Combination of betulinic acid with diazen-1-ium-1,2-diolate nitric oxide moiety donating a novel anticancer candidate.

Betulinic acid (BA) is a complex lupane triterpenoid with unique antineoplastic activity. However, its antiproliferative activity is far from satisfaction. In order to improve its anticancer efficacy, betulinic acid was conjugated with a nitric oxide (NO)-releasing moiety to get a novel hybrid, BA-78. The antiproliferative activity of BA-78 against 6 cell lines and the ability of releasing nitric oxide were determined. The pro-apoptosis mechanism of BA-78 was investigated as well. BA-78 exhibited time-dependent release of NO, and it displayed higher antiproliferative potential than BA through increasing apoptosis and inducing cell cycle arrest at G1 phase. Western blotting results showed that BA-78 increased the expression of Bax, Bid, Bad and cytochrome C and reduced the level of anti-apoptosis proteins including Bcl-2 and Bcl-xl. Our study revealed that novel compound BA-78, possessing betulinic acid and nitric oxide (NO)-releasing moiety, could be developed as an antitumor agent.