Research Article

Phytochemical Profiling (GC MS) and the Antibacterial Activity of The Aqueous and Ethanolic Leaf Extract of Guiera Senegalensis on clinically isolated Escherichia coli and Staphylococcus aureus

Abstract

Background: The global rise of antimicrobial resistance (AMR) is the main threat to public health which lead to the urgent search for alternative therapies for medicinal plant. The present study investigates the phytochemical profiling (GC-MS) and antibacterial activity of aqueous and ethanolic leaf extracts of Guiera senegalensis against clinical isolates of Escherichia coli and Staphylococcus aureus. Methods: The antibacterial activity was evaluated using standard in vitro assays, including agar well diffusion, Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive compounds were assayed using Gas chromatography–mass spectrometry (GC-MS) technique. Results: Antimicrobial susceptibility testing demonstrated a clear dose dependent inhibitory effect of both extracts, with mean zones of inhibition increasing significantly from 125 μg/ml to 1000 μg/ml for both bacterial species. The ethanolic extract exhibited superior antibacterial activity compared to the aqueous extract at all tested concentrations, with inhibition zones reaching up to 18.32 ± 0.11 mm and 19.28 ± 0.28 mm for E. coli and S. aureus respectively at 1000 μg/ml, although still slightly lower than the standard antibiotic controls. MIC and MBC assays further corroborated these findings, showing lower MIC and MBC values for both extracts relative to control antibiotics. Notably, E. coli was more susceptible to the extracts than S. aureus, as reflected by generally lower MIC and MBC values. Phytochemical analysis revealed the presence of multiple bioactive secondary metabolites in both extracts, including flavonoids, alkaloids, phenols, saponins, e.t.c. Quantitative analysis indicated higher yields of alkaloids, phenols, saponins, and tannins in the ethanol extracts compared to aqueous extracts, highlighting the efficacy of ethanol as a solvent for extracting bioactive compounds. GC-MS profiling identified a complex array of compounds in various extract fractions, including predominant propylcyclohexane, (16.56%), methyl n-octadecanoate (39.90%), diterpenes (phytol), esters, and 2-phenylcyclobutyl) benzene. Squalene (54.35%) was notably abundant in the F2 aqueous fraction, underscoring its potential contribution to biological activity. These chemical constituents, many with known antimicrobial, antioxidant, and anti inflammatory properties, likely act synergistically to inhibit bacterial growth. Conclusion: The findings highlight the significant antibacterial potential of Guiera senegalensis leaf extracts, especially the ethanolic fraction, against clinically relevant bacterial pathogens. The combination of phytochemical potential and confirmed bacterial susceptibility supports the therapeutic promise of this plant as a source of novel antimicrobial agents, warranting further pharmacological and mechanistic studies.