Antibacterial properties of Dioscorea alata (purple yam) peel extracts against selected gram-negative and gram-positive bacteria

MIKA MONIQUE Z. GRANTOZA, ALLYZZA T. MATIONG, IAN RODRIGO B. SEGUANO, and ZENNIFER L. OBERIO
Philippine Science High School – Western Visayas Campus, Brgy. Bito-on, Jaro, Iloilo City 5000, Department of Science and Technology – Science Education Institute, Philippines

Abstract
Rapid emergence of resistant bacteria is endangering the efficiency of antibiotics which previously saved millions of lives. The antibacterial agent in plants is a notable source of new antibiotics alternatives. In the Philippines, Dioscorea alata is a main export banner crop since the country is the only supplier of the tuber in the world market. D. alata tubers have bioactive compounds including alkaloids, tannins, flavonoids, and saponins. In this study, the antibacterial properties of Dioscorea alata peel extracts were evaluated against four selected human pathogens including gram-negative bacteria, Escherichia coli and Enterobacter aerogenes and gram-positive bacteria, Staphylococcus aureus and Bacillus subtilis. Extracts were obtained through maceration and rotary evaporation. Activities of different concentrations (25%, 50%, 75%, 100%) of the peel extracts were evaluated using agar-well diffusion method on Mueller-Hinton agar. Inhibitory properties were identified only against selected gram-positive bacteria strains, S. aureus (50%, 75%, 100%) and B. subtilis (75% and 100%). For more results, D. alata extracts are recommended to be tested against other bacteria strains by different solvents with varying polarity.

Keywords: antibacterial, agar well-diffusion method, Dioscorea alata, purple yam, peels