Phytochemical and antibacterial properties of root extracts from Portulaca oleracea Linn. (Purslane) utilised in the management of diseases in Nigeria

Abstract

Background: Bacteria as etiological agents have been reported to cause many diseases and have increased the rate of mortality globally. Their resistance to conventional medicine has made medicinal plants a credible alternative in the management of diseases caused by bacterial infection. In the recent times many research efforts have been directed towards the exploration of phytoconstituents with antibacterial potentials. Medicinal plants are widely used as antibacterial agents because of their high therapeutic performance, low toxicity, and affordability.

Aim: This work was designed to identify secondary metabolites present in root extracts of ethno-medicinally utilised Portulaca oleracea L. and evaluate their antibacterial activities.

Setting: The roots of P. oleracea L. were obtained from the Forest Research Institute of Nigeria (FRIN), Ibadan, Nigeria and authenticated in the Forest Research Herbarium, where voucher samples were deposited with specimen voucher number FIH-112030.

Methods: Phytochemical screening was carried out using standard qualitative tests and the antibacterial activity of extracts was evaluated using agar well diffusion method whilst the minimum inhibitory concentration (MIC) was evaluated by micro-dilution method. The screening was assessed against Bacillus subtilis, Candida albicans, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Micrococcus luteus, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus and Streptococcus agalactiae, which are responsible for the transmission of common diseases in Nigeria. Statistical analysis was performed by one-way analysis of variance (ANOVA) with GraphPad Prism 8.0 and results were expressed as mean ± s.d. Duncan’s New Multiple range test were applied at 0.05 level of significance (p < 0.05).

Results: Phytochemical screening of P. oleracea L. showed the presence of carbohydrates, steroids, triterpenes, cardiac glycosides, and saponins. All extracts showed a high level of minimum inhibition concentration against the pathogens except K. pneumoniae, M. luteus and P. aeruginosa. Generally the antibacterial activity of extracts increased with decrease in polarity as compared with ciprofloxacin. The mean (± s.d.) values were significantly different by Duncan’s multiple range tests with p < 0.05.

Conclusion: Portulaca oleracea L. has been identified for the first time as a good antibacterial agent, which corroborates the ethno-medicinal uses of the plant.