Phytochemical Constituents and Antioxidant and Antimicrobial Activity of Selected Plants Used Traditionally as a Source of Food

Abstract

Many indigenous plants have also been used as a source of food and medicine in many African rural communities in the past. The study investigated the antimicrobial activity, phytochemical constituent, and antioxidant activity of selected traditional plants used traditionally as a source of food and medicine. The methanol and water extracts of different plant parts were analyzed for phytochemicals using standard phytochemical screening reagents while the broth microdilution assays were used to analyze antimicrobial activities. Alkaloids, phenols, flavonoids, saponins, tannins, and terpenes were found in one or more of the plant extracts, and all the plant extracts demonstrated scavenging activities. The back extracts of Sclerocarya birrea and the leaf extracts of Garcinia livingstonei exhibit the best antioxidant activities, while the water and methanol back extracts of S. birrea and G. livingstonei were the most active against all the tested foodborne bacteria.

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Phytochemical constituents, antioxidant and antimicrobial activity of selected plants used
traditionally as a source of food
Frederick Tawi Tabit (PhD),
1
Naomi Tope Komolafe (MSc),
1
Thilivhali Emmanuel Tshlikalange
(PhD),
2
Monde Alfred Nyila (PhD),
1
1. Department of Life and Consumer Sciences, College of Agriculture and Environmental Sciences,
University of South Africa, Cnr Christiaan de Wet and Pioneer avenue, Florida 1710, South Africa.
2. Department of Plant Science, Faculty of Agriculture and Natural Science, University of Pretoria,
Hatfield, Pretoria, 0002.
Contact information for the Corresponding Author
Dr Frederick Tawi Tabit
Department of Life and Consumer Sciences, College of Agriculture and Environmental Sciences,
University of South Africa, Cnr Christiaan de Wet and Pioneer avenue, Florida 1710, South Africa.
Tel: +27 11 471 2080;
Fax: +27 11 471 2796
Email: tabitft@unisa.ac.za
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ABSTRACT Many indigenous plants have also been used as a source of food and medicine in
many African rural communities in the past. The study investigated the antimicrobial activity,
phytochemical constituent and antioxidant activity of selected traditional plants used traditionally as
a source of food and medicine. The methanol and water extract of different plant parts were
analysed for phytochemicals using standard phytochemical screening reagents while the broth
micro dilution assays were used to analyse antimicrobial activities. Alkaloids, phenols, flavonoids,
saponins, tannins, and terpenes were found in one or more of the plant extracts and all the plant
extracts demonstrated scavenging activities. The back extracts of S. birrea and the leaf extracts of
G. livingstonei exhibits the best antioxidant activities while the water and methanol back extracts of
S. birrea, and G. livingstonei were the most active against all the tested foodborne bacteria.
Key words: Adansonia digitata, , antibacterial activity, antioxidant activity
INTRODUCTION
Adansonia digitata (baobab) is a multipurpose tree whose fruit pulp, seeds, leaves, flowers, roots,
and bark are used as food.
1.2
The fruits of Garcinia livingstonei (mangosteen or imbe) and
Sclerocarya birrea (marula), are also edible and are used for the making of many traditional food
products.
3.4
A. digitata, G. livingstonei and S. birrea have also been used as a source of medicine for
thousands of years by many African communities.
5
The seeds, pulp and leaves of A. digitata, bark
of G. livingstonei, and S. birrea have been implicated traditionally in the treatment of digestive
problems and diarrhoea related diseases.
6.7.8.9
In recent years, the interest of many pharmaceutical
industries has been switched to the natural world, prompting investigations of medicinal plants for
their potential biological and health benefits which includes antioxidant activity, anticancer, anti-
aging, anti-atherosclerotic, antimicrobial and anti-inflammatory activities.
10
In Mexico, many
indigenous plants have been tested to have important antimicrobial properties and hence the
possibilities to research further for the purpose of drug diacovery.
11
Studies conducted in Nigeria
also found the methanol extracts of different plant parts to possess significant antioxidant and
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radical scavenging activities that may be due to their phytochemical content which makes them
potential natural chemoprophylactic agents.
12
The objective of this study is to determine the
phytochemical constituents, antioxidant activity and antimicrobial activities against selected food
borne bacteria, of extracts of the seed, pulp and leaf of A. digitata and extracts from the back of G.
livingstonei and S. birrea.
