Study On The Physicochemical Stability And Biological Activity Of Polyphenol Liposome

Polyphenol is a secondary metabolites, which possesses a lot of physiological activities such as antioxidant, anti-inflammatory, antibacterial, anticancer and antiviral activity. The short gastric residence time, low permeability and solubility, the sensitive against the environmental factors such as light, temperature and oxygen during storage, the unstability twoward pH, enzyme and other food matrix would result in the unstability of polyphenol and reduce its biological activity. Liposomes are formed by amphiphilic phospholipid, which could be used to encapersulate both hydrophobic and hydrophilic active ingredient. Currently, there are many reports which only focous on the preparation of polyphenol liposome, but there are only few reports which invole the stability and biological acticty of polyphenol after encapersulation. This project would mainly focous on three following subujuct:(1)hydrophilic polyphenol(tea polyphenol and EGCG)and hydrophobic polyphenol(eugenol)nanoliposome were prepared by combining ethanol injection with dynamic high pressure microfluidization(DHPM)methold; the physical and chemical properties and the polyphenol stability during alkaline pH and simulated gastrointestinal environment of polyphenol nanoliposome were envaluated.(2)The biological activity(chemical and celluar antioxidant activity, cytotoxity, celluar uptake and in vitro antibacterial activty)were further envaluated.(3)In order to enhance the stability of polyphenol liposome during in vitro digestion, a novel delivery system( dextran sulfate coated amphiphilic chitosan derivatives-based nanoliposome)which is not digetised in gastrointestinal tract and a polyelectrolyte coated nanoliposome were prepared. The results were as follows.(1): The tea polyphenol, EGCG and eugenol nanoliposome were prepred by combining ethanol injection with dynamic high pressure microfluidization(DHPM)methold. Tea polyphenol, EGCG and eugenol nanoliposome possessed a small average paticle size(66.8 nm, 71.7 nm and 58.6 nm)and low polydispersion index(0.213, 0.286 and 0.381). Nanoliposome exhibited a good sustaining release for tea polyphenol, EGCG and eugenol. The alkaline pH stability of tea polyphenol and stability of EGCG under simulated gastrointestinal environment have been enhanced by nanoliposomal encapsulation. The present of bile salt and pancreatin would decrease the EGCG protecting effect of nanoliposome. Eugenol nanoliposome exhibited a good storage stability at both 4 °C and room temperature. The water solubility of eugenol has been improved by nanoliposomal encapsulation.(2): Tea polyphenol after encapersulating in nanoliposome exhibited an equal or lower in vitro antioxidant activity. In the comparation with tea polyphenol solution, tea polyphenol nanoliposome exhibited low in vitro antibacterial activity(smaller inhibition zone and larger minimum inhibitory concentration and minimum bactericidal concentration). Eugenol nanoliposome also exhibited smaller inhibition zone and larger minimum inhibitory concentration and minimum bactericidal concentration in broth and milk. EGCG nanoliposome exhibited lower cellular antioxidant activity, cellular uptake and cytotoxicity.(3): Amphiphilic chitosan derivative nanoliposome were prepared by combining thin-film evaporator with dynamic high pressure microfluidization(DHPM)methold, which exhibited low average particle size, high zeta potential, high EGCG encapsulation efficiency and good EGCG sustaining release. However, amphiphilic chitosan derivative nanoliposome exhibited low stability under simulation intestine fluid, and it is easy to form semident when mixed with simulation intestine fluid. Dextran sulfate coated amphiphilic chitosan derivatives-based nanoliposome exhibited good in vitro digested stability, high EGCG sustaining release and good EGCG protecting effect. Polyelectrolyte layer by layer coated EGCG nanolipsome possessed a hard core-shell structure, high encapsulation efficiency and EGCG sustaining release. Polyelectrolyte layer by layer coated EGCG nanolipsome exhibited high EGCG protecting effect during simulated intestine fluid.