Abate-Pella Daniel, Freund Dana M, Slovin Janet P, Hegeman Adrian D, Cohen Jerry D
Department of Horticultural Science, University of Minnesota, Saint Paul, MN, USA; Microbial and Plant Genomics Institute, University of Minnesota, Saint Paul, MN, USA.
Department of Horticultural Science, University of Minnesota, Saint Paul, MN, USA; Microbial and Plant Genomics Institute, University of Minnesota, Saint Paul, MN, USA.
J Chromatogr B Analyt Technol Biomed Life Sci. 2017 Nov 1;1067:34-37. doi: 10.1016/j.jchromb.2017.09.039. Epub 2017 Sep 28.
Carotenoids are a large class of compounds that are biosynthesized by condensation of isoprene units in plants, fungi, bacteria, and some animals. They are characteristically highly conjugated through double bonds, which lead to many isomers as well susceptibility to oxidation and other chemical modifications. Carotenoids are important because of their potent antioxidant activity and are the pigments responsible for color in a wide variety of foods. Human consumption is correlated to many health benefits including prevention of cancer, cardiovascular disease, and age-related disease. Extreme hydrophobicity, poor stability, and low concentration in biological samples make these compounds difficult to analyze and difficult to develop analytical methods for aimed towards identification and quantification. Examples in the literature frequently report the use of exotic stationary phases, solvents, and additives, such as ethyl acetate, dichloromethane, and methyl tert-butyl ether that are incompatible with liquid chromatography mass spectrometry (LC-MS). In order to address these issues, we implemented the use of LC-MS friendly conditions using a low-hydrophobicity cyano-propyl column (Agilent Zorbax SB-CN). We successfully differentiated between isomeric carotenoids by optimizing two gradient methods and using a mixture of 11 standards and LC-MS in positive ionization mode. Three complex biological samples from strawberry leaf, chicken feed supplement, and the photosynthetic bacterium Chloroflexus aurantiacus were analyzed and several carotenoids were resolved in these diverse backgrounds. Our results show this methodology is a significant improvement over other alternatives for analyzing carotenoids because of its ease of use, rapid analysis time, high selectivity, and, most importantly, its compatibility with typical LC-MS conditions.
类胡萝卜素是一大类化合物，由植物、真菌、细菌和一些动物中的异戊二烯单元缩合生物合成。它们的特征是通过双键高度共轭，这导致许多异构体，同时也容易受到氧化和其他化学修饰的影响。类胡萝卜素因其强大的抗氧化活性而重要，并且是多种食物中负责颜色的色素。人类食用与许多健康益处相关，包括预防癌症、心血管疾病和与年龄相关的疾病。极高的疏水性、较差的稳定性以及生物样品中的低浓度，使得这些化合物难以分析，也难以开发用于鉴定和定量的分析方法。文献中的例子经常报道使用与液相色谱质谱联用（LC-MS）不兼容的特殊固定相、溶剂和添加剂，如乙酸乙酯、二氯甲烷和甲基叔丁基醚。为了解决这些问题，我们采用了使用低疏水性氰基丙基柱（安捷伦Zorbax SB-CN）的LC-MS友好条件。我们通过优化两种梯度方法，并使用11种标准品的混合物以及正离子模式下的LC-MS，成功区分了类胡萝卜素异构体。对来自草莓叶、鸡饲料添加剂和光合细菌嗜热栖热菌的三种复杂生物样品进行了分析，在这些不同背景下分离出了几种类胡萝卜素。我们的结果表明，这种方法相对于其他分析类胡萝卜素的方法有显著改进，因为它使用方便、分析时间短、选择性高，最重要的是，它与典型的LC-MS条件兼容。
