Antihypertensive Effect And Absorbtion Of Grass Carp Bioactive Peptides

In this paper, desalination for grass carp bioactive peptides GCP withmacroporous adsorption resin DA201-C was investigated. The ash content, peptidecontent, molecular weight, amino acids composition as well as the angiotensinI-converting enzyme (ACE) inhibitory activity and antioxidant activity werecompared. The antihypertensive effect of desalting GCP in vitro and in vivo wasevaluated. The human colon carcinoma cell line (Caco-2) cell model wasestablished to study the absorption of synthesized tripeptide Val-Ala-Pro (VAP)purified from GCP.Desalination for GCP with macroporous adsorption resin DA201-C was studied.Loading sample was10mg/mL, following with eluting, collecting, concentratingand freeze-drying. Results showed that the ash content decreased to3.89%with thedesaltation rate82.02%. The peptide content increased from62.07%to89.35%.GCP were enrichment, which molecular weight concentrate on400-900Da; Thetotal content of hydrophobic amino acids increased from272.6mg/g to338.3mg/gand accounted for44.15%in the all common ones.The IC50of ACE inhibitoryactivity decreased from0.34to0.26mg/mL; The concentration needed to scavenge50%DPPH radicals decreased from5.89to4.50mg/mL and the value of ferricreducing antioxidant potential assay (FRAP) increased from1.018to1.261.The angiotensin I-converting enzyme (ACE) inhibitory activity wasdetermined by high performance liquid chromatography (HPLC). The retentiontimes of hippurie acid (HA) and Hippuryl-His-Leu (HHL) were9.899min and10.522min, respectively. The detection limits of HA were3.125μg/mL. RSD was1.71%and the average recovery rate was99.5%, which indicated that the methodwas available and reliable. The result showed that the prepared bioactive peptideshad strong ACE inhibitory activity with IC50of0.26mg/mL.Spontaneously Hypertensive Rats (SHR) and Wistar Kyoto Rats (WKY) wereadministed to evaluate the antihypertensive effect of GCP. In the single study, the lowest blood pressure values were found at6-9h after single oral administration ofthese products. The administration of GCP (100mg/kg) produced the maximaldecreases, approximately30mmHg, which had the same effect as the positivecontrol Captopril (p>0.05). In the long term study, all rats in the experimentalgroups were orally administered GCP and captopril once a day according to theexperiment plan. systolic blood pressure (SBP) in SHR administered with GCP wasgenerally lower from the1st week and the effect increased dose-dependently andtime-dependently during the course of the experiment. When SHR wereadministered with100,50,20mg/kg GCP for four consecutive weeks, the SBPdecreased by20.7mmHg,14.0mmHg and7.2mmHg respectively compared withself pre-administration. For WKY, captopril could lower SBP significantly; littlechange occurred even when receiving the highest dose of GCP. After6wtreatment with GCP once a day, the ACE activity and Angiotensin (Ang)concentration in plasma of SHR have a significant descending trend in adose-dependent manner compared with SHR negative control (p<0.05). Plasmarenin (RA) and nitric oxide (NO) levels appeared in a negative correlation withdosage of GCP, which was much higher than the negative group when treated withGCP100mg/kg (p<0.05). All the above results indicated that the antihypertensiveeffect of GCP was probably associated with regulating rennin-angiotensin system(RAS) and NO.Caco-2cell model was established to evaluate the absorption of GCP in smallintestine. During the experiment (21d), transepithelial electrical resistane (TEER)values increased to385/cm2, indicating a good tight junction. The activity ratio ofalkaline phosphatase (AKP) between apical (AP) and basolateral (BL) wasenhanced to1:1.3and mostly located in brush side AP under the cultivationcondition, similar to the small intestine. The apparent permeability (Papp) value offluorescein disodium salt was0.67×10-6cm/s, within the scope of reported value. Inconclusion, the integrity, permeability of Caco-2cells monolayer model establishedin the study can be used to study the synthesized tripeptide Val-Ala-Pro (VAP) purified from GCP. Original concentration of VAP was1mg/mL. Results showedthat the absorption rate of VAP was20%-70%with the Papp7.66×10-6cm/s, whichbelong to a medium-absorption drug.