通过顺式十八碳三烯酸荧光监测水相脂质体悬浮液中自由基诱导的脂质过氧化作用。

Di Giulio A, Saletti A, Oratore A, Bozzi A

Department of Biomedical and Technological Sciences and Biometrics, University of L'Aquila, Italy.

J Microencapsul. 1996 Jul-Aug;13(4):435-45. doi: 10.3109/02652049609026029.

Cis-parinaric acid is fluorescent when partioned into a lipid environment and its fluorescence is destroyed upon reaction with free radicals. In our study 1-palmitoyl-2-parinoyl-phosphatidylcholine (cis-PnA) has been used to monitor the time-course of liposomal lipid peroxidation, using reverse-phase evaporation vesicles (REV) of different composition exposed to oxidative stress in various conditions. This methodology allowed us to estimate the potential damage produced by two different oxidizing systems, namely hydrogen peroxide (H2O2), a water soluble oxidant, and t-butyl hydroperoxide (t-BHP), a hydrophobic hydroperoxide. Furthermore, we evaluated the protective effects of bilayer-associated antioxidants, namely alpha-tocopherol acetate (alpha-THA), vitamin K1 and beta-carotene, as well as of two antioxidants dissolved in the aqueous bulk solution, that is, biverdin and uric acid. Under our experimental conditions, the results suggest that (i) both oxidizing compounds were able to interact with liposomal PnA leading to decay either of the excitation and of emission spectra of the probe; (ii) hydrogen peroxide seemed to be of most effective among the two stressing agents, when employed at similar concentrations; (iii) the alpha-THA appeared to be a stronger antioxidant than vitamin K1 and beta-carotene, resulting in a decrease of the liposomal membrane stress caused by those two oxidizing agents; (iv) among the water soluble antioxidant compounds, biliverdin displayed a protective effect at least 10 x higher than uric acid; (v) the overall damage, as well as the protection mechanisms, seemed to be dependent either on the lipid composition of the vesicles and on the pH of the liposomal suspension. This relatively easy experimental approach suggests the validity of the use of the bilayer associated fluorescent probe PnA in the monitoring of spontaneous and/or chemically induced liposomal lipid damage.

顺式十八碳四烯酸在分配到脂质环境中时会发出荧光，并且其荧光在与自由基反应时会被破坏。在我们的研究中，1-棕榈酰-2-顺式十八碳四烯酰磷脂酰胆碱（顺式-PnA）已被用于监测脂质体脂质过氧化的时间进程，使用不同组成的反相蒸发囊泡（REV）在各种条件下暴露于氧化应激。这种方法使我们能够估计由两种不同的氧化系统产生的潜在损伤，即过氧化氢（H2O2），一种水溶性氧化剂，和叔丁基过氧化氢（t-BHP），一种疏水性氢过氧化物。此外，我们评估了双层相关抗氧化剂，即α-生育酚醋酸酯（α-THA）、维生素K1和β-胡萝卜素，以及两种溶解在水相 bulk 溶液中的抗氧化剂，即胆红素和尿酸的保护作用。在我们的实验条件下，结果表明：（i）两种氧化化合物都能够与脂质体PnA相互作用，导致探针的激发光谱和发射光谱衰减；（ii）当以相似浓度使用时，过氧化氢似乎在两种应激剂中最有效；（iii）α-THA似乎比维生素K1和β-胡萝卜素是更强的抗氧化剂，导致由这两种氧化剂引起的脂质体膜应激降低；（iv）在水溶性抗氧化化合物中，胆红素显示出比尿酸至少高10倍的保护作用；（v）总体损伤以及保护机制似乎取决于囊泡的脂质组成和脂质体悬浮液的pH值。这种相对简单的实验方法表明使用双层相关荧光探针PnA监测自发和/或化学诱导的脂质体脂质损伤的有效性。