Lupane and 18α-oleanane derivatives substituted in the position 2, their cytotoxicity and influence on cancer cells

Lupane derivatives containing an electronegative substituent in the position 2 of the skeleton are often cytotoxic, however, the most active compounds are not selective enough. To further study the influence of a substituent in the position 2 in lupane and 18 alpha-oleanane derivatives on their biological properties, we prepared a set of 38 triterpenoid compounds, 19 of them new, most of them substituted in the position 2. From betulin, we obtained 2-bromo dihydrobetulonic acid and 2-bromo allobetulon and their substitutions yielded derivatives with various substituents in the position 2 such as amines, amides, thiols, and thioethers. Nitration of allobetulon and dihydrobetulonic acid gave 2-nitro and 2,2-dinitro derivatives. Fifteen derivatives had IC50 < 50 mu M on a chemosensitive CCRF-CEM (acute lymphoblastic leukemia) cell line and were tested on another seven cancer cell lines including resistant and two non cancer lines. 2-Amino allobetulin had IC50 4.6 mu M and caused significant block of the tumor cells in S and slightly in G2/M transition and caused strong inhibition of DNA and RNA synthesis at 5 x IC50. 2-Amino allobetulin is the most active derivative of 18 alpha-oleanane skeletal type prepared in our research group to date. (C) 2016 Elsevier Masson SAS. All rights reserved.