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

Abstract

The <i>in vitro</i> antibacterial activity of <i>Hibiscus rosa sinensis</i> leaf ( methanolic, dichloromethane, ethyl acetate, n-hexane, and aqueous ) extracts were studied against Gram-negative (<i>Escherichia coli and Pseudomonas aeruginosa</i> ) and Gram-positive ( <i>Streptococcus faecalis</i>) 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 <i>E. coli</i> and <i>S. faecalis</i>, and were partially active against <i>P. aeruginosa</i>. 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 <i>Hibiscus rosa sinensis</i> 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 <i>Hibiscus rosa sinensis</i> leaf extracts.