Bioactivities and ACE-inhibitory peptides releasing potential of lactic acid bacteria in fermented soy milk

This study was designed to evaluate the bioactivities such asβ-glucosidase activity,α-galactosidase activity,and the growth behavior of the Lactobacillus cultures in soy milk medium.Ten Lactobacillus cultures were considered in this study.L.fermentum(M2)and L.casei(NK9)were selected due to their betterα-galactosidase,β-glucosidase activity and growth behavior in soy milk medium during fermentation.Further,soy milk fermented with M2 showed higher proteolytic activity(0.67 OD)and ACE-inhibitory(48.44%)than NK9(proteolytic activity:0.48 OD and ACE-inhibitory activity:41.33%).Bioactive peptides produced during the fermentation of soy milk using the selected Lactobacillus cultures were also identified with potent ACE-inhibitory activity by MALDI-TOF spectrometry,and the identified ACE inhibitory peptide sequences from fermented soy milk were characterized using Biopep database.

Study of screening,transport pathway,and vasodilation mechanisms on angiotensin-Ⅰconverting enzyme inhibitory peptide from Ulva prolifera proteins

In this study,Ulva prolifera protein was used for preparing angiotensin-I converting enzyme(ACE)-inhibitory peptide via virtual gastrointestinal digestion and in silico screening.Some parameters of the obtained peptide,such as inhibition kinetics,docking mechanism,stability,transport pathway,were explored by Lineweaver-Burk plots,molecular docking,in vitro stimulate gastrointestinal(GI)digestion and Caco-2 cells monolayer model,respectively.Then,a novel anti-ACE peptide LDF(IC_(50),(1.66±0.34)μmol/L)was screened and synthesized by chemical synthesis.It was a no-competitive inhibitor and its anti-ACE inhibitory effect mainly attributable to four Conventional Hydrogen Bonds and Zn701 interactions.It could keep activity during simulated GI digestion in vitro and was transported by peptide transporter PepT1 and passive-mediated mode.Besides,it could activate Endothelial nitric oxide synthase(eNOS)activity to promote the production of NO and reduce Endothelin-1(ET-1)secretion induced by AngiotensinⅡ(AngⅡ)in Human Umbilical Vein Endothelial Cells(HUVECs).Meanwhile,it could promote mice splenocytes proliferation in a concentration-dependent manner.Our study indicated that this peptide was a potential ingredient functioning on vasodilation and enhancing immunity.