MATERIALS AND METHODS
Preparation of Plant Extract
The leaves, fruit pulps and seeds of A. digitata, bark of G. livingstonei, and S. birrea were collected
from Venda, South Africa, and voucher specimen were prepared and identified at the H.G.W.J
Schweikerdt Herbarium, University of Pretoria. Plant parts were air dried and ground to fine
powder. 20 g of each powdered material was macerated in 200 ml of each solvent (100% methanol
and water) in extraction pots. The extracts were then filtered out by vacuum filtration. The
methanol extracts were concentrated in a Buchi Rotavapor R-200 while the water extracts were
concentrated using a freeze dryer.
13
Phytochemical Screening
To test for alkaloid using the Wagner’s test, a fraction of extract was treated with Wagner’s test
reagent and observed for the formation of reddish brown colour precipitate.
14
To test for alkaloid
using the Dragendroff’s Test, 1 ml of extract, few drops of dragendroff’s reagent was added in test
tube and colour change was observed. Appearance of orange colour is an indication of the presence
of alkaloids.
15
To test for flavonoids using the sodium hydroxide test, plant extracts were treated with dilute
NaOH, followed by addition of dilute HCl. A yellow solution of NaOH which turned colorless with
added dilute HCl indicated the presence of flavonoids (Onwukaeme et al., 2007). A conclusive test
was further carried out using the aluminum chloride test in which 0.2 g of each extract was heated
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with 10 ml of ethyl acetate in boiling water for 3 min. 4 ml of the filtrate was shaken with 1 ml of
1% aluminum chloride solution. A yellow coloured solution indicated the presence of flavonoids.
17
To test for Phenols, the plant extracts were spotted on a filter paper and a drop of phoshomolybdic
acid reagent was added and exposed to ammonia vapors. Blue coloration of the spot indicated the
presence of phenols.
18
To test for Tanins, 10% alcoholic ferric chloride was added to 2–3 ml of
methanolic extract and a dark blue or greenish grey coloration of the solution indicated the presence
of tannins.
18.19
To test for Terpenoids, 5 ml of plant extract was added to 2 ml of chloroform and 3
ml of concentrated sulphuric acid. The presence of terpenoids was indicated by a reddish brown
colour of interface.
20
To test for Saponins, 0.5 ml of plant extract was added to 5 ml of distilled
water and shake well. The persistence of frothing after shaking indicated of the presence of
saponins.
19
Determination of Antioxidant Activity
The antioxidant activity was determined as described by Du Toit et al.
21
with some modification. 2
mg of both plant extract and vitamin C (positive control) were dissolved in 200 µl of ethanol to give
stocks of 10 mg/ml. 1,1-diphenyl-2-picrylhydrazyl (DPPH) was prepared by dissolving 20 mg in
500 ml ethanol to give a stock of 0.04 mg/ml. The start-up concentrations were 500 µg/ml each for
all plant extracts and 100 µg/ml for vitamin C. The samples were serially diluted from the first row
to the last row and DPPH was added. The plates were covered in foil and incubated for 30 min and
absorbance was read with ELISA plate reader (KC junior) at 515 nm.
Preparation of test bacteria
Foodborne pathogens; Staphylococcus aureus ATCC®11632, Escherichia coli 015:H7
ATCC®43888, Klebsiella oxytoca ATCC®43086, Salmonella enterica ATCC®51741and Shigella
sonnei ATCC®25931 were grown on nutrient agar at 37
o
C for 24 h after which colonies were
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suspended in a saline solution (0.85% NaCl) and adjusted to the turbidity of the 0.5 MacFarland’s
standard (approximately 10
6
colony forming units per ml) to form the inoculum.
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Broth microdilution assays
To determine the minimum inhibitory concentrations (MIC) of extracts, 100 µl of nutrient broth
was added to all the wells of a 96-well microtitre plate. 100 µl of each dissolved plant extract (50
mg/ml) and 100 µl of 2.5 mg/ml of dissolved ciprofloxacin (positive control) were then added to
each bacterial well on the first row of the plate. The mixtures in first row were then serially diluted
row by row and 100 µl of the mixture was discarded from the last row. 100 µl of each bacterial
suspension in nutrient broth was then added to the wells except the negative control wells. MIC
values were determined after 20 µL of Presto blue was added per well and incubating at 37°C for
30 min.
