South Asian Research Journal of Natural Products

Aims: This study aimed to investigate the antibacterial activity of Ficus sycomorus leaf and stem‑bark extracts against selected bacterial pathogens (Streptococcus pneumoniae, Klebsiella pneumoniae, and Pseudomonas aeruginosa), determine the phytochemical constituents, and identify bioactive compounds in the most active extracts.

Study Design: Laboratory-based experimental study involving sequential extraction, phytochemical screening, antibacterial susceptibility testing, and GC-MS profiling.

Place and Duration of Study: Department of Biological Sciences, Bingham University, Karu, Nasarawa State, Nigeria, between January and June 2025.

Methodology: Plant materials were extracted sequentially with hexane, ethyl acetate, methanol, and hot water (with a 24‑h standing step to maximise water‑soluble phytochemicals). Qualitative and quantitative phytochemical screening was performed using standard methods. Antibacterial activity was evaluated by disc diffusion (100–6.25 mg/mL) and broth microdilution (MIC/MBC) against standard strains of S. pneumoniae, K. pneumoniae, and P. aeruginosa. The most active extracts were analysed by gas chromatography–mass spectrometry (GC‑MS).

Results: The methanol extracts gave the highest yields (leaf 15.0%, stem bark 21.2%). Phytochemical screening revealed the presence of flavonoids, tannins, alkaloids, and steroids. The methanol stem‑bark extract (FSSM) produced the largest inhibition zone against S. pneumoniae (23.00 ± 1.00 mm at 100 mg/mL) and the lowest MIC (0.78 mg/mL). The methanol leaf extract was inactive against all three bacteria. GC‑MS of FSSM identified 12 bioactive compounds, including pyrazole dioxime (2.07%), 2‑myristonyl‑glycinamide (1.40%), and a benzodiazepine derivative (3.98%). The MBC of FSSM against S. pneumoniae was 100 mg/mL (MBC/MIC ratio ≈ 128), indicating predominantly bacteriostatic action. No bactericidal activity was detected against P. aeruginosa or K. pneumoniae at the tested concentrations.

Conclusion: The methanol stem‑bark extract of Ficus sycomorus exhibits significant in vitro antibacterial activity against S. pneumoniae, K. pneumoniae, and P. aeruginosa, attributable to its high flavonoid content and GC‑MS‑identified bioactive compounds. These findings support the traditional use of the plant for respiratory infections and justify further fractionation, toxicity assessment, and synergy studies.