<i>In vitro</i> antibacterial activity of <i>Hibiscus rosa sinensis</i> leaf extracts against some pathogens associated with urinary tract infections

Abstract

The in vitro antibacterial activity of Hibiscus rosa sinensis leaf ( methanolic, dichloromethane, ethyl acetate, n-hexane, and aqueous ) extracts were studied against Gram-negative (Escherichia coli and Pseudomonas aeruginosa ) and Gram-positive ( Streptococcus faecalis) bacteria. The methanolic extract was subjected to sequential liquid-liquid extraction using solvents of varying polarity and concentrations. Out of the 5 extracts, methanolic and dichloromethane extracts exhibited the highest antibacterial activity as measured using the zone of inhibition. This was followed by ethyl acetate and n-hexane extracts. At 200 mg/ml concentration, all extracts were considered active when tested with E. coli and S. faecalis, and were partially active against P. aeruginosa. The aqueous extract was inactive towards the three bacteria. The 200 mg/ml concentration showed no significant difference when compared with the positive control, amoxicillin (12.51μg/ml). This shows that Hibiscus rosa sinensis exhibits a promising antibacterial activity. Phytochemical analysis of the active fraction- the methanolic extract- showed the presence of alkaloids, tannins, glycosides, saponins, steroids, flavonoids, terpenoids, and anthraquinones. These bioactive components could be responsible for the antibacterial activity of Hibiscus rosa sinensis leaf extracts.