In vitro anti-platelet aggregation activity of the extracts of bulbine natalensis
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Date
2011
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Abstract
Bulbine natalensis Baker is a medicinal plant with succulent, aloe-like leaves from
the Asphodelaceae family, commonly used by Zulu traditional healers to treat blood
clotting-related diseases. The aim of this research was to test the anti-platelet
aggregation effect of B.natalensis’ extracts on rat platelet aggregation separately
induced by thrombin, ADP, collagen, epinephrine, papain, bromelain and trypsin.
Fresh plant material was extracted sequentially using hexane, chloroform, ethyl
acetate, methanol, and water. The chloroform extract had the highest yield of 0.20%.
Phytochemical screening revealed the presence of anthraquinones, cardiac
glycosides, saponins, tannins, flavonoids and alkaloids. The hexane extract
revealed the highest contents of total phenols (5.028 mg/g); flavonoid (3.293 mg/g)
and proanthocyanidin (2.565 mg/g). Hexane extract also displayed the highest
ABTS scavenging activity (IC50 4.72 mg/ml) followed by the ethyl acetate extract
(IC50 5.39 mg/ml). The water extract exhibited the highest reducing power; the
activity was even greater than the standard antioxidant BHA. Studies reveal that
B.natalensis is a good antioxidant. Brine shrimp lethality test indicated that all the
extracts were highly toxic to the larvae. The ethyl acetate extract was the most toxic
(LC50 2.21 mg/ml).
Anti-platelet aggregation activities on rat platelets were observed. The chloroform
extract inhibited ADP-induced clotting by 100% at doses 1 and 3 mg/ml with IC50
values of 5.32 mg/ml before tannin removal and >10 mg/ml after tannin removal.
Two compounds (F6/1 and F6/5) were isolated and purified from the chloroform
extract. It was apparent that the compounds were unstable and could not be
Description
A dissertation submitted in fulfillment of the requirement for the Degree of Masters of Science in the Department of Biochemistry and Microbiology, Faculty of Science and Agriculture, University of Zululand, 2011.
Keywords
Bulbine natalensis Baker