F. Design, synthesis, and vasore-
laxant and platelet antiaggregatory activities of coumarin-
resveratrol hybrids. Bioorg. Med. Chem. Lett., 2006, 16(2), 257-
261.
[42] Quezada, E.; Delogu, G.; Picciau, C.; Santana, L.; Podda, G.;
Borges, F.; Garcia-Morales, V.; Vina, D.; Orallo, F. Synthesis and
vasorelaxant and platelet antiaggregatory activities of a new series
of 6-halo-3-phenylcoumarins. Mole cules, 2010, 15(1), 27 0-279.
[43] Kim, S.Y.; Koo, Y.K.; Koo, J.Y.; Ngoc, T.M.; Kang, S.S.; Bae, K.;
Kim, Y.S.; Yun-Choi, H.S. Platelet anti-aggregation activities of
compounds from Cinnamomum cassia. J. Med. Food, 2010, 13(5),
1069-1074.
[44] Chen, Y.; Wang, T.; Lee, K.; Tzeng, C.; Chang, Y.; Teng, C. Syn-
thesis of Coumarin Derivatives as Inhibitors of Platelet Aggrega-
tion. Helv. Chim. Acta, 1996, 79(3), 651-657.
[45] Prosdocimi, M.; Zatta, A.; Gorio, A.; Zanetti, A.; Dejana, E. Action
of AD6 (8-monochloro-3-beta-diethylaminoethyl-4-methyl-7-
ethoxycarbonylmet hox y coumarin) on human platelets in vitro.
Naunyn-Schmiedeberg's Arch. Pharmacol., 1986, 332(3), 305-310.
[46] Teng, C.M.; Li, H.L.; Wu, T.S.; Huang, S.C.; Huang, T.F. Anti-
platelet actions of some coumarin compounds isolated from plant
sources. Thromb. Res., 1992, 66(5), 549-557.
[47] Macak ova, K.; Rehakova, Z.; M ladenka, P.; Karlickova, J.; Filip-
sky, T.; Riha, M.; Prasad, A.K.; Parmar, V.S.; Jahodar, L.; Pavek,
P.; Hrdina, R.; Saso, L. In vitro platelet antiaggregatory properties
of 4-methylcoumarins. Biochimie, 2012, 94(12), 2681-2686.
[48] Fonseca, F.V.; Baldissera, L. , Jr.; Camargo, E.A.; Antunes, E.; Diz-
Filho, E.B.; Correa, A.G.; Beriam, L.O.; Toyama, D.O.; Cotrim,
C.A.; Alvin, J., Jr.; Toyama, M.H. Effect of the synthetic coumarin,
ethyl 2-oxo-2H-chromene-3-carboxylate, on activity of Crotalus
durissus ruruima sPLA2 as well as on edema and platelet aggrega-
tion induced by this factor. Toxico n, 2010, 55(8), 1527-1530.
[49] Hsiao, G.; Ko, F.N.; Jong, T.T.; Teng, C.M. Antiplatelet action of
3',4'-diisovalerylkhellactone diester purified from Peucedanum ja-
ponicum Thunb. Biol. Pharm. Bull., 1998, 21(7), 688-692.
18 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
[50] Chen, Y.L.; Wang, T.C.; Liang, S.C.; Teng, C.M.; Tzeng, C.C.
Synthesis and evaluation of coumarin alpha-methylene-gamma-
butyrolactones: a new class of platelet aggregation inhibitors.
Chem. Pharm. Bull. (Tokyo), 1996, 44(8), 1591-1595.
[51] Wang, T.; Chen, Y.; Tzeng, C.; Liou, S.; Chang, Y.; Teng, C. Anti-
platelet α-Methy lidene-γ-butyrolactones: Synthesis and evaluation
of quinoline, flavone, and xanthone derivatives. Helv. Chim. Acta,
1996, 79(6), 1620-1626.
[52] Tzeng, C.; Zhao, Y.; Chen, Y. Synthesis and evaluation of α-
methylidene-γ-butyrolactone bearing flavone and xanthone moie-
ties. Phytochemistry, 1997, 80, 2337-2344.
