PHYTOCHEMICAL AND ANTIMICROBIAL SCREENING OF THE DIFFERENT SOLVENT EXTRACTS OF PILIOSTIGMA THONNINGI (FABACEAE)

ABSTRACT The World Health Organization studies have demonstrated that 80% of the world's population depends on medicinal plants for their primary health care. Many microorganisms are responsible for causing serious diseases of bacterial origin. Development of drug resistance in animal and human pathogens against commonly used antibiotics has necessitated a search for new antimicrobial substances from other sources including plants hence the adoption and integration of herbal practices in health systems. The study was carried out to determine and compare the phytochemical constituents and antibacterial activities of Piliostigma thonningii leaves using chloroform, dichloromethane, ethyl acetate and ethanol as extracting solvents. The plant materials were collected and crude extracts prepared by cold maceration using absolute chloroform, dichloromethane, ethyl acetate and ethanol to yield the chloroform (CHE), dichloromethane (DME), ethyl acetate (EAE) and ethanol (ETE) extracts respectively. The phytochemical screening of the extracts was performed using standard procedures. The extracts were tested in vitro against six clinical isolates of Staphylococcus aureus, Bacillus sublitis, Escherichia coli, Pseudomonas aeruginosa, Salmonella spp and Klepsiella pneumoniae at 0.06, 0.13, 0.25, 0.50 and 1.00mg/mL concentrations using the agar diffusion method and inhibitory zone diameters as the inhibitory parameters. The extractive yield of 1.46, 3.57, 2.37 and 8,94% was obtained for the CHE, DME, EAE and ETE respectively. Preliminary phytochemical screening revealed the presence of alkaloids, tannins, saponins, flavonoids, phytosterols, phenolics and terpenoids were present in the extracts except terpenoids which was absent in the CHE, DME and EAE. The activities of the crude extracts varied with the solvent used for extraction. The order of antibacterial activity of the extracts is in the order: EAE > ETE > CHE > DME. The ciprofloxacin standard at 5 pg/mL had superior activity than the extracts at the investigated concentrations. The activity of the plant extracts was found to be concentration dependent and could be attributed to the vital phytochemicals present in the extracts. The results suggested that the plant extracts could potentially contain antimicrobial compounds that hight bg uschul for the treatment of diverse microbial conditions, Future work should focus on the, isolation, and identification of the acrive compounds from the plant extrads that showed interesting activities and evaluation of their antimicrobial potential.