Uncovering New Antimelanoma Strategies: Experimental Insights into Semisynthetic Pentacyclic Triterpenoids

In view of the concerning rise in the incidence of cancer, natural products are a valuable source for the development of novel therapies. Among phytochemicals, the pentacyclic triterpenoids betulinic (BA), ursolic (UA), and oleanolic (OA) acids, as well as their 3-oxo-derivatives, have attracted considerable attention because of their significant anticancer potential. However, their clinical use is restricted by poor bioavailability, highlighting the need for obtaining semisynthetic derivatives with optimized pharmacokinetic and pharmacodynamic profiles. This study examined the biological effects of twelve new semisynthetic triterpenic and 3-oxo-triterpenic acid derivatives with methylphosphonate moieties of type C(17)-C(O)OCH₂P(O)(OMe)₂ and C(17)-C(O)OCH₂P(O)(ONa)₂ against the B164A5 murine melanoma cell line. Results have shown that cell viability declined in a dose-dependent fashion, as determined by the MTT assay. In comparison to their parent compounds, derivatives of BoA, OA, OoA, and UoA demonstrated enhanced antiproliferative potential. The Scratch method showed that the anti-migratory effect of all tested compounds was proportional to the dose, while the LDH test indicated no enhanced cytotoxicity relative to the parent compounds. According to the Hoechst 33342 staining, OA derivatives appeared to induce enhanced nuclear condensation signs than the parent compound. Additionally, the HET-CAM assay indicated no evidence of coagulation, hemorrhage, or vascular disintegration. Collectively, these findings suggest that these novel semisynthetic derivatives, particularly OA and OoA derivatives, may be included in future studies on their antimelanoma activity in light of the findings of this preliminary evaluation.