[53] Chen, I.S.; Lin, Y.C.; Tsai, I.L.; Teng, C.M.; Ko, F.N.; Ishikawa,
T.; Ishii, H. Coumarins and anti-platelet aggregation constituents
from Zanthoxylum schinifolium. Phytochemistry, 1995, 39(5),
1091-1097.
[54] Cerri, R.; Pintore, G.; Dessi, G.; Asproni, B.; Piseddu, G.; Sini, S.
Isolation, characterization and pharmacological activity of Magy-
daris pastinacea (Lam) Paol. glucosides. Farmaco, 1995, 50(12),
841-848.
[55] Tsai, I.L.; Wun , M.F.; Teng, C.M.; Ishikawa, T.; Chen, I.S. Ant i-
platelet aggregation constituents from Formosan Toddalia asiatica.
Phytochemistry, 1998, 48(8), 13 77-1382.
[56] Chen, K.S.; Wu, C.C.; Chang, F.R.; Chia, Y.C.; Chiang, M.Y.;
Wang, W.Y.; Wu, Y.C. Bioactive coumarins from the leaves of
Murraya omphalocarpa. Planta Med., 2003, 69(7), 654-657.
[57] Chia, Y.C.; Chang, F.R.; Wang, J.C.; Wu, C.C.; Chiang, M.Y.;
Lan, Y.H.; Chen, K.S.; Wu, Y.C. Antiplatelet aggregation coumar-
ins from the leaves of Murraya omphalocarpa. Molecules, 2008,
13(1), 122-128.
[58] Roma, G.; Braccio, M.D.; Carrieri, A.; Grossi, G.; Leoncini, G.;
Grazia Signorello, M.; Carotti, A. Coumarin, chromone, and 4(3H)-
pyrimidinone novel bicyclic and tricyclic derivatives as antiplatelet
agents: synthesis, biological evaluation, and comparative molecular
field analysis. Bioorg. Med. Chem., 2003, 11(1), 123-138.
[59] Roma, G.; Di Braccio, M.; Grossi, G.; Piras, D.; Leoncini, G.;
Bruzzese, D.; Signorello, M.G.; Fossa, P.; Mosti, L. Synthesis and
in vitro antiplatelet activity of new 4-(1-piperazinyl)coumarin de-
rivatives. Human platelet phosphodiesterase 3 inhibitory properties
of the two most effective compounds described and molecular
modeling study on their interactions with phosphodiesterase 3A
catalytic site. J. Med. Chem., 2007, 50(12), 2886-2895.
[60] Di Braccio, M.; Grossi, G.; Roma, G.; Grazia Signorello, M.;
Leoncini, G. Synthesis and in vitro inhibitory activity on human
platelet aggregation of novel properly substituted 4-(1-
piperazinyl)coumarins. Eur. J. Med. Chem., 2004, 39(5), 397-409.
[61] Leoncini, G. Mechanisms involved in the antiplatelet activity of 8-
methyl-4-(1-piperazinyl)-7-(3-pyridinylmethoxy )-2H-1-
benzopyran-2-one (RC414). Biochem. Pharmacol., 2004, 67(5),
911-918.
[62] Luzzatto, G.; Fabris, F.; Dal Bo Zanon, R.; Girolami, A. Lack of
antiplatelet activity of the new coumarin derivative 8-monochloro-
3-beta-diethylaminoethyl-4-methyl-7-ethoxy- carboxylmethoxy-
coumarin under in vivo conditions in man. Arzneimittel-Forschung,
1986, 36(6), 972-973.
[63] Xiao, W.L.; Li, S.H.; Shen, Y.H.; Niu, X.M.; Sun, H.D. Two new
coumarin glucosides from the roots of Angelica apaensis and their
anti-platelet aggregation activity. Arch. Pharm. Res., 2007, 30(7),
799-802.
[64] Matano, Y.; Okuyama, T.; Shibata, S.; Hoson, M.; Kawada, T.;
Osada, H.; Noguchi, T. Studies on coumarins of a Chinese drug
"qian-hu"; VII. Structures of new coumarin-glycosides of zi-hua
qian-hu and effect of coumarin-glycosides on human platelet ag-
gregation. Planta Med., 1986(2), 135-138.
