Study On The Antioxidant And Antitumor Activities Of Several Flavonoids And Their Structure-Activity Relationship

Flavonoids are a kind of natural products with rich physiological activities and exist widely in nature.Currently,a large number of researchers have focused on the antioxidant and anti-tumor activities of flavonoids,but the reported activities of flavonoids in different research systems are inconsistent or even contradictory.Therefore,it is of great theoretical value and practical significance to establish a set of reasonable and effective system for activity determination and evaluation,and to scientifically evaluate its activity from the perspective of mechanism and structure-activity relationship.In this paper,seven structurally representative flavonoid compounds were used as the research objects,their antioxidant activities were evaluated based on different experimental determination schemes and theoretical calculation systems,and the structure-activity relationship was analyzed.At the same time,their inhibitory activities against different tumor cells were investigated.The correlation between antioxidant and antitumor activity was analyzed and the intrinsic relationship between them was inferred.As for the study on the antioxidant activity of flavonoids,seven flavonoids including rutin,isoquercetin,quercetin,baicalin,baicalin,hesperidin and hesperidin were selected in this paper for evaluation based on quantum chemical calculation,free radical scavenging ability determination and antioxidant damage ability determination.Quantum chemical calculation mainly constructs the molecular model of seven flavonoids through GaussView5.0,AM1 is preliminarily optimized,and then the quantitative parameter of antioxidant--frontline molecular orbital--is calculated by density functional theory E_HOMO&E_LOMO)and energy gap??E?.It can be seen from the quantitative parameters of antioxidant that under the condition of gas phase,the electronic feeding ability?from strong to weak?of the above flavonoids and the difficulty?from easy to difficult?of the reaction are in the following order:quercetin,isoquercetin,hesperidin,rutin,hesperidin,baicalin and baicalein.DPPH method and ABTS method were used to determine the free radical scavenging capacity of the seven flavonoids mentioned above,from large to small:quercetin>baicalin>isoquercetin>baicalin>rutin>,hesperidin>.Establish HDHC?H₂O₂-induced apoptotic damage in H9C2 cardiomyocytes?model,found that H₂O₂When the concentration was 400 mol/L,the survival rate of H9C2 cells was about 52.49±4.44%of the control group,with a significant difference?P<0.001?,which could be used as an HDHC model for the evaluation of antioxidant activity.In the HDHC model,the antioxidant damage capacity was from large to small:quercetin>baicalin>hesperdin,and other flavonoid glycosides showed no protective effect.It can be seen from Pearson's coefficient that flavonoid compounds have a strong correlation in the ability of scavenging free radicals in pure chemistry,and the correlation coefficient is 0.839?P<0.001?.Therefore,in the pure chemistry determination system,the position and quantity of c2-c3 double bond,hydroxyl group and glycosylation are all the reasons affecting the antioxidant activity of flavonoid compounds.However,the antioxidant damage in the cell model was weakly correlated with the scavenging ability of free radicals determined by the purification method.Therefore,glycosylation became the main way to affect the antioxidant activity in the cell model.MTT assay was used to determine the inhibitory effect of the seven flavonoids on the proliferation of two types of tumor cells?HepG2 in liver cancer and Hela in cervical cancer?and normal liver cells?LO2?.According to three kinds of antioxidant system and the relativity analysis of two kinds of tumor cell proliferation resistance,can be concluded that flavonoids anti-tumor ability and the ability to resist oxidative damage have a certain correlation,inhibition of liver cancer cell proliferation ability and the ability to resist oxidative damage of the correlation coefficient was 0.746?P<0.01?,inhibit cervical cancer cell proliferation ability and the ability to resist oxidative damage of the correlation coefficient was 0.758?P<0.01?.According to the above studies,the following conclusions can be drawn:1)the same flavonoids will show different antioxidant activities in different antioxidant systems.2)the ability to inhibit tumor cell proliferation is strongly correlated with the ability to resist oxidative damage.3)in the cell model,glycosylation can significantly reduce the physiological activity of flavonoids.