Effects Of Cornel Iridoid Glycoside On Acetylcholine Metabolic Enzyme System

ObjectiveAlzheimer’s disease (AD) is the most common central neurodegenerative disease inthe elderly, of which clinical damage is characterized by progressive cognitivedysfunction and behavioral. The continuing loss of cholinergic neurons in the basalnucleus of Meynert can be observed during AD disease progression. Centralcholinergic dysfunction is one of the important pathogenesis of AD. Cholinesterases,as catabolic enzymes of the neurotransmitter acetylcholine (ACh), reduce the contentof ACh in the synaptic gap. Acetylcholine esterase (AChE) inhibitors can be used toimprove cognitive impairment symptoms of AD patients.Cornus officinalis Sieb.et Zucc is a traditional Chinese herb with liver and kidneytonic effects. Iridoid glycosides is one of the main active ingredient of Cornusofficinalis. Recent studies in our laboratory found that Cornel iridoid glycoside (CIG)can play a neuroprotective effect by inhibiting the Tau hyperphosphorylation, andsignificantly improved learning and memory ability in the fornix-hippocampalfimbria transection rat model. However, there has been no report on the effects ofCIG on cholinesterase. The purpose of the present study is to investigate the effectsof CIG on AChE, butyryl cholinesterase (BuChE) and choline acetyltransferase(ChAT) in vitro, in order to elucidate CIG’s action mechanisms.Methods(1) Taking human red blood cells, rat whole brain homogenates and electric eel AChE as the enzymatic sources, AChE activity was measured by using DTNBbiochemical method to detect the impact of drugs. Lineweaver-burk method wasused to determine the kinetics of inhibitive action.(2) Using rat whole brain homogenates and human plasma as the enzymatic sources,BuChE activity was detected with DTNB biochemical method to determine theinfluence of drugs. The kinetics of inhibitive action was measured byLineweaver-burk method.(3) Taking rat brain homogenates as the enzymatic source, the ChAT activity kit wasused to detect the effect of CIG on ChAT activity.Results(1) The screening test of4drugs showed that only CIG inhibited the activity ofAChE in human red blood cells and electric eel, but other3drugs including TSG、ICA and5-HMF had no effect on AChE in human red blood cells and electric eel.(2) CIG inhibited the activity of AChE in human red blood cells, rat brainhomogenates and electric eel, and the concentrations which could inhibit50%ofenzymatic activy (IC50) were1.6g L-1,3.3g L-1and0.37g L-1, respectively..The inhibitive effect of CIG on AChE was reversible, and was competitive andnon-competitive mixed-type inhibition.(3) CIG inhibited the activity of BuChE in human plasma and rat brain homogenates,and the IC50were2.9g L-1and0.96g L-1, respectively. The inhibitive effect ofCIG on BuChE was competitive and non-competitive mixed-type inhibition.(4) CIG plays certain role in promoting ChAT activity in rat brain homogenates. ConclusionCIG has dual inhibitive effects on AChE and BuChE, and certain promoting effecton the activity of ChAT in vitro. These suggest that CIG may enhance the functionsof cholinergic system, and have a good application prospect for the prevention andtreatment of AD. ObjectiveThe anti-AD Chinese herbal compound is the experience prescription for clinicaltreatment of Alzheimer’s disease (AD) from Professor Yongyan Wang. Thiscompound contains4herbs and the weight of a single dose is30g crude drug. Inorder to develop a new drug, the preclinical pharmaceutical research first needs tooptimize the extraction technics. The pharmaceutical research institution has initiallyidentified four different extraction technics by the orthogonal design and preparedthe concentrate. The purpose of the present study was to conduct thepharmacodynamic comparison of4different extraction technics and to ensure theeffectiveness of new drugs to treat AD.Methods(1) D-galactose-induced brain aging mouse model was used to observe the effects offour extracts on the object recognition ability and hippocampal neurotrophic factorexpression in the mouse model.(2) Scopolamine-induced memory impairment mouse model was used to observe theeffects of four extracts on the spatial memory and passive avoidance memorycapacity in the mouse model.(3) Sodium nitrite-induced memory impairment mouse model was used to observethe effects of four extracts on the object recognition capability and passive avoidancememory capacity in the mouse model. Results(1) Oral administration of4extracts from4extraction technics (5g crude drug/kg)increased the distinguish index of object recognition test in D-galactose mousemodel, with the result of pharmacodynamics comparison: technic1technic3technic2, and technic4is not effective; the pharmacodynamic comparison ofincrease in hippocampal neurotrophic factor expression: technic1technic3technic2, and technic4is not effective.(2)4extracts from4extraction technics (5g crude drug/kg) oral administrationimproved space learning and memory abilities by Morris water maze test inscopolamine mouse model, with the result of pharmacodynamics comparison:technic2technic1technic3technic4; the pharmacodynamic comparison ofimprovement of passive avoidance memory capacity by step-down test: technic1technic3technic2technic4.(3) Oral administration of2extracts with different doses (5g crude drug/kg,10gcrude drug/kg) increased the distinguish index of object recognition test insodium nitrite mouse model, with the result of pharmacodynamic comparison: smalldose of technic2small dose of technic1; large dose of technic1large dose oftechnic2; the pharmacodynamic comparison of improvement of passive avoidancememory capacity by step-through test: technic1=technic2.ConclusionThe general analyses of pharmacodynamic comparison of4extraction technicsdemonstrated that technic1was the best and ranked the first place; technic2rankedthe second and technic3ranked the third, but they were very close; technic4was theworst and ranked the fourth.