Sophoraflavanone G from Sophora pachycarpa enhanced the antibacterial activity of gentamycin against Staphylococcus aureus

Abstract

In this study the enhancement effect of Sophora pachycarpa roots' acetone extract on the antibacterial activity of gentamycin was evaluated against Staphylococcus aureus. Disc diffusion and broth dilution methods were used to determine the antibacterial activity of gentamycin in the absence and presence of plant extract and its various fractions separated by TLC. A clinical isolate of S. aureus was used as test strain. The active component of the plant extract involved in enhancement of gentamycin's activity had Rf = 0.72 on a TLC plate. The spectral data (1H NMR, 13C NMR) of this compound revealed that this compound was 5,7,2′,4′-tetrahydroxy-8- lavandulylflavanone (sophoraflavanone G), previously isolated from Sophora exigua. In the presence of 0.03 μg/ mL of sophoraflavanone G the MIC value of gentamycin for S. aureus decreased from 32 to 8 μg/mL (a four-fold decrease). These results signify that the ultra-low concentration of sophoraflavanone G potentiates the antimicrobial action of gentamycin suggesting a possible utilization of this compound in combination therapy against Staphylococcus aureus. © 2006 Verlag der Zeitschrift für Naturforschung.