Studies On The Chemical Constituents Of Dillenia Kerrii And Their In Vitro Bioactivities

Dillenia kerrii Craib., an evergreen shrub, belonging to the family Dilleniaceae, grows mainly in Asian tropic regions and Xishuangbanna area of Yunnan province, China. It has been used as a folk medicine to cure certain cancers by local people of China, but no reports had so far been seen on its chemical constituents and biologiacal activities. In our screening test, crude extract of Dillenia kerrii showed also antictumor activity on mammalian cancer cells. Thus, a study on the antitumor constituents of Dillenia kerrii was undertaken in the present dissertation.Pulverized dry-fruits (5 kg) of D. kerrii were extracted with 85% aqueous alcohol at room temperature. The aqueous alcohol solution obtained was evaporated under reduced pressure to remove alcohol and the remained water suspension (4 L) was extracted successively with the same volume of CHCl3, EtOAc and n-BuOH to obtain CHCl3 extract (146 g), EtOAc extract (45 g), n-BuOH extract (405 g) and H2O residue.The extracts was separated by repeated column chromatography over polyamide, silica gel, Sephadex LH-20 and by preparative thin-layer chromatography on silica gel to obtain compounds 1-14. Structures of the compounds obtained were investigated by modern spectroscopy (UV, IR, ESI-MS, 1H-NMR, 13C-NMR, difference NOE experiment) to elucidate their structures as given in Table. 1.The antitumor activity for 1-14 was assayed by the MTT method using human cancer K562 cells. Compounds 1, 2 and 5 showed stronger cytotoxicity and apoptosis activities with IC50 value of 31μg·mL-1 (1), 29μg·mL-1 (2) and 23μg·mL-1 (5). Compounds 3, 6, 9-11, 13 and 14 showed slightly inhibited K562 cells at high concentrations; while compounds 4, 7, 8, 12 showed no obvious activities at the concentration of 100μg·mL-1.MTT method was employed to evaluate anti-hypoxia activity with ECV304 cells or PC12 cells of some compounds. The analysis indicated that compound 5, 6, 7, 10, 12 showed stronger defended ability for hypoxia cells, and compound 8, 9, 13, 14 showed no obvious activities.We also test the antibiosis activity of the extracts and some compounds. But they almost show no antibiosis activity except EtOAc extracts and n-BuOH extracts. In conclusion, compounds 6~8,10,12 are obtained from the genus Dillenia for the first time. The other compounds are isolated from the fruit of Dillenia kerrii for the first time, all of which showed different bioactivities at different degree. In addition, the antitumor activeity for 1~3, 5, 6, 9~11, 13, 14 and the anti-hypoxia activity for 5, 6, 7, 10, 12 are reported from the genus Dillenia for the first time in the present study. However, no reports had been seen on the chemical constituents and their bioactivities of the title plant so far. Thus, the chemical investigation was undertaken in order to find out the active components, especially antitumor constituents of Dillenia kerrii in the present dissertation.