Design, synthesis, and structure-activity relationship study of novel GLP-1/GIP/GCG triple receptor agonists.

In this study, to achieve more effective blood sugar lowering and weight-loss effects, eight glucagon-like peptide-1 (GLP-1)/glucose-dependent insulinotropic peptide (GIP)/glucagon (GCG) triple receptor agonists were designed and synthesized. Their sixteen related conjugates were obtained through Cys alkylation and Lys esterification modifications with two fatty acid side chains, respectively. After chemical structure confirmation using high-resolution mass spectrometry and peptide mapping, in vitro and in vivo biological effects of TRA01-24 were assessed. The structure-activity relationship (SAR) data on the amino acids, fatty acids, linkers and biological effects in vitro and in vivo of TRA01-24 have been summarized. Furthermore, peptide-protein molecular docking elucidated the structural basis for the biased agonist activity of TRA22 at GLP-1R, characterized by strong GLP-1R activation but weak GCGR and GIPR activation. In conclusion, a lead compound with excellent efficacy in vitro and in vivo, TRA24, was screened, which had better in vivo efficacy than tirzepatide in both normal and db/db mice.