Glycosaminoglycan Conjugation for Improving the Duration of Therapeutic Action of Glucagon-Like Peptide‑1

Glucagon-like peptide-1 (GLP-1) is an incretin peptide that plays a crucial role in lowering blood glucose levels and holds promise for treating type II diabetes. In this study, we synthesized GLP-1 derivatives that were conjugated with glycosaminoglycans (GAGs), i.e., chondroitin (CH) or heparosan (HPN), to address the major limitation in their clinical use of GLP-1, which is its short half-life in the body. After exploring a variety of CHs with different molecular sizes and heterobifunctional linkers having different alkyl chains, we obtained CH-conjugated GLP-1 derivatives that stayed in blood circulation much longer (T 1/2 elim > 25 h) than unconjugated GLP-1 and showed blood glucose-lowering efficacy up to 120 h after subcutaneous injection in mice. By using the same optimized linker design, we eventually obtained a HPN-conjugated GLP-1 derivative with efficacy lasting 144 h. These results demonstrate that conjugation with GAG is a promising strategy for improving the duration of peptide drugs.