Changes Of Antioxidant Activity Of Jujube Pigment In Vitro Simulated Digestion

Jujube pigment is a natural pigment extracted from waste jujube residue obtained from jujube food production,which contains antioxidant active components such as polyphenols,flavonoids and anthocyanins.It has the ability to scavenge free radicals,inhibit lipid peroxidation,inhibit bacteria,protect the oxidative damage of vascular endothelial cells induced by H2O2,and improve kidney injury induced by KBrO3,atmospheric oxygen and restraint stress-induced liver damage.Therefore,it has been widely concerned as a natural antioxidant.Studies have shown that when an organism ingests active ingredients,it will interact with digestive enzymes in the digestive tract,which will cause changes in the biological activity of active ingredients,thus affecting the digestion and absorption of nutrients.Therefore,studying the change rule of active ingredients in the digestive tract has great significance for improving the effective utilization of active ingredients in organisms.So the gastric and intestinal simulated digestion model were established to study the changes of total polyphenols,flavonoids content,antioxidant activity and anti-lipid peroxidation ability of jujube pigment in simulated digestion in vitro,observed the kinetic behavior of simulated digestion of jujube pigment in vitro,and discussed the effects of some common food additives on simulated digestion of jujube pigment in vitro.The results are as follows:(1)The contents of total polyphenols and flavonoids,scavenging ability on DPPH·?O2-·?·OH?ABTS+· and reducing power in jujube pigment during simulated digestion in vitro were studied,and the correlation between antioxidant components and antioxidant activity was analyzed.The results showed that the contents of total polyphenols and total flavonoids of jujube pigment decreased with the increase of time in simulated gastric digestion in vitro,and the ability of scavenging DPPH·?O2-·?·OHx ABTS+· and reducing power also decreased significantly with the increase of time(P<0.05).However,the total polyphenols of red jujube pigment had no significant change in simulated intestinal digestion(P>0.05),but the content of total flavonoids and antioxidant activity decreased significantly(P<0.05),and there was a positive correlation between antioxidant components and antioxidant activity of jujube pigment in simulated gastric and intestinal digestion in vitro,indicating that antioxidant capacity of jujube pigment decreased after simulated digestion.(2)The effect of jujube pigment on lipid peroxidation,Fe2+-induced yolk lipoprotein lipid peroxidation,linoleic acid lipid peroxidation,spontaneous lipid peroxidation in mice,H2O2-induced lipid peroxidation in mice liver tissue,H2O2-induced erythrocyte membrane lipid peroxidation and H2O2-induced hemolysis of red blood cells in vitro were studied.The results showed that the ability of jujube pigment to inhibit lipid peroxidation,Fe2+-induced yolk lipoprotein lipid peroxidation,linoleic acid lipid peroxidation,spontaneous lipid peroxidation in mice,H2O2-induced lipid peroxidation in mouse liver tissue,H2O2-induced erythrocyte membrane lipid peroxidation and H2O2-induced hemolysis of red blood cells in simulated gastric and intestinal digestion in vitro decreased significantly,and the ability of red jujube pigment to inhibit lipid peroxidation in simulated gastric digestion was weaker than that in intestinal digestion(P<0.05),indicating that the anti lipid peroxidation ability of jujube pigment decreased after simulated digestion.(3)The kinetic behavior of jujube pigment in simulated digestion in vitro was studied.The results showed that the changes of total polyphenols and total flavonoids in jujube pigment in gastric and intestinal simulated digestion accorded with the second-order kinetic equation in vitro,and the fitting degree was high.The reaction rate constants were 0.0001,6×10-5,0.0089 and 0.0044,and the half-lives were 21.7,42.8,0.93 and 11.48 h,respectively,indicating that the kinetic behavior of jujube pigment in simulated digestion in vitro conforms to the second order kinetic equation.(4)The effects of some common food additives on flavonoids,polyphenols and antioxidant activity of jujube pigment during simulated digestion in vitro were studied.The results showed that adding ascorbic acid not only increased the contents of total polyphenols and total flavonoids of jujube pigment in gastric and intestinal simulated digestion,but also enhanced the ability of jujube pigment to remove DPPH· and inhibit Fe2+-induced yolk lipoprotein peroxidation(P<0.05).However,the addition of glucose,fructose,sucrose,starch,salt,potassium sorbate and citric acid had no significant effect on the antioxidant capacity of jujube pigment in gastric and intestinal simulated digestion(P>0.05),indicating that food additives can affect the simulated digestion of jujube pigment in vitro.