Cytotoxic Potential of Betulinic Acid Fatty Esters and Their Liposomal Formulations: Targeting Breast, Colon, and Lung Cancer Cell Lines

Betulinic acid is a lupane-type pentacyclic triterpene mostly found in birch bark and thoroughly explored for its wide range of pharmacological activities. Despite its impressive biological potential, its low bioavailability has challenged many researchers to develop different formulations for achieving better in vitro and in vivo effects. We previously reported the synthesis of fatty acid esters of betulinic acid using butyric, stearic, and palmitic acids (But-BA, St-BA, and Pal-BA) and included them in surfaced-modified liposomes (But-BA-Lip, St-BA-Lip, Pal-BA-Lip). In the current study, we evaluated the cytotoxic effects of both fatty acid esters and their respective liposomal formulations against MCF-7, HT-29, and NCI-H460 cell line. The cytotoxic assessment of BA derivatives revealed that both the fatty esters and their liposomal formulations acted as cytotoxic agents in a dose- and time-dependent manner. But-BA-Lip exerted stronger cytotoxic effects than the parent compound, BA and its liposomal formulation, and even stronger effects than 5-FU against HT-29 cells (IC50 of 30.57 mu M) and NCI-H460 cells (IC50 of 30.74 mu M). BA's fatty esters and their respective liposomal formulations facilitated apoptosis in cancer cells by inducing nuclear morphological changes and increasing caspase-3/-7 activity. The HET-CAM assay proved that none of the tested compounds induced any irritative effect, suggesting that they can be used safely for local applications.