Study On The Structure-Activity Relationship And The Capacites Of Antioxidants Containing Hydroxyl Group

Study on synthesis and antioxidant activity of bio-antioxidants was one of thecentral issues in organic chemistry in recent years. In this work, we selectedferrocenyl Schiff base, homoisoflavonoids and triphenyl pyrazoles as the center withdifferent position of hydroxyl substituent attached, synthesized10kinds ofcompounds, and researched their antioxidant activities.The antioxidants evaluation methods are usually defined as two types which arechemical systems and chemical mimic biological systems. The former contains DPPHmethod,ABTS method and galvinoxyl method. Chemical-system method couldrapidly quantitative determine the antioxidant activity, but because of the difference ofthe internal environments between chemical system and chemical mimic biologicalsystem, the results from this method usually do not match those of chemical simulatedbiological system. The latter contains AAPH-,Cu2+/GSH-and OH-induced DNAoxidation. This method overcomes the inadequacies of the chemical system method,still no objective quantitative criteria to evaluate the antioxidant activity.In this thesis, we combined two methods. The new method evaluates theantioxidant activities comprehensively and systematically. Chemical kinetic equationis introduced to both of the two methods, which provided quantitative criteria toevaluate antioxidant activity. The following is the main work: 1. Studies on synthesis and antioxidant activities of ferrocenyl Schiff baseWe synthesized o-(1-Ferrocenylethylideneamino)phenol (OFP), m-(1-Ferrocen-ylethylideneamino)phenol (MFP) and p-(1-Ferrocenylethylideneamino)phenol (PFP),and determined antioxidant activities by using scavenging ABTS+and DPPH freeradicals methods and protect DNA against AAPH-,Cu2+/GSH-and OH-inducedoxidation methods.The ability of OFP to scavenge DPPH free radical is the highest, shows weekantioxidant activity in·OH-induced DNA oxidation and plays a pro-oxidant role inCu2+/GSH-induced DNA oxidation. The antioxidant abilities of MFP are not too highfor all the methods. PFP shows a high capability to scavenge ABTS+free radical,plays a pro-oxidant role in both·OH-, Cu2+/GSH-induced DNA oxidation. But PFPshows the highest activity in AAPH-induced DNA oxidation. And for this method, theantioxidant activities of OFP, MFP and PFP are higher than those of non-ferrocenylSchiff base, indicating that the ferrocenyl group could improve the antioxidantactivities.2. Studies on synthesis and antioxidant activities of homoisoflavonoidsWe synthesized3-(2′-hydroxybenzylidene)-7-methoxychroman-4-one (o-HBM-C),3-(3′-hydroxybenzylidene)-7-methoxychroman-4-one (m-HBMC) and3-(4′-hydr-oxybenzylidene)-7-methoxychroman-4-one (p-HBMC), determined antioxidantactivities by using scavenging ABTS+, DPPH and galvinoxyl free radicals methods,reducing peroxynitrite method, quenching singlet oxygen method, β-carotenebleaching test, protect methyl linoleate against AAPH-induced oxidation and protectDNA against AAPH-,Cu2+/GSH-and OH-induced oxidation methods.The ability of m-HBMC to scavenge ABTS+is the highest, and shows thestrongest ability in·OH-induced DNA oxidation. o-HBMC shows the highestantioxidant activities in scavenging DPPH and galvinoxyl free radical, β-carotenebleaching test, protect methyl linoleate and DNA against AAPH-induced oxidationassay. But it plays a pro-oxidant role in Cu2+/GSH-,·OH-induced DNA oxidation. And the capability of p-HBMC is higher than the other two on reducing peroxynitritemethod, quenching singlet oxygen method and protecting DNA againstCu2+/GSH-induced oxidation methods aspect.3. Studies on synthesis and antioxidant activities of triphenyl pyrazolesWe synthesized1,3,5-triphenyl-1H-pyrazole (TPP),4-(1,5-diphenyl-1H-pyrazol-3-yl)phenol (APP),4-(1,3-diphenyl-1H-pyrazol-5-yl)phenol (BPP),4-(3,5-diphenyl-1H-pyrazol-1-yl)phenol (CPP), and determined antioxidant activities by usingscavenging ABTS+and DPPH free radicals methods, protect DNA against Cu2+/GSH-and OH-induced oxidation methods, protect DNA against AAPH-induced DNAoxidation in homogenous and micelle system.TPP is only sensitive to DPPH and ABTS+free radical, APP shows a highcapability to scavenge DPPH, but weak ability in other methods. The ability of BPP isquite high in any of the methods including protect DNA against AAPH-inducedoxidation in micelle system. And play a pro-oxidant role in protecting DNA against OH-induced oxidation methods. CPP has the same ability to APP.