Studies On The Antiumor Constituents Of Memecylon Polyanthum

Memecylon polyanthum H. L. Li, belonging to the family Melastomataceae, grows mainly in 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 research report had so far been seen on its chemical constituents and biologiacal activities. In our screening test, crude extract of M. polyanthum showed also antictumor activeity on mammalian cancer cells. Thus, a study on the antitumor constituents of M. polyanthum was undertaken in the present dissertation.Pulverized dry-stems (4.5 kg) of M. polyanthum 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 (5 L) was extracted successively with the same volume of CHCl3 and EtOAc to obtain EtOAc extract (84.4 g).The EtOAc extract (84 g) 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 1-7. Structures of the compounds obtained were investigated by modern spectroscopy (ESI-MS, HR-ESI-MS, UV, IR, 1H-NMR, 13C-NMR, DEPT, difference NOE experiment, 1H-1H COSY, HMQC, HMBC and NOESY) to elucidate their structures as given in Fig. 1. The antitumor activity for 1-7 was assayed by the SRB method using human cancer K562 cells. All the compounds tested showed to a different extent the antiproliferative effect against K562 cells.