[65] Niu, X.M.; Li, S.H.; Wu, L.X.; Li, L.; Gao, L.H.; Sun, H.D. Two
new coumarin derivatives from the roots of Heracleum rapula.
Planta Med., 2004, 70(6), 578-581.
[66] Bruno, O.; Brullo, C.; Schenone, S.; Bondavalli, F.; Ranise, A.;
Tognolini, M.; Impicciatore, M.; Ballabeni, V.; Barocelli, E. Syn-
thesis, antiplatelet and antithrombotic activities of new 2-
substituted benzopyrano[4,3-d]pyrimidin-4-cycloam ines and 4 -
amino/cycloamino-benzopyrano[4,3-d]pyrimidin-5-ones. Bioorg.
Med. Ch em. Lett., 2006, 14(1), 121-130.
[67] Cepelakova, H.; Roubal, Z.; Grimova, J.; Dlabac, A.; Cepelak, V.
Effect of pyrazolidine and coumarin derivatives on bleeding time
and prothrombin level in rats. Acta Universitatis Carolinae.
Medica . Monographia, 1972, 52, 55-60.
[68] Toyama, D.O.; Marangoni, S.; Diz-Filh o, E.B.; Oliveira, S.C.;
Toyama, M.H. Effect of umbelliferone (7-hydroxycoumarin, 7-
HOC) on the enzymatic, edematogenic and necrotic activities of
secretory phospholipase A2 (sPLA2) isolated from Crotalus duris-
sus collilineatus venom. Toxicon, 2009, 53(4), 417-426.
[69] Ribaldi, E.; Mezzasoma, A.M.; Francescangeli, E.; Prosdocimi, M.;
Nenci, G.G.; Goracci, G.; Gresele, P. Inhibition of PAF synthesis
by stimulated human polymorphonuclear leucocytes with clori-
cromene, an inhibitor of phospholipase A2 activation. British J.
Pharmacol., 1996, 118(6), 1351-1358.
[70] Porcellati, S.; Costantini, V.; Prosdocimi, M.; Stasi, M.; Pistolesi,
R.; Nenci, G.G.; Goracci, G. The coumarin derivative AD6 inhibits
the release of arachidonic acid by interfering with phospholipase
A2 activity in human platelets stimulated with thrombin. Agents
Actions, 1990, 29(3-4), 364-373.
[71] Stasi, M.; Gresele, P.; Prosdocimi, M.; Porcellati, S.; Quero, E.;
Pieretti, G.; Nenci, G.G.; Goracci, G. Cloricromene inhibits G-
protein-mediated activation of phospholipase A2 in human plate-
lets. J. Lipid Mediat., 1993, 7(3), 253-267.
[72] Lidbury, P.S.; Cirillo, R.; Vane, J .R. Dissociation of the anti-
ischaemic effects of cloricromene from its anti-platelet activity.
British J. Pharmacol., 1993, 110(1), 275-280.
[73] Jackson, S.P. The growing complexity of platelet aggregation.
Blood, 2007, 109(12), 5087-5095.
[74] Corsini, E.; Lucchi, L.; Binaglia, M.; Viviani, B.; Bevilacqua, C.;
Monastra, G.; Marinovich, M.; Galli, C.L. Cloricromene, a semi-
synthetic coumarin derivative, inhibits tumor necrosis factor-alpha
production at a pre-transcriptional level. Eur. J. Pharmacol., 2001,
418(3), 231-237.
[75] Bucolo, C.; Ward, K.W.; Mazzon, E.; Cuzzocrea, S.; Drago, F.
Protectiv e effects of a coumarin derivative in diabetic rats. Invest.
Ophthalmol. Vis. Sci., 2009, 50(8), 3846-3852.
[76] Mariot, R.; Zangirolami, L.; Bellato, P.; Chen, S.; Pieraccini, G.;
Moneti, G. Determination of the coumarin derivative cloricromene
acid in rabbit plasma and platelets. J. Chromatogr., 1992, 576(1),
143-148.
[77] Gresele, P.; Migliacci, R.; Di Sante, G.; Nenci, G.G.; Group, C.I.
