Attribution of Antioxidation of Quercetin in Vitro and Arbor Acre Broilers

The antioxidant effects of quercetin were studied in vitro and in vivo.In vitro,vitamin C was used as a positive control to evaluate the antioxidant capacity of quercetin in three aspects:scavenging free radicals,protecting biological macromolecules and the total reducing power.In vivo,a total of 240 AA broilers （1-day age） with similar body weight were randomly divided into four groups with six replicates in each group,and 10 broilers in each replicate.The four groups were fed with corn-soybean basal diet supplemented with 0.00%,0.02%,0.04% and 0.06% quercetin to study its effects on antioxidant indexes of AA broilers,and to explore the optimal dose of quercetin as a dietary additive.The results showed that quercetin scavenged superoxide anion,hydroxyl radical and 1,1-diphenyl-2-picrylhydrazyl （DPPH） in vitro,the scavenging effects of quercetin on O₂^-and ·OH first increased and then decreased with the increase of the concentrations （P＜0.01）,and its maximum scavenging effect was observed at concentrations of 40 and 300 mg·L^-1.The scavenging effects of quercetin on DPPH was increased constantly with increasing concentrations.The scavenging effect of quercetin on three free radicals was DPPH＞·OH＞O₂^-.The inhibition of vitelline lipoprotein peroxidation by quercetin was increased with increasing concentrations （P＜0.01） and the inhibitory effect was higher than that of vitamin C.The inhibition of red blood cell hemolysis by quercetin was increased with increasing concentrations at 0.05-1.25 mg·L^-1（P＜0.01）;however,the inhibition tended to decrease when the concentration was too high (31.25 mg·L^-1),and the inhibitory effect was higher than that of vitamin C.The inhibition of mitochondrial expansion by quercetin was increased with increasing concentrations,according to the degree of mitochondrial expansion at 60 min,the integrity of mitochondria in the experimental groups was significantly higher than that in the model group （P＜0.01）.The total reducing power of quercetin was increased with increasing concentrations （P＜0.01）;however,the total reducing power was less than that of vitamin C.In vivo,malondialdehyde （MDA） and nitric oxide （NO） were significantly decreased with increasing quercetin （P＜0.01）.Quercetin supplementation had no effect on the content of lipid peroxidation （LPO） in livers （P＞0.05）;however,superoxide dismutase （SOD） activity was significantly increased,whereas glutathione peroxidase （GSH-Px） and catalase （CAT） activities were significantly decreased in livers with increasing quercetin （P＜0.05）.These results suggested that quercetin exhibited strong antioxidant effects in vitro and in vivo.