23
To determine the maximum bacteriocidal concentrations (MBC) of extracts, 150 µl of nutrient broth
was pipetted into every well of a 96-well microtitre plate and 50 µl was taken from the 24-hour-old
bacteria culture without Presto blue in the MIC plates and added to it. The plates were incubated at
37
0
C for 24 h and 20 µl of presto blue was added to determine MBC values.
24
Analysis of cytotoxicity
100 µl of HEK cell suspension (1 x 10
5
cells/ml) was added to the inner wells of a 96-well
incubated at 37
o
C in a humidified atmosphere (5% CO2, 95% air) for 24 h. Serial dilutions of the
plant extracts dissolved in DMSO, Actinomycin D (positive control) and DMSO with the complete
medium
(
negative control) were transferred in a 24-well plate to give 1 ml of eight different
concentrations of each sample per well. 100 ul solutions from each sample was added to 50 µl of
XTT in a new plate and incubated for 2 h and 30 min absorbance was measured at 450 nm and 690
nm
to analyse cell proliferation and viability.
25
RESULTS
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Phytochemical Screening
Alkaloids were absent in both the water and methanol extracts of A. digitata seeds, pulps and
leaves. Flavanoids and phenol were present in both the water and methanol extracts of A. digitata
seeds, pulps and leaves. Tannin was only detected in the leaf extract of A. digitata but was absent in
the seed and pulp extracts. Also, terpenoid was only detected in the pulp extract of A. digitata but
not in its seed or leaf extracts. Saponin was present only in the pulp and leaf extract of A. digitata.
Alkaloids, flavonoids, phenol, tannins, terpenoids and Saponins were present in the bark extracts of
G. livingstonei and S. birrea (Table 1).
Antioxidant Activity
G. livingstonei and S. birrea bark extracts had the lowest IC
50
values. The water extract of A.
digitata pulp had the highest IC
50
value followed by the water extract of A. digitata seed. There was
a little difference in the IC
50
values between the water and methanol extract of G. livingstonei bark
but the IC
50
value of the water extract of S. birrea was slightly higher than the methanol extract.
The IC
50
of the water extracts of A. digitata seed and pulp was greater than that of their methanol
extracts (Table 2).
Minimum inhibitory concentration
The water and methanol extracts of A. digitata seeds and pulp had MICs greater than 12.5mg/ml.
The water extract of A. digitata leaf had MIC of 1.56 mg/ml for all the test bacteria except for S.
sonnei, with an MIC of 6.25 mg/ml (Table 2.0). Methanol extract of A. digitata leaf had MIC of
1.56 mg/ml for all the test bacteria, except for S. aureus with an MIC of 0.78 mg/ml and K. oxytoca
with an MIC of 0.39 mg/ml. Water extract of G. livingstonei bark had MIC of 1.56 mg/ml for all the
test organisms except for E. coli, and S. sonnei which had MIC of 0.78 mg/ml, while the methanol
extract of G. livingstonei bark had an MIC of 0.39 mg/ml for all the test organisms with the
exception of E. coli, and S. sonnei which maintained MIC of 0.78 mg/ml. Water extract of S. birrea
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bark had MIC of 0.78 mg/ml for all the test bacteria except E. coli and S. enterica which had lower
MIC’s of 0.39 mg/ml, while the methanol extract of S. birrea bark had varied MIC values ranging
from 0.39 to 1.56 mg/ml (Table 4).
Maximum bacteriocidal concentration
The water and methanol extracts of A. digitata seeds, pulp and leaves had MBCs greater than 12.5
mg/ml, while the water extract of G. livingstonei bark had MBC of 12.5 mg/ml for all the test
bacteria (Table 3.0). Similarly, the methanol extract of G. livingstonei bark had MBC of 12.5 mg/ml
for the other test bacteria except for S. aureus, with MBC of 6.25 mg/ml and S. enterica with MBC
greater than 12.5 mg/ml. The methanol extract of S. birrea bark had MBC of 12.5 mg/ml for all the
test bacteria except S. sonnei, with MBC of 6.25 mg/ml. On the other hand, water extract of S.
birrea bark also had MBC of 6.25 mg/ml for all the test organisms (Table 5).
