The Free Radical-Scavenging And Antioxidant Activity Of Carnosine

Carnosine is a dipeptide found in skeletal muscle and brain tissue of vertebrates that has been reported to possess radical scavenging and antioxidant function for a long time.Its structure(β-Alany-L-Histidine) was determined in the very beginning of the 20 century.In our contury,few people have studied on it.This thesis consisted of three parts:the radical scavenging ability of carnosine was studied in series Ⅰ;the inhibitory of BSA oxidation and glycationin in seriesⅡ;the inhibitory of lipid peroxidation in series Ⅲ. In series Ⅰ,we studied the scavenging activity of carnosine on free radicals. DPPH radical was used as a model system and we tested the scavenging ability of carnosine,β- alany ,L-histidine and the effect of different pH,temperature and time on the ability.The results illustrated that:compared with control group,different concerntration of carnosine had significant activity of scaveging DPPH radical in a dose-dependent manner( P＜0.01);the scaveging ability of DPPH radical of β- alany and L-histidine was notably under the carnosine;the scaveging ability of carnosine was not affected by pH value of reaction media,at pH 6.3,7.4,8.4,the scaveging rate was 42.78%,42.55%,36.88% respectively and at pH 6.3,the scaveging rate was the greastest;there was no significant difference in scaveging ability of different temperature treated groups(P＞0.05).The group of 60℃ water bath treatment for 15min could promote the activity;there was also no significant difference in the scaveging ability of carnosine solution being stored at 4℃ for three weeks.(P＞0.05) The effect of carnosine on deoxyribose oxidation induced by FeCl3/H2O2 was invested through measured the diminishing of MDA.The results showed that carnosine could scavege the ·OH radical and protect the deoxyribose from damage. 1-100mmol/L carnosine showed 17.94%～81.30% scaveging ability.The activity of carnosine as a quencher for superoxide anion radical was evaluated in the system of auto-oxidation of pyrogallol.The results indicated that Carnosine quenchered the superoxide anion radical on a low concentration(1,10,20mmol/L) and the ability decreased with a high concentration.In series Ⅱ,about the inhibitory of carnosine on BSA oxidation and glycation.First,the reducing power of carnosine,β- alany and L-histidine was invested. Carnosine exhibited the greast reducing power among compounds.Its reducing power increased significantly with an increasing amount of carnosine(P＜0.01). L-histidine has little reducing power. 100mmol/L L-histidine only has 14.14% reducing power and 100mmol/Lβ- alany has 64.01% reducing power compared with the same concerntration of carnosine.In the CuCl2-H2O2 catalyzed BSA oxidation system,carnosine significantly decreased the protein carbonyl formation with the increasing amount of carnosine(P＜0.01), The inhibition rate of 100mmol/L carnosine on BSA oxidation was 82.74% .In the glucose catalyzed BSA glycation system,the amount of 5-HMF and Fructosamine increased with the increasing amount of carnosine(P＜0.01) .we draw a conclution carnosine glycated by the glucose.In Series Ⅲ,about the inhibitory effect of carnosine of lipid peroxidation. High concerntration carnosine significantly inhibited the red blood cell membrane lipid peroxidation induced by auto-oxidation,H2O2,UV((P＜0.05).The inhibition rate of 100mmol/L carnosine on the three model system was 34.07%,42.80%,83.67% respectively. In liver homogate lipid peroxidation system induced by water bath in vivo, The inhibition rate of 100mmol/L carnosine was 50%,but in liver homogate lipid peroxidation system induced by CCl4 the inhibition rate was just 18%. In the mitochondria membrane lipid peroxidation induced by Fenton action,carnosine significant inhibited the TBARS formation in a dose-dependent manner(P＜0.05). The inhibition rate reach the summit of 54.01% in 50mmol/Lcarnosine,but was decreased in 100mmol/L.