Design, synthesis and biological evaluation of double fatty chain-modified glucagon-like peptide-1 conjugates

Twelve double fatty chains and Aib⁸-Arg³⁴-GLP-1 (7-37) were designed and obtained by microwave-assisted solid-phase synthesis. Then, twelve conjugates of Aib⁸-Arg³⁴-GLP-1 (7-37) were synthesized in 1% triethylamine aqueous solution. Conjugates 2, 3, 6, 7, 10 and 11 showed better GLP-1 receptor activation potency than semaglutide. However, conjugates 2, 6 and 10 showed slightly worse glucose-lowering effects in vivo than semaglutide but better effects than conjugates 3, 7 and 11. The CD spectra of conjugates 2, 6 and 10 indicated that they had the same secondary structure as liraglutide and semaglutide. The receptor affinity results for conjugates 2, 6 and 10 measured by SPR (surface plasmon resonance) showed that conjugate 2 had higher receptor affinity than conjugates 6 and 10. In addition, albumin binding assays indicated that double fatty acid chains had obvious synergistic effects compared with single fatty acid chains. In conclusion, the structure-activity relationship of different side chains was summarized and one candidate, conjugate 2, was screened.