Phytochemical composition and antibacterial efficacy of aqueous leaf extracts of Guiera senegalensis against selected clinical isolates

Abstract

The increasing prevalence of multidrug-resistant bacterial pathogens underscores the urgent need for alternative antimicrobial agents. This study evaluated the phytochemical composition and antibacterial activity of aqueous leaf extract of Guiera senegalensis against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus mutans. Fresh leaves of G. senegalensis were collected from Bidir village of Azare, Katagum local government Area in Bauchi state Nigeria, air-dried, and macerated in distilled water. The bacterial isolates were obtained from the stocked specimens of the Microbiology laboratory, Sa’adu Zungur University Gadau. Phytochemical screening of the extract revealed the presence of flavonoids, alkaloids, phenolic acids, carbohydrates, saponins, and tannins, while cardiac glycosides were absent. Antibacterial activity of the extract was assessed using the disk diffusion method at varying concentrations  62.5 mg/mL, 125 mg/mL, and 250 mg/mL. The extract produced concentration-dependent inhibition zones, with the highest activity at 250 mg/mL: 13.67 mm (S. aureus), 13.00 mm (S. epidermidis), and 11.33 mm (S. mutans). The minimum inhibitory concentrations (MICs) were 15.625 mg/mL for S. aureus and S. epidermidis, and 31.25 mg/mL for S. mutans. The minimum bactericidal concentration (MBC) for all isolates was 125 mg/mL. These findings provide scientific support for the ethnomedicinal use of G. senegalensis and highlight its potential as a source of bioactive compounds for developing novel antibacterial agents. Further studies are recommended to isolate and characterize the active constituents and evaluate their mechanisms of action.