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Propionylshikonin from the roots of Lithospermum erythrorhizon
Abstract
A shikonin derivative was isolated from the roots of Lithospermum erythrorhizon with silica gel column chromatography and preparative TLC. The structure of the isolated pigment was identified as propionylshikonin by NMR and mass spectrometric analysis. The isolation of propionylshiknin was for the first time in the nature.
... Isohexenylnaphthazarin pigments are well known constituents of certain plants of the Boraginaceae family [1,[6][7][8][9][10][11][12][13][14][15]. The stereochemistry of the herein isolated isohexenylnaphthazarins was assigned to be of the alkannin type, except for acetylshikonin (Figure 1), on the basis of their negative specific rotation values [9,14], albeit in different solvents and at slightly different temperatures from those of the literature. ...
... Isohexenylnaphthazarin pigments are well known constituents of certain plants of the Boraginaceae family [1,[6][7][8][9][10][11][12][13][14][15]. The stereochemistry of the herein isolated isohexenylnaphthazarins was assigned to be of the alkannin type, except for acetylshikonin (Figure 1), on the basis of their negative specific rotation values [9,14], albeit in different solvents and at slightly different temperatures from those of the literature. ...
Two plants from Boraginaceae family Lithospermum canescens (Michx.) Lehm., a common plant in northern America also known as Indian paint and Arnebia euchroma (Royle) Jonst., a perennial plant of the alpine region, were investigated. Shikonin and its derivatives are well known since ancient times and have been used for food products, as dyes for silk [1] and have been reported to possess antimicrobial, antiinflammatory and antitumor activities [2]. In the present study, hairy root cultures of L. canescens were established using three strains of Agrobacterium rhizogenes: ATCC 15834, LBA 9402 and NCIB 8196. In the n-hexane extract of the hairy root culture of L. canescens the presence of acetylshikonin (ACS), isobutylshikonin (IBS), β,β-dimethylacrylshikonin (DAS), β-hydroxyvalerylshikonin (HO-IVS), shikonofuran C and D has been confirmed. The callus culture and cell suspension culture of A. euchroma yielded likewise the pigments ACS, IBS, HO-IVS as well as shikonin, α-methylbutyrylshikonin (α-MBS), propionylshikonin (PS) and deoxyshikonin (DS). All chemical constituents have been determined by modern spectral means. Moreover, all isolated compounds showed a very interesting antimicrobial spectrum of activity against all assayed human pathogenic microogranisms. References: [1] Manjkhola, S. et al. (2005) In Vitro Cell. Dev. Biol. Plant 41:244. [2] Couladouros, E. et al. (1997) Tetrahedron Lett. 38:7263.
... Isohexenylnaphthazarin pigments are well known constituents of certain plants of the Boraginaceae family [1,[6][7][8][9][10][11][12][13][14][15]. The stereochemistry of the herein isolated isohexenylnaphthazarins was assigned to be of the alkannin type, except for acetylshikonin (Figure 1), on the basis of their negative specific rotation values [9,14], albeit in different solvents and at slightly different temperatures from those of the literature. ...
... Isohexenylnaphthazarin pigments are well known constituents of certain plants of the Boraginaceae family [1,[6][7][8][9][10][11][12][13][14][15]. The stereochemistry of the herein isolated isohexenylnaphthazarins was assigned to be of the alkannin type, except for acetylshikonin (Figure 1), on the basis of their negative specific rotation values [9,14], albeit in different solvents and at slightly different temperatures from those of the literature. ...
The phytochemical investigation of the n-hexane extract from callus and cell suspension culture of Arnebia euchroma (Royle) Jonst. resulted in the isolation of nine isohexenylnaphthazarins: deoxyalkannin (1), alkannin (2), acetylalkannin (3), isobutyrylalkannin (4), β-hydroxyisovalerylalkannin (5), 2''-(S)-α-methylbutyrylalkannin (6), propionylalkannin (7), teracrylalkannin (8) and acetylshikonin (9). Their structures were determined by MS and NMR spectroscopy. Pigments 2–8 are isolated for the first time from Arnebia in vitro cultures, 4 and 7 are reported in the present work as novel metabolites within the Arnebia genus, while 9 is a known constituent of both natural roots and in vitro cultures of A. euchroma. Moreover, methyl jasmonate and 1-monoglyceryl olate, palmitate and stearate are reported for the first time within the Boraginaceae family. The antimicrobial and cytotoxic activities of all isolated pigment compounds were tested, revealing a very interesting profile.
