Antimicrobial activities of phenolic containing extracts of some tropical vegetables

Abstract

The present study sought to investigate the antimicrobial properties of phenolic containing extracts of Vernonia amygdalina (Va), Ocimum gratissimum (Og) and Manihot utilissima (Mu). Phenolic compound was characterized with the aid of a reversed phase HPLC/DAD/MS, and the antimicrobial activities of the extracts was assessed using agar-well diffusion method against some microorganisms, namely; Bacillus cereus, Escherichia coli, Salmonella spp, Pseudomonas aeruginosa, Staphylococcus aereus, Shigella spp, Enterobacter, Clostridium sporogenes, Bacillus subtilis and Proteus vulgaris. Ten, eight and four phenolic compounds were identified in Va, Og, and Mu respectively. The major phenolic compounds identified in Va were, Luteolin-7-O-glucoside, luteolin-7-O-glucuronide, luteolin and 1,5 dicaffeoyl quinic acid; nevadensin, vicenin-2, cichoric acid and rosmarinic acid in Og, while the major polyphenol in Mu were rutin and Kaempferol 3-O-rutinoside. The antimicrobial investigation showed that M. utilissima is active against only B. cereus of the entire tested organism. V. amygdalina is active against B. cereus, S. aereus and Shigella spp, while O. gratissimum is active against B. cereus, S. aereus and Shigella spp. The results obtained in the present investigation showed that the use of the vegetable materials as nutraceuticals may reduce the risk of microbial infections, which may partly be due to their phenolic composition.