Evaluation of the Antimicrobial Properties of the Ethanolic Extracts of some Medicinal Plant Seeds from South-West Nigeria

Abstract

The present study was conducted to evaluate the antimicrobial properties of the ethanolic extracts of some medicinal plant seeds against some clinical pathogens. The medicinal plant seeds investigated were Canna bidentata, Ceasalpinia bunduc, Hunteria umbellata, Hydrocotyle asiata, Megaphrynium macrostarchyum, Perinari excelsa, Rauwolfia vomitoria, Solanum dasyphyllum, Cola millenii and Sphenocentrum jollyanum. And the micro-organisms used for the antimicrobial assay were seven clinical pathogens, four bacteria: Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and three fungi: Aspergillus niger, Penicillium notatum, and Candida albican. The extraction of the bioactive component of the seeds was done by cold extraction using ethanol as solvent and the antimicrobial assay was carried out using agar well diffusion method. The ethanolic extracts of all the selected seeds were active against all tested pathogens with maximum antimicrobial activity observed in S. dassyphylum ranging from 26 mm to 19 mm and minimum in M. macrostachyum ranging from 20 mm to 12 mm at concentration range of 200 mg/ml to 25 mg/ml. For minimum inhibitory concentration (MIC) at concentration of 12.25 mg/ml S. dassyphylum was active against Escherichia coli and Staphylococcus aureus at 25 mg/ml while S. jollyanum was active against Bacillus subtilis at 25 mg/ml. The broad spectrum of the antimicrobial activities observed in this study is an indicative that the ethanolic extract of these plant seeds possess significant antibacterial and antifungal properties that could probably serve as antimicrobial agents in new drug formulation against pathogenic microoganisms.