Abstract: Rhus chinensis Mill is a kind of Chinese medicine,which is parasitic gallnut in Anacardiaceae plants.In this study,high-speed counter-current chromatography was successfully applied to separate 7 active fractions from ethanol extract of R.chinensis. The best two-phase solvent system consisting of ethyl acetate-ethanolwater (5:1:5,v/v/v) was determined by HSCCC.The antibacterial activity of 7 fractions on Vibrio G1-1 was investigated by microcalorimetry.The fitting equation of relationship between constant of bacterial growth rate and drug concentration were calculated for each fraction,and the minimal inhibitory concentrations were got.The results showed that each separated fraction had a certain inhibitory effect on Vibrio G1-1, in which P5 fraction showed the best inhibitory activity.The minimum inhibitory concentration of P5 fraction was 0.10 mg/mL.This study established a useful method for the separation and preparation of active components from medicinal plants followed by the screening and evaluation of their antibacterial activity.It provided theoretical basis and reference to prevent and control bacterial disease in aquatic animal with Chinese medical plants.

Key words: Rhus chinensis Mill;high-speed counter-current chromatography;antibacterial fractions, Vibrio G1-1;microcalorimetry