In Vitro Cytotoxicity Assessment of Betulinic Acid Organic Salts on Triple-Negative Breast Cancer Cells

Abstract

The conversion of betulinic acid (BA) to organic salts is a strategic approach to modulate its physicochemical properties and biological activity. In our previous study, we demonstrated the enhanced cytotoxicity of certain amino acid ethyl ester betulinates ([AAOEt][BA]) compared to BA against hormone-dependent breast cancer cells (MCF-7). In this study, we extended our investigation to evaluate the cytotoxic response and thermodynamic properties of hormone-independent breast cancer cells (MDA-MB-231) following 72 h of treatment with the same series of betulinates. Our data reveal a lower cytotoxic response in MDA-MB-231 cells, indicated by higher half-maximal inhibitory concentration (IC50) values, which ranged between 31 and 109 µM. Differential scanning calorimetry analysis supported these findings, showing negligible changes in the thermodynamic parameters of the treated MDA-MB-231 cells. However, consistent with our previous observations, [LysOEt][BA]2, exhibited the highest cytotoxicity and induced the most pronounced morphological alterations in the cancer cells. Overall, our results suggest that MDA-MB-231 cells are less sensitive to [AAOEt][BA] compared to MCF-7 cells, likely due to their distinct phenotypic and genotypic profiles and differences in oncogenic signalling pathways. Nonetheless, the fact that [LysOEt][BA]2 enhances the cytotoxic activity of BA even in hormone-independent breast cancer cells underscores its therapeutic potential and warrants further investigation, particularly in the context of adjuvant breast cancer therapy.