Effects Of Oligosaccharides And Small Peptides On Scavenging Oxygen Free Radicals In Digestive System

Nowadays, the free radicals of animals will increase with the intake of the feed of high fat, high protein, high sugary and all kinds of high levels of vitamins and minerals to destroy easily the antioxidant defense system, and induce many digestive diseases. Oligosaccharide is full of some characters such as non-toxic, pyrogen free and no variation. Additionally, it also has special physiological activities and biological functions. The antioxidant peptides from the proteins of natural plants and animals have the characteristics of cheap, efficient and low toxicity, so they are suitable for the usage as antioxidants. The study of scavenging activities of different oligosaccharides and small peptides on oxygen free radicals in digestive system has very important practical significance. It was not only on the prevention and treatment of various diseases induced by unhealthy diet, but also on the improvement of animal production and product quality.In this research, we studied the scavenging effects of collagen peptides, rice peptides, mannose oligosaccharides and chitooligosaccharides on free radicals in vitro. Thus, the effects of different sources of small peptides and oligosaccharides alone or in combination on the role of oxygen free radical scavenging in digestive tract of mice fed with high-fat diet were investigated. The main results are as follows:(1) High performance liquid chromatography (HPLC) was used to measure the molecular weight distribution and amino composition of both collagen peptides and rice peptides. The results showed that 63.62% of collagen peptides and 76.89% of rice peptides have a molecular weight of 180-2000 Da. The antioxidant amino acids of collagen peptides and rice peptides accounted for 20.82% and 28.28% of total amino acids.(2) It was indicated that collagen peptides, rice peptides, mannose oligosaccharide and chitooligosaccharides had good scavenging effect on DPPH-. The scavenging activities of chitooligosaccharides was lower than the others on-OH. Rice peptides, mannose oligosaccharide and chitooligosaccharides showed no obvious scavenging effect on O2-·(3) Seventy-two male ICR mice were randomly divided into 6 groups, which were fed with basal diet, high-fat diet, high-fat with 0.5% CP,0.5%RP,0.5% MOS and 0.5% COS, respectively. After 6 weeks, mice were killed to determine the level of free radical and antioxidant capacity in the blood and gastrointestinal organ. And the mice’s small intestines in each group were HE stained and observed by light microscopy. The results showed that all the high-fat diets with 0.5% CP, 0.5% MOS and 0.5% COS could effectively decrease the level of free radical in blood and digestive system, which not only significantly enhanced the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and the level of total anti-oxidative ability (T-AOC), but also decreased the level of malondialdehyde (MDA) approaching to the controls. These effects were better than high-fat diet groups with 0.5% RP. The mice fed with high-fat diet lost small intestinal villus seriously and had a lower ratio of villus height and crypt depth than the controls. All the high-fat diets with 0.5% CP,0.5% RP,0.5% MOS and 0.5% COS could eased the phenomenon of small intestinal villus’s shedding and short fusion, which not only increased the height of small intestinal villus and the ratio of villus height and crypt depth, but also shallowed small intestinal crypt depth compared with the high-fat diet groups.(4) Seventy-two male ICR mice were randomly divided into 6 groups, which were fed with basal diet, high-fat diet, high-fat with 0.5% MOS+0.5% CP,0.5% MOS+0.5% RP,0.5% COS+0.5% CP,0.5% COS+0.5% RP, respectively. After 6 weeks, mice were killed to determine the level of free radical and antioxidant capacity in the blood and gastrointestinal organ. The results indicated that the combination of 0.5% MOS and 0.5% CP had significant interaction in decreasing the level of free radical in blood and increasing the antioxidant capacity of mice which were fed with high-fat diets, but the combination of 0.5% MOS and 0.5% CR had significant interaction in increasing the activities of catalase (CAT) and glutathione peroxidase (GSH-Px) in livers and pancreas of high-fat mice.All the high-fat diets with 0.5% CP,0.5% RP,0.5% MOS and 0.5% COS could be able to eliminate free radical in digestive system, increase the antioxidative capacity and relieve the intestinal mucosal injury caused by the high-fat diet effectively. Synergistic effects were observed in the combination of oligosaccharides and small peptides.