OBJECTIVETo investigate the effects of novel triterpene (12-oleanene-3beta, 6alpha-diol) from Celastrus hypoleucus on the proliferation and apoptosis of human colorectal cancer cell line RKO.

METHODThe inhibitory effect of the novel triterpene on RKO cell proliferation was assayed by MTT dye reduction. The morphology of apoptotic cells was observed with AO/EB double fluorescence staining and HE staining, DNA fragment with electrophoresis on agarose gels, sub-diploid peak and cell cycle with flow cytometer (FCM).

RESULTNovel triterpene (12-oleanene-3beta, 6alpha-diol) from C. hypoleucus significantly inhibited proliferation of RKO cells in dose-dependent and time-dependent manner, the IC50 was (12.20 +/- 0.79) microg x mL(-1) at 48 h. Typical apoptotic changes were observed in RKO cells under the fluorescence microscope and the light microscope. DNA ladder was detected on agarose gels at concentrations from 10 microg x mL(-1) to 20 microg x mL(-1) at 48 h. With FCM methods, dose-dependent apoptosis-induced effect was observed in RKO cell line after treatment of triterpene for 48 h, and the apoptotic rates were increased from(2.93 +/- 0.84) % to (50.79 +/- 6.61) % at concentrations from 2.5 microg x mL(-1) to 20 microg x mL(-1). DNA histograms data from FCM analysis showed that the number of cells was obviously reduced during G0-G1 phase and G2-M phase, but not during S phase for RKO cell line after treatment with various concentrations of the triterpene for 48 hours.

CONCLUSIONNovel triterpene (12-oleanene-3beta, 6alpha-diol) from C. hypoleucus can induce apoptosis and has inhibition effect on the proliferation in RKO cell line.