The Studies On Synthesis And Antioxidant Activities Of Quercetin Derivatives

As one of the most widely distributed of flavonoids in nature, quercetin isubiquitous natural important natural organic compound. Given their broad range ofpharmacological effects and biological activities, such as efficient anti-oxidant andscavenging oxygen free radicals injury, quercetin and its derivatives not only arevery efficient drugs for reducing the blood pressure, but also appear to be active inmany diseases related to aging such as vasodilatation, neurodegenerative, inhibitingcardiovascular diseases and lower toxicity. As lead compounds, they are wished tosynthesize better bioactive compounds.In this paper,12quercetin derivatives and metal complexes were successfullysynthesized via modifying the structure of3′,4′,7-Tri （-O-ethoxyl-） quercetin （THQ）. Their structures were characterized by¹H-NMR,¹³C-NMR, IR and MSspectroscopies.6of these compounds have not been reported so far. Additionally, theantioxidant activities of part of the compounds were tested by means of improvedpyrogallol autoxidation method, and the changes of the free radical scavengingability with variation of concentration. Vitamin C was used as a reference material.This thesis consists of five parts. The main content of the thesis is as follow:1. The recent research progress of quercetin derivatives receptors and metalcomplexes, including design, chemical synthesis and their applications in the fields ofpharmacological activities, was briefly reviewed.2. THQ was got from steam reforming of3′,4′,7-Tri （-O-ethoxyl-） rutin （THR）as the starting material, and then respectively reacted with alkylation and a lot ofmonoalkylated ethers derivatives of quercetin were synthesized. Their structures werecharacterized by1H-NMR,13C-NMR, IR and MS spectroscopies. Three of thesecompounds have not been reported so far. By physical chemistry calculation withGaussian.03, we found that the optimal configuration of THQ was approximate plane structure and the least binding energy of the five hydroxies is3-O-H via Hartree-Fockequation. The antioxidant activities of some quercetin derivatives were determined bymeans of improved pyrogallol autoxidation method, and the changes of the freeradical scavenging ability with variation of concentration.3. THQ respectively reacted with ethyl bromoacetate, methyl chloroacetate,propyl chloroacetate and butyl chloroacetate. Four derivatives of quercetin weregained, and their structures were characterized by1H-NMR,13C-NMR, IR and MSspectroscopies. Two of these compounds have not been reported so far. Theantioxidant activities of these compounds were determined by means of improvedpyrogallol autoxidation method, and the changes of the free radical scavenging abilitywith variation of concentration.4. THR as the starting material reacted with acetic anhy-dride underconcentrated sulfuric acid as the catalyst. An ester derivative of quercetin,3′,4′,7-Tri[-O-（2"-O-acetylethyl）] quercetin, was synthesized. Its structure was characterized by1H-NMR,13C-NMR and IR spectroscopies. The antioxidant activities of these twocompounds were determined by means of improved pyrogallol autoxidation method,and the changes of the free radical scavenging ability with variation of concentration.5. A new quercetin derivative-metal complex, THR:Cu2+=2:1（mol/mol）, weredesigned and synthesized. The structure was characterized by Vis-UV，MS and IRspectroscopies. The stability of the complex was studied by the adding of EDTA. Theantioxidant activities of these two compounds were determined by means of improvedpyrogallol autoxidation method, and the changes of the free radical scavenging abilitywith variation of concentration.