... , ïðîïèîíèëøèêîíèí (4, 5 ìã; t = 22.06 ìèí) [9], äåçîêñèøèêîíèí (5, 7 ìã; t = 22.79 ìèí) [10], β-àöåòîêñèèçîâàëåðèëøèêîíèí (6, 21 ìã; t = 23.37 ìèí) [7], èçîáóòèëøèêîíèí (7, 20 ìã; t = 24.26 ìèí) [8], òèãëîèëøèêîíèí (8, 14 ìã; t = 24.52 ìèí) [11], β,β-äèìåòèëàêðèëîèëøèêîíèí (9, 12 ìã; t = 24.81 ...
... , ïðîïèîíèëøèêîíèí (4, 5 ìã; t = 22.06 ìèí) [9], äåçîêñèøèêîíèí (5, 7 ìã; t = 22.79 ìèí) [10], β-àöåòîêñèèçîâàëåðèëøèêîíèí (6, 21 ìã; t = 23.37 ìèí) [7], èçîáóòèëøèêîíèí (7, 20 ìã; t = 24.26 ìèí) [8], òèãëîèëøèêîíèí (8, 14 ìã; t = 24.52 ìèí) [11], β,β-äèìåòèëàêðèëîèëøèêîíèí (9, 12 ìã; t = 24.81 ...
... 紫草는(생약명 : Lithospermi Radix) 지치과 Boraginacese 에 속하는 다년생 초본인 지치 (Lithospermum erythrorhizon)의 根으로서, 紫根, 紫芝, 紫丹 등의 여러 이 름으로 불리어 지고 있다.《神農本草經》에 "主心腹邪氣, 五疸, 補中益氣, 利九竅, 通水道"라고 처음 기재된 이래, 凉 血活血, 解毒透疹 효능으로 血熱毒盛, 斑疹紫黑, 痲疹不遂, 瘡瘍, 濕疹 등을 치료하는데 응용되어 지고 있다 9,10) . 현재 紫草에 대한 연구로는 아토피 피부염에 관련 효과 11,12) , 항 알러지 염증반응에 대한 효과 13) , Galactosamine으로 유도 된 간손상에 미치는 보호 효과 14 Fig. 2A), Griess 반응을 통한 세 포 상층액의 NO 생성을 측정한 결과, iNOS 측정 결과와 일치하게 LE 전 처리군에서 LPS로 유도한 NO 생성을 억 제하였다 (Fig. 2B). ...
Objective : Lithospermum Erythrorhizon (LE) has been used as an anti-bacterial and anti-inflammatory agent. However, it is unclear that LE aqueous extract could show the anti-inflammatory effects in RAW 264.7cells. The purpose of this study was to investigate the anti-inflammatory effect of aqueous extract from LE on lipopolysaccharide (LPS) - induced inflammatory response. Methods : To measure out the cytotoxicity of LE, we performed the MTT assay. To evaluate the anti-inflammatory effects of LE, we examined the inflammatory mediators such as nitric oxide (NO), prostaglandin E2 () and pro-inflammatory cytokines (tumor necrosis factor (TNF)-, interleukin, (IL)- and (IL)-6) on RAW 264.7 cells. We also examined molecular mechanisms such as mitogen-activated protein kinases (MAPKs) and nuclear factor-B (NF-) activation by western blot. Results : Aqueous Extract from LE itself did not have any cytotoxic effect in RAW 264.7 cells. Aqueous extract from LE inhibited LPS-induced productions of inflammatory mediators such as NO, , and pro-inflammatory cytokines including TNF-, IL- and IL-6 in RAW 264.7cells. In addition, LE inhibited the phosphorylation of p38 kinases (p38), c-Jun -terminal kinase (JNK), and NF- activation in RAW 264.7 cells. Conclusion : LE down-regulated LPS-induced production of inflammatory mediators through the inhibition of p38, JNK and NF- activation. Taken together, these results could provide the evidence for the anti-inflammatory effects of LE. Therefore, LE may be a novel target in the management of inflammation and help to support a potential strategy for prevention and therapy of inflammatory diseases.
... MS and NMR spectroscopic analysis allowed the determination of structure of four alkannins: isobutyrylalkannin (1), β,β-dimethylacrylalkannin (2), acetylalkannin (3) and β-hydroxyisovalerylalkannin (4), and of two shikonofuran: shikonofuran C (5) and shikonofuran D (6) (Fig. 6). The stereochemistry of alkannins characterized in our research is assigned on the basis of their negative values of optical rotation, which were in agreement with literature data [12,13]. ...
