| Epidemiological and clinical studies have shown that oxidative stress is one of the most critical factors that causing series of chronic diseases.Whole grains and their products contain higher content of active substances like polyphenol than refined grains.The intake of dietary polyphenols can alleviate or avoid oxidative stress.As a representative whole grain product,the potential antioxidant activity of whole grain rice noodles has not been clarified.In this study,white rice,flat rice noodles,brown rice and whole-grain flat rice noodles were used to analyze the content of free and bound polyphenols and phenolic acid composition.The in vitro chemical antioxidant model,human normal hepatocyte LO2 and human umbilical vein endothelial cell HUVEC oxidative stress model were used.The aging and stress resistance model of C.elegans evaluated the antioxidant activity of whole-grain flat rice noodles polyphenol extract in vitro and in vivo,and this study preliminarily explored the mechanism of whole-grain flat rice noodles polyphenol on prolonging the life span of C.elegans and resisting oxidative stress.The main results are as follows:(1)The results of single factor experiment showed that the best extraction method of free polyphenol from whole-grain flat rice noodles was solid-liquid ratio of 1:40,ethanol concentration of 80%,extraction temperature of 45℃ and extraction time of 1.5 h.During the processing of whole-grain flat rice noodles,the content of free total polyphenols decreased significantly,while the change of bound total polyphenols was not significant,but they were higher than that of flat rice noodles.The content of phenolic acid in the sample was determined by HPLC.The highest content of phenolic acid in whole-grain flat rice noodles was ferulic acid,and the contents of free and bound ferulic acid were 18.44 μg/g DW,331.95 μg/g DW respectively.Bound ferulic acid,p-coumaric acid,p-hydroxybenzoic acid and vanillic acid were not significant in rice noodles processing,but the content of free coumaric acid decreased,while the content of free ferulic acid,p-hydroxybenzoic acid and vanillic acid increased.DPPH radical scavenging capacity,ABTS radical scavenging capacity and FRAP antioxidant activity were used to preliminarily evaluate the in vitro antioxidant activity of whole-grain flat rice noodles.The in vitro antioxidant activity of free and bound extracts of whole-grain flat rice noodles was significantly higher than that of white rice and flat rice noodles,and the free in vitro antioxidant activity of whole-grain flat rice noodles was slightly lower than that of brown rice.SPSS analysis showed that the contents of free,bound and total polyphenols in whole-grain flat rice noodles,flat rice noodles,milled rice and brown rice were significantly positively correlated with phenolic acid content and antioxidant activity in vitro.(2)MTT method was used to verify that four polyphenols samples had no cytotoxicity to LO2 cells and HUVEC at the concentration of 10-500 μg/mL.The model concentration of oxidative stress induced by hydrogen peroxide was 0.6 mmol/L,and the survival rate of LO2 cells was 51.38%.Whole-grain flat rice noodles polyphenols can significantly improve the survival rate of LO2 cells stimulated by H2O2 at the concentration of 10 μg/mL or higher.Four kinds of polyphenols was can reduce the content of ROS in HUVEC cells,increase the activities of antioxidant enzymes SOD,CAT and GSH-Px,reduce the content of MDA,and protect HUVEC cells from oxidative stress at the concentration of 200 μg/mL and 500 μg/mL.(3)The model organism C.elegans was used to establish an antioxidant model in vivo.At the concentrations of 0.5 mg/mL and 1.0 mg/mL,whole-grain flat rice noodles polyphenols can significantly prolong the life span of C.elegans,improve the ability of C.elegans to resist heat stress,hydrogen peroxide oxidative stress and paraquat oxidative stress,significantly improve the average survival time and maximum life span of C.elegans,and delay the death of C.elegans.The treatment of nematodes with whole-grain flat rice noodles polyphenols can significantly reduce the content of ROS in nematodes,increase the activities of antioxidant enzymes such as SOD,cat and GSH-Px,reduce the content of MDA in nematodes and improve the antioxidant activity of nematode tissue lysate.Treatment of C.elegans with whole-grain flat rice noodles polyphenols can significantly reduce osr-1 and increase the expression levels of skn-1,DAF-16 and their downstream genes sod-3 mRNA,so as to improve the antioxidant stress ability of C.elegans. |
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