Synthesis and biological evaluation of antitumor-active gamma-butyrolactone substituted betulin derivatives

The plant triterpenes betulin and betulinic acid (BA) are triterpenes featuring interesting pharmacological properties. Starting from substituted betulinic aldehydes, we used them as lead structures for the synthesis of several gamma-butyrolactones and butenolides. Their antitumor activity was examined for 15 cancer cell lines using a SRB-assay and their apoptotic action was documented by trypan-blue test and DNA laddering. Several compounds revealed a higher activity than betulinic acid.