Effect of cloricromene on intermittent claudication. A randomized,
double-blind, placebo-controlled trial in patients treated with aspi-
rin: effect on claudication distance and quality of life. CRAMPS
Investigator Group. Cloricromene Randomized Arteriopathy Multi-
center Prospective Study. Vasc. Med., 2000, 5(2), 83-89.
[78] Jain, M.; Surin, W.R.; Misra, A.; Prakash, P.; Singh, V.; Khanna,
V.; Kumar, S.; Siddiqui, H.H.; Raj, K.; Barthwal, M.K.; Dikshit,
M. Antithrom botic activity of a newly synthesized coumarin de-
rivative 3-(5-hydroxy-2,2-dimethyl-chroman-6-yl)-N-{2-[3-(5-
hydroxy-2,2-dimethyl-chroman-6 -yl)-propionylamino]-ethyl}-
propionamide. Chem. Biol. Drug Des., 2013, 81(4), 499-508.
[79] Sibbin g, D.; vo n Beckerath, N.; Morath, T.; Stegherr, J.; Mehilli, J. ;
Sarafoff, N.; Braun , S.; Schulz, S .; Schomig, A.; Kastrati, A. Oral
anticoagulation with coumarin derivatives and antiplatelet effects
of clopidogrel. Eur. Heart J., 2010, 31(10), 1205-1211.
[80] Poller, L.; Thomson, J.M.; Priest, C.M. Coumarin therapy and
platelet aggregation. Br. Med. J., 1969, 1(5642), 474-476.
[81] Ojewole, J.A.; Adesina, S.K. Cardiovascular and neuromuscular
actions of scopoletin from fruit of Tetrapleura tetraptera. Planta
Med., 1983, 49(2), 99-102.
[82] Bertolino, M.; Prosdocimi, M.; Aporti, F.; Finesso, M.; Gorio, A.
The action of AD6 on experimental arrhythmias and on action po-
tentials of cardiac fibers. Arch. Int. Pharmacodyn. Ther., 1986,
281(1), 66-78.
[83] Du, G.Y.; Ye, W.H.; Lu, F.; Jing, H.D. Effects of 6,7-
dimethoxycoumarin on experimental arrhythmia. Zhongguo yao li
xue bao = Acta pharmacologica Sinica, 1993, 14 Suppl, S16-18.
[84] Nakayama, K.; Oshima, T.; Koike, H. Antiarrhythmic activity of
dextro- and levo-isomers of 5-methyl-8-(2-hydroxy-3-t-
butylamino-propoxy) coumarin hydrocholoride (bucumolol), a
beta-adrenergic blocking agent, on aconitine-induced atrial and
ouabain-induced ventricular arrhythmias in dogs. Jpn. J. Pharma-
col., 1979, 29(6), 935-945.
[85] Sirbulescu, R.; Scholtholt, J.; Nitz, R.E.; Kunath, B. [The effect of
carbocromen on the ST segment of the epicardial electrocardio-
Cardiovascular Effects of Coumarins Besides their Antioxidant Activity Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 19
gram in a model of intermitting myocardial ischemia (author's
transl)]. Arzneimittel-Forschung, 1976, 26(2 ), 2 04-208.
[86] Milei, J.; Ferreira, R.; Grana, D.; Beigelman, R.; Cirillo, R. Benefi-
cial effects of cloricromene in ischemic reperfused myocardium.
Cardiology, 1994, 84(4-5), 284-291.
[87] Lidbury, P.S.; Cirillo, R.; Vane, J.R. Dissociation of the anti-
ischaemic effects of cloricromene from its anti-platelet activity. Br.
J. Pharmacol., 1993, 110(1), 275-280.
[88] Wang, X.Y.; Dong, W.P.; Bi, S.H.; Pan, Z.G.; Yu, H .; Wang,
X.W.; Ma, T.; Wang, J.; Zhang, W.D. Protective effects of osthole
against myocardial ischemia/reperfusion injury in rats. Int. J. Mol.
Med., 2013, 32(2), 365-372.
[89] Fiedler, V.B .; Ni tz, R.E.; Buch heim, S. Effects of oral car-
bocromene pretreatment on infarct size following experimental
coronary artery occlusion. J. Cardiovasc. Pharmacol., 1982, 4(1),
14-25.
