Structural Characterization,Antioxidant Activity Of Inonotus Obliquus Polysaccharide And Its Effects On Chronic Pancreatitis

Inonotus obliquus has been used for alleviating pain and inflammation as folk remedies in Russia,Japan,Finland and Netherlands for more than four centuries.Many researches have identified that Inonotus obliquus polysaccharides(IOP)possess antioxidant and anti-inflammatory activities,and could be used as drugs to prevent and cure colitis,aids and cancer etc.Chronic pancreatitis(CP)is caused by genetic and environmental factor,and often accompanied with pain,fibrosis,inflammation and necrocytosis.Polysaccharide is efficient in attenuation of metabolic ailments and modulation of gut microbiota as prebiotics.In this study,IOP was extracted by water and alcohol,and then purified by an anion-exchange DEAE cellulose column and Sephadex G-200 gel.Structural characterization and antioxidant activity were analyzed by physical and chemical method.CP was induced in mice by repetitive injection of diethyldithiocarbamate(DDC).The amelioration of IOP for CP in mice was analyzed by change of body weight,histopathological characteristics of pancreas,hydroxyproline,antioxidant status of pancreas,metabolizing enzyme and cytokine levels.The change of gut microbiota of CP mice was analyzed by high throughput sequencing of fecal samples.The main results were as follows:(1)The crude IOP was extracted by water and alcohol.Three polysaccharide fractions were isolated from crude IOP on anion-exchange DEAE cellulose column.They were named as IOP-I,IOP-II,and IOP-III at a yield of 38.2%,9.3% and 10.5%,respectively.IOP-I with the highest yield and polysaccharide content was purified by Sephadex G-200 gel.The polysaccharide content of purified IOP was 98.6%.(2)IOP is a well-purified homogeneous polysaccharide with β-glycosides and pyranoid ring.The molecular weight of IOP is about 32.5 kDa.And IOP is composed of Man,Rha,Glu,Gal,Xyl and Ara in a molar ratio of 9.8: 13.6: 29.1: 20.5: 21.6: 5.4,respectively.(3)Reducing power of iron,scavenging activities for DPPH and hydroxyl radicals of IOP from 1 to 5 mg/m L exhibited concentration dependent patterns.And both scavenging activities for DPPH and hydroxyl radicals of IOP at 5.0 mg/m L level off to that of ascorbic acid.(4)IOP increased weight gain rate,SOD,GSH-Px,TAOC and metabolizing enzyme levels of CP mice,but decreased hydroxyproline,MDA and cytokine levels.Pathologic symptom was also lessened by IOP.These results showed that IOP exerted pharmacological activity on CP in mice,and exhibited concentration dependent patterns.The optimum efficiency was achieved in IOP-Hgroup.(5)High throughput sequencing revealed that IOP could regulate the structure and diversity of gut microbiota of CP in mice.Cluster analysis and unweighted principal coordinate analysis showed that DDC disturbed the structure of gut microbiota.DDC decreased the relative abundance of Bacteroidetes,increased the Firmicutes at phylum level,and decreased the relative abundance of Lactobacillus,Bacteroides,unclassified S24-7,unclassified Lachnospiraceae,unclassified Prevotellaceae,Roseburia and Prevotella,increased the Alistipes,Incertae_Sedis,Helicobacter,Parabacteroides and Rikenella at genus level.IOP regulated gut microbiota toward a healthy profile.These results showed that IOP is efficient in modulation of gut microbiota of CP in mice.