Optimization of pyrrolizine-based Schiff bases with 4-thiazolidinone motif: Design, synthesis and investigation of cytotoxicity and anti-inflammatory potency

Two new series of pyrrolizine-5-carboxamides were synthesized and evaluated for their anticancer and anti-inflammatory activities. The new compounds exhibited potent cytotoxicity (IC50 = 0.10–22.96 μM) against three cancer (MCF-7, A2780 and HT29) cell lines with selectivity index in the range of 1–258. Moreover, these compounds also exhibited significant anti-inflammatory activity (18.13–44.51% inhibition of inflammation) mediated by inhibition of COX-1/2 with preferential inhibition of COX-2. The study of SAR revealed favorable cytotoxic outcomes of the aliphatic side chain and 4-thiazolidinone moiety at C6 of the pyrrolizine nucleus, while anti-inflammatory activities was improved with the (hetero)aromatic substituents. The IC50 values which inhibit COX-2 were higher than those needed to inhibit the growth of cancer cell lines. Mechanistic studies also revealed inhibition of multiple kinases by compounds 12, 19 and 22. Moreover, compounds 12, 14, 16 and 22 induced cell cycle arrest and apoptosis in MCF-7 cells. Docking studies revealed nice fitting of the new compounds into COX-1/2. Additionally, compounds 12, 19 and 22 also exhibited higher affinity for CDK2 than CAN508. To sum up, the above-mentioned data highlight these compounds as promising anti-inflammatory and anticancer agents.