Study On The Inhibition Of Neu5Gc Synthesis In Rat And Its Effects On Xiang Pig

Owing to the absence of CMP-N-acetylneuraminic acid hydroxylase(CMAH),a key enzyme for synthetizing N-glycolylneuraminic acid(Neu5Gc),normal human body can't synthetize Neu5 Gc,and Neu5 Gc in human body mainly come from red meat-based diet.Bonding state of Neu5 Gc will trigger inflammation,and then trigger chronic illness.In order to identify the effective method decreasing Neu5 Gc in red meat,fluorescence high performance liquid chromatography(HPLC-FLD)was used to analyze the inhibition of genistein(Gen)(300 mg/(Kg·d))and Cytidine-5?-phosphate(1 mg/(Kg·d))on Neu5 Gc in rats and Xiang pigs in this dissertation.Effective inhibitor was optimized by analyzing the hind leg muscle,kidney and liver of rats fed with Gen or Cytidine-5?-phosphate for 15 days,30 days,45 days and 60 days,respectively.Optimum dose was discovered by analyzing the rats fed with Cytidine-5?-phosphate of 0.5 mg/(Kg·d),2 mg/(Kg·d)and 3 mg/(Kg·d),respectively.On these basis,the optimum inhibitor and dose were used to feed Xiang pigs to discover the inhibition mechanism of Neu5 Gc synthesis.The main research contents,results and conclusions are as follows:(1)The effects of Gen and Cytidine-5?-phosphate on Neu5 Gc synthesis in rats can be concluded as that both Gen and Cytidine-5?-phosphate can inhibit the Neu5 Gc synthesis in rats,and the inhibition effect from Cytidine-5?-phosphate is more significant than that from Gen.The inhibition effects from both Gen and Cytidine-5?-phosphate are first increased and then decreased with increasing time,and 30 days is the optimum feeding time.(2)The effects of Cytidine-5?-phosphate concentration on Neu5 Gc synthesis in rats reflect that Cytidine-5?-phosphate concentration has significant effect on Neu5 Gc synthesis in rats fed 30 days,and 1 mg/(Kg·d)Cytidine-5?-phosphate is much more effective(P<0.01)on inhibiting Neu5 Gc synthesis than 0.5 mg/(Kg·d),2 mg/(Kg·d)and 3 mg/(Kg·d).(3)Xiang pigs of 3 months,6 months and 9 months were fed with basic forage added 1 mg/(Kg·d)Cytidine-5?-phosphate for 30 days.The results show that,6 months is the most effective age of Xiang pig to inhibit Neu5 Gc synthesis by feeding Cytidine-5?-phosphate(P<0.01),and the added Cytidine-5?-phosphate improve the contents(P<0.05)of flavor amino acid and essential amino acid in meat without changing its physicochemical properties(P>0.05).(4)Molecular docking of Gen and Sialyltransferase(ST)was used to discuss the inhibition mechanism of Gen on Neu5 Gc synthesis.The result shows that,Genistein has formed the hydrogen bond with sialyltransferase active site residues His319,Ser151,Gly293,Thr328 and formed hydrophobic interactions with the residues His302,His301,Trp300,Ser271,Phe292,Thr328,Ser325 and Ile274.This demonstrates intermolecular interaction is the main reason causing the inhibition of Gen on ST.As a substrate inhibitor for synthesizing Neu5 Gc,Cytidine-5?-phosphate reduces enzymes activity,and then inhibits Neu5 Gc synthesis.