Effect of Plant Extract Combinations on Some Bacterial Pathogens

Abstract

Increase in antimicrobial resistance coupled with successful treatment of various diseases with herbal medications has triggered the upsurge in research geared towards harnessing the medicinal potentials of various plants. The aim of this study was to evaluate the phytochemical composition of Bryophyllum pinnatum, Ocimum gratissimum, Jatropha curcas and Ficus exasperata and their combined antibacterial activity on Escherichia coli, Salmonella typhi, Staphylococcus aureus, and Klebsiella pneumonia. Plant leaves were air–dried, extracted with ethyl-acetate and water with subsequent qualitative analyses for phytochemical compounds. Bacterial pathogens were obtained from University of Benin Teaching Hospital (UBTH), confirmed, and their zones of inhibition studied at 50, 40, 30, 20 and 10 mg/ml of extract combinations. The presence of phenols, tannins and saponins were confirmed in all extracts while alkaloids were present in all ethyl acetate extracts and terpenoids in all aqueous extracts. Different zones of inhibition were measured with the different extract combinations with E. coli having its highest zone of inhibition with the combination of Bryophyllum pinnatum and Ocimum gratissimum in 30 mg/ml (27.25 ± 1.70 mm). However, the highest zone of inhibition observed in the study was with S. aureus in 10 mg/ml concentration of ethyl acetate plant extracts of Ocimum gratissimum and Ficus exasperata (31.75 ± 3.07 mm). The Gram positive cell wall of S. aureus is less complex and therefore, more susceptible to bio-agents. Antibacterial activities of these extracts are attributed to the presence of secondary metabolites that make them good bio-agents for production of antibacterial drugs.

Keywords: Plant extracts, Inhibition zones, Escherichia coli, Staphylococcus aureus