Abstract: Tert-butyl ester of 3,28-di-o-succinyl-alanylamino-betulin(SAB) and tert-butyl ester of 3,28-di-o-succinyl-glycylamino-betulin(SGB) were synthesized from betulin. The structure of the products were identified by ¹H NMR and MS. In order to study the effects of betulin derivatives on inhibiting tumor cells, using MTT assay, the SAB and SGB carried out on the HepG-2(Human Hepatocellular carcinoma cells) activity analysis. The results showed that SAB and SGB were specific to promote their apoptosis of HepG-2. The apoptosis was time and concentration dependent. Effect after 72 h ,IC₅₀ were 15.33 μmol/L and 17.01 μmol/L. IC₅₀ of SAB and SGB was significantly lower than IC₅₀ of betulin. On HepG-2 cells, the IC₅₀ of SAB is about 1/6 of the IC₅₀ of betulin; The IC₅₀ of SGB is about 1/5 of the IC₅₀ of betulin. The results showed that SAB and SGB's anti-tumor activity was better than betulin.

Key words: betulin, tert-butyl ester of 3, 28-di-o-succinyl-alanylamino-betulin, tert-butyl ester of 3, 28-di-o-succinyl-glycylam-ino-betulin, HepG-2