| Oxidative stress refers to the body subjected to a variety of harmful stimulation,or lacking of antioxidant substances,imbalance between the production and scavenging of free radicals,thus leading to tissue damage.Free radical that is closely related with oxidative stress mainly was reactive oxygen species(ROS),that would directly cause biological membrane lipid peroxidation,protein and DNA damage,and finally lead to cell death or apoptosis,tissue injury,disease,such as atherosclerosis,Alzheimer’s,diabetes and so on.At the same time,epidemiological studies have found that often eating fruits,vegetables and whole grains can reduce the incidence of these diseases.Hull-less barley is endemic to the Tibetan Plateau region,the incidence of chronic diseases about Tibetan people with highland barley as staple food is relatively low,and exist many the longevous,this indicate that hull-less barley has high nutritional value,and also has good healthcare value such as antioxidant,anti-senility.For the nutritional potential,the feeding value of barley,food and industrial use,many scholars at home and abroad have done a lot of research reports.At the same time,the application of highland barley,effect factor of barley green in the field of medicine also has a more in-depth research,but it was seldom reported the system study about in vivo and vitro antioxidant activity of different varieties of barley,the efficacy component and the antioxidant mechanism.In view of this,this paper comprehensively determinated in vitro antioxidant activity of6 main cultivated varieties of whole hull-less barley in China’s Yunnan,Sichuan,Qinghai and Tibet,and the main contents of antioxidant compounds(polyphenols,flavonoids,vitamin E and beta glucan)were compared and analyzed,finally choosed two whole hull-less barley which had better antioxidant activity in vitro to study their antioxidant activity in vivo,finally use the theory of free radical and mitochondrion to explain the relationship among the antioxidant content of whole hull-less barley and the antioxidant activity in vitro and vivo,so as to provide theoretical basis for breeding the high health value varieties of hull-less barley,at the same time,provide a new perspective for the future in-depth study on the diseases of aging.The main results are as follows:(1)This paper used two pre-treatments of the hull-less barley samples: that is the simulated gastrointestinal tract digestion in vitro and soluble and insoluble treatment to extract the antioxidant components of six varieties(No.1-No.6)of whole hull-less barley,using the methods of the freeradical scavenging rate of DPPH,ABTS,AAPH,the method of copper ion chelating coefficient to evaluate the antioxidant activity in vitro about the extraction of six varieties of whole hull-less barley,The differences between the results were analyzed.Results showed that: DPPH clearance value of the six hull-less barley was between 0.38 mg GA/g DW to 2.93 mg GA/g DW mg;ABTS clearance value was between 3.23 mg GA/g DW to 7.95 mg GA/g DW;ORAC value was between 77.01 μmol TE/g DW to 346.82 μmol TE/g DW;Copper ion chelating rate was between 0.78 mg GA/g DW to3.68 mg GA/g DW.The results showed that the antioxidant activity sequence of the six highland barley samples was different while with different evaluation methods,but after the comprehensive comparative analysis,the No.1 Yunnan Diqing highland barley and No.3 Tibet Lhasa purple highland barley had stronger antioxidant ability in vitro than others.We also found that the antioxidant activity of these 6 varieties of hull-less barley was not entirely uniform after two different sample pretreatments.Therefore,how to standardize and unify the evaluation method of oxidation activity will be an important direction for the future research.