[90] Ledingham, I.M.; McArdle, C.S.; Parratt, J.R. Proceedings: Com-
parison of a coronary vasodilator drug (carbochromen) and a car-
diac stimulant (oxyfedrin) on blood flow and oxygen extraction in
experimental myocardial infarcts. Brit. J. Pharmacol., 1972, 44 (2),
323p-324p.
[91] Vimal, V.; Devaki, T. Linear furanocoumarin protects rat myocar-
dium against lipidperoxidation and membrane damage during ex-
perimental myocardial injury. Biomed. Pharmacother., 2004, 58(6-
7), 393-400.
[92] Sturniolo, R.; Squadrito, F. ; Campo, G.M.; Vinci, R.; Calatron i, A.;
Prosdocimi, M.; Caputi, A.P. Protective effect of cloricrome ne, a
coumarine derivative, in hypovolemic hemorrhagic shock in the rat.
J. Cardiovasc. Pharmacol., 1991, 17(2), 261 -266.
[93] van Leeuwen, Y.; Rosendaal, F.R.; van der Meer, F.J. The relation-
ship between maintenance dosages of three vitamin K antagonists:
acenocoumarol, warfarin and phenprocoumon. Thromb. Res., 2008,
123(2), 225-230.
[94] Pirmoh amed, M. Warfarin : almost 60 years old and still causing
problems. Br. J. Clin. Pharmaco l., 2006, 62(5), 509-511.
[95] Eriksson, N.; Wadelius, M. Prediction of warfarin dose: why, when
and how? Pharmacogenomics, 2012, 13(4), 429-440.
[96] van Schie, R.M.; Wessels, J.A.; le Cessie, S.; de Boer, A.;
Schalek amp, T.; van der Meer, F.J.; Verhoef, T.I.; van Meegen, E.;
Rosendaal, F.R.; Maitland-van der Zee, A.H. Loading and mainte-
nance dose algorithms for phenprocoumon and acenocoumarol us-
ing patient characteristics and pharmacogenetic data. Eur. Heart J.,
2011, 32(15) , 1909-1917.
[97] Ufer, M. Comparative pharmacokinetics of vitamin K antagonists:
warfarin, phenprocoumon and acenocoumarol. Clin. Pharmacoki-
net., 2005, 44(12), 1227-1246.
[98] Hirsh, J.; Fuster, V.; Ansell, J.; Halperin, J.L. American Heart
Association/American College of Cardiology Foundation guide to
warfarin therapy. Circulation, 2003, 107(12), 1692-1711.
[99] Baczek, V.L.; Chen, W.T.; K luger, J.; Coleman, C.I. Predictors of
warfarin use in atrial fibrillation in the United States: a systematic
review and meta-analysis. BMC Fam. Pract., 2012, 13, 5.
[100] Assiri, A.; Al-Majzoub, O.; Kanaan, A.O.; Donovan, J.L.; Silva,
M. Mixed treatme nt comparison meta-analysis of aspirin, warfarin,
and new anticoagulan ts for stroke prevention in patien ts with non-
valvular atrial fibrillation. Clin. Ther., 2013, 35(7), 967-984.e962.
[101] Andersen, L.V.; Vestergaard, P.; Deichgraeber, P.; Lindholt, J.S.;
Mortensen, L.S.; Frost, L. Warfarin fo r the Prevention of Systemic
Embolism in Patients with Nonvalvular Atrial Fibrillation: A Meta-
analysis. Heart, 2008.
[102] Hart, R.G.; Pearce, L.A.; Aguilar, M.I. Meta-analysis: antithrom-
botic therapy to prevent stroke in patients who have nonvalvular
atrial fibrillation. Ann. Intern. Med., 2007, 146(12), 857-867.
[103] Mant, J.; Hobbs, F.D.; Fletcher, K.; Roalfe, A.; Fitzmaurice, D.;
Lip, G.Y.; Murray, E . Warfarin versus aspirin for stroke prevention
in an elderly community population with atrial fibrillation (the
Birmingham Atrial Fibrillation Treatment of the Aged Study,
BAFTA): a randomised controlled trial. Lancet, 2007, 370(9586),
493-503.
