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To develop novel long-acting antidiabetics with improved therapeutic efficacy, two glucagon-like peptide-1 (GLP-1) analogs were constructed through the hybridization of key sequences of GLP-1, xenGLP-1B, exendin-4, and lixisenatide. Hybrids 1 and 2 demonstrated enhanced in vitro and in vivo biological activities and were further site-specifically lipidized at lysine residues to achieve prolonged duration of action and less frequent administration. Compared with their native peptides, compounds 3-6 showed similar in vitro activities but impaired in vivo acute hypoglycemic potencies due to decreased aqueous solubility and retarded absorption in vivo. To circumvent these issues, compound 3 (xenoglutide) was selected to be self-associated with sterically stabilized micelles (SSM). The α-helix and solubility of xenoglutide were significantly improved after self-associated with SSM. Notably, the improved physicochemical characteristics of xenoglutide-SSM led to revival of acute hypoglycemic ability without affecting its long-term glucose-lowering activity. Most importantly, preclinical studies demonstrated improved therapeutic effects and safety of xenoglutide-SSM in diabetic db/db mice. Our work suggests the SSM incorporation as an effective approach to improve the pharmacokinetic and biological properties of hydrophobicity peptide drugs. Furthermore, our data clearly indicate xenoglutide-SSM as a novel nanomedicine for the treatment of type 2 diabetics.

A pair of glucagon-like peptide-1 (GLP-1) analogs (1 and 2) were synthesized by hybridizing the key sequences of GLP-1, exendin-4, lixisenatide, and xenGLP-1B (Xenopus GLP-1 analog). To achieve long-acting hypoglycemic effects and to further improve their anti-diabetic potencies, lipidization and dimerization strategies were used to afford two lipidated dimeric conjugates (9 and 11). Conjugates 9 and 11 showed stronger receptor activation potency than GLP-1 and exendin-4 in vitro. Moreover, 9 and 11 exhibited superior hypoglycemic and insulinotropic activities to liraglutide in type 2 diabetic C57BL/6J-m Lepr (db/db) mice. Pharmacokinetic studies revealed that the circulating half-lives (t) of 9 and 11 were 2.3- and 1.7-fold longer than that of liraglutide. The improved pharmacokinetic profiles led to significantly protracted in vivo anti-diabetic effects as confirmed by multiple oral glucose tolerance tests and hypoglycemic duration tests. Most importantly, chronic treatment studies found that once daily administration of 9 or 11 in db/db mice achieved more beneficial effects on HbA1c reduction and glucose tolerance normalization than liraglutide. Our research demonstrated lipidization and dimerization as useful tools for the development of novel GLP-1 receptor agonists. The preclinical studies suggested the potential of 9 and 11 to be developed as novel anti-diabetic agents.