Cytotoxicity
The cytotoxicity results are expressed as EC
50
which is the maximal effective concentration needed
to kill fifty percent of the HEK cells. The water extract of G. livingstonei bark had the highest EC
50
value of 769.9 µg/ml ± 36.33, followed by the methanol extract while the methanol extract of S.
birrea bark had the lowest EC
50
value of 105.9 µg/ml ±19.50, followed by its water extract (Table
6). The therapeutic index (TI) is determined as the ratio of the cytotoxicity to that of the minimum
inhibitory concentration ranged from 0.19 to 0.98 with the water extract of G. livingstonei having a
relative higher index for all the test food borne bacteria.
DISCUSSION
Phytochemical composition
Alkaloids were absent in both the water and methanol extracts of A. digitata seeds, pulps and
leaves. Many chemicals components that have been characterised from A. digitata usually belong to
the classes of terpenoids, flavonoids, steroids, vitamins, amino acids, carbohydrates and lipids
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hence an explanation for the presence of flavonoids and phenols.
26
Tannin was only detected in the
leaf extract of A. digitata and was absent in the seed. Other authors have identified soluble and
insoluble tannins in the back extract of A. digitate.
27.28
Saponin was present in both the pulp and leaf extract of A. digitata but was not detected in its seed
extracts. However the slight presence of saponin has been reported in Adansonia digitata seed oil,
but this could due to differences in extraction solvent.
29
The fruit pulp of A. digitata have been
found to have anti-inflammatory properties due to the presence of sterols, saponins and triterpenes
in its aqueous extract.
30
Terpenoid was present only in the pulp extract of A. digitata but not in its
seed and leaf extracts. This is also consistent with the findings of other authors of who the presence
of triterpene in A. digitata fruit and seeds.
29.31
The presence of terpenoid in the seed extract of A.
digitata might the usage of hexane as the solvent of extraction.
Alkaloids, flavonoids, phenol, tannins, terpenoids and saponins were present in the bark extracts of
G. livingstonei and S. birrea with the exception of water extract of S. birrea which did not contain
flavonoid. The bark of S. birrea in previous work has been reported to contain tannins, flavonoids,
alkaloids, and steroids.
32
Xanthones and biflavonoids have also been isolated from the root and
bark extract of G. livingstonei.
33
Tannins and flavonoids are thought to be responsible for
antidiarrhoeal activity by increasing colonic water and electrolyte reabsorption
34
which explains
why the bark of these plants are used traditionally in treating diarrhoea. Terpenoids have been
shown to be active against bacteria, fungi, viruses, and protozoa and their mechanism of action is
speculated to involve membrane disruption by the lipophilic compounds. Furthermore, alkaloids
have been found to have antimicrobial properties with microbiocidal effects against Giardia and
Entamoeba species as well as antidiarrheal effect which are probably due to their effects on transit
time in the small intestine.
35
Saponins have several biological effects some of which are
antibacterial, antifungal, antiparasitic, antitumor / cytotoxicity, antiviral and antioxidant activities.
36
Antioxidant activity
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Water and methanol extracts of bark of S. birrea and G. livingstonei, exhibited excellent antioxidant
activities with their 50% inhibitory concentration of DPPH radical ranging from 0.28±0.02 µg/ml to
0.40±0.02 µg/ml. This is quite impressive when compared to the positive control vitamin C which
had a 50% inhibitory concentration of 10.62±0.87 µg/ml. These results can be attributed to the
presence of phenols, flavonoids, tannins, alkaloids, saponins and terpenoids and this in agreement
with studies in which these compunds have been associated with high antioxidant activities.
37.38.39.40
Extracts of A. digitata leaves also exhibited good antioxidant properties with their IC
50
values being 2.79±0.07 µg/ml and 2.82±0.05 µg/ml. These can also be attributed to the presence of
phenols, flavonoids, tannins and saponins.
Antimicrobial activity, cytotoxicity and therapeutic index of extracts
The broth microdilution method indicated that both the water and methanol extracts of A. digitata
leaves exhibited some inhibitory activities against the tested bacteria at concentrations ranging from
0.39 mg/ml to 6.25 mg/ml. Their bactericidal activity, however, was at concentrations greater than
12.5 mg/ml. The methanol extracts of A. digitata root bark and leaves have been shown to exhibit
antibacterial activity against Staphylococcus aureus, Streptococcus faecalis, Bacillus subtilis,
Escherichia coli and Mycobacterium phlei.
