Preparation Of Anti-obesity Peptides Derived From Spirulina Platensis And Study On Its Anti-obesity Activity

Spirulina platensis,a multicellular algae,which contains nutritional value and medicinal value.The biological activities of Spirulina platensis and Spirulina protein,such as anti-tumor,anti-oxidant,anti-bacterial and so on,have been extensively studied at home and abroad.In this paper,the anti-obesity activity of Spirulina protein and Spirulina polypeptide was studied,which extends the medicinal value of Spirulina further.By using the method of combination of repeated freezing and melting and ultrasonic-extraction,the yield of protein was 72.76% and the extraction rate was up to 43.69%.Then the extracted proteins were hydrolyzed by pepsin,protease,trypsin,alkaline,protease and papain,conducted in the optimum conditions of each enzyme respectively,and the degree of hydrolysis were determined.The results show that the degree of hydrolysis of pepsin for a minimum of 3.57%.Five hydrolysates were divided into 25 components by using 10 K,5K,3K ultrafiltration membrane,the protein content of the 25 components were determined by the BCA method,and then the inhibition rate of pancreatic lipase and inhibition rate of 3T3-L1 proliferation were used to evaluate its anti-obesity activity.Considering the protein content and the anti-obesity activity,the 3-5 K components were selected for further purification and separation.3-5 K components were separated by Sephadex G-15,the inhibition on 3T3-L1 were measured by MTT assay.The components of the ultrafiltration of the pepsin hydrolysate,Pe for short,which is separated by Sephadex G-15,showed the best inhibition effect on 3T3-L1.Four peptides were identified by MALDI-TOF/TOF-MS,the results are as follows: NALKCCHSCPA,LNNPSVCDCDCMMKAAR,NPVWKRK,CANPHELPNK.The results of the inhibitory effects of 4 synthetic peptides on 3T3-L1 indicated that CANPHELPNK showed better activity in 4 synthetic peptide,and the IC50 value is 785.98 μg/mL.The anti-obesity activity of Spirulina components were studied in vivo,dietary intake and body weight of mice was determined weekly.The results show that Spirulina components intervention has no effect on appetite of mice.Spleen,liver and kidney organ index were determined and as well as the contend of glucose,cholesterol(TC),triglyceride(TG),high density lipoprotein(HDLC),low density lipoprotein(LDLC)in blood.The results suggest that pepsin hydrolysate showed the best effect on weight loss,weight inhibition rate ws up to 39.77%.The content of TC and HDLC in the blood of mice could be reduced by the administration of Spirulina component,which were induced by high fat diet.The 44 genes that involved in obesity metabolic pathway expression in the liver and brain tissues of mice in the control group(GC)and pepsin hydrolysate intervention group(GPe)was measured by gene chip.The results show that the amount of gene expression in different tissues is different under the same intervention conditions.About 22 genes expression up-regulated in the brain under the high fat dietary intervention,19 genes expression were up-regulated highly and 10 genes expression down-regulated,5 genes of it were down-regulated significantly;About 21 genes expression were up-regulated and 16 of it up-regulated significantly in brain tissue of the GPe.About 12 gene expression was down-regulated and 9 of it changed significantly.The expression of 44 genes involved in obesity metabolic pathway is different in the same organ under different interference conditions,compared with the GC,22 genes expression were up-regulated in brain of the GPe,Gcg gene and Adra2 b gene expression were up-regulated significantly and 23 genes expression were up-regulated in the liver tissue of mice and 10 of it up-regulated significantly,17 genes expression was down-regulated in the brain tissue,the gene Acadm were down-regulated distinctly and 10 genes expression were down-regulated in liver tissue,the gene Ntrk2 and Ppard were down-regulated significantly.