Changes Of Polyphenols During The Germination Of Buckwheat Sprouts And Its Protective Effect On Oxidative Damage Of HepG2 Cells

Buckwheat is favorable grain resource containing abundant nutrients such as carbohydrates,fats,protein,vitamins,minerals,phenolic acid and so on,which possesses resistance to cancer,oxidation,inflammation,hyperglycemia,hyperlipidemia,hypertension,obesity,etc.However,buckwheat also contains protease inhibitors and other anti-nutritional factors,affecting the bioavailability of buckwheat.It was found that germination treatment could further improve the nutritional value and pharmacological activity of buckwheat and eliminate the effect of anti-nutritional factors,so the germination of buckwheat caused more and more attention.However,the intrinsic reason for the improvement of the active ingredient in the process of buckwheat germination is not clear.In addition,the protective effect of the active ingredient in buckwheat sprouts on the induced oxidative damage of H2O2 is less.In this study,the contents of total phenolics,total flavonoids,phenolic acids and their contents,antioxidant activity and the expression of phenylalanine aminotransferase(PAL)gene were measured at different germination time,different parts of buckwheat sprouts(cotyledons,hypocotyls and radicles)And the changes of the expression of polyphenols in the different tissues of buckwheat were studied.The effects of the freshly accumulated phenolic compounds in the ethanol extract of buckwheat and the germination of buckwheat were studied.Induced oxidative damage to provide a theoretical basis for the deep processing of buckwheat products.The main conclusions drawn from the study are as follows:(1)The content of total phenolics,total flavonoids,antioxidant activity and PAL gene expression in different tissues of buckwheat malt were significantly increased.Among them,the total phenol content,total flavonoid content and antioxidant activity of cotyledons in germination days were 8.04,16.9 and 8.08 times,respectively.Phenolic compounds accumulate mainly in cotyledons and hypocotyls.Rutin and ferulic acid accumulate in cotyledons.The content of rutin in buckwheat leaves is about 8 times of that in buckwheat kernel.Chlorogenic acid and syringic acid,is the new stage of buckwheat germination of phenolic compounds,mainly in the hypocotyl accumulation.The content of chlorogenic acid in the hypocotyls increased significantly at the germination stage,reached 7.84 mg/g DW on the 12th day of germination,but the content of chlorophyll was not significant.The expression of PAL gene was the highest in the radicle,and the highest expression was found in the radicle of buckwheat buds for 4 days,which was about 213 times of that of buckwheat seeds.This indicated that germination treatment could improve the content of polyphenols in buckwheat malt and the antioxidant activity.(2)The ethanol extract of buckwheat sprouts with concentration of 5,10 and 20μg/mL and chlorogenic acid with 5,10,20μmol/L could significantly increase the growth rate of HepG2 induced by 200μmol/L H2O2,and could make cell morphology remains intact.(3)The ethanol extract of buckwheat sprouts with concentration of 5,10 and 20μg/mL and the concentration of 5μmol/L,10μmol/L and 20μmol/L chlorogenic acid can increase the total protein content of oxidatived damaged HepG2 cells,actiity of glutathione-S-transferase GST)and the protein concentration of NQO1 and HO-1(2-phase enzyme).5μg/mL of buckwheat ethanol extract and 5μmol/L chlorogenic acid were the most significant.These data suggest that buckwheat ethanol extract and chlorogenic acid can protect against oxidative damage by inducing two-phase enzyme expression and increased enzyme activity.