Design Synthesis Ang α-glucosidase Activity Evaluation Of Betulinic Acid Derivatives

Changes in modern living conditions,diabetes has become a common disease and has been listed as one of the major diseases endangering human life safety in the world.Therefore,drug research on diabetes is very important.Betulinic acid,a natural pentacyclic triterpenoid compound,has many good biological activities,especially in hypoglycemia.It was found that betulinic acid has multiple active inhibitory targets for hypoglycemia,especiallyα-glucosidase inhibition.However,due to its poor solubility and low bioavailability,the use of betulinic acid is limited.Therefore,effective structural modification of betulinic acid is needed to improve the inhibitory effect of betulinic acid on alpha-glucosidase,so as to further develop betulinic acid in diabetes research.In this study,α-glucosidase was used as the research target,betulinic acid was used as the main skeleton,and C-2,C-3,C-28 of its biological carbon were modified by derivatives,and65 derivatives of styrene betulinic acid,indole and acylhydrazone were synthesized and screened for their activities.The synthetic styrene derivative 3a-3u and naphthalene ring substituted derivative 3m were further derived 4a-4e and screened for inhibition ofα-glucosidase activity.Compound3m(IC₅₀=0.56±0.05μmol/L)had the best inhibitory effect,so the kinetic test of compound3m was conducted.Compounds 3m and 6e are non-competitive reversible inhibitors.And add compounds in alpha glycosidase enzymes after 3m,3D fluorescence Trp residues of Tyr wavelengths was reduced by 11.93%,protein structure from n→*cause fluorescence characteristics was reduced by 34.64%.Circular dichroism（CD）analysis showed that compound 3m caused changes in the secondary structure ofα-glucosidase proteins,includingα-helix,β-helix,β-folding and irregular helix.The indole derivatives 5a-5u of betulinic acid were synthesized,and the tert-butyl-substituted compound 5j（IC50=2.27±0.23μmol/L）had the best inhibitory effect onα-glucosidase.Compound 5j is a mixed reversible inhibitor.Compound 5j mixed withα-glucosidase resulted in a 3.78%and 7.08%decrease in the two peaks of 3D fluorescence and a change in the secondary structure ofα-glucosidase protein,respectively.The acylhydrazone derivatives 6a-6r of betulinic acid were synthesized.Theα-glucosidase activity of the derivatives was tested.The structure-activity relationship was analyzed.The results showed that the 4-Br-substituted derivative 6e（IC50=2.18±0.22μmol/L）had the best inhibitory activity in the hydrazone series.6e is a non-competitive reversible inhibitor.The mixing of compound 6e withα-glucosidase reduced the peak value of 3D fluorescence by 8.69%and 25.73%,and resulted in the change of the secondary structure ofα-glucosidase protein.It was concluded that the changes of betulinic acid structure in each series produced new inhibitory effects onα-glucosidase.