Design, synthesis, in vitro antiproliferative activity evaluation of 2-alkanoylamidothiophene-3-carboxamide derivatives

A series of 2-alkanoylamidothiophene-3-carboxamide derivatives were synthesized based on the hit compound 1. The anti-proliferative activity of all the compounds in vitro against MGC-803 (stomach) and HCT-116 (colon) cancer cell lines using SRB assays were tested. Several compounds showed improved anti-proliferative activity against MGC-803 and HCT-116. SAR study revealed that chlorine substituent in the 2-acetylamino part was important for anti-proliferative activity. 5a, 11b, 11c and 11d were the most potent compounds against MGC-803 (IC₅₀s = 2.32-2.95 μM), and 5a and 11c also showed good anti-proliferative activity against HCT-116 cells (IC₅₀s = 3.41-3.75 μM). In addition, the anti-proliferative activity of 11b and 11d could be attributed to the apoptosis in HCT116 cells via caspase 3 activation, confirmed by flow cytometry assay and western blot analysis. Meanwhile, 11b and 11d decreased the mitochondrial membrane potential (MMP) in HCT116 cells.