Phytochemical Composition and Antifungal Actions of Aqueous and Ethanolic Extracts of the Peels of two Yam Varieties
The phenolic composition and antifungal actions of aqueous and ethanolic extracts of the peels of Dioscorea bulbifera and Dioscorea alata were investigated using standard techniques. The aqueous extract of the peel of Dioscorea bulbifera, contained 1.80 ± 0.14% flavonoids, 2.21 ± 0.16% tannins, 0.38 ± 0.04% alkaloids and 3.72 ± 0.03% saponins, while the ethanolic extract contained 1.70 ± 0.14% flavonoids, 1.47 ± 0.03% tannins, 0.68 ± 0.04% alkaloids and 6.07 ± 0.10% saponins. The aqueous extract of Dioscorea alata peel contained 1.95 ± 0.05% flavonoids, 2.18 ± 0.03% tannins, 0.25 ± 0.00% alkaloids and 3.96 ± 0.06% saponins, while the ethanolic extract contained 1.85 ± 0.14% flavonoids, 1.33 ± 0.04% tannins, 0.60 ± 0.00% alkaloids and 5.36 ± 0.01% saponins. There were no significant differences (P>0.05) in the flavonoid contents of the aqueous and ethanolic extracts of peels of the yam varieties, the aqueous extracts of the peels of Dioscorea bulbifera and Dioscorea alata contained significantly higher (P<0.05) amounts of tannins than their ethanolic extracts, while the ethanolic extracts of the peels of Dioscorea bulbifera and D.alata contained significantly higher (P<0.05) amounts of alkaloids and saponins than their aqueous extracts. The extracts of the yam peels exhibited various antifungal actions in a dose dependent manner and at 40% concentration exhibited higher inhibitory action on Botryodiploidia theobromae than standard Griseofulvin. Results show antifungal actions and medicinal potentials of the aqueous and ethanolic extracts of the peels of Dioscorea alata and Dioscorea bulbfera.