Studies On Stability And Security Of Antihypertensive Peptides Derived From Soybean Protein

On the basis of work ahead,with the hyrolysate from soybean protein for researchobject,stability and security of antihypertensive peptides derived from soybean wereinvestigated.Activity detection in vitro and in vivo were used to evaluate the antihypertensivepeptides,that is to say that the ACE inhibition activity detection and the SBP-lowing effect ofpeptides after administrating spontaneously hypertensive rats(SHR).Volme of reaction system was enlarged gradually,and the activity of hyrolysate in vitroand in vivo were detected;Several method were used to deal with the hyrolysates,such as heatand acid treatment,sterilizing,filtration sterilizing,vacuum concentration and lyophilization,then the activity of samples in vitro and in vivo were also measured respectively;The heatsterilizing samples,filtration sterilizing samples and lyophilization samples were preserved formonths,and the periodic activity detection of them was performed.Furthermore,therelationship between dose of administration and SBP-lowering effect was investigated.Acutetoxicitytest was performed to evaluate the security of the hyrolysate after administrating KMrats.The result in vitro show that:the volume of reaction systems was enlarged from1L to5L,but the ACE activity inhibition rates of the hyrolysate were all more than80%;In the range of30℃~90℃and pH4~pH10,the ACE inhibition activity keep stability;The ACE inhibitionactivity of hyrolysate after sterilizing at85℃and100℃didn’t decline any more,while thesamples’ after sterilizing at121℃for1h went down to59.69%,and as is also the pH5.4samples and pH4.5samples after the same heat sterilizing treatment.The ACE activityinhibition rate of filtration sterilizing sample was85.85%,that of the vacuum concentrationsample and lyophilization sample were84.47%and84.9%,which had been diluted to originalconcentration.ACE activity inhibition rate of the samples in store did not fluctuate intensely in180d.The result in vivo show that:the maximum decrease(P＜0.05)in SBP of SHR was18.2mmHg2h after oral administration of hyrolysate;The SBP fell by11.6mmHg (P＜0.05)afteradministration of the sample which was sterilized at85℃for15min,and the reduction in SBP were less than10mmHg after admimistration of the other sterilizing samples;The maximumdecrease in SBP of SHR were17.9mmHg,18.8mmHg,18.4mmHg after admimistration offiltration sterilizing sample,vacuum concentration sample and lyophilization sample;TheSBP-lowering effect was not influenced by a dosage of4times more than original’s;In90d,the activity in vivo keep stability.The discrepancy of samles between in vitro and in vivoinferred that the composition or structure of peptide solution changed after heat sterilizing,andthe active ingredient of peptides losed the vasodilation effect when it arrived at the targetorgans or tissues in the course of physiology metabolism.Acute toxicitytest show that,thehyrolysate from soybean protein was not poisonous.