Nutritional Quality Of Selenium Enriched Radish Sprouts And Its Mechanism Of Alleviating Liver Injury In Mice

With the improvement of inhabitants' living standards,the nutritional quality of vegetables has been attracted more and more attention.Radish sprouts belonging to vegetables can be large-scale industrialized production in all seasons and are popular in East Asian countries.Meanwhile,Radish sprouts are rich in a variety of bioactive substances that are beneficial to the human health.Hence,it makes great sense to further increase the content of these bioactive substances in radish sprouts.Selenium(Se),which has the reputations of "longevity element" and "king of anti-cancer",is an essential nutrient for human beings.After being absorbed by plants,Se is converted into organic selenium which then becomes soluble and more active nutrient.However,whether exogenous selenium treatment could increase the content of bioactive substances has not been reported.In this study,radish sprouts were used to explore the effects of different selenium treatments on the bioactive substances in radish sprouts.The protective effect of selenium-enriched radish sprouts on liver injury induced by carbon tetrachloride(CC14)in mice was investigated as well.The main findings of this study are as follows:1.Treated with sodium selenite,the total selenium content in radish sprouts was significantly lower than that treated with the same concentration of sodium selenate,but the conversion rate of organic selenium was higher than treated with sodium selenate.Moreover,15 sodium selenite could significantly improve the content of anthocyanins,total phenols,total flavonoids and ascorbic acid as well as the DPPH free radical scavenging ability and the FRAP antioxidant capacity in radish sprouts.Besides,the activities of SOD,POD and GSH-Px were also significantly improved in response to 15?M sodium selenite treatment.The results above indicated that 15 ?M sodium selenite treatment could remarkably improve the nutritional quality and strengthen the antioxidation capacity of radish sprouts.2.Transcriptome ananlysis was used to analyze the mechanism of anthocyanins synthesis induced by selenium in the hypocotyl of radish sprouts.We set up three treatments:0 ?M,15 ?M Na2SeO4 and 15?M Na2SeO3.By splicing the transcriptome sequences,we obtained a total of 100727 unigenes and 125970 transcripts.By comparison between two treatments,there were 534 differentially expressed genes(DEGs)between Con(control)and Se(VI)treatments and 3254 DEGs between Con and Se(IV)treatments.KEGG analysis found that these DEGs were mainly enriched in plant hormone signal transduction,phenylpropane biosynthesis pathway,phenylpropanoid metabolic pathway,total flavonoid biosynthesis pathway,thioglucose biosynthesis pathway,photosynthetic synthesis,sulfur metabolism and other pathways.15 sodium selenite treatment could remarkably up-regulate the expression of related genes in total flavonoid biosynthesis pathway.Besides,most of MYB,bHLH,NAC,bZIP families transcription factors and WD40 family transcriptional regulators involved in biosynthesis of anthocyanins were up-regulated by 15 ?M sodium selenite treatment.Through the analysis of 55 DEGs between the three treatments by GO enrichment,it indicated that 3 genes responded to the abscisic acid(ABA)signaling pathway.Validation of transcriptome was verified by qRT-PCR,the expression of 12 DEGs involved in anthocyanin biosynthesis was consistent with the results of transcriptome analysis and this indicated that selenium treatments could significantly up-regulate anthocyanins biosynthesis related genes to promote the accumulation of anthocyanins in radish sprouts.3.In this study,the model of liver injury induced by CCl4 was used to explore the protective effect of selenium-enriched radish sprouts on the liver of mice.The results showed that radish sprouts treated with 15 ?M sodium selenite could significantly alleviate the liver injury caused by CC14 in mice,and HE staining showed that the area of necrosis of hepatocytes in mice was significantly reduced after fed with selenium-enriched radish sprouts,as well as,the ALT and AST activities in mice serum were also decreased.On the other hand,we found that the activities of SOD and GSH-Px in the liver of mice were significantly increased,but the content of MDA was decreased.Besides,the improvement of NO content and iNOS expression quantity in mouse liver caused by carbon tetrachloride was also alleviated.The qRT-PCR analysis found that the expression of IL-6,IL-1?,iNOS,COX-2,TNF-? and MCP-1 in the liver of mice fed with selenium-enriched radish sprouts was decreased sharply.At the same time,the expression of proapoptotic genes,TGF-?1,Smad3,Caspase-3 and Bax,was down-regulated and the expression of anti-apoptotic genes,Bcl-xL and Bcl-2,was up-regulated.The tunel staining showed that the number of apoptosis liver cells induced by CCl4 was significantly reduced after fed with selenium-enriched radish sprouts.Taken together,we found that selenium-enriched radish sprouts could alleviate the liver damage caused by carbon tetrachloride via enhancing the antioxidant enzyme activities and inhibiting the inflammatory reaction and liver cell apoptosis in mice.