Antibacterial activity of persicaria minor (Huds.) leaf-extracts against bacterial pathogens

Abstract

Persicaria minor (Huds.) Opiz known as Small water-pepper and well recognized locally in Malaysia as “daun kesum” is an edible vegetable with nutritional and medicinal benefits utilized generally by South-east Asians. The present study was conducted to evaluate the antibacterial activity of standardized aqueous-ethanolic and water extracts of P. minor leaves. The leaves of the plant undergone extraction based on Malaysian Standard Guideline which is 30% aqueousethanol and absolute water as normally used in traditional medicine to produce the respective extract concentrates. Both extracts were evaluated for total protein and polysaccharide contents in which aqueous-ethanolic extract was found to possess high contents of proteins (1713.67 µg/ml) while contents of polysaccharides were high in absolute water extract (17.6 µg/ml). These measurements were used as a standard for different batch extract. The extracts were then tested against four standard strains of bacteria which are Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 11229, Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 15442 at different concentrations using discdiffusion (qualitative) and microplate dilution (quantitative) assays. For positive and negative control, penicillin and dimethylsulfoxide were used as controls, respectively. Both extracts showed antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values in the range of 50 to 100 mg/mL against S. aureus, E. faecalis, and E. coli, respectively with aqueous-ethanolic extract being more potent. However, none of the extracts were active against P. aeruginosa. Results from this study truly illustrated high potential of P. minor leaves as natural antibacterial agent for the elimination of various bacterial disease and infections.