Studies On The Antitumor Constituents Of Rhus Chinensis

Rhus chinensis Mill.(family Anacardiaceae), a traditional Chinese medicinal plant recorded in the Dictionary of Chinese Crude Drugs (Zhongyao Da-Cidian in Chinese), has long been used in traditional Chinese medical care system to treat many diseases such as inflammation, impaludism, and so on. It is used also as a folk medicine to cure certain cancers by local Chinese people, and its cell cycle inhibitory and apoptosis inducing activities were recognized in our preliminary screening test.Even though there are several kinds of bioactive compounds reported from Rhus chinensis, no more research report had been so far seen on its anti-tumor constituents except for 2-hydroxy-6-pentadecylbenzoic acid isolated from the leaves of the same plant as its only one anti-tumor constituent. Thus, a research work was undertaken on the title plant in the present dissertation to explore its anti-tumor constituents.In a preliminary experiment, a little amount (1 g) of the pulverized heartwood of R. chinensis was extracted with 75% aqueous alcohol to obtain a crude extract. A part of this extract was suspended in water and then extracted with CHCl3, EtOAc and n-BuOH successively to divide into four parts, CHCl3 extract, EtOAc extract, n-BuOH extract and a water soluble part. Then, the anti-tumor activity of these extracts was assayed by the SRB method using human K562 cancer cells. In the bioassay, the EtOAc extract showed the strongest activity among the samples tested.According to the result of the above preliminary experiment, the large amounts (5 Kg) of the pulverized dry-stems of R. chinensis were exhaustively extracted with 75% aqueous alcohol at room temperature to give an aqueous alcohol solution. After the aqueous alcohol solution was evaporated to remove alcohol, the remained water suspension (1 L) was extracted successively with the same volume of CHCl3, EtOAc and n-BuOH to obtain CHCl3 extract (30.5 g), EtOAc extract (91.8 g), n-BuOH extract (44.5 g) and a water soluble part (1 L). As the strongest activity was recognized on the EtOAc extract, further investigation was carried out on the anti-tumor components of EtOAc extract.The EtOAc extract (91.8 g) was separated by repeated colum chromatography over polyamide, silica gel and Sephadex LH-20 and by preparative sililca gel thin-layer chromatography to obtain compounds 1-6. The chemical structures of 1-6 were investigated by morden spectroscopy and eventually they were identified as...