Phytochemical composition and antibacterial activity of selected medicinal plants in a local community in the Philippines

Abstract

A survey of medicinal plants in a local community in Guimbal, Iloilo, Philippines identified ten plant species namely, hagonoy (Chromolaena odorata), pitogo (Cycas rumphii), adgao (Premna odorata), labnog (Ficus leucantatoma), talus (Homalomena rubescens), sinaw-sinaw (Peperomia pellucida), palochina (Senna alata), badyang (Alocasia macrorrhizos); bagacay (Bambusa vulgaris) and karupi (Alpinia sp). From these plants, two least-studied medicinal plants, B. vulgaris and Alpinia sp. were determined of their phytochemical composition and antibacterial properties following standard procedures. Aqueous and ethanolic extracts were prepared from these plants and the antibacterial activity of the extracts against two Gram-negative bacteria, Aeromonas hydrophila and Vibrio harveyi, and a Gram-positive, spore-forming bacterium, Bacillus albus were determined using Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC).Phytochemical analyses of B. vulgaris and Alpinia sp., indicated the presence of alkaloids, carbohydrates, glycosides, phytosterols, flavonoids and phenols and tannins. All extracts of the two medicinal plants inhibited the growth of A. hydrophila at a concentration of 0.5 g ml -1 . The MBC and MIC for B. vulgaris aqueous extract and Alpinia sp. ethanolic extract against V. harveyi showed inhibition at 0.5g ml -1 except for the MIC of B. vulgaris aqueous extract which was at 0.25 g ml -1 . There was no inhibition of B. albus from all extracts of both medicinal plants. These two medicinal plants can be further explored as potential sources of ingredients for the development of novel antibacterial drugs particularly in inhibiting Gram-negative bacteria.