Four alkannins, isobutylalkannin (1), β,β-dimethylacrylalkannin (2), acetylalkannin
(3) and β-hydroxyisovalerylalkannin (4), two shikonofurans: shikonofuran C (5),
shikonofuran D (6), and a number of sterols as well as esterified acids, have been isolated
and determined from the n-hexane extract of Lithospermum canescens transgenic
roots. Pigments 1 and 4 are reported in the present work as novel metabolites within
Lithospermum genus, while it is also the first detailed chemical analysis of transgenic
roots from the studied species. All chemical structures were determined by modern
chromatographic and spectral means as GC-MS, ESI-MS and NMR.
... MS and NMR spectroscopic analysis allowed the determination of structure of four alkannins: isobutyrylalkannin (1), β,β-dimethylacrylalkannin (2), acetylalkannin (3) and β-hydroxyisovalerylalkannin (4), and of two shikonofuran: shikonofuran C (5) and shikonofuran D (6) (Fig. 6). The stereochemistry of alkannins characterized in our research is assigned on the basis of their negative values of optical rotation, which were in agreement with literature data [12,13]. ...
... However, the stereochemistry may vary between ester derivatives from the same plant or between plants from different locations, even though both samples were collected from India. Another shikonin derivative, propionylshikonin ( Table 1) was for the first time isolated and identified in nature from the roots of L. erythrorhizon [129]. ...
Isohexenylnaphthazarins (IHN), commonly known as Alkannins and Shikonins (A/S), are lipophilic red pigments. They are found in the outer surface of the roots of at least a hundred and fifty species that belong to the genera Alkanna, Lithospermum, Echium, Onosma, Anchusa and Cynoglossum of the Boraginaceae family. The chiral pairs A/S are potent pharmaceutical substances with a well-established and wide spectrum of wound healing, antimicrobial, antiinflammatory, antioxidant, anticancer and antithrombotic biological activity. For organic chemists uninitiated in the chemistry of quinones, the structures of alkannin (1) and shikonin (2) may look misleading simple. However, in spite of great efforts over many years by several research groups worldwide, a much needed viable synthetic route to these enantiomers has remained elusive until very recently. The value of A/S motivated biotechnologists to develop the world's first manufacturing process utilizing plant cell cultures. The research in this area has provided a wealth of knowledge to the field of biotechnology. In addition, great insights into the biosynthesis of these natural products and to our understanding of plant secondary metabolism in general, has been gained from this work. The last years there has been extensive scientific research in many areas throughout the disciplines of chemistry and biology and more specifically in cancer chemotherapy and a number of papers have appeared in the literature. Significant research has been conducted on A/S effectiveness on several tumors and on their mechanism of anticancer action. The aim of this paper was to review the recent advances in chemistry, biology, biotechnology and biosynthesis of alkannins and shikonins.
Allergy is still the main problem related to Coronavirus disease-19 (COVID-19), climate change, and the use of many toxic and chemical materials in the world. Thus, many studies keep finding new ways to prevent or treat allergies. Nowadays, many medicinal and aromatical plants can be utilized for allergy treatment, and one of them Echium italicum L. is common generally in Europe, Mediterranean, and many cities such as Istanbul, Erzurum, and Balıkesir in Turkey. Under biotic and abiotic stresses in nature, Echium italicum produces secondary metabolites, which are alkaloid, terpene, and phenolic compounds, from its hairy roots for adaptation to these conditions. Shikonin is one of the phenolic compounds produced from Echium italicum, has anticancer, antibacterial, and wound-healing properties. It is also used as a coloring agent in the pharmaceutical, cosmetic, and textile industries. Moreover, shikonin has antihistaminic activity, and it can be used in treatment of the main allergic diseases. Due to its biological activity, it has been started to produce shikonin by using many cell and tissue cultures in biotechnology. This chapter focused on the antihistaminic activity of shikonin produced from Echium italicum grown biotechnologically, and shed light on plant secondary metabolites and their antiallergic activity via reporting previous studies.
