ABSTRACT
In a search for novel multifunctional anti-Alzheimer agents, a congeneric set of seventeen flavone-8-acrylamide derivatives (8aâq) were synthesized and evaluated for their cholinesterase inhibitory, antioxidant, neuroprotective and modulation of Aß aggregation activities. The target compounds showed effective and selective inhibitory activity against the AChE over BuChE. In addition, the target compounds also showed moderate anti-oxidant activity and strong neuroprotective capacities, and accelerated dosage-dependently the Aß aggregation. Also, we presented here a complete study on the interaction of 8a, 8d, 8e, 8h and 8i with AChE. Through fluorescence emission studies, the binding sites number found to be 1, binding constants were calculated as 2.04â¯×â¯104, 2.22â¯×â¯104, 1.18â¯×â¯104, 9.8â¯×â¯103 and 3.2â¯×â¯104 M-1 and free energy change as -5.83, -5.91, -5.51, -5.41 and -6.12â¯kcalâ¯M-1 at 25⯰C which were well agreed with the computational calculations indicating a strong binding affinity of flavones and AChE. Furthermore, the CD studies revealed that the secondary structure of AChE became partly unfolded upon binding with 8a, 8d, 8e, 8h and 8i.
Subject(s)
Acetylcholinesterase/metabolism , Acrylamide/pharmacology , Alzheimer Disease/drug therapy , Amyloid beta-Peptides/antagonists & inhibitors , Cholinesterase Inhibitors/pharmacology , Flavones/pharmacology , Neuroprotective Agents/pharmacology , Acrylamide/chemical synthesis , Acrylamide/chemistry , Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Binding Sites/drug effects , Cell Death/drug effects , Cell Line, Tumor , Cholinesterase Inhibitors/chemical synthesis , Cholinesterase Inhibitors/chemistry , Dose-Response Relationship, Drug , Flavones/chemical synthesis , Flavones/chemistry , Humans , Hydrogen Peroxide/antagonists & inhibitors , Hydrogen Peroxide/pharmacology , Molecular Structure , Neuroprotective Agents/chemical synthesis , Neuroprotective Agents/chemistry , Protein Aggregates/drug effects , Structure-Activity Relationship , ThermodynamicsABSTRACT
BACKGROUND: Extensive epidemiological and clinical studies revealed that Alzheimer's Disease (AD) and Type 2 Diabetes Mellitus (T2D) are most likely to appear simultaneously in aged people as T2D is a major risk factor for AD. Therefore, development of potential multifunctional agents for dual therapy of AD and T2D has received much attention. Buchanania axillaris, Hemidesmus indicus and Rhus mysorensis have been used extensively in popular medicine. The present study was aimed at phytochemical profiling and evaluating multifunctional ability of titled plants in the AD and T2D dual therapy. METHODS: Methanolic extracts and their derived fractions were evaluated for their inhibitory capacities against acetylcholinesterase (AChE) & butyrylcholinesterase (BuChE), and α- & ß-glucosidase besides kinetic analysis of inhibition using methods of Elmann and Shibano, respectively. Antioxidant potency of active fractions was assessed by their DPPH and ABTS radical scavenging activities. Active fractions were tested by the MTT assay to verify cytotoxicity and neuroprotective ability in human nueroblastoma cell lines. Phytochemical screening was done with the aid of spectrophotometric methods. RESULTS: All the methanolic extracts of test plants (BAM, HIM, RMM) showed concentration dependent inhibitory activities against AChE, BuChE, α- and ß-glucosidase enzymes. Subsequent fractionation and evaluation revealed that chloroform fractions BAC, HIC and RMC with IC50 values of 12.29±2.14, 9.94±2.14, 16.65±1.99 and 27.38±1.24; 28.14±0.9, 5.16±0.22, 11.03±0.5 and 87.64±15.41; 41.35±1.6, 15.86±7.3, 26.04±0.37 and 25.33±0.3 were most prominent with regard to inhibition potential against AChE, BuChE, α- and ß-glucosidase, respectively. Kinetic analysis of these active fractions proved that they disclosed mixed-type inhibition against AChE, BuChE, α- and ß-glucosidase enzymes. In the MTT assay, active fractions BAC, HIC, RMC showed significant cell viability at high concentrations (400 µg). Moreover, in MTT assay, the active fractions displayed excellent neuroprotective effects against oxidative stress induced cell death and significant cell viability in SK N SH cells at all concentrations. CONCLUSION: The strong anticholinesterase, antiglucosidase, antioxidant and neuroprotective activities of methanolic extracts and their derived chloroform fractions indicate the potential of Buchanania axillaris, Hemidesmus indicus and Rhus mysorensis as multifunctional therapeutic remedies for the dual therapy of T2D and AD.
