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.