Xuekun Wang

Design, synthesis and Structure-activity relationship studies of new thiazole-based free fatty acid receptor 1 agonists for the treatment of type 2 diabetes.

The free fatty acid receptor 1 (FFA1/GPR40) has attracted interest as a novel target for the treatment of type 2 diabetes. Several series of FFA1 agonists including TAK-875, the most advanced compound terminated in phase III studies due to concerns about liver toxicity, have been hampered by relatively high molecular weight and lipophilicity. Aiming to develop potent FFA1 agonists with low risk of liver toxicity by decreasing the lipophilicity, the middle phenyl of TAK-875 was replaced by 11 polar five-membered heteroaromatics. Subsequently, systematic exploration of SAR and application of molecular modeling, leads to the identification of compound 44, which was an excellent FFA1 agonist with robustly hypoglycemic effect both in normal and type 2 diabetic mice, low risks of hypoglycemia and liver toxicity even at the twice molar dose of TAK-875. Meanwhile, two important findings were noted. First, the methyl group in our thiazole series occupied a small hydrophobic subpocket which had no interactions with TAK-875. Furthermore, the agonistic activity revealed a good correlation with the dihedral angle between thiazole core and the terminal benzene ring. These results promote the understanding of ligand-binding pocket and might help to design more promising FFA1 agonists.

Synthesis and biological evaluation of phenoxyacetic acid derivatives as novel free fatty acid receptor 1 agonists

Free fatty acid receptor 1 (FFA1) is a new potential drug target for the treatment of type 2 diabetes because of its role in amplifying glucose-stimulated insulin secretion in pancreatic β-cell. In the present studies, we identified phenoxyacetic acid derivative (18b) as a potent FFA1 agonist (EC50=62.3 nM) based on the structure of phenylpropanoic acid derivative 4p. Moreover, compound 18b could significantly improve oral glucose tolerance in ICR mice and dose-dependently reduced glucose levels in type 2 diabetic C57BL/6 mice without observation of hypoglycemic side effect. Additionally, compound 18b exhibited acceptable PK profiles. In summary, compound 18b with ideal PK profiles exhibited good activity in vitro and in vivo, and might be a promising drug candidate for the treatment of diabetes mellitus.

Design, synthesis and biological activity of phenoxyacetic acid derivatives as novel free fatty acid receptor 1 agonists

The free fatty acid receptor 1 (FFA1) is a novel antidiabetic target for the treatment of type 2 diabetes based on particular mechanism in amplifying glucose-stimulated insulin secretion. We have previously identified a series of phenoxyacetic acid derivatives. Herein, we describe the further chemical modification of this series directed by ligand efficiency and ligand lipophilicity efficiency. All of these efforts lead to the discovery of the promising candidate 16, an excellent FFA1 agonist with robust agonistic activity (43.6 nM), desired LE and LLE values. Moreover, compound 16 revealed a great potential for improving the hyperglycemia levels in both normal and type 2 diabetic mice without the risk of hypoglycemia even at the high dose of 40 mg/kg.

Evaluation of hypoglycemic and antioxidative effects of synthesized peptide MC62.

Diabetes mellitus has been considered as a major health problem in the world today. This study aimed to investigate the hypoglycemic and antioxidative effects of peptide MC62 which was synthesized by solid‐phase peptide synthesis method against diabetes induced by streptozotocin. MC62 was administered daily and injected intraperitoneally to the diabetic mice at a dose of 1 μmol/kg body weight for 20 days. The levels of fasting blood glucose and HbA1C, pancreatic islet damage, and associated changes in antioxidative activities were evaluated in streptozotocin‐induced diabetic mice used the exenatide as positive control. After the administration of MC62 together with exenatide for 20 days, the elevated fasting blood glucose and HbA1C levels were reduced, and antioxidative activities were restored. It was confirmed with the histological finding that MC62 prevented the islet from damage in diabetic mice. This indicated that MC62 can prevent mice from hyperglycemia which may be associated with oxidative stress. It also suggested that MC62 could be used as a safe alternative hypoglycemic candidate for treatment of diabetes.

Design, synthesis and biological evaluation of novel peptides with anti-cancer and drug resistance-reversing activities.

Chemotherapy is an important approach used to treat cancer, but severe side effects and emerging drug resistance restrict its clinical application. In this present study, we found that peptide B1 showed specific cytotoxicity to tumor cells. Moreover, a helix-wheel plot predicted that the Ser14 in this peptide is located at the interface of the hydrophobic and hydrophilic faces of B1. Subsequently, we wondered whether replacing Ser14 would alter the activity of B1, and so a series of B1 analogs were synthesized where the Ser14 was replaced by amino acids with distinct physicochemical properties. Amongst them, peptides where Ser14 was substituted by a nonpolar and basic amino acid had improved anti-cancer activity. Further investigations revealed that B1 and its analogs were capable of penetrating into cytoplasm and triggering cytochrome C release from mitochondria, which ultimately resulted in apoptosis. Meanwhile, B1 and its analogs inhibited the migration of cancer cells. The peptides also acted against drug-resistant cells and had drug resistance-reversing effects. In conclusion, these peptides might be promising candidates for oncotherapy.

