Effects Of Steam Explosion Treatment On The Release Of Polyphenols Form Tartary Buckwheat Bran And Its Alleviating Influence Of Colitis In Mice

Polyphenols in whole grains showed the bioactivities to protect human body from types of chronic diseases.Polyphenols widely exist in various grain by-products,such as rice bran,Tartary buckw heat bran,oat bran,etc.Tartary buckwheat bran contains more flavonoids such as rutin and quercetin,which have anti-inflammatory,hypotensive and lipid-lowering effects.However,due to the poor palatability to be directly used by human body,most of its functional active substances are wasted.The utilization rate of bran,rice bran and other processing by-products is far less than 60%.Steam Explosion(SE)is an environmentally friendly,economical and efficient technology,which is widely used as a way of pretreatment for plant materials.The instantaneous release of steam pressure can destroy the connection between the fiber bundles and break the cell wall,which shows a great effect in the process of extraction of plant functional components.Chronic inflammatory bowel disease(IBD)could cause poor absorption of nutrients,abdominal pain and rectal bleeding.Both genetic susceptibility and environmental factors could increase the risk of IBD.While changes in gut microbiota and poor dietary habits are also the important factors in the incidence of IBD.Moreover,high fat and sugar diets can increase the prevalence of IBD.The common drugs used to treat IBD have shown significant side effects,while higher intake of fruits and vegetables can dramatically reduce the risk of developing IBD.Therefore,dietary intervention may be a new target for treatment of IBD.Based on these backgrounds and hypothesises,in this paper,steam explosion technology was used as a pretreatment for Tartary buckwheat bran,to explod effect on the content,antioxidant activities and compnents of polyphenol of different steam explosion strength and time.By using the dextran sodium sulfate salt(DSS)induced colitis model in C57BL/6J mice,we explored the alleviating effects and related mechanisms of steam exploded free polyphenols extract on C57BL/6J mice colitis,to provide some theoretical basis for the further processing of Tartary buckwheat bran polyphenols functional food and adjuvant intervention for IBD.The main research results are as follows:(1)We exploded the changes of content and in vitro antioxidant activities of polyphenols from Tartary buckwheat bran with different intensity of steam explosion treated.The results showed that the SE treatment made the free polyphenols content in Tartary buckwheat bran reduced by 6.24%?21.65%,and on the condition of 3.2 MPa,60 s,the maximum free polyphenols content of was 60.84 mg GAE/g DW.Steam explosion treatment significantly increased the content of bound polyphenols,and on the condition of 0.8 MPa,90 s,the content was 4.26 mg GAE/g DW,2.20-fold increased before treatment.After SE,the contribution rate of free polyphenols was still above 92.11%,and with the increase of steam explosion intensity(higher pressure,longer time),its rate of free polyphenols was increased.The IC50 values of DPPH·scavenging rates of free and bound polyphenols were significantly decreased after SE treatment(P<0.05),indicating that SE can effectively improve the polyphenol free radical scavenging ability of Tartary buckwheat bran.On the condition of 1.6 MPa,60 s the maximum free phenolic oxygen radical absorption capacity of Tartary buckwheat bran reached 1607.88?mol TE/g DW,which was 44.77%higher than that of the unexploded treatment(P<0.05),and the total oxygen radical absorption capacity of Tartary buckwheat bran polyphenols was the highest.The content of free quercetin was increased by 4.18?6.00 times,and the content of free rutin was decreased by 60%?75%.The maximum content of free quercetin reached 38.18 mg/g on the condition of 1.6 MPa 60 s.(2)The dense structure of original Tartary buckwheat bran was destroyed after steam explosion,and the overall pores increased and the more debris fell.Steam explosion treatment changed the grain size of Tartary buckwheat bran,and significantly increased the specific surface area(P<0.05).At the same time,it significantly improved the thermal stability of Tartary buckwheat bran,and the PPO activity in the raw material was significantly decreased(P<0.05).The free polyphenols extract of Tartary buckwheat bran without SE treatment showed a small round particle structure similarly to that of rutin standard,while it caused the polyphenol extract to have more rod structure similarly to that of quercetin standard.All the free phenol extracts of Tartary buckwheat bran before and after steam explosion showed similar absorption peaks in infrared spectrum except some detalis.(3)Fee polyphenols extract of steam explosive Tartary buckwheat bran(SE-FPE)was used to alleviate the colitis in C57BL/6J mice induced by DSS.The results showed that both SE-FPE with both high dose(400 mg/kg)and low dose(100 mg/kg)had positive effects on the colitis in mice.Especially high dose of SE-FPE could significantly improve C57BL/6J mice symptoms related colitis such as weight loss,fecal occult blood,short of colon,and the organ index was decreased obviously.Moreover,the hypotorenal toxicity in mice caused by DSS,and proinflammatory factors IL-6 and TNF-? expression were decreased,too.However,the level of IL-10 and SOD were increased.SE-FPE could effectively reduce the damage of colon,while the degree of degeneration cell necrosis,fibrous hyperplasia,inflammatory cell infiltration and crypt structure damage of colonic mucosa in mice can be improved.At the same time,SE-FPE could significantly increase the deletion of tight junction proteins Claudin,Occludin and ZO-1 caused by DSS,and maintain the intestinal integrity of mice.(4)SE-FPE could inhibit the transcription activity of NF-?B in colon tissue of C57BL/6J mice,and reduce the expressions of IKK-?,I?B,NF-?B p65 and COX-2 proteins in NF-?B signaling pathway in colon cell,and alleviate the inflammatory response caused by DSS.At the same time,SE-FPE may act as an antioxidant to replace the endogenous antioxidant defense ability in the colon and decrease the expressions of DSS-activated proteins related with Nrf2 signaling pathway,thus playing a protective role against DSS-induced oxidative stress injury in the colon of mice.(5)SE-FPE could improve the diversity and abundance and of gut microbiota in mice with colitis to restore the structure of it.SE-FPE could also increase the number of beneficial bacteria(Muribaculaceae,Lactobacillus,Ruminococcaceae and Akkermansia),and reduce harmful ones(Escherichia-Shigella,Parasutterella and Enterobacter).Meanwile,it could promote the contents of SCFAs produced by gut microbiota,and alleviate the symptoms of colitis caused by DSS to restore the intestinal health.