Characterization and antimicrobial properties of Prosopis africana, Pentaclethra macrophlla, and Erythrophleum suaveolen (Fabaceae) seed extracts and fractions on selected wood pathogens

Abstract

The study investigated antimicrobial properties of extracts and fractions characterized from seeds of three tropical trees species (Prosopis africana, Pentaclethra macrophlla, and Erythrophleum suaveolen). Methanol extracts of P. africana, P. macrophylla, and of E. suaveolens seeds were prepared and characterized using X-ray diffraction (XRD), column chromatography, and nuclear magnetic resonance (NMR) spectrometry. Results obtained revealed that P. macrophylla fractions contained lupenone in PM35, while a combination of triterpenes and lupeol in PM57 and daucosterol present in PM72 from P. africana. In contrast, E. suaveolens seed fraction EM86 contain Sitosterol/stigmasterol, wax and fatty substances. The extracts were active against Bacillus subtilis, Pseudomonas aeruginosa, Serratia marcescens, and Klebsiella spp test bacteria at zone of inhibition (ZoI) ranged from 18 mm to 20 mm. E. suaveolens methanol seed extract demonstrated notable activity against six fungi viz: Aspergillus nigre, Coniophora puteana, Fusarium sp, Rhizopus spp, and Sclerotium rolfsii, with ZoI values ranging from 16 mm to 20 mm. The results demonstrated varying degrees of antibacterial and fungicidal activities among the extracts against test bacterial and fungal strains. Only P. mycrophylla extract inhibited and killed Aspergillus nigre and Serpula lacrymans at MIC of 2.5 and 5 mg/ml, and MFC of 10 mg/Ml respectively.