41
The disadvantage of using the agar diffusion method to determine antimicrobial activity is that the
antimicrobial effect may be affected by the agar type, salt concentration, incubation temperature
and molecular size of the antimicrobial component. Furthermore, it does not distinguish between
bactericidal and bacteriostatic effects.
24
The MIC results showed that the G. livingstonei plant extracts displayed antimicrobial activity
against all the test bacteria. This similar to the acetone extracts of G. livingstonei leaves which were
shown to exhibit antimicrobial activity against Escherichia coli, Staphylococcus aureus and
Enterococcus faecalis with MIC’s ranging from 8-100 µg/ml, while the methanol extract of its root
bark showed antiparasitic activity against some selected parasites.
33.42.43
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The water and methanol extracts of S. birrea bark showed both significant inhibitory and
bactericidal effect on all the test organisms with MIC which ranged from 0.39 to 1.56 mg/ml. This
is in line with prevoius findings in which the acetone extracts of S. birrea bark and leaves showed
significant antimicrobial activities with MIC values ranging from 0.15 to 3 mg/ml against
Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis.
24
Based on the EC50 levels, these extracts are considered safe, considering that the values greater
than 100 µg/ml has been considered safe for extracts of other plant extracts.
45
Of all the extracts
studied, water extract of G. livingstonei bark had the highest therapeutic index for E. coli and S.
sonnei.
CONCLUSION
The phytochemicals phenols, flavonoids and saponins are present in at least one of the extracts. The
bark extracts of S. birrea and G. livingstonei contains all the six phytochemicals analysed. The
leaves of A. digitata contain more phytochemicals than the seed and pulp extract. The back extracts
of S. birrea and the leave extracts of G. livingstonei exhibits the best antioxidant activities.
Furthermore, the water and methanol extracts of S. birrea, and G. livingstonei were the most active
against all the tested foodborne bacteria.
Based on these results there is some justification for the
usage of these plants as food and medicinal agents.
ACKNOWLEDGMENTS
We acknowledge the research department of the University of South Africa for providing the funds
required for this research.
AUTHOR DISCLOSURE STATEMENT
No competing financial interests exist.
REFERENCES
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diversity of use of Sclerocarya birrea. J Ethnobiol Ethnomed 2011;7(8):2-9.
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10. Pirbalouti AG, Siahpoosh A, Setayesh M, Craker L: Antioxidant Activity, Total Phenolic
and Flavonoid Contents of Some Medicinal and Aromatic Plants Used as Herbal Teas and
Condiments in Iran. J Med Food 2014;17 (10):1151-1157.
11. Bustos ER, Velazquez C, Garibay-Escobar A, Garcı´a Z, Plascencia-Jatomea M, Cortez-
Rocha MO, Hernandez-Martı´nez J, Robles-Zepeda RE: Antibacterial and antifungal
activities of some Mexican medicinal plants. J Med Food 2009;12 (6):1398-1402.
12. Akinmoladun AC, Obuotor EM, Farombi EO: Evaluation of antioxidant and free radical
scavenging capacities of some Nigerian indigenous medicinal plants. J Med Food 2010;13
(2): 444-451.
13. Ndip RN, Malange AE, Tarkang AE, Mbullah SM, Luma HN, Malongue A, Ndip LM,
Nyongbela K, Wirmum C, Efange SM: In vitro anti-Helicobacter pylori activity of extracts
of selected medicinal plants from North West Cameroon. J Ethnopharmacol
2007;114(3):452-457.
14. Lalitha TP, Jayanthi P : Preliminary studies on phytochemicals and antimicrobial activity of
solvent extracts of Eichhornia crassipes (Mart.) Solms. Asian J Plant Sci Res
2012;2(2):115-122.
15. Firdouse S, Alam P: (2011). Phytochemical investigation of extract of Amorphophallus
campanulatus tubers. Int J Phytomed 2011;3(1):32-35.
16. Onwukaeme DN, Ikuegbvweha TB, Asonye CC: Evaluation of phytochemical constituents,
antibacterial activities and effect of exudates of Pycanthus angolensis Weld Warb
(Myristicaceae) on corneal ulcers in rabbits. Trop J Pharma Res 2007;6(2):725-730.
17. Subash KR, Muthulakshmi BG, Jagan RN, Binoy VC: Phytochemical screening and acute
toxicity study of ethanolic extract of Alpinia galanga in rodents. Int J Med Res Health Sci
2013;2(1):93-100.
