Novel Semisynthetic Betulinic Acid−Triazole Hybrids with In Vitro Antiproliferative Potential

Betulinic acid, BA, is a lupane derivative that has caught the interest of researchers due to the wide variety of pharmacological properties it exhibits towards tumor cells. Because of their prospective increased anti−proliferative efficacy and improved pharmacological profile, BA derivatives continue to be described in the scientific literature. The current work was conducted in order to determine the antiproliferative activity, under an in vitro environment of the newly developed 1,2,4−triazole derivatives of BA. The compounds and their reaction intermediates were tested on three cancer cell lines, namely RPMI−7951 human malignant melanoma, HT−29 colorectal adenocarcinoma, A549 lung carcinoma, and healthy cell line (HaCaT human keratinocytes). BA−triazole derivatives 4a and 4b revealed lower IC50 values in almost all cases when compared to their precursors, exhibiting the highest cytotoxicity against the RPMI−7951 cell line (IC50: 18.8 μM for 4a and 20.7 μM for 4b). Further biological assessment of these compounds executed on the most affected cell line revealed a mitochondrial level induced apoptotic mechanism where both compounds inhibited mitochondrial respiration in RPMI−7951 cells. Furthermore, the triazole−BA derivatives caused a significant decrease of the anti−apoptotic Bcl−2 gene expression, while increasing the pro−apoptotic BAX gene’s expression.