RESUMEN
The Croton genus (Euphorbiaceae) is recognized as a promising source for identifying bioactive compounds with antiproliferative activity. However, knowledge on the chemical composition and activity of Croton floribundus, Croton echinocarpus, and Croton zehntneri is limited. Thus, this study aimed to investigate the antiproliferative activity of these species on cells derived from tumoral breast, lung, and melanoma cells, and primary fibroblasts derived from human skin. Metabolomic strategies were applied via ultra-performance liquid chromatography coupled with high-resolution mass spectrometry and multivariate statistical analysis to target the main active compound. The C. floribundus leaf extract exhibited the highest activity, with an IC50 value lower than that of the reference drug - temozolomide - in the most responsive cell line - SK-MEL-147 - and in all the evaluated melanoma cell lines (SK-MEL-147, CHL-1 and WM-1366). Four tetrahydrofurofuran lignans were isolated for the first time from the most promising fraction of the C. floribundus extract. According to the metabolomic and multivariate statistical analyses, the isolated lignan epi-yangambin constituted the main antiproliferative compound against SK-MEL-147; furthermore, it exhibited selective antiproliferative activity for this cell line (IC50 = 13.09 µg/mL and selectivity index = 3.82; temozolomide, IC50 = 121.50 µg/mL) due to, at least in part, its ability to inhibit cell cycle progression at G2/M. This is especially relevant considering the high resistance of melanoma cells to available drugs. Thus, epi-yangambin can serve as a prototype for further antiproliferative investigations.