Comparative Phytochemical and In Vitro Antimicrobial Activities of Four Nigerian Medicinal Plants

Abstract

Medicinal plants play significant role in healthcare delivery system as it have been utilized in the treatment and prevention of several diseases. Despite their importance, these plants are seldom handled within an organized and regulated sector; however, there is little regard to their future sustainability. This research was aimed at validating the phytochemical contents and in vitro antimicrobial effects of the extracts of the rootbark of Hamatostaphis barteri, stembark of Milicia excelsa, rootbark of Parkia biglobosa and aerial part of Polygonum senegalensis using standard methods. The plants were found to contain variably: alkaloids, anthraquinone, cardiac glycoside, flavonoid, saponins, tannins and terpenoids. Antimicrobial activities were assayed on Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Shigella dysenteriae, Aspergillus niger and Candida albicans. Haematostaphis barteri was resistant to most of the organisms except against Klebsiella pneumoniae with 10.00±0.00 mm. The extracts of Milicia excelsa, Parkia biglobosa and Polygonum senegalensis respectively 
inhibit with highest activity the growth of: Bacillus subtilis (21.33±0.58, 18.00±0.00, 19.67±0.58 mm) and Klebsiella pneumonia (20.00±0.00, 10.00±0.00, 18.67±1.15 mm). Milicia excelsa exhibited 20.00±0.00 mm against Candida albicans. The highest MBC/MIC was shown by Milicia excelsa against Bacillus subtilis and Staphylococcus aureus at 25.00/12.50 mg/mL while the lowest MBC/MIC of 50.00/25.00 mg/mL were expressed by Milicia excelsa, Parkia biglobosa and Polygonum senegalensis respectively against Candida albicans, Bacillus subtilis and Pseudomonas aeruginosa. Therefore, Milicia excelsa is the most highly active broad-spectrum extract followed by Polygonum senegalensis and Parkia biglobosa. Therefore, these activities against the test microorganism indicated that the extracts from most of these medicinal plants have a scientific backing in their use in the  African Traditional medicine owing to their effects against various microbial related infections.