The feasibility of liposomes with cholesterol substituted by phytosterols and the effect of antihypertensive oligopeptides encapsulated in liposomes on blood pressure of spontaneously hypertensive rats

• Main Authors: YungHsu-Chan, 詹詠絮
• Other Authors: 盧義發
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/09351080049537964457

碩士 === 輔仁大學 === 食品營養學系 === 91 === Liposomes that are made up with multilamellar phosphobilayers have cell-membrane-like hollow sphere. Their special characteristics and structure can be used to encapsulate substances to transport and protect materials. The purpose of this study was to use phytosterols, such as β-sitosterol and stigmasterol, as a substitute for cholesterol in liposomes. Their physicochemical properties such as encapsulation efficiency (EE), stabilities of storage, pH, oxidization and pepsin were investigated to assess it possibility. Liposomes prepared with phytosterols or cholesterol exhibited higher encapsulation efficiency of bovine serum albumin (BSA) (EE: 24-36% and 28%, respectively) than those prepared without addition of sterols (EE: 19%). The EE of glucose in liposomes increased with the increasing level of cholesterol or phytosterols added in liposomes, but EE values were not so good as in BSA. In addition, EE of liposomes were increased with repeating dehydration-rehydration cycle in five times. Liposomes at pH 6 or 7 were most stable, irrespective of their sterol compositions. Liposomes storage at 4℃ had a higher residual percentage than those of storage at -20℃ or room temperature. Sterols-containing liposomes were more stable during long-term storage at various temperatures than sterol-free counterparts. Addition of sterols to liposomes was effective in decreasing the TBARS during storage periods, it effects was more markedly when α-tocopherol was added. Fatty acid compositions were comparable after storage, no matter what sterols or α-tocopherol were added or not. Liposomes containing cholesterol or phytosterols were effective in protecting encapsulated oligopeptide from pepsin digestion. Furthermore, Encapsulated oligopeptide in sterols-containing liposomes orally administrated to spontaneously hypertensive rats (SHR) lowered blood pressure slowly but sustainedly, and it blood pressure-lowering effect was similar to that induced by Captopril. The results indicated that replacing cholesterol with phytosterols in preparing liposomes is feasible and recommended.