The phytochemical constituents and relative antimicrobial activities against clinical pathogens of different seed extracts of Cola nitida (Vent.), Cola acuminata (Beauvoir) and Garcinia kola (Heckel) grown in South West, Nigeria

Abstract

The aim of the study was to investigate the phytochemical properties and the relative antimicrobial activity of aqueous, ethanol and methanol seed extracts of Cola nitida, Cola acuminata and Garcinia kola respectively. The phytochemicals were screened by qualitative and quantitative methods. Three different solvents: aqueous, ethanol and methanol were used to extract the bioactive compounds from the three species of Kola Qualitatively analyzed phytochemical constituents in the seed extracts of the three Cola species included Alkaloids, tannins, flavonoids, steroids, terpenoids and cardiac glycosides. The microorganisms assayed for antimicrobial activity using the agar diffusion method were: the gram positive Staphylococcus aureus and Bacillus spp, the gram-negative Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae respectively. Studies on sensitivity patterns of zones of inhibition exhibited by the crude methanol, ethanol and aqueous extracts of Garcinia kola, Cola nitida and Cola acuminata nuts showed relative degree of inhibitory effects against the test microorganisms: Escherichia coli, Staphylococcus aureus, Lactobacillus, Pseudomonas aeruginosa and Klebsiella pneumonia. The zones of inhibition for Escherichia coli was the highest with methanol extract of 36.0mm followed by Klebsiella pneumonia with 25.5mm followed by Staphylococcus aureus with 23.5mm, and Pseudomonas aeruginosa with 18.5mm and Lactobacillus with 17.5mm respectively. Highest zones of inhibition started from methanol, ethanol and aqueous, their diameter of inhibition increases with increase in their concentrations. The methanol preparation of Garcinia cola nut was found to exhibit more significant inhibitory action (p