DOI: 10.11648/j.ijpc.20261203.12 ISSN: 2575-5749

Antibacterial Potential of Polyalthia longifolia (Sonn. Thwaites) Seed and Pericarp Extracts Against Salmonella typhi

Pass Chijindu, Jude Igborgbor, Michael Nwayo
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This study evaluated the antibacterial activity of ethanolic extracts of Polyalthia longifolia seeds and pericarp against Salmonella typhi and Escherichia coli . Antibacterial screening using agar diffusion revealed concentration-dependent effects, with maximum inhibition observed at 100% concentration. The seed extract exhibited slightly higher activity against S. typhi (13 mm) compared to the pericarp extract (12 mm), while the pericarp extract showed greater inhibition of E. coli (9 mm) than the seed extract (7 mm). Both extracts displayed reduced activity at lower concentrations, consistent with the dose-dependent nature of crude plant extracts and reflecting the influence of bioactive metabolite concentration on antibacterial potency. Further insights were obtained through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. The seed extract inhibited E. coli at 50 mg/mL and demonstrated bactericidal effects against both S. typhi and E. coli at 100 mg/mL. In contrast, the pericarp extract required 100 mg/mL to inhibit both organisms and primarily exhibited bacteriostatic activity. These findings indicate that the seed extract possesses greater antibacterial potency than the pericarp, particularly against E. coli , aligning with previous studies highlighting the antimicrobial potential of P. longifolia seeds and their bioactive phytochemicals. Although ciprofloxacin produced larger inhibition zones (16–22 mm), the antibacterial activity of both extracts remains pharmacologically relevant. Collectively, these results demonstrate that P. longifolia seeds and pericarp have significant antibacterial properties and support their potential as a natural source of bioactive compounds for managing enteric bacterial infections.

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