Study On Hypoglycemic Effects And Its Mechanism Of Action Of Mangiferin Derivative 1-Hydroxy-3,6,7-Propylene Acyloxy-Ketone(X-3)

The prevalence of diabetes is increasing rapidly worldwide with the influence of economy,transition of living styles,and social aging.In 2014,there were 387 million people with diabetes worldwide.The number is predicted to reach 592 million by 2035.So is the prevalence of diabetes in China,which had reached 9.3% in 2014,and the number of diabetes patients in 2014 is up to 96.3 millions,of which Type 2 Diabetes(T2D)accounted for 93.7%.Diabetes causes a variety of complications,such as cardiovascular disease,blindness,renal failure and lower extremity amputation.The high mortality of diabetes related complications is second only to cardiovascular disease,cerebrovascular disease and cancer.Therefore,with respect to the increasing prevalence of diabetes,new therapeutic strategies are urgently needed.Previous studies found that mangiferin(MF),the main active component of Rhizoma Anemarrhenae,exhibits antidiabetic,hypolipidemic and antiatherogenic properties.However,the major shortcomings of MF are its poor oral bioavailability,which was only 1.7% in rats.We did chemical modification of mangiferin and obtained 1-hydroxy-3,6,7-propylene acyloxy-ketone(X-3)with potential hypoglycemic and hypolipidemic activity.In this paper,X-3 was investigated if it made the improvement about glucose and lipid metabolism activity in db/db mice of T2 D model.The result show that treatment of db/db mice with X-3 120 mg/kg for consecutive 2 weeks resulted in 48% decrease in fasted glucose levels(Pioglitazone 75 mg/kg: 34%).Therapeutic administeration of X-3 significantly and dose-dependently reduced postprandial and fasting blood glucose,serum insulin,triglycerides,and nonestesterified fatty acid,and liver triglycerides levels in db/db mice following 8 week-treatments.To further evaluate if X-3 is a promising lead compound for antidiabetic drug development,we explored its mechanism of action.The results showed that X-3 increased phosphorylation of AMPK and its downstream target,ACC.X-3 activates AMPK in both LKB1(liver kinaseB1)-dependent and CaMKK?(calmodulin-dependent protein kinase kinase ?)-dependent manner.Furthermore,administration of X-3 resulted in activation of AMPK and its downstream target,ACC in the hypothalamus,liver,muscle and adipose tissues of C57BL/6 mice.80 mg/kg X-3 was more potent than metformin at 500 mg/kg in the hypothalamus,and interscapular fat tissues,potent than MF at the same dose in the liver.Related research results have been published in Mol Cell Endocrinol.2015 Apr 15;405: 63-73.In order to identify the direct molecular target of X-3,we employed the recently developed drug affinity responsive target stability(DARTS)technique,which uses reduction in the protease susceptibility of the target protein upon drug binding.The study showed that the possible target proteins of X-3 are CLTC(clathrin heavy chain1)?HSP90?(heat shock protein 90 ?)?HSP90?(heat shock protein 90?).Molecular docking results showed that X-3 binds CLTC with weak affinity,while X-3 binds HSP90? or HSP90? with strong affinity,indicating that the potential target of X-3 is HSP90.This suggest that HSP90? and HSP90?,as the theory target of X-3,need further validation and will be the main component of our continuing mechanism research.Taken together,X-3 has a regulatory role in blood glucose level and lipids and mediates activation of AMPK by LKB1 or CaMKK?.The potential direct target of X-3 is HSP90.This study provide scientific support to the development of X-3 for the treatment of T2 D.