School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China.
Anal Chem. 2024 Jul 16;96(28):11189-11197. doi: 10.1021/acs.analchem.4c00410. Epub 2024 Jul 4.
Lipids play integral roles in biological processes, with carbon-carbon double bonds (C═C) markedly influencing their structure and function. Precise characterization and quantification of unsaturated lipids are crucial for understanding lipid physiology and discovering disease biomarkers. However, using mass spectrometry for these purposes presents significant challenges. In this study, we developed a microwave-assisted magnesium monoperoxyphthalate hexahydrate (MMPP) epoxidation reaction, coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), to analyze unsaturated lipids. Microwave irradiation expedited the MMPP epoxidation, achieving complete derivatization in 10 min without byproducts. A diagnostic ion pair, displaying a 16 Da mass difference, effectively identified the location of the C═C bond in mass spectra. Microwave irradiation also significantly facilitated the epoxidation reaction of polyunsaturated lipids, achieving yields greater than 85% and yielding a complete epoxidation product. This simplifies chromatographic separation and aids in accurate quantification. Additionally, a purification process was implemented to remove excess derivatization reagents, significantly reducing mass spectrometry response suppression and enhancing analytical reproducibility. The method's effectiveness was validated by analyzing unsaturated lipids in rat plasma from a type I diabetes model. We quantified nine unsaturated lipids and characterized 42 fatty acids and glycerophospholipids. The results indicated that unsaturated fatty acids increased in diabetic plasma while unsaturated glycerophospholipids decreased. Furthermore, the relative abundances of Δ9/Δ11 isomer pairs also exhibited a close association with diabetes. In conclusion, microwave-assisted MMPP epoxidation coupled with LC-MS/MS provides an effective strategy for characterization and quantification of polyunsaturated lipids, offering deeper insight into the physiological impact of unsaturated lipids in related diseases.
脂质在生物过程中发挥着重要作用，碳-碳双键（C═C）显著影响其结构和功能。准确地描述和定量不饱和脂质对于理解脂质生理学和发现疾病生物标志物至关重要。然而，使用质谱法进行这些分析具有重大挑战。在这项研究中，我们开发了一种微波辅助过氧单酸镁六水合物（MMPP）环氧化反应，结合液相色谱-串联质谱（LC-MS/MS），用于分析不饱和脂质。微波辐射加速了 MMPP 的环氧化，在 10 分钟内实现了完全衍生化，没有副产物。一对诊断离子对显示出 16 Da 的质量差异，有效地确定了质谱中 C═C 键的位置。微波辐射还显著促进了多不饱和脂质的环氧化反应，产率大于 85%，生成完全的环氧化产物。这简化了色谱分离，有助于准确定量。此外，还实施了一种纯化过程来去除多余的衍生化试剂，显著减少了质谱响应抑制，提高了分析重现性。该方法通过分析 I 型糖尿病模型大鼠血浆中的不饱和脂质进行了验证。我们定量了九种不饱和脂质，并对 42 种脂肪酸和甘油磷脂进行了描述。结果表明，糖尿病血浆中不饱和脂肪酸增加，而不饱和甘油磷脂减少。此外，Δ9/Δ11 异构体对的相对丰度也与糖尿病密切相关。总之，微波辅助 MMPP 环氧化结合 LC-MS/MS 为多不饱和脂质的特征描述和定量提供了一种有效的策略，为相关疾病中不饱和脂质的生理影响提供了更深入的认识。
