Phytochemical Screening and Antimicrobial Activity of Ocimum gratissimum Leaf Extracts Obtained from Enugu State Markets

Ocimum gratissimum, commonly called scent leaf, is widely used in traditional medicine across South Eastern Nigeria for the treatment of bacterial infections, fever, and skin disorders. Despite its popularity, systematic phytochemical and antimicrobial investigations using standardised methods remain limited for samples sourced from Enugu State. This study aimed to determine the phytochemical constituents and evaluate the antimicrobial properties of ethanol, methanol, and aqueous extracts of O. gratissimum leaves obtained from three major markets in Enugu State. Standard qualitative and quantitative phytochemical analyses were conducted to identify alkaloids, flavonoids, tannins, saponins, and phenolic compounds. The antimicrobial activity was assessed using the agar well diffusion method against selected clinical isolates including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Candida albicans. Minimum inhibitory concentrations were determined using the broth microdilution technique. Preliminary results indicated the presence of flavonoids, alkaloids, and phenolic compounds at considerable concentrations across all extracts. The ethanol extract exhibited the highest zone of inhibition against S. aureus and E. coli, with MIC values comparable to standard antibiotics. These findings support the ethnopharmacological use of O. gratissimum and provide a scientific basis for its potential development into herbal antimicrobial formulations. Further isolation and structural characterisation of bioactive compounds are recommended. Keywords: Ocimum gratissimum, phytochemical screening, antimicrobial activity, Enugu State, minimum inhibitory concentration.