| In recent years,people have been paying more and more attention to antioxidant,especially proanthocyanidins,which have strong antioxidant activity 20 times higher than vitamin C and 50 times higher than vitamin E.Mangosteen pericarp is used as waste.Studies have shown that it contains a variety of bioactive ingredients including proanthocyanidins.However,the research on the proanthocyanidins of mangosteen pericarp mostly focuses on the extraction method and the antioxidant evaluation,but the research on the antioxidant activity of proanthocyanidin extracts lacks the bioavailability consideration.To have physiological effects,proanthocyanidins must survive through the gastrointestinal tract.This study preliminarily surveyed the chemical changes and cellular antioxidant activity analysis of proanthocyanidins in mangosteen after digestion,and effect on intestinal flora.These findings provide a theoretical basis for the application of mangosteen pericarps in functional foods,healthy products and pharmaceuticals.The main findings are as follows:1.The results showed that the proanthocyanidins of mangosteen pericarps had characteristic absorption peaks at 280 nm,and there were absorption peaks in stretching vibration zone include OH,C-C of six-membered rings and C=C on benzene ring,which could preliminarily identify the structure of proanthocyanidins.Further,UPLC-MS/MS identified the main monomer components as catechin and epicatechin,and contained the isomers of proanthocyanidin dimers,trimers and tetramers.There are catechins,three types of B-type proanthocyanidin dimers and the original fisetin dimers in the proanthocyanidins of mangosteen pericarp.It indicated that the structure and composition of mangosteen pericarp changed after in vitro digestion.2.The total polyphenol content,total flavonoid content and proanthocyanidin content of the extracts of mangosteen pericarps in vitro digestion were significantly decreased(P<0.05),which were reduced by 84.5%±0.12%,90.63%±0.33%and 78.05%±0.1%,respectively,which may be the result of degradation of polyphenolic compounds in the stomach acid environment.However,the relative antioxidant capacity was increased by 2 times,and the liquid phase results showed that the catechins increased by 27.68±0.19?g/mL,and the three B-type proanthocyanidin dimer isomers increased by 17.29 times,14.04 times,3.29,respectively.And the original fisetin-type dimer increased by 2.03 times,which confirmed that the polymer may degrade in vitro digestion process.The increase is likely to be related to antioxidant activity.3.The antioxidant activity at the cellular level showed that compared with the ZEN-induced group,the cell viability of the MPP+ZEN group increased by 32.01%±0.03%,and the ZO-1gene was up-regulated by 2.3-fold,which alleviated the dislocation of ZO-1 protein.And the inflammatory factors are down-regulated,include TNF-?,IL-6,NLRP3 and IL-18.HCA showed that the mitochondrial membrane potential increased,and its relative fluorescence intensity increased by 353.15%±0.18%,which reduced intracellular ROS levels.Further,compared with the ZEN-induced group,the activity of SOD in the MPP-GID+ZEN group was increased by 39.26±0.43 U/mg protein(P<0.05)and the activity of CAT enzyme was increased by 0.48 times,so that the activity of antioxidant enzymes was restored.Studies have shown that proanthocyanidins from mangosteen pericarp have protective effects against zearalenone-induced oxidative damage,which may be related to increased catechins,epicatechins,proanthocyanidins B2,and proanthocyanidin dimers in MPP-GID.4.The results of the effects of proanthocyanidins on the intestinal flora of mangosteen pericarp after digestion showed that the gas components in MPP-GID_H were different from the control group,indicating that the samples were fermented by microorganisms.Compared with the control group,the short-chain fatty acid content increased significantly(P<0.05),which may promote the production of metabolite short-chain fatty acids by the number and quantity of certain microorganisms.16S high-throughput sequencing results showed that the relative abundance of Bacteroides in MPP-GID_H increased and Firmicutes decreased,compared with the control group,which resulting in an increase in the ratio of Bacteroides to Firmicutes,increased by 2.71 times,which may help to alleviate metabolic diseases such as obesity.The relative abundances of the genus Acidogens(Kordella,Roche,Clostridium,Clostridium,and Clostridium)were significantly increased in the proanthocyanidin oligomers and polymers after digestion(P<0.05),increased by 1.83,2.73 times,respectively.Thus,the short-chain fatty acids increased,to avoid the intestinal inflammatory disease.MPP-GID_H promoted the growth and reproduction of Bifidobacteria,which protected the intestinal health.Therefore,the proanthocyanidins of mangosteen pericarp can be degraded in the large intestine and colon,which can improve the intestinal microbial metabolism and the abundance of the main flora community,thereby protecting the intestinal diseases. |
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