Influence Of Liposomes And Micelles On The Stability Of Natural Antioxidants

Flavonoids such as catechins derived from natural plants, including teas, grapes, citruses, and persimmon etc. have been shown to exert a wide range of antioxidants, serum lipid reduction, ant if lamination and anticancer properties, resulting in deeply research on its' autoxidation and mechanisms of antioxidant activies and in healthy function recognition by scholars of medical science and food nutrition. However, most of the natural antioxidants lost activities, resulting from exerting healthy functions. They were fairly unstable during harvesting, transportation, storage and processing of plant food. For instance, oxidative browning of phenolic compounds is a major cause of quality degradation of fruit and vegetable -derived foods . Hence it is important to understand the factors which influence the stability of phenolic compounds and identify methods to control the oxidative degradation of phenolics.Scientific workers attached importance to amphiphilic structures(liposomes and micelles)since its' discovery, especially in extensive use in slow-release and target drug carriers. Since the eighties last century, some advanced countries such as Germany, Sweden and USA have done much basic researches on application of amphiphilic structures at the expense of much manpower and financial resources, resulting in appearance of liposome target anticancer drugs. And since the nineties last century, some domestic scientific workers dedicated to do the similar researches, unfortunately no sucessful liposomal target drugs went into market.The objective of this study is to investigate the effects of the presence of amphiphilic structures on the chemical stability of catechins, a primary basic work which was intended to expand the application range of it.1 Determination of the K(octanoi-i/water)values of CG, EC, (-)C, EGCG and EGC demonstrated hightest K(octanoi-i/water) value of CG and the lowest of EGC, which meant that, in the case of different pH values and in the presence of Cu2+, in vitro tests CG obtained the extensivest protection from oxidation after incorporated in the amphiphilic structures among the five catechins, especially in the case of higher pH values.2 Comparision of the influence of amphiphilic structures (liposome and micelle)built with different components (PC, PE, Tween-20, Tween-80 etc.)on the stability of (-)C revealed that the liposome built with DPPC+DMPG had best pretection effection on the autoxidation of (-)C.3 Flexible liposome constituted with PC+DONa were exhibited under transmission electron microscopy.4 PFG-NMR analysis indicated that the use of 25:1 of Tween-20: (-)C, most of it(>90%) has been incorporated in the Tween-20 micelle structures.5 Tests(in vivo) showed that the (-)C could obviously reduce serum lipids and enhance SOD, compared with the controls. And if incorporated in the liposome or micelle, (-)C declared much more obviously superior affection to cntrols(P<0.01).6 The results of pharmacokinetic parameter analysis meant that when (-)C was incorporated in liposomes, the a , or1), CL(L.h''), K2K KHK Ki2 were obviously lower than that of free (-)C(unembeded) , and the ti/ze one time longer, F value (absolute bioavailability)30% increase.