C-Aryl Glucosides with Substituents at the Distal Aryl Ring as Sodium-Dependent Glucose Cotransporter Inhibitors for the Treatment of Diabetes Mellitus.

A series of novel C‐aryl glucosides with various substituents at the distal aryl ring have been synthesized and evaluated for hypoglycemic effect in normal and diabetic mice and in type 2 diabetic rats. The results indicated that introduction of electron‐donating group at the distal aryl ring could improve glucose tolerance in normal mice, whereas introduction of electron‐withdrawing group at this position could deteriorate. The urinary glucose excretion was significantly increased after glucose (3 g/kg) administration in normal mice with the treatment of 13c. Moreover, compound 13c could reduce fed blood glucose levels in a dose‐dependent manner in type 2 diabetic rats, showed a remarkable antihyperglycemic effect with 2 weeks of treatment in diabetic mice, and might be a promising drug candidate for the treatment of diabetes mellitus.

Design, Synthesis, and Biological Evaluation of Novel Cholesteryl Peptides with Anticancer and Multidrug Resistance‐Reversing Activities

Antimicrobial peptides have been suggested as promising chemotherapeutics for cancer therapy due to their efficient antitumor activity and lower toxicity to benign cells. In previous study, we find the peptide B1 presents specific cytotoxicity to cancer cells. As hydrophobicity plays a pivotal role in the anticancer activity of peptide, we introduce cholesterol‐like moiety (3β‐amino‐5‐cholestene) to the N‐terminus of B1 expect to ameliorate the anticancer activity of B1. Biological evaluations revealed that target peptides show improved anticancer activity. The peptides can also penetrate into the cytoplasm and activating mitochondria–cytochrome c apoptosis pathway. Besides, the peptides acted on multidrug‐resistant cells and had multidrug resistance‐reversing activity. It is therefore suggested these peptides might be promising candidates for oncotherapy.

Design, Synthesis and in vivo Evaluation of Novel C‐Aryl Glucosides as Potent Sodium‐Dependent Glucose Cotransporters Inhibitors for the Treatment of Diabetes

A series of novel C‐aryl glucosides with substituents at the 3′‐position or cyclization at 3′, 4′‐positions of the distal aryl ring were designed and synthesized, which might decrease the oxidative metabolism of dapagliflozin. Preliminary evaluation for hypoglycemic effect and the risk of hypoglycemia were carried out both in normal and in streptozotocin‐induced diabetic mice. Among the synthesized compounds, compound 19a exerted potency‐similarity with dapagliflozin and triggered the hypoglycemic effect in a dose‐dependent manner. Besides, compound 19a, even at the high dose of 10 mg/kg, revealed a low risk of hypoglycemia. In further studies, 19a exhibited sustained antihyperglycemic effect without particular side‐effects in 30‐day chronic diabetic mice studies. Moreover, histological changes in the pancreas of diabetic mice indicated 19a might protect pancreatic β‐cell from apoptosis by reducing the damage of glucotoxicity. All of these results demonstrated that compound 19a, with excellent in vivo pharmacological activity and safety profile, was considered to be a promising drug candidate for the treatment of diabetes mellitus.

Design, Synthesis, and Biological Evaluation of Novel Peptide Gly3‐MC62 Analogues as Potential Antidiabetic Agents

Two series of conformationally constrained analogues from Gly3‐MC62 were designed by scanning the residues Lys1, Thr2, Met4, Lys5, Met7, and Ala8 with an i‐(i + 2) lactam bridge consisting of a Glutamic acid–xaa–lysine (Glu–Xaa–Lys) scaffold and a diproline fragment. They were synthesized and evaluated for their antihyperglycemic effects. Through screening in normal and mice with diabetes mellitus, peptides II‐5, III‐3, III‐4, and III‐5 showed significant improvement in antihyperglycemic and antioxidative activities compared with Gly3‐MC62, especially the compound III‐4. The primary mechanism of the compounds (II‐5, III‐3, III‐4, and III‐5) underlying this effect is the islet β‐cells against oxidative damage induced by STZ, and III‐4‐treated mice showed considerable improvement in the preservation of beta cells in the pancreatic islets of DM mice. These data suggested that III‐4 could be candidate for the future treatment of diabetes mellitus.