Synthesis and biological evaluation of glucagon-like peptide-1 analogs with the C-terminal helix 3 of albumin-binding domain 3

[Display omitted] •Compounds 0-VI were synthesized under microwave irradiation.•Linkers can significantly affect the albumin-binding rates.•The structure–activity relationship of compounds 0-VI was summarized.•Derivative IV was screened out as a lead compound. Based on peptide 6 (Ser8-GLP-1 [7–35]-GVKALIDEILAA-NH2; GVKALI-DEILAA is the C-terminal helix 3 of albumin-binding domain 3 of protein G from bacterial Streptococcal G strain 148 [G148-ABD3]), a series of its analogs (compounds 0-VI: Aib8-GLP-1 [7–35]-linkers-GVKALIDEILAA-NH2) were designed and synthesized using microwave-assisted solid-phase synthesis. First, to monitor the reaction process and reduce potential risks, the synthesis process of compounds 0-VI was divided into three stages. Next, to explore the effect of these linkers on their albumin-binding rates, albumin-binding assays were performed. Finally, to evaluate their biological activities in vitro and in vivo, receptor potency, surface plasmon resonance (SPR), weight-loss, and glucose-lowering assays were carried out. These results indicated the linkers of different polarities between Aib8-GLP-1 (7–35) and the C-terminal helix 3 of ABD3 can significantly affect the albumin-binding rate of the C-terminal helix 3 of ABD3. And compound IV had the highest albumin-binding rates, weight-loss, and glucose-lowering effects among them.