In the Indian ayurvedic system of medicine, Nymphaea nouchali is used for the treatment of diabetes, cutaneous diseases, inflammation, liver disorders, urinary disorders, menorrhagia, blenorrhagia, menstruation problem, as an aphrodisiac, and as a bitter tonic. However, despite its traditional usage as an antimicrobial agent, there is no information regarding its effectiveness in infections caused by pathogenic microbes. Hence, we evaluated 70% ethanol extract of the seeds of N. nouchali for its antimicrobial activity.
The antimicrobial activity of the extract at five different concentrations was tested against few common human pathogenic microorganisms by agar disc diffusion assay. The Minimum Inhibitory Concentration of the extract was determined by the modified resazurin method. Streptomycin (10 μg/ml) and amphotericin B (10 μg/ml) were used as standards for antibacterial and antifungal study respectively. Few phenolic compounds were identified and quantified by standard HPTLC technique.
The zone of inhibition was extremely great for P. aeruginosa (25 mm), S. aureus (20 mm) and C. albicans (19 mm). MIC value was the least at 0.03 mg/ml for bacteria: K. pneumoniae, S. dysenteriae and E. coli and 0.31 mg/ml for fungi: C. albicans and T. mentagrophytes. Moreover, through HPTLC analysis few phenolic compounds were quantified, among which catechin content was found to be the highest (3.06%), followed by gallic acid (0.27%) and quercetin (0.04%).
The results therefore clearly indicates that the crude extract from N. nouchali seeds could be used as a potential source of natural antimicrobial agent owing to the presence of the phytoconstituent catechin in abundance along with other active compounds and supports the traditional use of the plant in the treatment of infections.