A2E的光化学氧化作用会导致形成一种5,8,5',8'-双呋喃型氧化物。

The photochemical oxidation of A2E results in the formation of a 5,8,5',8'-bis-furanoid oxide.

作者信息

Dillon J, Wang Z, Avalle L B, Gaillard E R

机构信息

Department of Ophthalmology, Columbia University, New York, NY 100322, USA.

出版信息

Exp Eye Res. 2004 Oct;79(4):537-42. doi: 10.1016/j.exer.2004.06.024.

Abstract

With age and certain diseases, the retinal pigment epithelium (RPE) accumulates a complex mixture of fluorophores generally called lipofuscin. This mixture has been implicated in those diseases via several possible mechanisms including photochemically mediated damage and detergent effects. Recently, a component of that mixture has been identified, a bis-retinoid pyridinium compound called A2E. Furthermore, the photolysis of this compound has been shown to lead to a series of photooxidation products each differing by 16 amu; with the addition of up to a total of nine oxygen atoms to A2E. It has been suggested that these products consist of a series of epoxides forming along the acyclic side chains. The present study reinvestigates this hypothesis and demonstrates that the bis-oxygenated product is in fact a relatively stable 5-8 5'-8'-bis-furanoid oxide. This is in agreement with the oxidation products observed for a homologue of A2E, beta-carotene. In addition, it was found that the bis-oxygenated photoproduct of A2E contained a mixture of symmetrical and unsymmetrical oxidized products where the second oxygen was present in the cyclohexenyl ring structure in the unsymmetrical product. Most importantly, both of these oxidation products of A2E were detected in lipofuscin extracts from human RPE cells, suggesting that these processes occur in vivo.

摘要

随着年龄增长以及患有某些疾病,视网膜色素上皮(RPE)会积累一种通常称为脂褐素的荧光团复杂混合物。这种混合物通过多种可能机制与这些疾病有关,包括光化学介导的损伤和去污剂效应。最近,已鉴定出该混合物的一种成分,一种称为A2E的双视黄醛吡啶鎓化合物。此外,已证明该化合物的光解会导致一系列光氧化产物,每个产物相差16原子质量单位;A2E总共最多添加九个氧原子。有人提出这些产物由沿着无环侧链形成的一系列环氧化物组成。本研究重新调查了这一假设,并证明双加氧产物实际上是一种相对稳定的5-8 5'-8'-双呋喃氧化物。这与A2E的同系物β-胡萝卜素所观察到的氧化产物一致。此外,发现A2E的双加氧光产物包含对称和不对称氧化产物的混合物,其中不对称产物中环己烯基环结构中存在第二个氧。最重要的是,在人RPE细胞的脂褐素提取物中检测到了A2E的这两种氧化产物,表明这些过程在体内发生。

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