Stereoselective Cytotoxicity of Enantiopure 3,3-Dichloro-γ-lactams: Correlating In Vitro Activity with In Vivo...

Enantiopure γ-lactams have emerged as promising scaffolds for anticancer drug development, yet the influence of stereochemistry on their biological activity remains insufficiently explored. In this study, we evaluated the in vitro cytotoxicity and in vivo toxicity of selected enantiopure 3,3-dichloro-γ-lactams and their corresponding epimers, with particular focus on their selectivity toward tumor versus non-tumor cells. The compounds were synthesized through green photoredox processes and tested for cytotoxicity using MTT and NRU assays in human cancer cell lines (A431, HeLa, MCF-7) and non-tumor controls (3T3, HaCaT). Toxicity and tolerability were further assessed in vivo using zebrafish (Danio rerio) embryos. Among the series, compound 3 displayed the most favorable selectivity index, combining potent anticancer effects with reduced activity toward non-tumor cells (HaCaT). Consistent with the in vitro results, compound 3 also demonstrated superior tolerability in zebrafish embryos compared with compound 4. These findings highlight the critical role of stereochemistry in modulating the cytotoxic and safety profiles of γ-lactams. Overall, compound 3 ((R)-3,3-dichloro-4-methyl-1-((S)-1-phenylethyl)pyrrolidin-2-one) emerges as a promising candidate for further preclinical development.