Antibacterial Activity of Sequential Organic Extracts from Gliricidia sepium Leaves against Staphylococcus aureus

Natural products remain one of the most important sources of structurally diverse compounds for the discovery of new antimicrobial agents. Gliricidia sepium (Jacq.) Kunth ex Walp. is a medicinal species widely distributed in tropical regions and recognized as a rich source of flavonoids, phenolic acids, coumarins, glycosides, and other specialized metabolites with diverse biological activities. Previous phytochemical investigations of this species have led to the isolation of compounds such as oxytroside, o-coumaric acid, and melilotic acid, highlighting its potential as a source of bioactive natural products. In the present study, the influence of sequential solvent extraction on the recovery of antibacterial metabolites from G. sepium leaves was evaluated. Dried leaves were sequentially extracted by maceration using n-hexane, ethyl acetate, and methanol, and the resulting crude extracts were tested against Staphylococcus aureus using the agar disk diffusion assay at concentrations of 12.5, 25, 50, 100, and 200 mg/mL. Antibacterial activity depended on both solvent polarity and extract concentration. The ethyl acetate extract exhibited the highest antibacterial activity, producing inhibition zones of up to 0.8 cm at 200 mg/mL, followed by the methanolic extract (0.7 cm), whereas the hexane extract showed only slight activity (0.3 cm). The positive control produced inhibition zones ranging from 2.8 to 3.7 cm, confirming assay reliability. These findings demonstrate that sequential solvent extraction significantly influences the recovery of antibacterial constituents from G. sepium and further support this species as a promising source of bioactive metabolites for future bioactivity-guided fractionation, phytochemical characterization, and antimicrobial drug discovery.