Six new naphthoquinones, euchronin A–F (1–6) and nine known naphthoquinones (7–15), were isolated from the roots of Arnebia euchroma (Royle) Johnst. The structures of the new compounds were confirmed by extensive spectroscopic analyses, including UV, IR, HR-ESI–MS, 1D and 2D NMR. In the present study, we estimated the anti-proliferative activities of these compounds with HaCaT cells. The results indicated that compounds 2 and 4 showed strong anti-proliferative activities at 25 μM, with relative viability at 38.83% and 68.44%, respectively.Graphical Abstract
Chemical investigation on the whole plants of Stenosolenium saxatile led to the isolation of three naphthoquinones (1–3), five pyrrolizidine alkaloids (PAs) (4–8), and six phenolic acids (9–14). The structure of the isolated compounds was elucidated by different spectrometric methods (¹H NMR, ¹³C NMR and ESI-MS). These results are the first chemical data on constituents of this genus. The chemotaxonomic relationships between the genera Stenosolenium, Onosma, Arnebia, Echium and Lithospermum are also discussed.
Counter-current Chromatography (CCC) has gradually become a popular method for preparative separation, especially in natural product isolations. As an effective separation method, one-dimensional (1D) CCC often result in insufficiently resolved peaks, due to limitations in the separation efficiency and peak capacity in an equipment. Therefore, off-line two dimensional (2D)/multi-dimensional (multi-D) CCC strategies with recycling elution mode were developed to achieve successful separation of target compounds. However, the reported 2D or multi-D CCC approaches lead to experimental costs, complicated procedures, higher requirements for equipment, and increased time consumption. In this study, an online-storage recycling CCC strategy was designed to achieve sequential recycling elution for multi-fractions of effluent in non-stop separation with single instrument using three 6-port valves and two storage loops, which would be realized by introducing 2D or multi-D CCC method before. In this non-stop separation system, the fraction C of effluent was subjected to recycling separation while the other fractions (A and B) were storing online, following which these two fractions were subjected to subsequent recycling separations in order, after the completion of the previous recycling elution. Then, six natural occurring naphthaquinone analogues, namely, shikonin (1), propionylshikonin (2), deoxyshikonin (3), isobutyrylshikonin (4), β, β-dimethylacrylshikonin (5) and isovalerylshikonin (6), were isolated from the crude extract of Arnebia euchroma in single run. The purities of all compounds were > 95.0% as determined by HPLC, and their structures were determined by means of UV, MS, 1H NMR, 13C NMR, and optical rotatory dispersion (ORD).
The methanolic extract of the roots of Lithospermum erythrorhizon (Boraginaceae) was found to show inhibitory activity towards farnesyl protein transferase (FPTase). Bioassay-guided fractionation of the methanolic extract resulted in the isolation of three naphthoquinone compounds, as inhibitors of FPTase. These compounds inhibited the FPTase activity in a dose-dependent manner.
Phytochemical constituents were isolated from the seeds of Lithospermum erythrorhizon through open column chromatography and prep-HPLC. Their structures were identified as β-sitosterol (1), daucosterol (2), luteolin (3), and allantoin (4) on the basis of spectroscopic analysis. Among them, luteolin (3) was isolated for the first time from the plant.
The crude methanol extract of roots of Lithospermum erythrorhizon was subjected to successive chromatographic fractionation which afforded two new dimeric naphthoquinone derivatives shikometabolin E (2) and shikometabolin F (3) as well as one known compound shikometabolin A (1). The structures of compounds 1-3 were elucidated by using UV, MS, 1D and 2D NMR spectroscopic analysis. The two new dimeric naphthoquinone derivatives showed significant neuraminidase inhibitory activities.
This study was performed to investigate the enhancement of immunomodulatory activities of Lithospermum erythrorhizon by extreme process. The extracts are WE100 (water extract for 24 hours at ), WE80 (water extract for 24 hours at ), EE (70% ethyl alcohol extract for 24 hours at ) and EPE (extreme process for 30 minutes at , 500 MPa after 70% ethyl alcohol extracts for 3 hours at 40, 50, ). Extraction yield was increased up to 5~10% by extreme process, compare to the normal extraction such as water solvent extraction, 70% ethyl alcohol solvent extraction. The cytotoxicity of the extracts was showed in the range of 12.68~15.89% at for human lung cell (HEL299). The EPE40 was showed the lowest cytotoxicity 12.68%. The EPE60 extracted by extreme process increased the growth of human B and T cells up to and , respectively and the EPE60 greatly increased the cytokine secretion of both IL-6 and TNF-. The extracts by extreme process also exhibited higher levels of nitric oxide production from macrophages than the lipopolysaccaharides. It can be concluded that Lithospermum erythrorhizon has immune activities and The extreme process could increase higher immune activities possibly by immunomodulatory compounds.