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18. Kumar GS, Jayaveera KN, Kumar CKA, Sanjay UP, Swamy BMV, Kumar DVK:
Antimicrobial effects of Indian medicinal plants against acne-inducing bacteria. Trop J
Pharm Res 2007;6(2):717-723.
19. Parekh J, Chanda SV: In vitro antimicrobial activity and phytochemical analysis of some
Indian medicinal plants. Turk J of Biol 2007;31:53-58.
20. Edeoga HO, Okwu DE, Mbaebie BO: Phytochemical constituents of some Nigerian
medicinal plants. Afr J Biotechnol 2005 ;4(7):685-688.
21. Du Toit R, Volsteedt Y, Apostolides Z : Comparison of the antioxidant content of fruits,
vegetables and teas measured as vitamin equivalents. Toxicology 2001;166(1-2):63-69.
22. Kalyoncu F, Oskay M, Sağlam H, Erdoğan TF, Tamer AU: Antimicrobial and antioxidant
activities of mycelia of 10 wild mushroom species. J Med Food 13 2010;(2):415-419.
23. Fabri RL, Nogueira MS, Moreira JDR, Bouzada MLM, Scio E: Identification of antioxidant
and antimicrobial compounds of Lippia species by bioautography. J Med Food 2011;14
(7/8): 840-846.
24. Eloff JN: A sensitive and quick microplate method to determine the minimal inhibitory
concentration of plant extracts for bacteria. Planta Med 1998;64:711-713.
25. Guil-Guerrero JL, Ramos-Bueno R, Rodríguez-García I, López-Sánchez C: Cytotoxicity
screening of several tomato extracts J Med Food 2011;14 (1/2):40-45.
26. Shukla YN, Dubey S, Jain SP, Kumar S: Chemistry, biology and uses of Adansonia digitata
— a review. J Med Arom Plant Sci 2001;23:429-434.
27. AyeleY, Kim J, Park E, Kim Y, Retta N, Dessie G, Rhee S, Koh K, Nam K, Kim HS: .
(2013). A methanol extract of Adansonia digitata L. leaves inhibits pro-inflammatory iNOS
possibly via the inhibition of NF-κB activation. Biomol Ther (Seoul) 2013;21(2):146-152.
28. Yusha’u M, Hamza MM, Abdullahi N: Antibacterial activity of Adansonia digitata stem
bark extracts on some clinical bacterial isolates. Int J Biomed Healthcare Sci 2010;6(3):129-
135.
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29. Warra AA, Umar RA, Atiku FA, Nasiru A, Gafar MK: Physical and phytochemical
characteristics of seed oils from selected cultivars grown in northern Nigeria. Research and
Reviews: J. Agri. Allied Sci 2012;1(1):4-7.
30. Ramadan A, Harraz FM, El-Mougy SA: Anti-inflammatory, analgesic and antipyretic
effects of the fruit pulp of Adansonia digitata. Fitoterapia 1994;65(5):418-422.
31. Al-Qarawi AA, Al-Damegh MA, El-Mougy SA: Hepatoprotective influence of Adansonia
digitata pulp. J Herbs Spices Med Plants 2003;10(3):1-6.
32. Ojewole JAO, Mawoza T, Chiwororo WDH, Owira PMO: Sclerocarya birrea (A. Rich)
Hochst. [‘Marula’] (Anacardiaceae): a review of its phytochemistry, pharmacology and
toxicology and its ethnomedicinal uses. Phytother Res 2010;24(5):633-639.
33. Mbwambo ZH, Kapingu MC, Moshi MJ, Machumi F, Apers S, Cos P, Ferreira D, Marais
JPJ, Berghe DV, Maes L, Vlietinck A, Pieters L: Antiparasitic activity of some xanthones
and biflavonoids from the root bark of Garcinia livingstonei. J Nat Prod 2006;69(3): 369-
372.
34. Palombo EA: Phytochemicals from traditional medicinal plants used in the treatment of
diarrhoea: modes of action and effects on intestinal function. Phytother Res 2006;20(9):717-
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36. Sparg SG, Light ME, Van Staden J: Biological activities and distribution of plant saponins. J
Ethnopharmacol 2004;94 (2–3):219-243.
37. Dangles O, Fargeixa G, Dufourb C: Antioxidant properties of anthocyanins and tannins: a
mechanistic investigation with catechin and the 3′,4′,7-trihydroxyflavylium ion. J. Chem.
