Preparation Of RLSFNP Liposomes Coated With Lactobacillus Acidophilus Surface Layer Protein And Studies On Its Intestinal Transport

Angiotensin-I Converting enzyme inhibitory peptide is one kind of peptide which is derived from milk protein and has the characteristic of inhibiting ACE activity.It achieves the goals of preventing and curing hypertension through inhibiting the activity of ACE which can reduce both the generation of angiotensin and destruction of the bradykinin.However,the low bioavailability of milk-derived ACE peptide in oral way is the main reason that limits its application in the functional foods market.As a new carrier,liposome has driven extensive attention from people since its characteristics of biological target therapy,long-time remission and light toxicity.Also the S-layer protein of Lactobacillus acidophilus contains the related functions to be carrier of milk-derived peptides,such as the performance of self-assembly outside the body,intestinal adhesion,gastrointestinal proteases digested resistance,biological security and so on.Thus,with the application of embedding the low bioavailability ACE inhibitory peptide,embellishing with the S-layer protein of Lactobacillus acidophilus,which has the performance of self-assembly,developing functional milk-derived peptide as the oral earrier,it would offer the new way for running of milk-derived peptides in the functional foods market.This subject chose Arg-Leu-Ser-Phe-Asn-Pro(RLSFNP)as the sample model,with the liposomes as carriers,researched the preparation technology of RLSFNP liposemes,prepared S-layer protein of Lactobacillus acidophilus,coated RLSFNP liposomes,and established Caco-2 cell model to study intestinal transport.1.Single factor and response surface methodology were conducted to optimize the RLSFNP liposome preparation and encapsulation efficiency was use to be the assessment index to choose the preferred formulation.The optimum conditions to determine the optimal prescription RLSFNP liposome preparation was:120 mg soy lecithin,24.64 mg cholesterol,15.33 mg RLSFNP,15 mL ether,5.837 mL PBS,ultrasonic time 5.25 minutes.The average diameter of produced liposome was 89 nm,potential was-31.2 mV,theoretical encapsulation efficiency was 67.8%,and the practical encapsulation efficiency was 67.5±0.8%.The RLSFNP had some kind of slow-release effectiveness after encapsulating by liposome.And the best storage condition was seal up at 4?.2.The liposome had dark face,faint white outline,a large area adhesion between different liposomes with the diameter of 142 nm and potential of-12.8mV through observation of microscope after embellished by S-layer protein of Lactobacillus acidophilus.From these observation and change of potential we could judge that S-layer protein has been successfully coated on the liposomes.Also,trypsin damage to the liposome was larger than the pepsin.S-layer protein modified liposome had more powerful tolerability of enzyme contained in the gastric and intestinal liquids than the ordinary liposome after the research of stability of the gastrointestinal tract between ordinary liposome and S-layer protein coated liposome.It showed that S-layer protein had a certain level of protection of the liposome.3.RLSFNP,RLSFNP liposome and S-layer protein modified RLSFNP liposome was conducted the intestinal transport experiment using the Caco-2 cell model.The results showed that liposomes encapsulated with ACE inhibitory peptide RLSFNP could increase the RLSFNP concentration transported to the BL(basolateral)side of Caco-2 cells.Liposomes as a carrier can protect RLSFNP,however,RLSFNP liposomes coated with S-layer protein of Lact.obacillus acidophilus failed to promote the transport of RLSFNP,and it may be related to its intestinal adhesion character.