Zhang Yan-Xia, Zhao Xiao-Bo, Ha Wei, Zhang Yi-Da, Shi Yan-Ping
Chinese Academy of Sciences Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Chinese Academy of Sciences Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
J Chromatogr A. 2021 Aug 16;1651:462302. doi: 10.1016/j.chroma.2021.462302. Epub 2021 May 30.
Phospholipids are one of the main nutrients in rice, which have a positive effect on cancer, coronary heart disease and inflammation. However, phospholipids will become small molecular volatile substances during the aging process of rice, resulting in change the flavor of rice. Therefore, mapping the concentration and the spatial distribution of phospholipids in rice are of tremendous significance in its function research. In this work, we established a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) imaging method for the spatial distribution analysis of phospholipids in rice. A total of 12 phospholipid compounds were found in the range of m/z 500-1000 through a series of conditions optimization. According to the results, lysophosphatidylcholine (LPC) species spread throughout the rice tissue sections and phosphatidylcholine (PC) species distributed in the bran and embryo (particularly in the scutellum). We also compared the signal intensities of phospholipids in different parts of white rice and brown rice by region of interest (ROI) analysis, which showed the relative content of PC species was higher in the embryo and gradually decreased until disappeared with the increase of processing degree during the processing of brown rice to white rice. The PC species on the surface of rice could be used as an important indicator to identify the processing degree of rice. Our work not only establish a MALDI-TOF-MS imaging method for spatial distribution analysis of rice, but also provide the necessary reference for ensuring food security, improving the eating quality of rice and the health benefits of consumers.
磷脂是大米中的主要营养成分之一，对癌症、冠心病和炎症具有积极作用。然而，在大米的陈化过程中，磷脂会变成小分子挥发性物质，从而改变大米的风味。因此，绘制大米中磷脂的浓度和空间分布对于其功能研究具有重要意义。在这项工作中，我们建立了一种基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF-MS）成像方法，用于分析大米中磷脂的空间分布。通过一系列条件优化，在m/z 500-1000范围内共发现了12种磷脂化合物。结果显示，溶血磷脂酰胆碱（LPC）类物质分布于整个大米组织切片中，而磷脂酰胆碱（PC）类物质分布在麸皮和胚中（特别是在盾片中）。我们还通过感兴趣区域（ROI）分析比较了白米和糙米不同部位磷脂的信号强度，结果表明，在糙米加工成白米的过程中，PC类物质在胚中的相对含量较高，并随着加工程度的增加而逐渐降低直至消失。大米表面的PC类物质可作为鉴定大米加工程度的重要指标。我们的工作不仅建立了一种用于大米空间分布分析的MALDI-TOF-MS成像方法，还为保障食品安全、改善大米食用品质以及对消费者的健康益处提供了必要的参考。
