The Study On The Prebiotic Effect Of Neoagaro-oligosaccharides

Prebiotics are non-digestible food ingredients which can selectively stimulate thegrowth and activity of some of benefical bacteria to improve the host health.Prebiotics are widely researched because of its benefical effects, such as stimulatingthe growth of benefical bacteria, reducing the growth of harmful bacteria,anti-inflammatory, anti-tumor and anti-oxidation. As the most studied non-digestibleoligosaccharide, just like fructooligosaccharide (FOS) and xylooligosaccharide (XOS),has become a focus because of its high activity and little side effects.The neoagaro-oligosaccharides (NAOS) is composed of3,6-inner ether-a-L-galactose and β-D-galactose. Currently, the study on its physiological activity is verylittle. And its regulating effect under high-fat diet is more rare. This paper aims toinvestigate the preventive effect of NAOS on obesity. Feed mice with oligosaccharidefour weeks to regulate the intestinal flore; then feed high-fat diet two weeks (whileoligosaccharide were also fed), the effect of oligosaccharide on the growthperformance, intestinal flora,serum appetite-related hormones and hypothalamicappetite-related genes were investigated.In our experiment, we use becombinant bacteria BL21-PET24-AgaB by enzymaticmethod (preparing enzyme solution, dialyzing to clear salt, degradating agarose andultrafiltrating to clear protein) to product NAOS which includes negoagarooctaose,neoagarodecaose and neoagarododecaose.In vitro experiments, we fed common diet for4weeks, while fed NAOS and FOSin their drinking water, we found that during lonely feeding oligosaccharide, comp-ared with control, the bady weight of group NAOS was significantly reduced. Thenumber of bifidobacteria and lactobacilli on group FOS and group NAOS wassignificantly higher than the control, and bacteroidetes increased, firmicutesdecreased.After high-fat diet was fed two weeks, we found that the weight of high-fat diet fed group NAOS and group FOS was obviously lower than control group, also thedetection of abdominal fat, kidney fat, total fat and fat slices was consistent withweight change. The number of bifidobacteria and lactobacilli on high-fat diet fedgroup NAOS and group FOS was higher than control; after high-fat diet fed, thenumber of bacteroidetes and firmicutes had no obviously change. The content ofglucagon-like peptide-1(GLP-1) on high-fat fed group NAOS was highest, the secondwas high-fat fed group FOS and the lastest was group control. From these results, weknow NAOS has good effects on suppressing appetite; the research on PYY didn’tfind significant difference. Hypothalamic appetite-related genes:pro-opiomelanocortin(POMC) decreased on group FOS and NAOS. Also we detected other appear-relatedgenes,like agouti-related peptide (AGRP)、glucagon-like peptide-1receptor (GLP-1R)and neuropeptide Y (NPY), there was no significant difference among groups.To study the role of oligosaccharide on mice on fasting blood glucose, fasting bloodglucose and glucose tolerance was detected. We found that after feeding the high-fatdiet, the group NAOS and FOS was obviously lower and the ability of glucosetolerance was significantly improved than control.In summary, we have proved that NAOS has the ability of stimulating the growthof beneficial bacteria, improving glucose tolerance, slowing down the increasing ofweight under high-fat diet and it can change the concent of serum appeartite-relatedhormone GLP-1. All these results proved that NAOS is a potential prebiotic.