Abstract: The barks of Pterocarya stenoptera, a traditional Chinese drug normally used to treat bacterial and fungous skin diseases for hundreds of years,was used to screen antibacterial constituents systematically in this study.By methods of extraction,precipitation,silica gel column adsorption chromatography and Sephadex LH-20 gel chromatography using a bioassay-guided fractionation technique with antibacterial experiments in vitro, it was found that only the low polarity components (chloroform portion,ethyl acetate portion and petroleum ether portion) from the ethanol extract of P.stenoptera showed antibacterial activities,and 4 needlelike liposoluble compounds with antibacterial activity were firstly isolated from chloroform portion and ethyl acetate portion.After the purity were confirmed by TLC,the 4 compounds were identified as 5-hydroxynaphthalene-1,4-dione (1),5-hydroxy-2-methoxynaphthalene-1,4-dione (2),2,6-dimethoxycyclohexa-2,5-diene-1,4-dione (3) and 3,4,5-trihydroxybenzoic acid (4) by EI-MS,1D NMR (¹H, ¹³C,DEPT) and 2D NMR (HSQC, ¹H-¹H COSY,HMBC).Antibacterial substance basis of P.stenoptera include several antibacterial compounds,which separately belong to 3 kinds of parent nucleus (benzoquinone,naphthoquinone and benzoyl structure).The multiple activities center antibacterial substance basis may not only provide the foundation for studying of the quality criteria of P.stenoptera,but also for production of antibacterial plant drugs with low drug resistance for externally used.

Key words: bark of Pterocarya stenoptera C.DC., antibacterial compound, bioassay-guided fractionation technique, isolation and purification, structural identification