The content of luteolin in the different parts of Lithospermum erythrorhizon was determined by high performance liquid chromatography (HPLC). Luteolin was quantified by a reverse-phase column with gradient solvent program (water : ACN = 90 : 10 to 77 : 23 for 60 min). UV detection was conducted at 330 nm. The content of luteolin was measured in the seeds (0.28 mg/g), stems (0.30 mg/g), and roots (0.16 mg/g) of L. erythrorhizon. The presence of luteolin in Lithospermum species is important in agricultural crop production for increasing the amounts of clinically available medicine and health supplements.
A paraben derivative, methyl 3-acetyl-4-hydroxybenzoate (1), was isolated from the seeds of Lithospermum erythrorhizon, together with β-sitosterol and daucosterol, through open column chromatography and prep-HPLC. Methyl 3-acetyl-4-hydroxybenzoate (1) was isolated for the first time from nature, and elucidated by extensive spectroscopic analysis.
A method involving reverse transcription and real-time polymerase chain reaction (PCR) was developed in this study to detect the effects of the antiviral compound propionylshikonin on the binding of tobacco mosaic virus (TMV) RNA and tobacco mRNA to wheat germ ribosome in vitro. TMV RNA–wheat germ ribosome and tobacco mRNA–wheat germ ribosome binding systems were constructed, and the TMV RNA–ribosome and tobacco mRNA–ribosome complexes were isolated from the binding systems using 30% sucrose cushion. The target genes for the quantitative detection of TMV RNA and tobacco mRNA were the TMV coat protein gene and tobacco elongation factor-1α gene, respectively. The designed protocol was efficient for rapid and conclusive determination of the variations in the bound TMV RNA and tobacco mRNA from the complexes with and without propionylshikonin. The inhibition rates, ranging from 26.4% to 63.6%, were detected in the bound TMV RNA with 2–10 μg/mL propionylshikonin in the binding systems. The amount of bound tobacco mRNA did not decrease in the presence of propionylshikonin, indicating that propionylshikonin did not inhibit the binding of tobacco mRNA to wheat germ ribosome. To the best of our knowledge, this is the first study on the interactions among an anti-TMV agent, TMV RNA, and a host using real-time PCR to be reported.
Withania somnifera, commonly known as Ashwagandha, is an important medicinal plant that has been used in Ayurvedic and indigenous medicine for over 3,000 years. In view of its varied therapeutic potential, it has also been the subject of considerable modern scientific attention. The major chemical constituents of the Withania genus, the withanolides, are a group of naturally occurring C 28 -steroidal lactone triterpenoids built on an intact or rearranged ergostane framework, in which C-22 and C-26 are appropriately oxidized to form a six-membered lactone ring. In recent years, numerous pharmacological investigations have been carried out into the components of W. somnifera extracts. We present here an overview of the chemical structures of triterpenoid components and their biological activity, focusing on two novel activities, tumor inhibition and antiangiogenic properties of withaferin A and the effects of withanolide A on Alzheimer's disease. The most recent attempts in biotechnological production of withanolides are also discussed.
Tigloylshikonin, a new shikonin derivative esterified with tiglic acid ((E)-2-methylbut-2-enoic acid), was isolated as a minor pigment from a food colorant "Shikon color," a commercial root extract from Lithospermum erythrorhizon SIEBOLD et ZUCCARINI. The structure of tigloylshikonin was elucidated using (1)H, (13)C, the difference nuclear Overhauser effect (NOE), and 2D NMR techniques. Its stereochemistry was determined by chiral-phase HPLC analysis. Tigloylshikonin was also found in the roots of L. erythrorhizon, which indicated that this new shikonin derivative is a typical component of naphthoquinone pigments in the roots of L. erythrorhizon.
The purplish red pigment from the roots of Lithospermum erythrorhizon, a Korean edible wild plant, has been investigated concerning it's value as a natural colorant for Korean traditional foods. An attempt was made to isolate pigments and define their characteristics. Two compounds of isobutylshikonin and acetylshikonin were identified by melting point determination and spectra of UV, IR, and . To examine the utility of these naphthoquinone pigments for foods, the effect of various pH values on stability were determined over a period of storage. Buffered solutions of acetylshikonin and isobutylshikonin at pH 3 and 5 showed stable purplish red. The absorption maxima if acetylshikonin and isobutylshikonin over the range of pH 3 to 7 were 518 nm and 520 nm, respectively. A bathochromic shift to 588 nm at pH 10 was observed on these two naphthoquinone pigments. Sensory evaluation was performed with acetylshikonin and isobutylshikonin of identical absorbance. These two pigments revealed purplish red color in Munsell system.
