Effects Of 2-hydroxy-4-methylthiobutanoic Acid On Antioxidantion And Growth Of Mice

HMTBA can be converted to MET in the body and provide essential amino acids for the body, also it has low cost and low toxicity characteristics. Because of its structure, HMTBA may have a role in scavenging free radicals, but its biological antioxidant has not been recognized. In this thesis, the vitro antioxidant activity of MET and HMTBA were compared, we also studied the effect of long-term feeding MET and HMTBA on mice growth performance, nutrient digestion and growth-related gene expression, as well as the mice antioxidant capacity and blood lipids.(1)VC as the control, the difference of HMTBA and MET in vitro free radical scavenging (O-2·, DPPH·,·OH) capacity and the liver and kidney lipid peroxidation inhibition were studied; (2)After pre-feeding one week,110 four-week old Kunming male mice were randomly divided into 11 groups:normal (fat content 2.8%)+0.2% MET,normal+0.2% HMTBA, middle fat (fat content 9.0%)+0.2% MET, middle fat+0.2% HMTBA,high fat (fat content 18.0%) were added to 0.1%,0.2%,0.4% MET; 0.1%,0.2%,0.4% HMTBA; 0.2% MET+0.2% HMTBA. After four weeks,the effect of HMTBA and MET on the redox state of mice were studied in different dietary energy levels and in different additives levels. (3)90 four-week old Kunming male mice after pre-feeding one week, were randomly divided into 6 groups:normal(fat content 2.8%)+0.2% MET, normal+0.1% MET+0.1% HMTBA, middle fat(fat content 9.0%)+0.1% MET+0.1% HMTBA, high fat (fat content 18.0%)+0.2% MET, high fat+0.2% HMTBA, high fat+0.1% MET+0.1% HMTBA. Four weeks later, body weight, body weight gain, feed intake, feed conversion ratio were measured weekly.After four weeks digestive enzymes (amylase, lipase, protease) activity of duodenum and jejunum were measured and the effect on protein and fat digestibility and related gene IGF-I, Myostatin and the relative expression of Myogegin were also studied.At the same time, the impact on oxidation-related indicators (ROS, GSH-Px, CAT, SOD, GSH, T-AOC, MDA) of plasma and tissues and lipid parameters (HDL, LDL, TG, TC, AI) were researched.Experiment results:(1) the scavenging capacity on-OH, DPPH-radicals and the mice liver, kidney lipid peroxidation of HMTBA were higher than MET; the scavenging capacity of MET on the O-2-was higher than HMTBA; (2) In MET groups, redox state of the bodies decreased with dietary energy levels, the antioxidant capacity of the normal group with 0.2% MET was the highest. Adding 0.4% MET in the high fat group produced toxic effect and reduced antioxidant capacity; the high fat groups with 0.1% and 0.2% HMTBA could improve the bodies' redox state. Normal diets with 0.2% HMTBA and high-fat diets with 0.4% HMTBA caused oxidative stress, decreased antioxidant capacity.(3) HMTBA could significantly increase body weight gain, lower feed intake and feed conversion ratio (P<0.05) in oxidative stress state. Except the amylase of jejunum, the digestive enzyme activity of high-fat with HMTBA groups was higher than high-fat with 0.2% MET group; HMTBA significantly increased dry matter and crude protein digestibility (P<0.05); compared with the MET, HMTBA significantly increased expression of IGF-I in liver, jejunum and Myogegin in muscle (P<0.05), leg muscle ratio, and significantly reduced the expression of Myostatin in muscle (P<0.05).(4) Moderate HMTBA could improve the antioxidant capacity of mice, significantly increased GSH-Px, CAT, SOD activity and GSH, T-AOC levels (P<0.05); significantly decreased free radicals levels and MDA content of plasma and tissues (P<0.05); deleted blood lipid levels.