Protocatechuic Acid Enhances Intestinal Mucosal Barrier Function In Hfd-fed Mice And Development Of Intestinal Protective Solid Beverage

The intestinal mucosa is the most important site for the absorption and digestion of nutrients in the body,and its barrier function is a central element in maintaining homeostasis.In recent years,the prevalence of intestinal diseases has increased with the consumption of Western-style diets.At the same time,the morbidity of endotoxemia,chronic inflammation,and other parenteral diseases was also on the rise along with the destruction of intestinal mucosal barrier.Research has found that some dietary polyphenols can regulate gut microbiota,reduce gut inflammation,and enhance the intestinal mucosal barrier function.Protocatechuic acid(PCA)is a natural phenolic acid and the major metabolite of polyphenols such as anthocyanins,Its daily intake is much higher than other phenolic acids,and it has various biological activities such as antioxidant,antibacterial,antiviral,and antitumor,which are beneficial to human health.However,the effects of phenolic acids on the intestinal mucosal barrier and the mechanisms of its action are still unclear.The purpose of this project was to study the effect of PCA on intestinal mucosal barrier damage in mice fed with high-fat diet(HFD).And on this basis,a solid beverage for potential intestinal protection was developed.The main findings are as follows:1.HFD-fed mice were treated with PCA at 200 mg/kg for 12 weeks.The results showed that PCA significantly reduced food intake and food efficiency,slowed down weight gain and fat accumulation,reduced blood lipid levels,and alleviated abnormal glucose tolerance in HFD-fed mice.In addition,PCA significantly decreased levels of pro-inflammatory factors(Interleukin-1β,IL-1β and Interleukin-6,Il-6)in serum and improved liver steatosis and inflammatory infiltration in HFD-fed mice.2.PCA enhanced intestinal mucosal barrier function in HFD-fed mice.The results revealed that PCA effectively inhibited the morphological and structural changes,significantly reduced intestinal permeability,and increased intestinal alkaline phosphatase(IAP)content.Meantime PCA promoted the secretion of mucin2(Muc2)and improved the thickness of the mucus layer by increasing the number of goblet cells;and improved the barrier function of the mucus layer by improving the abnormal glycosylation of Muc2 and enhancing the characteristics of Muc2.3.The results of 16 Sr DNA sequencing showed that PCA significantly increased the abundance and diversity of intestinal flora in HFD-fed mice,improved the composition of intestinal microorganisms,decreased the ratio of the Firmicutes to the Bacteroidetes,and inhibited the relative abundance of the harmful bacteria Campilobacterota.Meanwhile,the supplementation of PCA promoted the content of acetic acid,propionic acid,and isobutyric acid in mouse chyme,and did no effect on butyric acid.Spearman correlation analysis revealed that IAP,serum total cholesterol(TC),and epididymal fat weight were closely associated with several specific bacterial phyla or genera.4.Grape powder rich in PCA was used as raw material and added trehalose,kumquat powder,and citric acid.The formula of solid beverage was optimized by single-factor experiments and response surface methodology,the optimal formula:grape powder supplemental level was 4.39 g,trehalose supplemental level was 2.46 g,kumquat powder supplemental level was 0.67 g,citric acid supplemental level was0.08 g,and the average sensory score was 87.3.In vitro fermentation experiments showed that this solid drink has a promotional effect on the growth of Bifidobacterium longum L693,Lactobacillus acidophilus La28,and Lactobacillus plantarum LP45,and has prebiotic properties,so it can be considered as a product with intestinal protection potential.In summary,PCA effectively enhanced the intestinal mucosal barrier function in HFD-fed mice,and the main mechanisms of action include: inhibition of fat accumulation,reduction of inflammatory response,remodeling of mucus layer and regulation of intestinal flora structure.At the same time,PCA has some weight loss effects.In addition,this study developed a solid beverage with prebiotic protection potential with PCA-rich grape powder as the main ingredient.