Abstract:
Kotschya africana and Antidesma venosum plants are widely used in traditional
medicine to treat bacterial, fungal and viral infections. As a result there is need to
investigate extracts of these plants and to provide scientific proof for their wide
application in traditional medicine system. Extraction of leaves, stem and roots of K.
africana and A. venosum using solvents of increasing polarity, namely, hexane,
dichloromethane, ethyl acetate and methanol respectively afforded dry extracts. The
extracts were tested for anti-fungal and anti-bacterial activities, for brine shrimp
toxicity test and anti-oxidant activities. Using the disc diffusion method, it was
demonstrated that extracts of the leaves, stem and roots of these plants have moderate
anti-bacterial activities against Escherichia coli and Staphylococeus aureus and low
anti-fungal activity against Candida albicans. The root extracts were the most active
followed by the stem and the leaf extracts. Extracts from these plants also exhibited
mild cytotocixity to brine shrimp larvae with LD50 values ranging from 89.21 to
3876.69 for K. africana and 32.61 to 2515.39 for A. venosum. The results support the
traditional uses of extracts of these plants for the management of bacterial and fungal
infections.
Five compounds were also isolated and identified. From the roots of A. venosum,
3,5,7,3´,4´-pentahydroxyflavanol commonly known as epicatechin, 5,7,8,2´,3´,4-
hexahydrodihydroflavanol-4-O-β-D-glucoside, and 5,7,4´-trihydroxyl-isoflavone
(genistein) were isolated. Lupeol and compound 25 were isolated from K. africana
leaves. Compound 25 was a diterpenoid with the labdan skeleton.
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Anti-oxidant screening of semi-pure compounds and fractions and a pure compound
from K. africana and A. venosum, showed that the semi-pure compounds, KAL11 and
KAL227302 had the lowest radical scavenging characteristics at a loading of 50 μg.
β-sistosterol, lupeol and AVLHB36 had moderate scavenging characteristics while the
fraction AVRM8286 had the highest radical scavenging activity at a loading of 0.5
μg. Ascorbic acid (standard) showed activity at the lowest loading of 0.05 μg.
