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采用UHPLC-QTOF-MS技术筛选亚麻籽油脂质分子标志物

Screening lipidmolecular markers of flaxseed oils by UHPLC-QTOF-MS technology

  • 摘要: 为了探究亚麻籽油中脂质的真实属性和发掘其有价值的脂质分子,该研究基于超高效液相色谱-四级杆飞行时间质谱联用技术(Ultra High Performance Liquid Chromatography-Quadrupole Time-of-Flight Spectroscopy, UHPLC-QTOF-MS)表征了亚麻籽油的脂质轮廓。结果表明:在正离子模式下检测到15个脂质分子小类共668种脂质分子;在负离子模式下检测到31个脂质分子小类共404种脂质分子;共有7个脂质分子小类脂质在正、负离子下均被检测到;此外,该研究首次在亚麻籽油中发现甜菜碱脂、甘油糖脂、神经节苷脂、鞘磷脂、神经酰胺、羟基脂肪酸的脂肪酸酯、酰基肉碱和植物固醇,这些脂质都具有特殊的生物学功能。多元变量统计分析结果表明每两个品种亚麻籽油间相对定量值差异显著的脂质分子均超过200种(P<0.05),并筛选出6种甘油磷酸肌醇、1种甘油磷酸胆碱、1种甘油磷酸乙醇胺和1种三酰基甘油作为亚麻籽A油的标志性脂质分子;6种三酰基甘油和1种半单酰基甘油磷酸酯作为亚麻籽B油的标志性脂质分子;1种神经节苷脂和1种硫代异鼠李糖甘油二酯作为亚麻籽C油的标志性脂质分子。总之,该研究在亚麻籽油中鉴定出39个脂质分子小类共1 072种脂质分子,其中有22个脂质分子小类共415种脂质分子首次在亚麻籽油中被检测到,此外不同品种亚麻籽油在脂质分子层面存在显著差异(P<0.05),这些脂质分子作为标志物,可用于植物油的品质判别、营养评价,真伪鉴别和安全性评价等,也为其他植物油的分析提供方法参考。

     

    Abstract: Abstract: Flaxseed Oil (FO) is one of the commonly-used edible vegetable oil in food production. But the complete lipid molecular composition and content are still unclear. This study aims to explore the true properties of the lipid composition in FO and discover the valuable lipid components. An ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) was used to characterize the lipid profile of FO. The results showed that there were the same lipid molecules in the three varieties of flaxseed (A, B, and C) oil. A total of 1 072 lipid molecules in 39 lipid molecule subclasses were identified in FO. In positive ion mode, a total of 668 lipid molecules in 15 lipid molecule subclasses were detected. In the negative ion mode, a total of 404 lipid molecules in 31 lipid molecules were detected. In both positive and negative ions mode, a total of 7 lipid molecules subclasses were detected. Among the 39 lipid molecule subclasses were detected under positive and negative ions, 30 lipid molecule subclasses are searchable in the LMSD database, while 9 lipid molecule subclasses are currently in the subclasses of the LMSD database could not be retrieved. Furthermore, 86 Diacylgycerol-N-trimethylhomoserine (DGTS) molecule species and 129 glyceroglycolipid molecule species glycosyldiacylglycerols (GlcADG), acylglycosyldiacylglycerols (AcylGlcADG), sulfoquinovosyldiacylglycerols (SQDG) and monogalactosyldiacylglycerols (MGDG), 151 ceramide lipid molecule species, 3 Gangliosides (GM3) molecule species and 3 Sphingomyelin (SM) molecule species, 32 FAHFA molecule species, 9 Fatty esters Acyl carnitine (ACar) molecule species and 1 Cholesterol molecule CE (18:2) were firstly found in FO. Among these subclass lipids, the triacylglycerols (TG) presented the largest number (471 molecule species) and the highest relative content (67.93%-68.91%), followed by diacylglycerols (DG), DGTS, and GlcADG. In addition, the content of 39 lipid molecule subclasses was compared in the three kinds of FO. It was found that there were significant differences between the GM3 and fatty acyl esters of hydroxy fatty acid (FAHFA) in the three kinds of FO (P<0.05), whereas, there was no significant difference among the other 37 lipids molecule subclasses (P>0.05). More importantly, a multivariate statistical model was also established to screen the different lipid molecules among different kinds of FO, in order to fully and accurately reflect the differences between the three kinds of FO. Specifically, the three varieties of FO were well distinguished in the unsupervised Principal Component Analysis (PCA). The difference among the three varieties of FO was greater than that within each group, which was explained by the supervised Orthogonal Partial Least Squares Discrimination Analysis (OPLS-DA). Furthermore, there were more than 200 lipid molecule species significantly different between the two varieties of flaxseed oil (P<0.05), where the marker lipid molecules of flaxseed A oil were further screened out as 6 PI molecules, 1 PC molecule,1 PE molecule, and 1 TG molecule. The marker lipid molecules of flaxseed B oil were 6 TG molecules and 1 HBMP molecule. The marker lipid molecules of flaxseed C oil were 1 GM3 molecule and 1 SQDG molecule. Correspondingly, these lipid molecules were used as the markers of the three types of FO, suitable for the quality and authenticity identification, as well as the nutritional and safety evaluation of vegetable oil. In summary, 39 subclasses totaling 1 072 lipid molecule species were identified in FO. There were also significant differences in the lipid molecular level of different FOs. A total of 415 lipid molecule species in the 22 subclasses were found, which has not been reported yet in FO. This discovery can make a sound theoretical foundation to develop the nutritional value of FO, particularly for the comprehensive and systematic investigation of the lipid profile in other lipid foods.

     

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