ANTIMICROBIAL EFFECT OF AIR POTATO (Dioscorea bulbifera) LEAF EXTRACTS ON SOME PATHOGENIC MICROORGANISMS

Abstract

This study investigated the antimicrobial effect of air potato (Dioscorea bulbifera) leaf extracts on some pathogenic microorganisms. Air potato (Dioscorea bulbifera) is a species of yam (Discoreaceae) family. Different extracts were obtained by using ethanol, petroleum-ether and distilled water and 100 grams of different prepared Air potato leaves (dropped, yellow, fresh) powder were soaked in 1000 ml of the solvents for 72 hours. The crude extracts were concentrated through rotatory evaporation. Escherichia coli, Salmonella typhi, Proteus vulgari, Pseudomonas aeruginosa, Streptococcus pneumonia, Staphylococcus aureus, Candida albicans and Aspergillus niger were obtained from Microbiology Laboratory, University College Hospital, Ibadan, and Lagos University Teaching Hospital (LUTH), Nigeria. In this study, the antimicrobial activity of air potato (Dioscorea bulbifera) leaves (dropped, fresh, yellow) extracts were investigated against these pathogens. All extracts of Dioscorea bulbifera inhibited the growth of the tested bacterial isolates with the dropped leaf showing the highest potency against the bacteria, while none of the leaf extracts inhibited the growth of the tested fungi at 1000 mg/ml. Ethanolic extracts have high potency against the tested bacteria. Salmonella typhi, Proteus vulgaris and Pseudomonas aeruginosa have zones of inhibition greater than 15 mm with Nitrofurantoin, while Streptococcus pneumoniae and Staphylococcus aureus were susceptive to cotrimonazole. The minimum inhibitory concentration of ethanol, petroleum ether and aqueous extracts of air potato (Dioscorea bulbifera) required to totally eradicate the growth of tested bacteria was determined ranging from 62.5-250 mg/ml for ethanolic extracts; from 125-500 mg/ml for petroleum ether and from 125 mg/ml to 1000 mg/ml for aqueous extracts. The leaf extracts were purified using chloroform, methanol and ethyl acetate. Phytochemical analysis showed the presence of flavonoids, tannins, saponins, and carbohydrates.