Soc., Perkin Trans 2 2000;2(8):1653-1663.
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38. Moura DJ, Richter MF, Boeira JM, Henriques JAP, Saffi J: Antioxidant properties of β-
carboline alkaloids are related to their antimutagenic and antigenotoxic activities.
Mutagenesis 2007;22 (4): 293-302.
39. Gülçin I, Mshvildadze V, Gepdiremen A, Elias R: Antioxidant activity of saponins isolated
from Ivy: α-Hederin, Hederasaponin-C, Hederacolchiside-E and Hederacolchiside-F. Planta
Med 2004;70(6):561-563.
40. Grabmann J: Terpenoids as plant antioxidants. Vit Horm 2005;72:505-535.
41. Anani K, Hudson JB, De Souza C, Akpagana K, Tower GHN, Arnason JT, Gbeassor M:
Investigation of medicinal plants of Togo for antiviral and antimicrobial activities. Pharm
Biol 2000;39(1):40-45.
42. Kaikabo AA, Samuel
BB, Eloff JN: Isolation and activity of two antibacterial biflavonoids
from leaf extracts of Garcinia livingstonei (Clusiaceae). Nat Prod Commun
2009;4(10):1363-1366.
43. Kaikabo AA, Eloff
JN: Antibacterial activity of two biflavonoids from Garcinia livingstonei
leaves against Mycobacterium smegmatis. J Ethnopharmacol 2011;138(1):253-255.
44. Eloff JN: Antibacterial activity of marula (Sclerocarya birrea) (A. Rich.) Hochst. subsp.
caffra (Sond.) Kokwaro (Anacardiaceae) bark and leaves. J Ethnopharmacol 2001;76:305-
308.
45. Patel PR, Raval BP, Karanth HA, PateL VR: Potent antitumor activity of Rubia cordifolia.
Int J Phytomed 2010;2:44-46.
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TABLE 1. PHYTOCHEMICAL ANALYSIS OF EXTRACTS OF SELECTED TRADITIONAL
PLANTS
β
Ads
β
Adp
β
Adl
β
Gab
β
κ
Scb
α
Alkaloids - - - + +
Flavonoid
+
+
+
+
+
Phenol + + + + +
Tannins - - + + +
Terpenoids - + - + +
Saponins - + + + +
Ads= Adansonia digitata seed extracts, Adp= Adansonia digitata pulp extracts Adl= Adansonia
digitata leave extracts, Gab= Garcinia livingstonei bark extracts, Scb = Sclerocarya birrea bark
extract, += positive test, - =negative test. α = same alkaloid test results for Wagner’s &
Dragendorf’s test, β = similar test results for both water and methanol extracts of plants parts, Κ=
only the methanol extract was positive for Flavonoids.
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TABLE 2. THE FREE RADICAL ACTIVITY OF EXTRACTS OF SELECTED TRADITIONAL
PLANTS
Plant Extracts Solvent used IC
50
(µg/ml)
Ads Water 23.11± 1.37
Methanol
6.65± 1.51
Adp
Water 28.58± 2.07
Methanol
9.65± 2.19
Adl
Water 2.79±0.07
Methanol 2.82±0.05
Gab
Water
0.35±0.06
Methanol 0.39±0.04
Scb Water 0.40±0.02
Methanol
0.28±0.02
Vit C Water 10.62±0.87
Ads = Adansonia digitata seed extracts, Adp = Adansonia digitata pulp extracts Adl = Adansonia
digitata leave extracts, Gab = Garcinia livingstonei bark extracts, Scb = Sclerocarya birrea bark
extracts. Values are expressed as mean±SD (n=3). The IC
50
of Vitamin C, the positive control was
10.62±0.87.
