Study on the antibacterial activities of Hibiscus rosa-sinensis leaf extracts against Staphylococcus aureus and Klebsiella pneumoniae

Abstract

Hibiscus rosa-sinensis has been used in folk medicine to treat inflammation and bacterial infections for a long time. This study aims to evaluate the antibacterial activity of H. rosa- sinensis leaf extracts against Staphylococcus aureus and Klebsiella pneumoniae. Both are the major causes of hospital acquired infections. The results showed that the hexane and ethyl acetate fractions were similarly active to S. aureus but very weak active to K. pneumoniae. Both of these fractions were subjected to chromatograph using silica gel column eluted with hexane and ethyl acetate, and yielded 24 hexane subfractions (H1–H24) and 25 ethyl acetate subfractions (E1–E25). All subfractions had no or little activities to K. pneumoniae. Subfractions as H4, H14–H16, and E1, E7, E17–E19 had strong activities against S. aureus. Especially, E7 subfraction exhibited the strongest activity with MIC and MBC values of 0.1 and 0.2 mg/mL, respectively. GC-MS data showed that the main constituents of the E7 subfraction were neophytadiene, trans-phytol and 3,7,11,15-tetramethyl-2-hexadecen-1-ol.