[104] Segal, J.B.; McNamara, R.L.; Miller, M.R.; Kim, N.; Goodman,
S.N.; Powe, N.R.; Robinson , K.A.; Bass, E.B. Prevention of
thromboembolism in atrial fibrillation. A meta-analysis of trials of
anticoagulants and antiplatelet drugs. J. Gen. Intern. Med., 2000,
15(1), 56-67.
[105] Anand, S.S.; Yusuf, S. Oral anticoagulant therapy in patients with
coronary artery disease: a meta-analysis. JAMA : the journal of the
American Medical Association, 1999, 282(21), 2058-2067.
[106] Keeling, D.; Baglin, T.; Tait, C.; Watson, H.; Perry, D.; Baglin, C.;
Kitchen, S.; Makris, M. Guidelines on oral anticoagulation with
warfarin - fourth edition. Br. J. Haematol., 2011, 154(3), 311-324.
[107] Boulanger, L.; Kim, J.; Friedman, M.; Hauch, O.; Foster, T.; Men-
zin, J. Patterns of use of antithrombotic therapy and quality of anti-
coagulation among patients with non-valvular atrial fibrillation in
clinical practice. Int. J. Clin. Pract., 2006, 60(3), 258-264.
[108] Saokaew, S.; Permsuwan, U.; Chaiyakunapruk, N.; Nathisuwan, S.;
Sukonthasarn, A. Effectiveness of pharmacist-participated warfarin
therapy management: a systematic review and meta-analysis. J.
Thromb. Haemost., 2010, 8(11), 2418-2427.
[109] Zineh, I.; Pacanowski, M.; Woodcock, J. Pharmacogenetics and
Coumarin Dosing - Recalibrating Expectations. N. Engl. J. Med.,
2013, 369(24), 2273-2275.
[110] Linkins, L.A.; Choi, P.T.; Douketis, J.D. Clinical impact of bleed-
ing in patients taking oral anticoagulant therapy for venous throm-
boembolism: a meta-analysis. An n. Intern. Med., 2003, 139(11),
893-900.
[111] Ruff, C.T.; Giugliano, R.P.; Braunwald, E.; Hoffman, E.B.;
Deenadayalu, N.; Ezekowitz, M.D.; Camm, A.J.; Weitz, J.I.;
Lewis, B.S.; Parkhomenko, A.; Yamashita, T.; Antman, E.M.
Comparison of the efficacy and safety of new oral anticoagulants
with warfarin in patients with atrial fibrillation: a meta-analysis of
randomised trials. Lan cet, 2014, 383(9921), 955-962.
[112] Granger, C.B.; A lexander, J.H.; McMurray, J.J.; Lopes, R.D.;
Hylek, E.M.; Hanna, M.; Al-Khalidi, H.R.; Ansell, J.; Atar, D.;
Avezum, A.; Bahit, M.C.; Diaz, R.; Easton, J.D.; Ezekowitz, J.A.;
Flaker, G.; Garcia, D.; Geraldes, M.; Gersh, B.J.; Golitsyn, S.;
Goto, S.; Hermosillo, A.G.; Hohnloser, S.H.; Horowitz, J.; Mohan,
P.; Jansk y, P.; Lewis, B.S. ; Lopez-Sendon, J.L.; Pais, P.; Park-
homenko, A.; Verheugt, F.W.; Zhu, J.; Wallentin, L. Apixaban ver-
sus warfarin in patients with atrial fibrillation. N. Engl. J. Med.,
2011, 365(11), 981-992.
[113] Abdelhafez, O.M.; Amin, K.M.; Batran, R.Z.; Maher, T.J.; Nada,
S.A.; Sethumadhavan, S. Synthesis, anticoagulant and PIVKA-II
induced by new 4-hydroxycoumarin derivativ es. Bioorg. Med.
Chem., 2010, 18(10), 3371-3378.
[114] Eberhardt, R.T.; Raffetto, J.D. Chronic venous insufficiency. Cir-
culation, 2005, 111(18), 2398-2409.
