ABSTRACT
Aims: The study aims to investigate the antimicrobial activities of the leaves, seeds, bark, and root of Pterocarpus santalinoides plant. Study Design: Agar well diffusion and Agar well dilution methods were used to test the preliminary antimicrobial and minimum inhibitory/bactericidal/fungicidal concentrations respectively of Pterocarpus santalinoides plants. Place and Duration of Study: Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmaceutical Sciences, Nnamdi Azikiwe University, Agulu Campus, Nigeria, between February – October, 2017. Methodology: Primary extraction and fractionation of the plant parts were undertaken with methanol, butanol, ethyl acetate, and n-hexane. Agar diffusion method for the primary antimicrobial screening on Muller-Hinton agar (bacteria) and Sabouraud dextrose agar (fungi) were used to assess the antimicrobial activities of the sixteen (16) samples on some microbial isolates namely Salmonella typhi, Escherichia coli, Candida albicans, Aspergillus niger, Microsporon canis, and Trichophyton rubrum. The minimum Inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration (MBC/MFC) and percentage inhibition diameter growth (PIDG) of the samples that yielded positive activity were also evaluated. Results: Twelve (12) samples exhibited inhibitory activity on at least one or more of the test isolates. The MIC range observed for the extracts and fractions that yielded positive activity was 12.5 – 100 mg/ml. The n-hexane fraction of the plant root indicated the best value of 12.5 mg/ml against M. canis. The best MBC/MFC value of 25 mg/ml was observed with the ethyl acetate fraction of the bark (against E. coli and M. canis) and the n-hexane fraction of the root (against M. canis). The result showed S. typhi to be the most sensitive organism to the metabolites of P. santalinoides. Extended-spectrum activity was observed with the ethyl acetate fraction of the bark against three (3) of the test isolates namely S. typhi, E. coli and M. canis. The determination of PIDG values for the test organisms against the plants’ extracts/fractions showed that crude methanol extract (28.57%) and ethyl-acetate fraction (0.14%) of the leaves, butanol fraction (0.14%) of the root (all against S. typhi) were the most potent test samples. Conclusion: The results indicated that the plant parts may have potential medicinal values and confirmed its use in traditional medicine.