Abstract:
Dioscorea bulbifera Linn has been documented to be effective in treating several complicated
ailments in many parts of the world, but remain an underutilized tuber in this part of world, Nigeria
both for food and medicinal purposes. The present study, hence evaluated the antibacterial activities of
ethanolic and aqueous extract of parts of the tuber against ten (10) clinical pathogens, using agar well
diffusion. The bioactive constituents in these tubers were also determined using standard techniques.
The proximate composition of the bulbils of the tuber ranged as follow; moisture content (4.58 -
4.61%); ash (4.46 - 4.52%); crude protein (8.29 - 8.44%); fat (1.96 - 1.99%); fibre (2.22 - 2.28%) and
carbohydrate (78.31 -78.34%); while those of the peel of the tuber ranged as follow; moisture content
(3.68 - 3.74%); ash (9.00 - 9.11%); crude protein (8.47 - 8.50%); fat (2.98 - 3.02%); fibre (22.67 -
22.58%) and carbohydrate (53.05 - 53.20%). The tuber was recorded to contain higher amount of
saponin with the average of 24 mg/g, followed by cardiac glycosides with 13.13 mg/g, terpenoid with
8.48 mg/g, flavonoids followed with 5.36 mg/g and tannin with 4.21 mg/g was the least among the
bioactive ingredients. Except for Proteus vulgaris, Serratia liquefaciens, Micrococcus luteus, Bacillus
cereus and Citrobacter freundii, other test organisms were susceptible to the effect of the ethanolic
extract of the peel of D. bulbifera at 500 μg/mL. High inhibition zones (between 17 and 22 mm) were
recorded against 80% of the test organisms at 1000 μg/mL, except for 15 mm zone recorded against
Bacillus cereus. The Minimum Inhibitory Concentrarion (MIC) and the Minimum Bactericidal
Concentration (MBC) of extract of D. bulbifera ranged in respect to the part (peel and bulbil) from
125 μg/mL to 500 μg/mL; and 250 μg/ml to 1000 μg/mL for peels and bulbils respectively.
Antibacterial activity of the ethanolic and aqueous extracts of the bulbils of D. bulbifera was however,
not significant in this present study compared to that of the peel. This study therefore, affirmed that
the peel of D. bulbifera is a novel source of bioactive compounds which do not only enhance the
antibacterial properties, but also ascertain its good health-promoting qualities.
