Effects Of Different Processed Carrots And Carotenoids On Ulcerative Colitis In Mice

Ulcerative colitis(UC)is a chronic intestinal inflammatory disease with unknown etiology and is easy to relapse.In recent years,the incidence of colitis has been increasing all over the world,which seriously affects the physical and mental health of patients and becomes a global public health problem.Studies have confirmed that traditional Chinese medicine and some common edible fungi,vegetables,fruits and their extracts have a good effect on the prevention and treatment of colitis,and their side effects is rare or mild.Carrot(Daucus carota L.)is rich in nutrients and contains a number of bioactive substances that play a role in anti-inflammation,antioxidation,anti-tumor,immune regulation,blood lipids regulation,prevention of cardiovascular diseases and so on.It has great potential in preventing and alleviating UC.Modification of food physical structure by processing methods are known to significantly affect the release,absorption,transformation and metabolism of phytochemicals,and consequently changes their bioavailability and biological activity in the body.However,the effects of differently processed carrots on relieving colitis and the relevant bioactive compounds are unclear.Therefore,in this study,carrots were treated by pulping,high-temperature cooking and fermentation,and the contents of carotenoids and dietary fiber,carotenoid composition and bioaccessibility of carotenoids were determined to study the effects of processing on the main bioactive components of carrots.Afterwards,C57BL/6J mice were treated with different processed carrot diet for 14 consecutive days to comprehensively evaluate the effects of carrots on sodium dextran sulfate-induced colitis.At last,fermented carrots were used as objects to investigate whether carotenoids play a major role in relieving colitis by removing or adding carotenoids and further explore its potential mechanism.The main contents and results are as follows:(1)The effects of three processing methods on the main bioactive components of carrots.Compared with pulping,high-temperature cooking and fermentation had no significant effect on the content of total carotenoids in carrots,but changed carotenoids’ trans-cis configuration.High-temperature cooking and fermentation decreased the content of all-trans-β-carotene and induced the production of 13-cis-β-carotene and 9-cis-β-carotene,and significantly(p<0.05)increased the content of cis-isomers.In addition,hightemperature cooking and fermentation can destroy the cell wall structure,promote the release of carotenoids,and significantly(p<0.05)improve the bioaccessibility of carotenoids,of which the ranking is as follows: fermented carrots > high-temperature cooked carrots> pulped carrots.These two treatments also significantly(p<0.05)decreased the contents of soluble,insoluble and total dietary fiber,while the latter significantly(p<0.05)increased the proportion of soluble dietary fiber in total dietary fiber.(2)The relieving effects of three different processed carrots on ulcerative colitis.Compared with the model group,the three different processed carrots could significantly(p<0.05)inhibit weight loss and the increase of DAI index,decrease the levels of TNF-α,IL-1 β and IL-6,increase the level of IL-10,and up-regulate the expression of tight junction proteins(ZO-1,Claudin-1 and Occludin)in colitis mice.Only high-temperature cooked and fermented carrots could significantly(p<0.05)alleviate colonic shortening and pathological damage.In addition,fermented carrots could significantly(p<0.05)inhibit the production of malondialdehyde,improve the decrease of colonic goblet cells and increase the level of butyric acid,and had the strongest inhibitory effect on IL-6.The results of 16 S r DNA sequencing showed that the three different processed carrots could relieve colitis by reducing the relative abundance of Escherichia＿Shigella.(3)Taking fermented carrots as the object,removing or adding carotenoid,to investigate whether it significantly contributes to the relief of colitis.Fermented carrots without carotenoids(FCP-BC),fermented carrots(FCP)and fermented carrots supplemented with 100 mg/kg β-carotene(FCP+BC)could significantly(p<0.05)inhibit weight loss and increase DAI index,improve colon shortening and tissue damage,and significantly(p<0.05)reduce the concentration of pro-inflammatory factors TNF-α,IL-1βand IL-6,increase the concentration of anti-inflammatory factor IL-10 and inhibit the level of MDA in colon tissue,while the addition of 100 mg/kg β-carotene(BC)only significantly(p<0.05)improved the level of inflammatory factors and MDA.FCP and FCP+BC significantly(p<0.05)increased the number of goblet cells,FCP-BC and FCP significantly(p<0.05)up-regulated the expression of ZO-1,Occludin and Claudin-1,but FCP+BC only significantly(p<0.05)increased the expression of Claudin-1 protein,while BC had no effect.Furthermore,FCP-BC,FCP and FCP+BC could regulate gut microbiota composition by reducing the relative abundance of Proteobacteria,but BC had no effect on the proliferation of potential pathogenic bacteria Proteobacteria in the intestine of colitis mice.In summary,this paper found different processed carrots could ameliorate ulcerative colitis to different extend,and the best effect was seen with the fermented one.The results of animal experiments showed that the removal and supplementation of carotenoids for fermented carrots had little effect on colitis mice,indicating that carotenoids were not the main anti-colitis active component of fermented carrots.However,the anti-inflammatory and anti-oxidative effects of 100 mg/kg β-carotene alone on colitis mice should not be neglected.This study provides a theoretical basis and ideas for the development and utilization of carrot products and provides a scientific theoretical reference for the prevention and treatment of colitis through dietary intervention.