Absorption Mechanism Across Intestinal Of Milk-derived ACE Inhibitory Peptides Using Caco-2 Cell Model

Angiotensin-I converting enzyme inhibitory peptides in milk can be extracted from the fermented milk or milk protein hydrolysate.Thepeptides can inhibit the activity of ACE effectively so as to have anti hypertensive effects.With the effect to reduce blood press and with no side effects,the natural and active ACE inhibitory peptides has become a hot topic in current study of anti hypertension drugs.Due to low perneability of intestinal mucosa and degradation of digestive enzynme,the oral bioavailability of ACE inhibitroy peptides was low.So,to explore ways to enhance the bioavailability of peptides on the basis of the intestinal absorption mechanism of ACE inhibitory peptides can lay the foundation for downstream application of ACE inhibitory peptides.The Caco-2 cell model was established to compare the factors that affect absorption of peptides.The absorption mechanism of VPP?IPP and RLSFNP was specially studied.Impact of absorption accelerators to RLSFNP was studied because of low absorption of RL SFNP.First,the Caco-2 cell model was evaluated by morphology feature,transepithelial electrical resistance and the transmittance of fluorescein sodium.The Caco-2 cell monolayer had become an analogy of small intestinal epithelium with good integrity and cell polarity so as to be used to study the intestinal absorption mechanism.Secondly,the impact of molecular size,charge,hydrophobicity and amino acid to of peptides was summarized and validated by comparing the transepithelial flux of a variety of peptides.The greater the molecule size,the more difficultly the peptides went through the cell membrane.Charge also had some influence on the transit of peptides.As the molecule went larger,the impact of charge could be ignored.The larger hydrophobicity,the higher membrane permeability.With proline in the C-terminal,peptides had higher transepithelial flux.Thirdly,the effects of time,concentration,enhancers and inhibitors were i nvestigated to compare the way of transport and the mechanism of efflux of VPP and IPP.The results showed the transport of VPP was concentration-dependent.Paracellular diffusion was suggested to be the main mechanism for the absorption of VPP and IPP.The transport of VPP and IPP were both influenced by the efflux pump.The efflux effected VPP more than IPP,so IPP showed higher bioavailability.Last,the transport of hexapeptide RL SFNP across Caco-2 cell was observed.Only a little intact RLSFNP reached BL side of the membrane.Some was digested i nto smaller peptides of which the structure were F?SF?FNP?SFNP and RLSF respectively by mass spectrometry.Na2EDTA and bacitracin had better effects to promote the absorption of RLSFNP.