(2)The main antioxidant content(total phenolics,flavonoids,beta glucan and alpha vitamin E)in 6 varieties of whole hull-less barley were determined.The comparative analysis found that the total phenolic content was between 217.05 mg GA/100 g DW to 369.69 mg GA/100 g DW,total flavonoids content was between 0.71 mg Ru/g DW to 1.01 mg Ru/g DW,beta glucan content was between 4.13% w/DW and 5.36% w/DW,alpha vitamin E was between 0.37 mg/100 g DW to 0.71mg/100 g DW.In addition to the content of total phenol was No.5(369.69 mg GA/g DW)the highest,No.1 and No.3 were better than the other varieties in total flavonoids(0.95 mg Ru/g DW and 1.01 mg Ru/g DW),beta glucan(5.36% w/DW and 5.02% w/DW)and alpha vitamin E(0.71 mg/100 g DW and 0.60 mg/100 g DW)content,and the whole grain content of No.1 was higher than that of No.3.And it was similar to the antioxidant activity evaluation results in vitro.The results showed that the two kinds of varieties had better antioxidant activity in vitro was due to not single but multiple substances,at the same time,the rich material was bound to lay a good health value,and guessed that No.1 had better health value than No.3.This study also found that the differences in the different pretreatment system and antioxidant evaluation indexes was related to the content and types of antioxidant.It was found in the Pearson correlation analysis that the content of total flavonoids in whole hull-less barley had a significant positive correlation with the copper chelating coefficient and ABTS removal rate(p<0.05),the R2 were 0.896 and 0.897,respectively.The clearance rate of DPPH had a significant positive correlation with the alpha vitamin E and copper chelating coefficient(p<0.05),the R2 were 0.827 and 0.911,respectively.There was no significant correlation between other indexes.Therefore,in different systems,the related antioxidant components were not exactly the same.Reminding that studying the antioxidant activity in vitro in the future,just from the aspect of phenols and flavonoids content to determine the antioxidant activity of grain was not suitable,andwhich is the most representative components,need further study in the future,establishing a more reasonable antioxidant in vitro evaluation model is necessary.(3)This study continuously intraperitoneal injected high dose(450 mg/kg.bw/d)of D-galactose for 40 days to establish of animal aging model which was caused by oxidative stress,and at the same time,No.1 and No.3 were fed,using recognized antioxidant vitamin E as positive control,to explore the antioxidant activity in vivo and mechanism of the two varieties of barley that had good performance in the determination of antioxidant activity in vitro.The result found that feeding whole hull-less barley and vitamin E could effectively decrease the level of oxidative stress in the body,improve the antioxidant defense system,nervous system and immune system function,reduce damage of mitochondrial mtDNA in mouse brain,play a good health effect in aging body.No.1 had a better effect than that of No.3 and vitamin E,but there was no absolute pros and cons between No.3and vitamin E,it was known that No.1 performed better than No.3 in simulated gastrointestinal digestion in vitro,and its antioxidant substances content was higher than that of No.3,this prompted that the high antioxidant content in whole hull-less barley played a key role in the antioxidant in vivo,they could delay senescence through the directly scavenging of free radicals,inhibiting free radical chain reaction,and improving the activity of antioxidant enzymes.At the same time,the measured results of in vitro simulated gastrointestinal digestive had more credibility for antioxidant activity evaluation.In addition,in the determination of antioxidant enzyme activity,GSH-Px and SOD activity in the heart didn’t obey the aging rule,reminding that the physiological characteristics of constantly beating of this organ might maintain the myocardial mitochondrial function good,so as to maintain the balance between antioxidant capacity and free radical production in heart.In future research,it can’t be ignored that the metabolic characteristics of various organs and as much as possible to conduct a comprehensive determination.Conclusion:This study found that,the whole grain of No.1 and No.3 had higher antioxidant content and better antioxidant activity in vitro than other varieties;In the D-galactose-induced aging process,excessive ROS attacking mitochondrial mtDNA caused mutational damage and attacking biological macromolecules caused oxidative damage,mitochondrial dysfunction and tissue cell apoptosis would lead to HPA axis dysfunction,decrease the function of immune system,metabolic disorder,liver tissue lesion,causing vicious spiral,but No.1 and No.3 could improve this circulation by removing ROS,and the effect of No.1 is better than No.3,it was related with its higher content of antioxidants,namely Yunnan Diqing hull-less barley has better preventive effect on oxidative stress caused by aging. |
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