| Summary: | 碩士 === 長庚大學 === 天然藥物研究所 === 93 === Tea polyphenols, including (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin-3-gallate (EGCG), have been shown to possess potent antioxidant and chemopreventive activities. The aim of this study was to evaluate the possibility of using liposomes encapsulating tea catechins for local delivery, including tumor and skin deposition of these polyphenols. Liposomes containing egg phosphatidylcholine, cholesterol, or anionic species were prepared by the solvent evaporation method and then passed through a probe sonicator. The size, zeta potential, and entrapment efficiency of these liposomal formulations were determined to correlate with the following in vivo study. The release rate study had showed that the inclusion of ethanol and the anionic species such as deoxycholic acid (DA) or dicetyl phosphate (DP) could reduce the rigidity of lipid bilayers, leading to the fast release from these formulations. Liposomes delivered catechins into the solid tumor to a greater amount than the aqueous solution. The drug release rate and vesicle size of liposomes may predominate the drug deposition in tumor tissues. No significant increase of skin deposition of catechins was observed after topical application of liposomes in absence of 15% ethanol. On the other hand, incorporation of anionic surfactants in the liposomes in the presence of 15% ethanol increased the (+)-catechin permeation by 5~7-fold as compared to the control in trandstermal delivery. The flexibility of the bilayers is suggested to be an important factor governing the enhancing effect of liposomes. Intercellular spaces within the stratum corneum but not shunt routes are the major pathways for (+)-catechin delivery from liposomes.. The presence of gallic acid ester in structures (EGCG) significantly increased the tissue uptake of catechins. The skin tolerance test assured the safety of the practical use of liposomes developed in this study local deposition in skin or tumor
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