[Synthesis and cytotoxicity of allobetulin derivatives].

The synthesis and screening of antitumor activity in vitro (cytotoxicity) of various oxygen, nitrogen, sulfur and platinum-containing derivatives of allobetulin, including different arrangements of the double bonds in the A and B rings, penta- and hexacyclic ring A, 21-acetyl-20,28-epoxy-18α,19βH-ursane-isomeric cycle E, was carry out. (3R,5R)-19β,28-Epoxy-4,5-seco-18α-olean-3(5)-ozonide and 2,3-indolo-21β-acetyl-20β,28-epoxy-18α, H-19β-ursane showed significant cytotoxic activity against melanoma MeWo and Leukemia SR cells, appropriately. (3S,5S)-Diastereomer of the first compound showed no cytotoxicity.