Synthesis and biological evaluation of 4-hydroxy-5-oxo-2,5-dihydro-1H-pyrrole-3-carboxamides and their zinc(ii) complexes as candidate antidiabetic agents†
Abstract
The newly designed 1-(arylmethyl)-2,5-dihydro-4-hydroxy-5-oxo-1H-pyrrole-3-carboxamides (1a–e) were synthesized by using N-tritylated acrylamide as a starting material, and their zinc(II) complexes (10a–e) were readily prepared by simply mixing 1a–e and ZnSO4 in the presence of LiOH. The aldose reductase (AR) inhibitory activity of 1a–e was evaluated to reveal important structural features for 2,5-dihydro-5-oxo-1H-pyrrole derivatives to exhibit high AR inhibitory activity. The in vitro insulin–mimetic activity of these complexes was evaluated from 50% inhibitory concentrations (IC50) on free fatty acid (FFA) release from isolated rat adipocytes treated with epinephrine. Four out of the five newly synthesized complexes exhibited higher in vitro insulin-mimetic activities than ZnSO4, a positive control. This study proved that the newly synthesized N2O2-coordination-type zinc(II) complexes based on pyrrole-3-carboxamide derivatives (1a–d) are potential hypoglycemic agents.