New betulinic acid derivatives induce potent and selective antiproliferative activity through cell cycle arrest at the S phase and caspase dependent apoptosis in human cancer cells

► This paper reports the activity of new betulinic acid derivatives in human cancer cell lines. ► The new compounds showed 2-45 times improved cytotoxic when compared to betulinic acid. ► All the compounds could effectively trigger cell apoptosis in vitro. ► They also induced cell cycle arrest at the S phase.