Toronto Research Chemicals, Inc., 2 Brisbane Rd., North York, ON, Canada M3J 2J8.
Bioorg Med Chem. 2010 Jan 15;18(2):777-86. doi: 10.1016/j.bmc.2009.11.051. Epub 2009 Nov 27.
A polyunsaturated analogue of alpha-tocopherol was synthesized that is both fluorescent and sensitive to peroxidative chemistry that occurs in phospholipid membranes. alpha-Tocohexaenol 1, [(S)-2,5,7,8-tetramethyl-2-((1E/Z,3E,5E,7E,9E)-4,8,12-trimethyltrideca-1,3,5,7,9,11-hexaenyl)chroman-6-ol, alpha-T6] was prepared by condensing a known triene fragment triphenyl-(2,6-dimethyl-octa-2,4,6-trienoic acid methyl ester)-phosphonium bromide with a protected chromanol aldehyde, (2S)-6-{[tert-butyl(dimethyl)silyl]oxy}-2,5,7,8-tetra-methyl-3,4-dihydro-2H-chromene-2-carbaldehyde. The full side chain was then completed with isopentyl(tri-n-butyl)phosphonium bromide to give 1. The geometry of the C1'-C2' alkene appears to be Z (cis) although the coupling constants of the olefinic protons are intermediate between values normally assigned to E and Z-isomers. In ethanol, alpha-T6 has a maximum absorption at 368nm with an absorption coefficient of 45,000M(-1) cm(-1), and displays a maximum fluorescence emission at 523nm. The susceptibility of alpha-T6 to peroxidative chemistry was dependent on the concentration of azo-initiators of lipid oxidation in acetonitrile solution as well as in phospholipid vesicles. A loss of fluorescence at 520nm was observed when alpha-T6 (vesicles or alpha-T6-lipid mixtures) was exposed to peroxidative conditions, and this loss mirrored the production of conjugated dienes and trienes during the peroxidation of bulk phospholipids. Addition of natural alpha-tocopherol during the AMVN induced oxidation of 4microM alpha-T6 and 0.5mg/ml soybean PC induced a characteristic lag phase, after which the fluorescence of alpha-T6 began to lessen. Thus, alpha-T6 may be a useful reporter not only of tocopherol location in cells, but also of the extent of peroxidative events.
一种多不饱和α-生育酚类似物被合成出来，它不仅具有荧光性，而且对磷脂膜中发生的过氧化化学敏感。α-生育六烯醇 1，[(S)-2,5,7,8-四甲基-2-((1E/Z,3E,5E,7E,9E)-4,8,12-三甲基十三-1,3,5,7,9,11-六烯基)色满-6-醇，α-T6]是通过缩合一种已知的三烯片段三苯基-(2,6-二甲基-辛-2,4,6-三烯酸甲酯)-溴化膦与一种保护的色满醛，(2S)-6-[[叔丁基(二甲基)硅基]氧基]-2,5,7,8-四甲基-3,4-二氢-2H-色满-2-甲醛。然后用异戊基(三正丁基)溴化膦完成全侧链，得到 1。C1'-C2' 烯键的几何形状似乎为 Z（顺式），尽管烯质子的偶合常数介于通常分配给 E 和 Z-异构体的值之间。在乙醇中，α-T6 在 368nm 处具有最大吸收，吸收系数为 45,000M(-1)cm(-1)，并在 523nm 处显示最大荧光发射。α-T6 对过氧化化学的敏感性取决于在乙腈溶液中和在磷脂囊泡中脂质氧化的偶氮引发剂的浓度。当α-T6（囊泡或α-T6-脂质混合物）暴露于过氧化条件下时，在 520nm 处观察到荧光的损失，并且这种损失反映了在大量磷脂的过氧化过程中共轭二烯和三烯的产生。在 AMVN 诱导的 4μM α-T6 和 0.5mg/ml 大豆 PC 氧化过程中添加天然α-生育酚会导致一个特征性的滞后期，之后α-T6 的荧光开始减弱。因此，α-T6 不仅可以作为细胞中生育酚位置的有用报告物，而且还可以作为过氧化事件程度的有用报告物。