[115] Adam, B.S.; Pentz, R.; Siegers, C.P.; Strubelt, O.; Tegtmeier, M.
Troxerutin protects the isolated perfused rat liver from a possible
lipid peroxidation by coumarin. Phytomedicine, 2005, 12(1-2), 52-
61.
[116] Vanscheidt, W.; Rabe, E.; Naser-Hijazi, B.; Ramelet, A.A.;
Partsch, H.; Diehm, C.; Schultz-Ehrenburg, U.; Spengel, F.;
Wirsching, M.; Gotz, V.; Schnitker, J.; Henneicke-von Zepelin,
H.H. The efficacy and safety of a coumarin-/troxerutin-
combination (SB-LOT) in patients with chronic venous insuffi-
ciency: a double blind placebo-controlled randomised study. Vasa,
2002, 31(3), 185-190.
[117] Oda, K.; Yamaguchi, Y.; Yoshimura, T.; Wada, K.; Nishizono, N.
Synthetic models related to furanocoumarin-CYP 3A4 interactions.
comparison of furanocoumarin, coumarin, and benzofuran dimers
as potent inhibitors of CYP3A4 activity. Chem. Pharm. Bull. (To-
kyo), 2007, 55(9), 1 419-1421.
[118] Schmiedlin-Ren, P.; Edwards, D.J.; Fitzsimmons, M.E.; He, K.;
Lown, K.S.; Woster, P.M.; Rahman, A.; Thummel, K.E.; Fisher,
J.M.; Hollenberg, P.F.; Watkins, P.B. Mechanisms of enhanced
oral availability of CYP3A4 substrates by grapefruit constituents.
Decreased enterocyte CYP3A4 concentration and mechanism-
based inactivation by furanocoumarins. Drug Metab. Dispos.,
1997, 25(11) , 1228-1233.
[119] Kharasch, E.D.; Hankins, D.C.; Taraday, J.K. Single-dose methox-
salen effects on human cytochrome P-450 2A6 activity. Drug Me-
tab. Dispos., 2000, 28(1), 28-33.
[120] Ueng, Y.F.; Chen, C.C.; Chung, Y.T.; Liu, T.Y.; Chang, Y.P.; Lo,
W.S.; Murayama, N.; Yamazaki, H.; Soucek, P.; Chau, G.Y.; Chi,
C.W.; Chen, R.M.; Li, D.T. Mechanism-based inhibition of cyto-
chrome P450 (CYP)2A6 by chalepensin in recombinant systems, in
human liver microsomes and in mice in vivo. British J. Pharmacol.,
2011, 163(6), 1250-1262.
20 Current Topics in Medicinal Chemistry, 2015, Vol. 15, No. 6 Najmanová et al.
[121] von Weymarn, L.B.; Murphy, S.E. Coumarin metabolism by rat
esophageal microsomes and cytochrome P450 2A3. Chem. Res.
Toxicol., 2001, 14(10), 1386-1392.
[122] Born, S.L.; Caudill, D.; Fliter, K.L.; Purdon, M.P. Identification of
the cytochromes P450 that catalyze coumarin 3,4-epoxidation and
3-hydroxylation. Drug Metab. Dispos., 2002, 30(5), 483-487.
[123] Vassallo, J.D.; Hicks, S.M.; Daston, G.P.; Lehman-McKeem an,
L.D. Metabolic Detoxification Determines Species Differences in
Coumarin-Induced Hepatotoxicity. Tox icol. Sci., 2004, 80(2), 249-
257.
[124] Felter, S.P.; Vassallo, J.D.; Carlton, B.D.; Daston , G.P. A safety
assessment of coumarin taking into account species-specificity of
toxicokinetics. Food Chem. Toxicol., 2006, 44(4), 462-475.
[125] Rietjens, I.M.; Punt, A.; Schilter, B.; Scholz, G.; Delatour, T.; van
Bladeren, P.J. In silico methods for physiologically based bioki-
netic models describing bioactivation and detoxification of cou-
marin and estragole: implications for risk assessment. Mol. Nutr.
Food Res., 2010, 54(2), 195-207.
Received: ???????????????? Revised: ???????????????? Accepted: ??? ?????????????
