Deuterated Curcuminoids: Synthesis, Structures, Computational/Docking and Comparative Cell Viability Assays against Colorectal Cancer.

A series of deuterated curcuminoids (CUR) were synthesized, bearing two to six OCD₃ groups, in some cases in combination with methoxy groups, and in others together with fluorine or chlorine atoms. A model ring-deuterated hexamethoxy-CUR-BF₂ and its corresponding CUR compound were also synthesized from a 2,4,6-trimethoxybenzaldehyde-3,5-d₂ precursor. As with their protio analogues, the deuterated compounds were found to remain exclusively in the enolic form. The antiproliferative activities of these compounds were studied by in vitro bioassays against a panel of 60 cancer cell lines, and more specifically in human colorectal cancer (CRC) cells (HCT116, HT29, DLD-1, RKO, SW837, and Caco2) and in normal colon cells (CCD841CoN). The deuterated CUR-BF₂ adducts exhibited better overall growth inhibition by NCI-60 assay, while for other CUR-BF₂ adducts the non-deuterated analogues were more cytotoxic. Results of the more focused comparative cell viability assays followed the same trend, but with some variation depending on cell lines. The CUR-BF₂ adducts exhibited significantly higher cytotoxicity than CURs. Structural studies (X-ray and DFT) and computational molecular docking calculations comparing their inhibitory efficacy with those of known anticancer agents used in chemotherapy are also reported.