Solvent Fractions of Terminalia Superba Engl. and Diels (Combretaceae) Leaves Extract Exhibit Broad-Spectrum Antibacterial Activity

Abstract

Amid the escalating global crisis of antibiotic resistance, Terminalia superba, an African traditional medicinal plant, was investigated for antibacterial activity. The methanol extract of the leaves was fractionated in ethylacetate, n-butanol, and n-hexane to afford the respective fractions. Using Fourier-transform infrared (FTIR), UV-Vis, and Gas Chromatography-Mass Spectrometry (GC-MS), the bioactive compounds were characterized. Antibacterial activity was evaluated via cup-plate agar diffusion and Minimum Inhibitory Concentration (MIC) tests against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Serratiam arcescens, Proteus mirabilis, and Candida albicans. The ethylacetate fraction (EF) demonstrated broad-spectrum activity against five pathogens (MICs: 5.33–10.67 mg/ml), while the n-butanol fraction (BF) inhibited mostly S. aureus and P. mirabilis (MICs: 5.33–10.67 mg/ml). The n-hexane fraction (HF) showed no activity. P-Cymene, Dodecane, and Undecane derivatives, were characterized as the antimicrobial constituents in the leaf extract.