Antibacterial activities and phytochemical properties of extracts of Dioscorea bulbifera Linn (Air Potatoe) tubers and peels against some pathogenic bacteria

Abstract

The antibacterial activities and bioactive constituents of ethanolic and aqueous extract of parts of the tuber against ten (10) clinical pathogens were determined, using agar well diffusion and standard techniques respectively. The proximate profile of this tuber included moisture content, ash, crude protein, fat, fibre and carbohydrate with varying percentages. 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 isolates 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 MIC and MBC of extract of D. bulbifera ranged in respect to the parts 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 profound in this present study compared to that of the peel. This study therefore, affirmed that D. bulbifera is a novel source of bioactive compounds which do not only enhance the antibacterial properties, but also ascertain its health promoting qualities.