Design,Synthesis,Biological Evalution And Mechanism Of FFA1 Agonists

Diabetes,a chronic metabolic disorder,is characterized by the elevated levels of blood glucose owing to insulin deficiency and/or desensitization.Due to the persistent hyperglycemia and metabolic disturbance,diabetes is usually associated with the high burden of complications including diabetic neuropathic pain,non-alcoholic fatty liver disease(NAFLD),and diabetic nephropathy.Several insulin secretagogues such as glimepiride and repaglinide are widely used in the prescriptions for diabetes.However,because insulin secretion mechanism of these drug is independent of blood glucose concentration,the risk of hypoglycemia is relatively high in these agents.Therefore,it is urgently needed to explore new insulin secretagogues with lower side effect of hypoglycemia.The free fatty acid receptor 1(FFA1)was considered as a promising target for several diseases,such as diabetes,pain and non-alcoholic fatty liver.FFA1 is mainly expressed in pancreatic β-cells,brain,and enteroendocrine cells,which provided a lower potential of systemic side effects.The activation of FFA1 in pancreatic β-cells promotes the insulin secretion in a glucose concentration dependent manner,which provided a lower risk of hypoglycemia.Currently,drug repurposing is increasingly becoming an attractive drug discovery strategy to reduce the attrition rates and costs of drug development.Considering that the structure type of the current FFA1 agonist is extremely single,a drug repurposing strategy was adopted to design and synthesize a series of novel FFA1 agonists with Fenbufen as the lead compound and explore their structure-activity relationship(SAR)in this paper.The optimal compound ZLY50(EC50 = 23 n M)was screened by comprehensive evaluation of in vitro agonistic activity,LE and stability of liver microsomes.Different species of liver microsome stability experiments for evaluating the stability of ZLY50 liver microsomes indicated that it has excellent in vitro metabolic stability in different species of liver microsomes.Based on these positive results,the in vivo pharmacokinetic properties of ZLY50 were evaluated in rats.After oral administration,ZLY50 had a very long half-life and high oral bioavailability in rats.Selectivity experiments on other related targets of ZLY50 showed that it was a promising FFA1 agonist with good selectivity for other related targets,which might be minimized off-target side effects.Encouraged by the positive results above,the oral dose-response relationship of ZLY50 was evaluated in normal mice during an oral glucose tolerance test(OGTT).The results showed that a single oral dose of ZLY50 significantly reduced plasma glucose levels in a dose-dependent manner.The activation of FFA1 in neurone regulates the descending pain control system,and thereby FFA1 agonist might be provided analgesic effects.However,existing FFA1 agonist has poor blood brain barrier permeability,and researchers usually use intraventricular injections to study the analgesic effects of FFA1 agonist.Considering that the molecular size of ZLY50 is much smaller than that of existing FFA1 agonists,we speculated that it will activate FFA1 in central nervous system to provide analgesic effect.To verify this,the brain exposure and analgesic effects of ZLY50 was evaluated in ICR mice.All of these results suggested that ZLY50 has enough brain exposure to activate FFA1 in brain,and it is the first orally available FFA1 agonist with analgesic activity.Recent studies have shown that activation of FFA1 can not only reduce blood sugar but also improve fatty liver,which was confirmed in our previous study of FFA1 agonist HWL-088.In addition,the hypoglycemic effect and anti-fatty liver effect of HWL-088 was better than that of TAK-875.Based on the robust efficacy and long half-life in vivo,the anti-diabetic and anti-fatty liver effects of ZLY50 were evaluated in an ob/ob mouse model.The experimental results showed that the hypoglycemic effect of ZLY50(once a week)is better than that of HWL-088(once a day).In addition,ZLY50 also improved hepatic steatosis,inflammation,and ballooning,and decreased serum and liver biochemical index.Therefore,ZLY50 has excellent anti-diabetic and fatty liver effects.Based on the above excellent anti-diabetic and anti-fatty liver effects,the db/db mouse model was adopted to verify the anti-fatty liver effect of ZLY50 and explore its anti-fatty liver mechanism.The experimental results indicated that ZLY50 also improved hepatic steatosis,inflammation,and ballooning,and decreased serum and liver biochemical index.Moreover,ZLY50 alleviates fatty liver by regulating the expressions of genes related to lipid metabolism,mitochondrial function,and oxidative stress in liver.In summary,ZLY50 was the first once-weekly FFA1 agonist with completely new chemotype,highly agonistic activity and selectivity on FFA1.And it was the first orally available FFA1 agonist with analgesic activity.In addition,it also had excellent anti-diabetic and anti-fatty liver effects,and provided a new drug candidate for the treatment of T2 DM and fatty liver.