Integrated in silico design, synthesis, and biological evaluation of a brominated betulin derivative with anticancer and antibacterial activities

Betulin is a promising starting compound, but previous chemical modifications often yielded mixtures of isomers with unpredictable activity. To address this, we employed an integrated strategy combining in silico design with controlled chemical synthesis to create a novel, pure derivative. Our key innovation is the regioselective bromination at the C-30 position of the betulin scaffold. We obtained a unique derivative with a purity of >99% (confirmed by HPLC), which eliminates the problem of isomeric variability. Molecular docking predicted favorable binding and a dual mechanism of action against melanoma targets: BRAF kinase and Caspase-3 (CASP3). Pharmacokinetic (ADMET) profiling suggested high intestinal absorption and low toxicity, despite an increase in lipophilicity (LogP from 7.00 to 9.29). Biological studies demonstrated superior and selective cytotoxicity against metastatic melanoma cells (Lu1205 and Me45), with minimal toxicity to normal fibroblasts (NHDF IC₅₀ > 25 μg/mL). This resulted in a high Selectivity Index (SI >1.0). The mechanism of action involves the induction of apoptosis and the generation of reactive oxygen species (ROS). Furthermore, the compound exhibited selective antibacterial activity against Staphylococcus aureus (MIC 15.6 μg/mL).In summary, the highly pure C-30 brominated betulin derivative is a promising, multi-target therapeutic candidate for melanoma treatment.