Reis Salette, Lúcio Marlene, Segundo Marcela, Lima José L
REQUIMTE, Universidade do Porto, Portugal.
Methods Mol Biol. 2010;606:167-88. doi: 10.1007/978-1-60761-447-0_13.
Cellular membranes, which contain abundant phospholipids, such as phosphatidylcholine, are major targets subjected to the damage caused by free radicals. Cellular damage due to lipid oxidation is strongly associated with ageing, carcinogenesis and other diseases. In addition, lipid oxidation is an important deteriorative reaction in the processing and storage of lipid-containing foods. Liposomes have been used extensively as biological models for in vitro lipid oxidation studies. The resemblance between the liposomal and membrane bilayer core makes liposomes a very useful tool to investigate the significance of the antioxidant-membrane interactions for antioxidant activity. The antioxidant activity of a compound is strongly influenced by numerous factors including the nature of the lipid substrate, the hydrophilic-lipophilic balance of the antioxidant, the physical and chemical environments of the lipids, and various other interfacial interactions. Thus, compounds that are effective antioxidants in one model system or food matrix may be unsuitable in other systems.This chapter describes fluorescent probes-based methods commonly used for testing antioxidant activity in liposomes and stresses the need to combine antioxidant assays and drug-membrane interaction studies to get a better description of the antioxidants' profile considering their location in lipid bilayer and their effect on membrane fluidity and consequently provide additional information to that obtained currently from assays performed in aqueous buffer media.
细胞膜含有丰富的磷脂，如磷脂酰胆碱，是自由基造成损伤的主要靶点。脂质氧化导致的细胞损伤与衰老、致癌作用及其他疾病密切相关。此外，脂质氧化是含脂食品加工和储存过程中的一种重要劣化反应。脂质体已被广泛用作体外脂质氧化研究的生物学模型。脂质体与膜双层核心的相似性使脂质体成为研究抗氧化剂与膜相互作用对抗氧化活性的重要性的非常有用的工具。化合物的抗氧化活性受到多种因素的强烈影响，包括脂质底物的性质、抗氧化剂的亲水亲脂平衡、脂质的物理和化学环境以及各种其他界面相互作用。因此，在一种模型系统或食品基质中有效的抗氧化剂化合物在其他系统中可能不合适。本章描述了基于荧光探针的常用于测试脂质体中抗氧化活性的方法，并强调需要将抗氧化剂测定与药物-膜相互作用研究相结合，以便更好地描述抗氧化剂的特性，同时考虑到它们在脂质双层中的位置及其对膜流动性的影响，从而提供比目前在水性缓冲介质中进行的测定所获得的更多信息。
