Design, synthesis and biological evaluation of betulin-3-yl 2-amino-2-deoxy-β-d-glycopyranosides.

Betulin is a natural pentacyclic triterpenoid, possessing a lupane-structure, with a wide range of pharmacological activities. Its weak hydrosolubility hinders the biological activity of the compound and its derivatives. To circumvent this problem, we synthesized and tested in vitro three d-glycosaminosides of betulin. The structure of betulin was modified by incorporation of 2-amino-2-deoxy-d-gluco- and -d-galactopyranosyl moieties to its C-3 position. So far betulinyl glycosides containing these amino-sugars have not been reported in the literature. The structure of the studied derivatives was confirmed by ¹H and ¹³C NMR spectroscopy as well as mass spectrometry. The 28-O-acetylbetulin-3-yl 2-amino-2-deoxy-β-d-glucopyranoside and betulin-3-yl 2-amino-2-deoxy-β-d-gluco- and β-d-galactopyranoside were tested against the human pathogenic fungi and Gram-positive and Gram-negative bacteria. Moreover, the MTT assay of their cytotoxicity was performed on the MCF-7 breast cancer cell line and on the HDFa, human dermal fibroblasts. The Ames test on mutagenic properties completed our biological assays.