Glycosidase Inhibition Effect Based On The Self-assembly Of Amphiphilic 1-Deoxynojirimycin

Glycosidase plays a key role in many biological processes through the selective hydrolysis of glycosidic bonds in carbohydrates.Abnormal glycosidase activity is relevant to a series of diseases,including diabetes,Gaucher's disease,cancer and viral infection.Multivalent glycosidase inhibitors are a novel and rapidly growing topic that have been discovered and achieved successful results.A large number of multivalent1-deoxynojirimycin(DNJ)derivatives have been reported,that show high activities against glycosidase.Although multivalent glycosidase inhibitors based on a covalent glycodendrimer have achieved great success,the synthesis of such glycodendrimers is both time-and costconsuming.However,very few examples of multivalent glycosidase inhibitors have been reported.In this work,a series of novel amphiphilic 1-deoxynojirimycin(DNJ)derivative was designed and synthesized.The selfassembly behaviour,effect on the inhibition of multivalent glycosidase and postprandial blood glucose(PBG)effect in vivo were investigated.The supramolecular self-assembly of compounds showed potent glycosidase activity and a PBG effect in mice.The details are as follows:(1)The octadecyl-modified DNJ derivatives FA-DNJ-1 was synthesized,and the structure was characterized by ¹H NMR,¹³C NMR and HRMS analysis.Self-assemble properties of FA-DNJ-1 were investigated by the surface tension,NPN fluorescence probe,dynamic light scattering and TEM.These results indicated that FA-DNJ-1 formed 20?150 nm spherical micelle,and was stable at p H 2.0?7.0.Furthermore,the?-glycosidase inhibition of FA-DNJ-1 was investigated by glycosidase inhibition assay in vitro and hypoglycemic assay in vivo.The results showed that FA-DNJ-1 possessed potent inhibitory effect on?-mannosidase with a low K_i value of 0.11±0.04?M.The self-assembly of FA-DNJ-1showed a 990-fold(330-fold,valency corrected)degree of enhancement compared to that of the control drug(miglitol).When DNJ-1 was the control molecule,the self-assembly of FA-DNJ-1 showed a 2054-fold(684-fold,valency corrected)degree of enhancement.Moreover,FA-DNJ-1 showed more excellent hypoglycemic effect than miglitolin in mice.Compared with the molar hypoglycemic rate,FA-DNJ-1 showed 20-fold enhancement than that of miglitol.These results developed a new perspective for a self-assembled multivalent glycosidase inhibitor to treat glycosidase-related diseases in clinical applications.(2)Aliphatic 1-deoxynojicin derivatives(FA-DNJ-2 and FA-DNJ-3)with peptide conjugates were synthesized.The self-assemble properties of FA-DNJ-2 and FA-DNJ-3showed that they could form spherical assemblies with the diameters between 5 nm and 15nm under the p H value of 2.0?7.0.In addition,FA-DNJ-2 and FA-DNJ-3 showed strong inhibitory against?-mannosidase with the K_i values of 0.43±0.02?M and 0.066±0.002?M,respectively.Compared with the monovalent compounds,FA-DNJ-3 showed potent inhibitory effect on?-mannosidase with enhancement of 6742 fold and 2247 fold,relatively.FA-DNJ-3 exhibited the similar PBG effect with miglitol(2 mg/kg)at a dose of 0.5 mg/kg in vivo.Compared with the molar hypoglycemic rate,FA-DNJ-2 and FA-DNJ-3 was approximately 23-fold compared with miglitol.Compounds FA-DNJ-2 and FA-DNJ-3exhibited a reversible mixing inhibition mechanism for?-mannosidase(Jack bean)due to the introducing of phenylalanine dipeptide.(3)In order to investigate the relationship between the hydrophobic effect and the inhibition activity,double aliphatic chains modified DNJ derivatives(FA-DNJ-4 and FA-DNJ-5)were synthesized.FA-DNJ-4 and FA-DNJ-5 were assembled into spherical micelles with diameter of 30?80 nm and 50?110 nm in water,respectively.Glycosidase inhibitory activity of FA-DNJ-4 and FA-DNJ-5 showed potent glycosidase inhibition activities against?-mannosidase with the K_i values of 0.034±0.08?M and 0.033±0.09?M,respectively,which were 2?13 fold than that of compounds FA-DNJ-1,FA-DNJ-2 and FA-DNJ-3.Moreover,FA-DNJ-5 showed a 13485-fold increase over the monovalent compound,and the relative mono-potency increased by 2247 times.Glycosidase inhibition experiments in vivo showed that FA-DNJ-5 had higher efficacy than miglitol at a low dose of0.5 mg/kg.According to the molar hypoglycemic rate,FA-DNJ-5 was 68 times than that of miglitol.FA-DNJ-5 showed the best glycosidase effect in mice in our tested multivalent glycosidase inhibitors.(4)Increasing of the?-?stacking interactions,the assembly and glycosidase properties of the multivalent glycosidase inhibitor might show obvious change.Therefore,the amphiphilic deoxynojirimycin derivative NI-DNJ conjugated with 1,8-naphthalimide moiety was synthesized.NI-DNJ formed stable assembly in water between the p H values 2.0?7.0.It is interestingly found that NI-DNJ showed high glycosidase inhibition activity against?-glucosidase(Aspergillusniger)with a K_ivalue of 0.15±0.03?M,137-fold higher than miglitol.NI-DNJ possessed potential application in diabete.