| Gastric ulcer is a typical type of peptic ulcer,and excessive alcohol intake is one of the main causes of this disease,whose pathogenesis is based on direct damage to the gastric mucosa of excessive alcohol intake,leading to the imbalance between defensive and offensive factors.There are several drugs available on the market to heal gastric ulcers,but the mechanism is homogeneous.At present,researchers are actively exploring ways to prevent acute ethanol-induced gastric ulcer by nutritional intervention.In order to research and develop functional products to prevent ethanolinduced gastric ulcer,the co-fermentation collagen peptide-jackfruit juice(FPJ)was prepared by mixing tilapia skin collagen peptide with jackfruit rich in nutrients and fermenting with compound lactic acid bacteria.This research focuses on(1)the main nutritional components of FPJ and its biological activities;(2)the changes of FPJ after fermentation and in vitro gastrointestinal digestion;(3)the evaluation of the nutritional intervention of FPJ on ethanol-induced gastric ulcer and its related mechanisms.The specific studies are as follows.(1)Nutritional components and antioxidant properties of FPJIn order to evaluate the functional characteristics of FPJ,it was compared with unfermented collagen peptide jackfruit juice(PJ)and the levels of saccharides,total phenols,total flavonoids,polypeptides and antioxidant activity before and after fermentation were evaluated.After fermentation,the polysaccharide content decreased from 14.85 mg/m L to 9.81 mg/m L,while the reducing sugar content also declined from153.34 mg/m L to 77.56 mg/m L.Conversely,the total phenol and total flavonoid contents of FPJ were 8.25 mg/m L and 1.31 mg/m L,respectively,which were significantly higher than those of PJ(2.85 mg/m L and 1.23 mg/m L,respectively).The antioxidant properties of FPJ were 60.63% for DPPH and 60.90% for ABTS,both of which were significantly higher than those of PJ.The molecular weight and sequence identification of peptides of FPJ further indicated the potential physiological activity of FPJ.The total heavy average molecular weight of peptides of FPJ was 3799 Da,of which 53.45% of peptides in FPJ had molecular weight below 3000 Da.In addition,Peptide Ranker scored the top 50 peptides with confidence,and screened out 10 peptides with scores higher than 0.5 and the amino acid composition lower than 10.Besides,after identified by comparison with the Biopep database,there were also five peptides with proven antioxidant or antimicrobial properties(NSAAL,PGLG,IEWE,LLPHH and VPNS).Therefore,it is inferred that the nutritional components of FPJ obtained by lactic acid bacteria fermentation has changed.Not only the contents of bioactive components from jackfruit,such as sugars,total phenols and total flavonoids,increased,but also more collagen peptides were produced,which improved the antioxidant activity of FPJ.(2)Gastrointestinal digestibility tolerance of FPJIn order to evaluate the gastrointestinal digestive tolerance of FPJ,chemical and biological activities of FPJ and PJ,simulated gastrointestinal digestion experiment was performed.Gastrointestinal digestion simulations revealed that the contents of FPJ and PJ polysaccharide decreased gradually with the increase of digestion time of gastric and intestinal juice,reaching 1.24 mg/m L and 2.22 mg/m L after stomach digestion and gastrointestinal digestion,respectively.Meanwhile the reducing sugar content increased gradually to 162.67 mg/m L and 155.60 mg/m L,respectively.In terms of total phenol and total flavonoid content,both FPJ and PJ increased continuously,with the final content of total phenol reaching 12.89 mg/m L and 11.75 mg/m L,respectively,and total flavonoid content reaching 1.49 mg/m L and 1.87 mg/m L,respectively.The oxidation activities of PJ and FPJ were both significantly improved after gastrointestinal digestion.The antioxidant activity of FPJ was better than PJ with 76.08 %DPPH and 66.99 % ABTS scavenging rates.It was shown that compared with PJ,FPJ has better gastrointestinal tolerance,and gastrointestinal digestion can increase its total phenols and total flavonoids,as well as improve antioxidant activity.(3)The regulatory effect and its mechanism of FPJ on inflammation and oxidative stress in mice with ethanol-induced gastric ulcerIn order to explore the preventive effect and mechanism of FPJ on acute ethanolinduced gastric ulcer,the ethanol-induced gastric ulcer model in KM mice was established after 14 days of FPJ nutrition intervention.Macroscopic observation,HE staining,ELISA,q RT-PCR and Western Blot were used to analyze the antiinflammatory,anti-oxidation and tissue repair related factors in the gastric tissues.It was found that FPJ could effectively prevent and reduce gastric mucosal damage caused by alcohol,decreasing the area of damage and gastric edema,and prevent tissue ulceration and inflammatory cell infiltration.FPJ intervention can effectively inhibit the expression of pro-inflammatory factors such as TNF-α,IL-6 and IL-1β,and significantly increase the levels of anti-inflammatory or antioxidant factors such as PGE2,SOD and CAT.In addition,q RT-PCR and Western Blot experiments both show that FPJ can significantly up-regulate the m RNA and protein expression levels of Nrf2,HO-1 and IKBα,and inhibit the m RNA and protein expression of NF-κB p65,and the regulatory effect is better with the increase of FPJ dose.Therefore,it is inferred that FPJ shows anti-oxidative stress by activating Nrf2/HO-1 pathway,and inhibit NF-κB pathway to restrain inflammatory reaction,thus can effectively prevent the ethanolinduced gastric ulcer.(4)The regulatory effect and its mechanism of FPJ on wound healing in mice with ethanol-induced gastric ulcerTo investigate the healing effect of FPJ on gastric mucosal damage in ethanolinduced acute gastric ulcer mice,Masson staining and immunofluorescence staining were used.FPJ was found to significantly increase the expressions of growth factors such as VEGF,CD34,PDGF,ICAM-1,and can also obviously enhance collagen deposition in gastric tissues.Besides,FPJ was found to significantly increase the m RNA expression of e NOS,AKT and ERK by q RT-PCR assay.Through WB experiment,the protein expression of p-AKT and p-ERK were also strongly improved by FPJ. |
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