Different strains of callus cultures of Lithospermum erythrorhizon showed wide variations in the production of shikonin derivatives. From these cultures, two high pigment-producing strains, whose content of shikonin derivatives are stable and similar to that of intact plant root, have been established by repeated selection.
Compounds bearing an acyl group of a various size at 1'-OH of shikonin were synthesized as acyl analogues of shikonin, which was isolated from the root of Lithospermum erythrorhizon, and evaluated for inhibitory effect on topoisomerase-I activity. A selective acylation at 1'-OH of shikonin in the presence of dicyclohexylcarbodiimide and 4-(dimethylamino)pyridine gave rise to a good yield of corresponding acylshikonin derivatives. In general, analogues with an acyl group of shorter chain lengths (C-2-C-6) exerted a stronger inhibitory action than those with longer chain lengths (C-7-C-20). While the halogen substitution at C-2 of the acetyl moiety failed to increase the inhibitory potency, the placement of double bonds in the acyl group (C-5-C-7) augmented the potency remarkably. Of the 32 derivatives evaluated, 15 compounds exhibited a higher inhibitory effect than shikonin. Noteworthy, the inhibitory potency of acetylshikonin, propanoylshikonin, and 4-pentenoylshikonin was approximately 4-fold greater than that of camptothecin. All these data suggest that the size of acyl moiety is important for the enhancement of potency, and the presence of olefinic double bonds is also beneficial.
A pharmacological comparison between the enantiomers, shikonin (R) and alkannin (S), was made with regard to their inhibitory effects on the increased capillary permeability and thermal edema in rats, using phenylbutazone as a positive control in both models. The results of experiments have shown that there is no significant difference in the anti-inflammatory activity between the two compounds.
Compounds bearing an acyl group of a various size at 1'-OH of shikonin were synthesized as acyl analogues of shikonin, which was isolated from the root of Lithospermum erythrorhizon, and evaluated for inhibitory effect on topoisomerase-I activity. A selective acylation at 1'-OH of shikonin in the presence of dicyclohexylcarbodiimide and 4-(dimethylamino)pyridine gave rise to a good yield of corresponding acylshikonin derivatives. In general, analogues with an acyl group of shorter chain lengths (C2-C6) exerted a stronger inhibitory action than those with longer chain lengths (C7-C20). While the halogen substitution at C-2 of the acetyl moiety failed to increase the inhibitory potency, the placement of double bonds in the acyl group (C5-C7) augmented the potency remarkably. Of the 32 derivatives evaluated, 15 compounds exhibited a higher inhibitory effect than shikonin. Noteworthy, the inhibitory potency of acetylshikonin, propanoylshikonin, and 4-pentenoylshikonin was approximately 4-fold greater than that of camptothecin. All these data suggest that the size of acyl moiety is important for the enhancement of potency, and the presence of olefinic double bonds is also beneficial.
Five red shikonin pigments, deoxyshikonin, shikonin, acetylshikonin, isobutylshikonin, and beta-hydroxyisovalerylshikonin, were isolated from the roots of Lithospermum erythrorhizon cultivated in Korea. The purified pigments were red, purple, and blue at acidic, neutral, and alkaline pH values, respectively. Physical stability of the purified pigments against heat and light in an aqueous solution was examined for possible value-added food colorants. The thermal degradation reactions were carried out at pH 3.0 (50 mM glycine buffer) in 50% EtOH/H(2)O. Deoxyshikonin (t(1/2) = 14.6 h, 60 degrees C) and isobutylshikinin (t(1/2) = 19.3 h, 60 degrees C) are relatively less stable than other shikonin derivatives (t(1/2) = 40-50 h, 60 degrees C). Activation energies of thermal degradation of the isolated pigments were calculated. The activation energy of deoxyshikonin was the highest (12.5 kcal mol(-)(1)) and that of beta-hydroxyisovalerylshikonin was the lowest (1.71 kcal mol(-)(1)) value. Light stabilities of the pigments were similar to each other in that the half-life values of photodegradation for 20000 lx light intensity were 4.2-5.1 h.
Antineoplastic Natural Products and the Analogues(XI); Cytotoxic Activity against L1210 Cells of Some Raw Drugs from the Oriental Medicine and Folklore
- J.-H Lee
- B.-Z Ahn
- J.-H. Lee
New Naphthoquinone Derivatives fromLithospermum erythrorhizon
- I Morimoto
- Y Hirata