Nakagawa Kiyotaka, Ibusuki Daigo, Suzuki Yoshihiro, Yamashita Shinji, Higuchi Ohki, Oikawa Shinichi, Miyazawa Teruo
Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
J Lipid Res. 2007 Dec;48(12):2779-87. doi: 10.1194/jlr.D700016-JLR200. Epub 2007 Sep 11.
We previously discovered that squalene monohydroperoxide (SQ-OOH) was produced on human forehead skin and suggested that skin squalene (SQ) may be the principal target lipid for oxidative stress (e.g., sunlight exposure). Because of its six double bonds, SQ peroxidation can yield various positional hydroperoxide isomers. However, the structural characterization of skin SQ-OOH isomers has never been reported. Here, we prepared pure SQ-OOH isomers and developed an analytical method for SQ-OOH isomers using a quadrupole/linear ion-trap mass spectrometer (QTRAP) MS/MS system. Collision-induced dissociation produced specific fragment ions for each SQ-OOH isomer, which permitted discrimination between SQ-OOH isomers by multiple reaction monitoring (MRM). When lipid extract from human forehead skin was subjected to LC-MS/MS with MRM, individual SQ-OOH isomers could be separated and detected with a sensitivity of 0.05 ng/injection. The total concentration of SQ-OOH isomers in forehead skin was approximately 956 microg/g skin lipids, but it increased up to 2,760 microg/g skin lipids after 3 h of sunlight exposure. The LC-MS/MS method was useful for investigating the peroxidation mechanisms of SQ as well as SQ-OOH-mediated skin disorders.
我们之前发现，人前额皮肤会产生单氢过氧化角鲨烯（SQ - OOH），并提出皮肤角鲨烯（SQ）可能是氧化应激（如阳光照射）的主要靶脂质。由于其含有六个双键，SQ过氧化可产生各种位置的氢过氧化物异构体。然而，皮肤SQ - OOH异构体的结构表征从未被报道过。在此，我们制备了纯的SQ - OOH异构体，并开发了一种使用四极杆/线性离子阱质谱仪（QTRAP）MS/MS系统分析SQ - OOH异构体的方法。碰撞诱导解离为每个SQ - OOH异构体产生特定的碎片离子，这使得通过多反应监测（MRM）能够区分SQ - OOH异构体。当对人前额皮肤的脂质提取物进行带有MRM的LC - MS/MS分析时，各个SQ - OOH异构体能够被分离并检测到，灵敏度为0.05 ng/进样。前额皮肤中SQ - OOH异构体的总浓度约为956 μg/g皮肤脂质，但在阳光照射3小时后增加到2760 μg/g皮肤脂质。LC - MS/MS方法对于研究SQ的过氧化机制以及SQ - OOH介导的皮肤疾病很有用。
