Junjie Fu

Glucagon-like peptide-1 loaded phospholipid micelles for the treatment of type 2 diabetes: improved pharmacokinetic behaviours and prolonged glucose-lowering effects

Glucagon-like peptide-1 (GLP-1) and GLP-1 receptor agonists are actively pursued as therapeutic agents for type 2 diabetes mellitus (T2DM). However, the therapeutic utility of GLP-1 is limited due to its rapid inactivation by dipeptidyl peptidase IV, and many GLP-1 receptor agonists suffer from innegligible adverse effects. In the present study, in order to develop long-acting GLP-1 derivatives with improved hypoglycemic activity, native GLP-1 (7-36)-NH2 was loaded into sterically stabilized phospholipid micelles (SSM), affording GLP-1-SSM. In vitro stability test and in vivo pharmacokinetic study demonstrated that the association of GLP-1 with SSM led to enhanced stability and drug utilization without affecting its insulinotropic and glucose-lowering activities. Single and multiple glucose tolerance tests confirmed that GLP-1-SSM was a long-acting antidiabetic agent comparable or even better than exendin-4. More importantly, preclinical studies found out that a chronic twice daily treatment of GLP-1-SSM in type 2 diabetic db/db mice suppressed body weight gain and food uptake, decreased HbA1c value, and restored the glucose tolerance ability. Collectively, our results suggest that GLP-1-SSM is a promising therapy for the treatment of T2DM and deserves further investigation.

Micellar Nanomedicine of Novel Fatty Acid Modified Xenopus Glucagon-like Peptide-1: Improved Physicochemical Characteristics and Therapeutic Utilities for Type 2 Diabetes

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.

Xenopus GLP-1-inspired discovery of novel GLP-1 receptor agonists as long-acting hypoglycemic and insulinotropic agents with significant therapeutic potential

ABSTRACT We here report the discovery and therapeutic efficacy of a novel series of glucagon‐like peptide‐1 (GLP‐1) receptor agonists derived from Xenopus GLP‐1. First, five amino acid‐mutated Xenopus GLP‐1s were synthesized, and xGLP‐3 with the best acute and long‐acting hypoglycemic activity was selected for further modification. Next, PEGylation of xGLP‐3 was performed at specific sites, which were determined using cysteine mutagenesis scanning. Twelve PEGylated conjugates tethered with Mal‐PEGs of 1, 2, and 5 kDa were synthesized. Conjugates 7b and 7c, which exhibited comparable hypoglycemic and insulinotropic effects to Gly8‐GLP‐1, were selected for in‐depth evaluation. It was found that 7b and 7c exhibited prolonged in vivo half‐life and improved pharmacokinetic behaviors. The long‐term hypoglycemic effects of 7b and 7c were further confirmed by pre‐OGTT and multiple OGTT. Importantly, long‐term administration of 7b or 7c in db/db mice achieved beneficial effects on body weight loss, food intake and HbA1c reduction, and glucose tolerance normalization. These preclinical studies indicate the promising role of 7b and 7c as long‐acting type 2 diabetes therapeutics. In addition, our research demonstrated the feasibility of developing novel antidiabetic agents based on Xenopus GLP‐1.

Xenopus‐derived glucagon‐like peptide‐1 and polyethylene‐glycosylated glucagon‐like peptide‐1 receptor agonists: long‐acting hypoglycaemic and insulinotropic activities with potential therapeutic utilities

Incretin‐based therapies based on glucagon‐like peptide‐1 (GLP‐1) receptor agonists are effective treatments of type 2 diabetes. Abundant research has focused on the development of long‐acting GLP‐1 receptor agonists. However, all GLP‐1 receptor agonists in clinical use or development are based on human or Gila GLP‐1. We have identified a potent GLP‐1 receptor agonist, xGLP‐1B, based on Xenopus GLP‐1.

Preparation and Pharmaceutical Characterizations of Lipidated Dimeric Xenopus Glucagon-Like Peptide-1 Conjugates

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+/+ Leprdb (db/db) mice. Pharmacokinetic studies revealed that the circulating half-lives (t1/2) 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.

