Studies On The Anti-tumor Constituents Of Chinese Folk Medicine Pterocarya Tonkinesis (Franch.) Dode.

Pterocarya tonkinesis (Franch.) Dode. (Juglandaceae) forms a typical community of riverside season rain forest in Xishuangbanna area of Yunnan province, China. It has been used as a folk medicine for cancer by local people. No report of the chemical constituents and biological activities of this plant have been found up to now. In the course of screening for new anti-tumor agents from natural resources using mouse cdc2 mutant cell line tsFT210, we found that the alcoholic extract of P. tonkinesis significantly induced apoptosis and necrosis in tsFT210 cells. Thus, we have undertaken an investigation on the anti-tumor constituents of the title plant.The pilot experiments showed that the chloroform extract was the active ingredient of P. tonkinesis. The stems / barks of P. tonkinesis were extracted at room temperature with 60% aqueous alcohol to give an alcoholic extract, which was extracted successively with the same volume of chloroform to afford an active chloroform extract. Monitoring by the bioassay-guided isolation, the chloroform fraction was chromatographed on silica gel, Sephadex LH-20 and prepared TLC, and preparative reversed phase HPLC, respectively, to give 18 compounds. Their structures were elucidated on the basis of spectroscopic methods (1D-NMR, 2D-NMR, MS, IR, UV, etc.). The structure of pterocaryquinone (1), which was a new naphthoquinone derivative with a novel skeleton , pterocarine (6), which was a new cyclic diarylheptanoid, and pterocarinic acid (8), which was a new norsesquiterpene were determined, including the relative stereochemistry of 1 and 7 and the absolute configuration of 6 as R. The other compounds were identified as 5-hydroxy-2-ethoxy-1, 4-naphthoquinone (2), 4, 8-dihydroxy-l-tetralone (3), 3, 4-dihydro-2r, 4t, 8-trihydroxynaphthalen-l(2H)-one (4), 3, 4-dihydro-2r, 4c, 8-trihydroxynaphthalen-l (2H)-one (5), , myricatomentogenin (7), , alnincanone (9), oleanolic acid (10),arjunolic acid (11), ursolic acid (12), betulinic acid (13), 3-O- acetyl-betulinic acid (14), (24S)-ergosta-4, 6, 8 (14), 22-tetraen-3-one (15), (24R)-5oc-stigmastane-3, 6-dione (16), stigmasterol (17) and palmitic acid (18), respectively. Among them, compounds 2 and 7 are new natural products and compounds 1-11/13-18, were isolated from the genus Pterocarya for the first time.The anti-tumor activities of compounds 1-18 were evaluated by SRB method and flow cytometry, accompanied with the morphological observation of the cells under light microscope using mouse cdc2 mutant cells tsFT210, human leukemia carcinoma cells K562 and human colon carcinoma cells HCT-15. There were 15 compounds showed potential anti-tumor activities. Compound 1 exhibited apoptosis inducing activity, compounds 6, 7, 12, 15 and 18 showed both cell cycle inhibiting and apoptosis inducing activities, compounds 2, 3, 4, 5, 8, 10, 11, 13 and 14 inhibited the proliferation of the tumor cells. Among them, compound 2 showed the highest activity (ICso<4.59 nmol/mL). The anti-tumor activities of three new compounds 1, 6, 8 and five known compounds 2, 3, 7, 14, 15 were reported for the first time in the present study. Naphthoquinone and triterpenoids might play a main role of anti-tumor constituents of P. tonkinesis on the basis of their contents in the chloroform extract.To our knowledge, it was the first report on anti-tumor constituents of P. tonkinesis, which supported the record of its anti-tumor property. Furthermore, it also provided a clue for the future research and development of plants in Pterocarya.