Phytochemical Screening and Antibacterial Activity of Gmelina arborea Leaf and Bark Extracts on Selected Bacterial Species

Abstract

_{Gmelina arborea, a deciduous tree in the family Lamiaceae, is widely used in traditional medicine for its therapeutic properties. This study investigates the phytochemical composition and antibacterial activity of G. arborea leaf and bark extracts against Staphylococcus aureus, Escherichia coli, and Salmonella typhi. The extracts were subjected to phytochemical screening using standard methods. Antibacterial activity was evaluated using the agar well diffusion method. Phytochemical screening revealed the presence of alkaloids, tannins, flavonoids, steroids/terpenoids, saponins, anthraquinones, and cardiac glycosides, while phenols were absent. Results indicated that the methanolic extracts exhibited a low antibacterial activity. The highest zones of inhibition were observed against E. coli, with 5.7 mm at 50 mg/ml for the leaf extract and 3.5 mm at 100 mg/ml for the bark extract. For Staphylococcus aureus, the inhibition zones were 3.5 mm at 50 mg/ml for the leaf extract and 2.2 mm at 100 mg/ml for the bark extract. Salmonella typhi showed inhibition zones of 3.8 mm at 50 mg/ml for the leaf extract and 4.1 mm at 100 mg/ml for the bark extract. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined, showing no inhibition at lower concentrations but indicating antibacterial properties at higher concentrations. These findings suggest that G. arborea possesses slightly potent antibacterial properties, validating its low traditional medicinal use but also indicating potential for developing new antibacterial agents from this plant. Further research, including clinical trials, is recommended to explore its full therapeutic potential.}