Ding Lin, Chen Zhaozheng, Lu Yang, Su Xiong
Department of Biochemistry and Molecular Biology, Suzhou Medical College of Soochow University, Suzhou 215123, China.
J Agric Food Chem. 2023 Nov 1;71(43):16362-16370. doi: 10.1021/acs.jafc.3c04017. Epub 2023 Oct 20.
Abnormal levels of 2-hydroxy fatty acids (2-OH FAs) are characterized in multiple diseases, and their quantification in foodstuffs is critical to identify the sources of supplementation for potential treatment. However, due to the structural complexity and limited available standards, the comprehensive profiling of 2-OH FAs remains an ongoing challenge. Herein, an innovative approach based on gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed to determine the full profile of these FA metabolites. MS and MS/MS spectra of the trimethylsilyl (TMS) derivatives of 2-OH fatty acid methyl esters (FAMEs) were collected for peak annotation by their signature fragmentation patterns. The structures were further confirmed by validated structure-dependent retention time (RT) prediction models, taking advantage of the correlation between the RT, carbon chain length, and double bond number from commercial standards and pseudostandards identified in the whole-brain samples from mice. An in-house database containing 50 saturated and monounsaturated 2-OH FAs was established, which is expandible when additional molecular species with different chain lengths and backbone structures are identified in the future. A quantitation method was then developed by scheduled multiple reaction monitoring (MRM) and applied to investigate the profiling of 2-OH FAs in echinoderms. Our results revealed that the levels of total 2-OH FAs in sea cucumber (8.40 ± 0.28 mg/g dry weight) and starfish (7.51 ± 0.18 mg/g dry weight) are much higher than that in sea urchin (531 ± 108 μg/g dry weight). Moreover, 2-OH C24:1 is the predominant molecular species accounting for 67.9% of the total 2-OH FA in sea cucumber, while 2-OH C16:0 is the major molecular species in starfish. In conclusion, the current innovative GC-MS approach has successfully characterized distinct molecular species of 2-OH FAs that are highly present in sea cucumbers and starfish. Thus, these findings suggest the possibility of developing future feeding strategies for preventing and treating diseases associated with 2-OH FA deficiency.
2-羟基脂肪酸（2-OH FAs）水平异常在多种疾病中均有表现，对其在食品中的定量分析对于确定潜在治疗补充剂的来源至关重要。然而，由于结构复杂且可用标准有限，2-OH FAs的全面剖析仍是一项持续的挑战。在此，开发了一种基于气相色谱-串联质谱（GC-MS/MS）的创新方法来确定这些脂肪酸代谢物的完整谱图。通过2-羟基脂肪酸甲酯（FAMEs）的三甲基硅烷基（TMS）衍生物的质谱和串联质谱谱图，根据其特征性碎片模式进行峰注释。利用从小鼠全脑样品中鉴定出的商业标准品和伪标准品的保留时间（RT）、碳链长度和双键数之间的相关性，通过经过验证的结构依赖性保留时间预测模型进一步确认结构。建立了一个包含50种饱和和单不饱和2-OH FAs的内部数据库，未来当鉴定出具有不同链长和骨架结构的其他分子种类时，该数据库可进行扩展。然后通过定时多反应监测（MRM）开发了一种定量方法，并应用于研究棘皮动物中2-OH FAs的谱图。我们的结果表明，海参（8.40±0.28 mg/g干重）和海星（7.51±0.18 mg/g干重）中总2-OH FAs的水平远高于海胆（531±108 μg/g干重）。此外，2-OH C24:1是海参中占总2-OH FA 67.9%的主要分子种类，而2-OH C16:0是海星中的主要分子种类。总之，当前的创新GC-MS方法成功地鉴定了海参和海星中高度存在的2-OH FAs的不同分子种类。因此，这些发现提示了制定未来喂养策略以预防和治疗与2-OH FA缺乏相关疾病的可能性。
