Studies On The Anti-oxidant Activity And Synergistic Effect Of Citrus Flavonoids

Recent research indicates that the premature citrus fruits contains different kinds of flavonoids in a great amount.In order to utilize premature citrus fruits.Many of which fall off every June due to wind and may be with some other factors.The extract of citrus flavones can be obtained with ethanol as solvent.In this study its types, content as well as the antioxidative activity of this extract in four systems were analyzed.Analysis of the antioxidant activity of flavonoid monomers,antioxidative synergy between them.Further research work was carried out on an antioxidative synergy between extracts of citrus flavone,flavonoid monomers,Tea polyphenols and Vitamin C(Vc).Huyou(Citrus paradise Macf.Changshanhuyou),Oukan(Citrus suavissima Hort.ex Tanaka),poonkan(Citrus poonensis Hort.ex Tanaka),mandarin oranges (Citrus unshiu var.praecox),were used as raw materials for these experiments.The extract of citrus flavone was obtained and research was carried out on its types and content of flavonoids.The result obtained showed that flavone extracts of different types of citrus contain different types and also vary in the contents of flavonoids.The total content offlavone are as follows:Huyou(385.61mg/g on Dry Weight basis)＞Oukan(228.57mg/g DW)＞poonkan(161.04mg/g DW)＞mandarin orange(67.35 mg/g DW).Maximum flavone contained in Huyou,Oukan,poonkan,mandarin orange naringin(220.87mg/g DW),neohesperidin(121.3mg/g DW),hesperidin (59.3mg/g DW) and hesperidin(49.74mg/g DW)was,recorded respectively..Thus, it indicates that the total content of flavone in mandarin orange was found lowest,but the yield of flavone extract was highest.The antioxidative activity of flavone extract of 4 types of citrus premature fruits were evaluated in four antioxidative systems,namely DPPH,FRAP,ABTS,TBARS. It was found that under these 4 systems and under concentrations(100-2000μg/ml), the antioxidative activity become higher with higher,concentration.Presenting a dose relationship.When the extract's concentration reaches to 2000μg/ml,antioxidative activity become morer efficient.Under FRAP,ABTS,TBARS antioxidative systems,antioxidatiive activities of the flavone extract of four types of citrus premature fruits were shown in this order:Huyou＞Oukan＞poonkan＞mandarin orange.This order is in the same pattern as that of total content of flavone.Under DPPH system,however,this order is changed to be Huyou＞poonkan＞Oukan＞mandarin orange.(2)Under DPPH,FRAP systems,antioxidative activity of 7 types of common citrus flavonoid monomers were evaluated under different concentrations(quercetin, rutin,neohesperidin,hesperetin,hesperidin,naringenin,naringin),while the antioxidative synergy between uniting 6 types of flavonoid monomers under different concentrations(quercetin,rutin,hesperetin,hesperidin,naringenin,naringin) were evaluated.Result indicates,in DPPH,FRAP systems,within the concentration of 1mmol/l,antioxidative activity mentioned here becomes stronger with higher concentration The antioxidation activity of these 7 types of flavonoid monomers is shown in this order:quercetin > rutin > neohesperidin > hesperetin > hesperidin > naringenin > naringin.In terms of antioxidative activity,glycosides flavonoid is close to corresponding aglycone,but aglycone is stronger than glycosides.In DPPH system, when analyzing antioxidative Synergistic effects of 6 types of flavonoid monomers which were under different concentrations,we found quercetin and rutin not only have good antioxidative activity themselves,but also showed synergistic effects if united with other flavonoid monomers at the same time.(3)Under DPPH,FRAP antioxidant systems,synergistic effect between 2 types of citrus flavone extracts.Different concentrations of Huyou and Oukan and Tea polyphenols under different concentrations as well as Vc,also had synergistic effect between flavonoid monomers and Tea polyphenols The result indicates,natural antioxidants have a certain degree of synergistic effect with each other under these two antioxidant systems.The antioxidant synergy is related with antioxidant systems, oxidation resistance of the antioxidant itself,as well as the effective concentration of antioxidants.Under DPPH system,if the concentration of Huyou flavone extract is 400μg/ml, it shows synergistic effect with Tea polyphenols.The extract of Oukan flavone did not showed synergistic effect.When it was under any concentration used,Under FRAP system,2 types of citrus flavone extracts shows synergistic effect with Tea polyphenols when it was under any concentration used,moreover,synergistic influence was more noticeable if the extract is under high concentration(1600μg/ml). Under DPPH system,the Huyou flavone extract shows synergistic effect with Vc if it was under low concentration(400μg/ml);the Oukan flavone extract showed synergistic effect with Vc when it was under any concentration used.Under FRAP system,the flavone extract of 2 types of citrus showed good synergistic effect(P＜0.05) with Vc when they were under high concentration(1600μg/ml).When analysing synergistic effect between flavonoid monomers and Tea polyphenols as well as Vc,we found that,under DPPH system,quercetin and rutin, though they were highly active antioxidants,did not show synergistic effect with Tea polyphenols;however,all other 5 types of flavonoid monomers showed antioxidant synergy in a certain degree with Tea polyphenols.Under FRAP system,quercetin and rutin showed significant synergistic effect with Tea polyphenols(P＜0.05).The synergistic effect of other monomers and Tea polyphenols was not obvious.When uniting flavonoid monomers and Vc,it showed good synergistic effect(P＜0.05) under each of these 2 systems,furthermore,it was obvious that synergistic effect was observed at higher concentration...