The Stability Of ACE Inhibitory Peptide RVPSL With The Modification Of Nano-material In Gastrointestinal

This work was funded by the National Key R&D Program of China(2018YFD0400300).In previous study,angiotensin converting enzyme(ACE)inhibitory peptide RVPSL(IC₅₀was 20?M)has been identified and its antihypertensive effect on spontaneous hypertension rat(SHR)was well.However,it could be degraded by digestive enzymes because of its poor stability in gastrointestinal tract.In this work,nano-materials graphene oxide(GO),metal oxide(the porous Mn₃O₄)and silicon dioxide(Si O₂)were used as carriers loading ACE inhibitory peptide RVPSL to improve its stability in gastrointestinal tract.Our research includes three fields of work as the follows:1.GO was used as carrier loading the bioactive peptide RVPSL because of its good hydrophilicity and high specific surface area.The loading efficiency was calculated to be 95.02%.The morphology and ACE inhibitory activity of the formed composite RVPSL-GO were measured using FT-IR,XPS,XRD and HPLC.When the concentration of RVPSL successfully loaded to the GO was 0.05 mg/m L,its ACE inhibition rate could reach 39.70%which is 1.5 folds that of without GO protection.The simulated gastrointestinal digestion results indicated that GO could protect RVPSL to improve its stability in gastrointestinal tract.What's more,GO and RVPSL-GO were not toxic to the growth of Hep G2 cells in the concentration range of 0-100?g/m L after co-incubation with Hep G2 cells for 48 h.2.The porous Mn₃O₄could be used as carrier to against acidic environment and digestive enzymes due to its nanosized pores and high surface area,which could be decomposed to Mn²⁺under acidic condition and metabolized by kidneys.Therefore,the porous Mn₃O₄loaded ACE inhibitory peptide RVPSL based on the two-dimensional network structure was prepared and its morphology was characterized.The synthesized Mn₃O₄exerted the porous structure,connected with each other presenting a two-dimensional network structure with a particle size of 50-200nm.The results of zeta potential showed that the porous Mn₃O₄loaded peptide RVPSL by electrostatic interaction.The loading efficiency of RVPSL was 0.43 mg(1 mg the porous Mn₃O₄could load 0.43 mg RVPSL).What's more,Mn₃O₄/RVPSL could be stable under neutral condition(p H 7.4)and exhibited p H-sensitive under acid environment(p H 4.0 and 2.0).The results of in vitro simulated gastrointestinal digestion showed that the retention and the ACE inhibitory activity of RVPSL in Mn₃O₄/RVPSL were significantly higher than RVPSL without protection of the porous Mn₃O₄,implying that the porous Mn₃O₄could improve the gastrointestinal stability and ACE inhibitory activity of peptide RVPSL.3.Due to its unique mesoporous structure,large specific surface area,adjustable pore size and good biocompatibility,mesoporous silica can be used as a stimulating reaction carrier after modification.Mesoporous hollow silica(HMSNs-NH₂)was used as the carrier to load the ACE inhibitory peptide RVPSL by covalent bonding.The release results of HMSNs-RVPSL under different p H conditions showed that HMSNs-RVPSL could be stable under the acidic environment(p H 5.5).The results of in vitro simulated gastrointestinal digestion showed that the retention of RVPSL in HMSNs-RVPSL was higher than the peptide without protection of HMSNs-NH₂.Compared with the ACE inhibitory of RVPSL without protected,the ACE inhibitory activity of HMSNs-RVPSL was obviously higher.In addition,the effect of HMSNs-NH₂and HMSNs-RVPSL on the proliferation activity of Hep G2 cells showed that both cell viability of Hep G2 cells were higher than 90%after 48 h incubation,suggesting that HMSNs-NH₂and HMSNs-RVPSL were not toxic to the growth of Hep G2 cells in the concentration range of 0-100?g/m L which exhibited non-toxicity and good biocompatibility,could be used as the carrier to load peptide RVPSL.