Study On The Preparation Of Stomolophus Meleagris ACE Inhibitory Peptide And Its Preventive Effect And Mechanism Against Hypertension

China is rich in Stomolophus meleagris resources, and frequent outbreaks evenoccurred in recent years, but the Stomolophus meleagris resources are not fullyutilized due to its current simple processing method. This paper attempts to establish anew Stomolophus meleagris processing method, which mainly includes deodorization,desalination and spray drying three processes, then obtain a new foodborne ACEinhibitory peptide, and at last the preventive effect of the obtained Stomolophusmeleagris ACE inhibitory peptide powder against high blood pressure and themechanism are studied.At first, the preparation of ACE inhibitory peptide made from fresh Stomolophusmeleagris using the alkaline protease enzyme was studied. Use the degree ofhydrolysis (DH) and ACE inhibition rate as indicators，the single factor experimentand orthogonal experiment were done to get the best hydrolysis conditions: reactiontemperature50℃, enzyme dosage of5%, enzymatic hydrolysis starting pH9.5. Theimproved high performance liquid chromatography method was used for thedetermination of ACE inhibition rate, and found that the maximum rate of ACEinhibition was get after hydrolyzing7h in the above condition. Through desalted andlyophilized, the inhibition of0.5mg/mL Stomolophus meleagris ACE peptide was54.53%. Finally, the average molecular weight of the obtained Stomolophus meleagrisACE peptide was measured by exclusion chromatography with about500Da.Then, the preparation of Stomolophus meleagris ACE inhibitory peptide from itsenzymatic solution was explored. The process includes mainly deodorization,desalination and spray drying three processes, and at last the composition of theobtained Stomolophus meleagris ACE inhibitory peptide was analyzed. Firstly, useprotein-loss rate (%) and trimethylamine content (mg/L) as indicators, single factor experiment and orthogonal experiment were done to get the best condition fordeodorization: activated carbon dosage (w/v, g/mL)0.2%, deodorization temperature20℃, deodorization time40min. Then the enzyme solution was concentrated underreduced pressure, filtration through a0.45micron filter, nanofiltration desalinationwith200nanofiltration membrane, spray drying (inlet temperature165-175℃,outlet temperature85-95℃), at last obtained white Stomolophus meleagris ACEinhibitory peptide powder. The composition of it was determinated, with protein81.50±0.42%、moisture6.23±0.24%、salt2.88±0.11%t、fat0.21±0.03%、sugar5.97±0.21%，through the data we can know it is low-fat and low-sugar healthyfunctional food.Finally, the preventive effect and the mechanism of the obtained Stomolophusmeleagris ACE inhibitory peptide against L-NAME-induced hypertension werestudied.80rats were randomly divided into five groups, the control group was givendistilled water (0.5mL/d), L-NAME group was given L-NAME (20mg/Kg.bw), lowand high Stomolophus meleagris ACE inhibitory peptide powder dose groups(referred to low and high dose group) were administered L-NAME (20mg/Kg.bw)together with100mg/Kg.bw and500mg/Kg.bw Stomolophus meleagris ACEinhibitory peptide powder simultaneously, and captopril group was treated with L-NAME (20mg/Kg.bw) together with10mg/Kg.bw captopril. When administeredorally before and after1,2,3weeks, the weight and blood pressure of rats weremeasured. One week after gavage, the blood pressure of5groups rats are significantlydifferent, to study the relationship between blood pressure and blood pressure-relatedfactors in plasma, five groups of rats were sacrificed half (8), and the activity orcontent of plasma ACE, renin (PRA), NO, NO synthase (NOS), Ang Ⅱ are measured.Three weeks after gavage, the remaining rats were sacrificed, ACE activity, NO andNO synthase (NOS) content in plasma and microalbuminuria (MAU/ALB) level inurine were determined, and the index of the heart and kidney were calculated. Theresult showed that, administered orally L-NAME can reduce rat plasma NO and NOSlevels, while active RAAS, and led to a significant increase in blood pressure. Butmay be due to L-NAME administered dose was not high enough, the blood pressure of rats fed L-NAME increased first and then decreased gradually towards normallevel. The Stomolophus meleagris ACE inhibitory peptides can serve to suppress ACEactivity and AngⅡ level rise, promote high blood pressure caused by L-NAMEgavage to restore normal level, and reduce the damage of heart and kidney inL-NAME-induced hypertension model.The effect was stronger in the high-dosegroup than in the low dose group.