Cytotoxic Profiling of 3',4',5'-Trimethoxychalcones Reveals Cell-Line-Dependent Cytotoxic Activity: An In Vitro and In Silico Study.

Cytotoxic activity of a series of 3',4',5'-trimethoxychalcones (1-25) was evaluated against multiple human cancer cell lines under uniform experimental conditions. The compounds were designed to bear simple substitutions on ring B to allow direct comparison of substitution effects. Most derivatives showed higher cytotoxic potency than the reference drug melphalan in the more responsive models. Several compounds exhibited submicromolar half-maximal inhibitory concentration (IC50) values (7, 8, 12, 13, 14, 17, 18, 20, 23). Low-nanomolar activity was also observed. Compounds 4, 5, 9, 10, 15, 16, and 24 showed particularly high potency. However, cytotoxic responses were strongly cell-line dependent. MCF-7 (estrogen receptor-positive breast carcinoma) and SKW-3 (T-cell leukemia) cells were highly sensitive, whereas MDA-MB-231 (triple-negative breast carcinoma) and K-562 (BCR-ABL-positive leukemia) cells were less responsive. In the doxorubicin-resistant HL-60/DOX (multidrug-resistant promyelocytic leukemia) subline, 10 retained activity. Compound 16 showed a nine-fold increase in potency relative to HL-60. Hierarchical clustering, principal component analysis (PCA), and descriptor-based quantitative structure-activity relationship (QSAR) revealed no transferable trends. Molecular docking showed moderate, non-selective interactions with multiple targets. Similar binding to human serum albumin was observed. Overall, these findings support cell-line-resolved evaluation and context-aware optimization in 3',4',5'-trimethoxychalcone-based anticancer research.