Antibacterial activity and phytochemical characterization of Boswellia dalzielii Hutch. (Burseraceae) stem bark methanol extract and fractions against selected pathogenic bacteria

Abstract

The increasing prevalence of antimicrobial resistance has led to a more intensive search for alternative antimicrobial agents from medicinal plants. Boswellia dalzielii (Burseraceae) is traditionally used to treat infections, with previous studies reporting antibacterial activity. However, further investigation of its antibacterial properties and bioactive constituents is warranted. This study evaluated the antibacterial activity and phytochemical composition of B. dalzielii stem bark extracts against selected pathogenic bacteria. The stem bark was collected, dried, and extracted with methanol using cold maceration. The crude extract was fractionated into n-hexane, ethyl acetate, and aqueous fractions. Antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Salmonella bongori was assessed using agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by broth dilution. Gas Chromatography-Mass Spectrometry (GC-MS) analysis were performed to identify bioactive compounds. The extracts showed varying antibacterial activity, with the aqueous fraction demonstrating the highest activity (7.50 ± 0.00 mm to 18.45 ± 0.25 mm). MIC values ranged from 18.75 – 150 mg/mL, while MBC indicated bactericidal effects at higher concentrations. The identified compounds, including n-hexadecanoic acid, tetradecanoic acid, and 9,12-octadecadienoic acid, may contribute to the observed antimicrobial activity of B. dalzielii and warrant further investigation as potential antimicrobial agents.