In vitro anticancer studies of alpha- and beta-D-glucopyranose betulin anomers

Four derivatives of betulin containing a D-glucopyranosyl moiety at C3 position were synthesized and characterized by (1)H and (13)C NMR spectroscopy as well as mass spectrometry. The crystal structure of 28-O-acetylbetulin-3-yl-beta-D-(2',3',4',6'-tetra-O-acetyl)glucopyranoside was determined. The compounds were tested against fifteen tumor cell lines of different histogenic origins. The alpha- and beta-anomers of 28-O-acetylbetulin-3-yl-D-glucopyranoside, exerted a dose dependent antiproliferative action towards the tumor cell lines. Treatment of HCT-116 cells for 24h induced apoptosis, which was confirmed by the appearance of a typical ladder pattern in the DNA fragmentation assay and cell cycle analysis. The alpha- and beta-anomers of 28-O-acetylbetulin-3-yl-D-glucopyranoside seem to induce apoptosis by activation of different upstream caspases on colon cancer HCT-116 cell line.