title: Novel coumarin modified GLP-1 derivatives with enhanced plasma stability and prolonged in vivo glucose-lowering ability.
abstract: OBJECTIVE
  The short biological half-life limits the therapeutic use of glucagon-like peptide-1 (GLP-1) and chemical modification to improve the interaction of peptides with serum albumin represents an effective strategy to develop long-acting peptide analogues. Coumarin, a natural product, is known to bind tightly to plasma proteins and possesses many biological activities. Therefore, we designed and synthesized a series of coumarin-modified GLP-1 derivatives, hypothesizing that conjugation with coumarin would retain the therapeutic effects and prolong the biological half-life of the conjugates.
  
  
  METHODS
  Four cysteine-modified GLP-1 analogues (1-4) were prepared using Gly8 -GLP-1(7-36)-NH2 peptide as a starting point. These analogues were conjugated with two coumarin maleimides to yield eight compounds (conjugates 6-13) for testing. Activation of human GLP-1 receptors, stability to enzymic inactivation in plasma and binding to human albumin were assessed in vitro. In vivo, effects on oral glucose tolerance tests (OGTT) in rats and on blood glucose levels in db/db mice were studied.
  
  
  RESULTS
  Most conjugates showed well preserved receptor activation efficacy, enhanced albumin-binding properties and improved in vitro plasma stability and conjugate 7 was selected to undergo further assessment. In rats, conjugate 7 had a longer circulating t1/2 than exendin-4 or liraglutide. A prolonged antidiabetic effect of conjugate 7 was observed after OGTT in rats and a prolonged hypoglycaemic effect in db/db mice.
  
  
  CONCLUSIONS
  Cysteine-specific coumarin conjugation with GLP-1 offers a useful approach to the development of long-acting incretin-based antidiabetic agents. Conjugate 7 is a promising long-lasting GLP-1 derivative deserving further investigation.
authors.affiliation: Center of Drug Discovery, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Han
authors.forename: Lidan
authors.initials: L
authors.lastname: Sun
authors.forename: Xun
authors.initials: X
authors.lastname: Huang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.forename: Chenyu
authors.initials: C
authors.lastname: Zhang
authors.forename: Hai
authors.initials: H
authors.lastname: Qian
authors.forename: Wenlong
authors.initials: W
authors.lastname: Huang
mesh_terms: D000818:Animals; D003374:Coumarins / Q000737:chemistry*; D003924:Diabetes Mellitus, Type 2; D004195:Disease Models, Animal; D000077270:Exenatide; D052216:Glucagon-Like Peptide 1 / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D000067757:Glucagon-Like Peptide-1 Receptor; D005947:Glucose; D005951:Glucose Tolerance Test; D057809:HEK293 Cells; D006801:Humans; D007004:Hypoglycemic Agents / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D000069450:Liraglutide; D008297:Male; D008810:Mice, Inbred C57BL; D010455:Peptides / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D018027:Receptors, Glucagon / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism; D014688:Venoms / Q000494:pharmacology
chemical_list: D003374:Coumarins; C000593833:GLP1R protein, human; C000593834:Glp1r protein, mouse; C000593835:Glp1r protein, rat; D000067757:Glucagon-Like Peptide-1 Receptor; D007004:Hypoglycemic Agents; D007328:Insulin; D010455:Peptides; D018027:Receptors, Glucagon; D012709:Serum Albumin; D014688:Venoms; D000069450:Liraglutide; D052216:Glucagon-Like Peptide 1; D000077270:Exenatide; C030123:coumarin; D005947:Glucose