A Lithocholic Acid-Based Peptide Delivery System for Enhanced Pharmacological and Pharmacokinetic Profile of Xenopus GLP-1 Analogs

GLP-1 analogs suffer from the main disadvantage of a short in vivo half-life. Lithocholic acid (LCA), one of the four main bile acids in the human body, possesses a high albumin binding rate. We therefore envisioned that a LCA-based peptide delivery system could extend the half-life of GLP-1 analogs by facilitating the noncovalent binding of peptides to human serum albumin. On the basis of our previously identified Xenopus GLP-1 analogs (1-3), a series of LCA-modified Xenopus GLP-1 conjugates were designed (4a-4r), and the bioactivity studies of these conjugates were performed to identify compounds with balanced in vitro receptor activation potency and plasma stability. 4c, 4i, and 4r were selected, and their LCA side chains were optimized to further increase their stability, affording 5a-5c. Compound 5b showed a more increased albumin affinity and prolonged in vitro stability than that of 4i and liraglutide. In db/ db mice, 5b exhibited comparable hypoglycemic and insulinotropic activity to liraglutide and semaglutide. Importantly, the enhanced albumin affinity of 5b resulted in a prolonged in vivo antidiabetic duration. Finally, chronic treatment investigations of 5b demonstrated the therapeutic effects of 5b on HbA1c, body weight, blood glucose, and pancreatic endocrine deficiencies on db/ db mice. Our studies revealed 5b as a promising antidiabetic candidate. Furthermore, our study suggests the derivatization of Xenopus GLP-1 analogs with LCA represents an effective strategy to develop potent long-acting GLP-1 receptor agonists for the treatment of type 2 diabetes.

Lipidation and conformational constraining for prolonging the effects of peptides: Xenopus glucagon-like peptide 1 analogues with potent and long-acting hypoglycemic activity

ABSTRACT The main disadvantages of glucagon‐like peptide 1 (GLP‐1) are its rapid degradation and excretion. These bottlenecks can be overcome by lipidation or other structural modification. The aim of this study was to design a series of long‐acting GLP‐1 analogues based on our previously discovered Xenopus GLP‐1 analogs (1–3). The structure‐activity relationship around lipidated 1–3 derivatives (1a–3l) with respect to in vitro potency as well as protraction was firstly explored. Compound 3g was selected for further modification. The Gly2 of 3g was replaced with Aib2, and a lactam constraint between Glu16 and Lys20 (i to i + 4) was introduced to further improve the in vivo activity and stability, affording compound 4. The receptor activation capability and in vitro stability of 4 were better than 3g and liraglutide. In addition, the hypoglycemic and insulinotropic activity of 4 was significantly better than liraglutide in db/db mice. Moreover, the enhanced in vitro stability of 4 translated into improved in vivo pharmacokinetic profiles and a prolonged antidiabetic duration. Administration of 4 twice daily for one week in diet‐induced obese mice caused a significant decrease in food intake, body fat and body weight. The five‐week treatment study on db/db mice of 4 further demonstrated the therapeutic effects of 4 on body weight, HbA1c and glucose tolerance. These preclinical studies demonstrate the therapeutic potential of 4 for type 2 diabetes and obesity. The present study also suggests that combined lipidation and conformational constraint strategy has potential to be used for improving the therapeutic properties of peptides. Graphical Abstract Figure. No Caption available.

Xenopus GLP-1 derived and PEGylated GLP-1 receptor agonists: long-acting hypoglycemic and insulinotropic activities with potential therapeutic utilities

Incretin‐based therapies based on glucagon‐like peptide‐1 (GLP‐1) receptor agonists are effective treatments of type 2 diabetes. Abundant research has focused on the development of long‐acting GLP‐1 receptor agonists. However, all GLP‐1 receptor agonists in clinical use or development are based on human or Gila GLP‐1. We have identified a potent GLP‐1 receptor agonist, xGLP‐1B, based on Xenopus GLP‐1.