Page 17 of 21
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TABLE 3. MINIMUM INHIBITORY CONCENTRATION (MG/ML) OF EXTRACTS OF
SELECTED TRADITIONAL PLANTS ON SELECTED FOOD BORNE BACTERIA
Plant Extract
Bacteria Adlw Adlm Gabw Gabm Scbw Scbm Cipro
S. aureus 1.56 0.78 1.56 0.39 0.78 0.39 0.002
E. Coli 1.56 1.56 0.78 0.78 0.39 1.56 0.002
K. oxytoca 1.56 0.39 1.56 0.39 0.78 0.78 0.002
S. enterica 1.56 1.56 1.56 0.39 0.39 0.39 0.002
S. sonnei 6.25 1.56 0.78 0.78 0.78 0.78 0.002
Key: Adsw= water extract of Adansonia digitata seeds, Adsm= methanol extract of Adansonia
digitata seeds, Adpw= water extract of Adansonia digitata pulp, Adpm=methanol extract of
Adansonia digitata pulp, Adlw= water extract of Adansonia digitata leaves, Adlm= methanol
extract of Adansonia digitata leaves, Gabw= water extract of Garcinia livingstonei bark, Gabm=
methanol extract of Garcinia livingstonei bark, Scbw= water extract of Sclerocarya birrea bark,
Scbm= methanol extract of Sclerocarya birrea bark, Cipro = Ciprofloxacin. NB: Adsw, Adsm,
Adpw and Adpm had MIC values >12.5 mg/ml, figures not presented in the table.
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TABLE 4. MINIMUM BACTERICIDAL CONCENTRATION (MG/ML) OF EXTRACTS OF
SELECTED TRADITIONAL PLANTS ON SELECTED FOOD BORNE BACTERIA
Bacteria Plant Extracts
Gabw Gabm Scbw Scbm Cipro
S. aureus 12.5 6.25 6.25 12.5 0.002
E. Coli 12.5 12.5 6.25 12.5 0.002
K. oxytoca 12.5 12.5 6.25 12.5 0.002
S. enterica 12.5 12.5 6.25 12.5 0.002
S. sonnei 12.5 12.5 6.25 6.25 0.002
Key: Adsw= water extract of Adansonia digitata seeds, Adsm= methanol extract of Adansonia
digitata seeds, Adpw= water extract of Adansonia digitata pulp, Adpm=methanol extract of
Adansonia digitata pulp, Adlw= water extract of Adansonia digitata leaves, Adlm= methanol
extract of Adansonia digitata leaves, Gabw= water extract of Garcinia livingstonei bark, Gabm=
methanol extract of Garcinia livingstonei bark, Scbw= water extract of Sclerocarya birrea bark,
Scbm= methanol extract of Sclerocarya birrea bark, Cipro = Ciprofloxacin. NB: Adsw, Adsm,
Adpw, Adpm, Adlw, and Adlm had MBC values >12.5 mg/ml, figures not presented in the table.
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TABLE 5. THE HALF MAXIMAL EFFECTIVE CONCENTRATION OF EXTRACTS OF
SELECTED TRADITIONAL PLANTS AND ACTINOMYCIN D ON HEK CELL LINES
Key: Gabw= water extract of Garcinia livingstonei bark, Gabm= methanol extract of Garcinia
livingstonei bark, Scbw= water extract of Sclerocarya birrea bark, Scbm= methanol extract of
Sclerocarya birrea bark, Act = Actinomycin D.
Plant Extract EC
50
(µg/ml) R
2
value
Gabw 769.9µg/ml ± 36.33 0.35
Gabm 400µg/ml ± 36.33 0.89
Scbw 149.3µg/ml ±1.4 0.99
Scbm 105.9µg/ml ±19.50 0.96
Act 0.003±0.000095 0.88
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TABLE 6. CYTOTOXICITY AND THERAPEUTIC INDEX OF OF EXTRACTS OF SELECTED
TRADITIONAL PLANTS ON SELECTED FOOD BORNE BACTERIA, CALCULATED BY
DIVIDING CYTOTOXICITY VALUES BY MIC VALUES
Therapeutic index (Cytotoxicity values /MIC values
Plant
Extracts
Cytotoxicity
(mg/ml)
S. aureus E. coli K.
oxytoca
Salmonella
enterica
S.
sonnei
Gabw 0.7699 0.49 0.98 0.49 0.49 0.98
Scbw 0.1493 0.19 0.38 0.19 0.38 0.19
Scbm
0.1059
0.27
0.067
0.14
0.27
0.14
Key: Gabw= water extract of Garcinia livingstonei bark, Gabm= methanol extract of Garcinia
livingstonei bark, Scbw= water extract of Sclerocarya birrea bark, Scbm= methanol extract of
Sclerocarya birrea bark. NB: Therapeutic index for Gabm could not be determined because its
cytotoxic value was greater than 400 µg/ml. MIC = Minimum inhibitory concentration
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