Study On The Antioxidation And Lipid-Reduction Of Supernatant Of Fermented Lotus Leaf By Enterococcus

Obesity threatens human health and its incidence continues to rise,becoming an important public health problem in the world.Obesity easily results in oxidative stress and a series of inflammatory reactions in the body,leading to metabolic chronic diseases such as atherosclerosis and diabetes.Reducing the inflammatory reaction caused by oxidative stress is an effective means for treating obesity,and the combination of homologous food ingredients with probiotics owning cholesterol-lowering functions is the direction for the development of lipid-lowering diet products.Lotus leaf is a kind of medicine and food homologous material that has anti-oxidation,anti-inflammation,weight-reducing and lipid-lowering effects.The research on enhancing its antioxidant capacity through probiotic fermentation is rarely studied.Therefore,upon the previously isolation of two cholesterol-lowering strains of Enterococcus,we further investigated its fermentation of lotus leaf,and try to understand its in vitro and in vivo effects on antioxidant and intestinal flora of mice.The whole study is divided into five chapters.In chapter one,both lotus leaf and enterococci was detailed.The anti-oxidation and lipid-lowering functions of lotus leaf,the probiotic function of enterococci,and the plant fermentation liquor were reviewed respectively,and the enhanced probiotic function of fermented lotus leaf by enterococci was prospected.In chapter two,the antibacterial and antioxidative properties of the supernatant of fermented lotus leaf by probiotic Enterococcus faecium WEFA23 and Enterococci hirae WEHI01 were evaluated.The Oxford cup method was used to determine the antibacterial abilities of the supernatant.The scavenging rate of DPPH and hydroxyl free radical,and the enzyme activities of SOD,GSH-Px and CAT were also determined;the cell oxidative stress model was established to analyze the active oxygen clearance and the activities of above three enzyme.SD rat obesity model was established to study the antioxidant enzymes(SOD,GSH-Px and CAT)in the serum of rat fed with WEFA23 fermented lotus leaf.The results showed that the fermented supernatant of WEFA23 had antibacterial activities against six foodborne pathogens,with the best inhibitory effect on Salmonella and Listeria monocytogenes.When compared with the supernatant of pre-fermentation,the supernatant of both strains had strong DPPH and OH· radical scavenging activities,and the antioxidant activity was positively correlated with antioxidant enzymatic activity.By fermentation of lotus leaf,two kinds of supernatant strengthen both the capacity of scavenging active oxygen and activities of antioxidative enzyme(SOD,GSH-Px,CAT)on Caco-2 cells.WEFA23 can effectively increase serum SOD and GSH-Px activity in SD rats,but has no effect on CAT enzyme activity.In chapter three,the lipid-lowering effect of the supernatant of fermented lotus leaf by E.faecium WEFA23 on rats with high-fat and high-sugar diet was evaluated.The results showed that the fermentation supernatant of E.faecium WEFA23 can effectively reduce the increase of body weight and organ index in rats,and reduce the levels of serum TC,TG and LDL-C in high-fat diet rats,and increase the serum HDL-C level.The level of liver indicators improves the pathological symptoms of colon and liver tissue.In chapter four,the effects of gavage of WEFA23 on the intestinal microbiota of high fat diet SD rats were investigated.Based on high-throughput sequencing and bioinformatics analysis,the differences in intestinal microbiota among 7 groups were analyzed from the aspects of alpha diversity,beta diversity,and Venn diagrams.The results showed that a high-fat diet reduced the abundance of intestinal flora in SD rats,increased the Spirochete phylum,reduced the proportion of Bacteroidetes in the gut microbiota.The proportion of Spirochetes in the gut microflora declined,suggesting that the supernatant of the lotus leaf fermentation can regulate the balance of intestinal flora to some extent.In chapter 5,the conclusion of the antioxidant and probiotic functions of the supernatant of Enterococcus fermented lotus leaf was drawn,and the prospects of functional of fermented lotus leaf was proposed.In summary,Enterococcus can enhance the anti-oxidation and lipid-lowering effects of lotus leaf,and also regulate the intestinal flora balance to some extent.The results of this paper will provide ideas and methods for the development of probiotics for the production of microecological preparations of lotus leaf,and for the guidance of studies on homopharmaceuticals.