DFT and Raman study of all-trans astaxanthin optical isomers
DFT and Raman study of all-trans astaxanthin optical isomers
复制标题
DOI：
10.1101/2021.03.11.434912
复制
发表时间：
2021-03
期刊：
影响因子：
--
通讯作者：
Guohua Yao;Shuju Guo;WEN-JIE Yu;M. Muhammad;Jianguo Liu;Qing Huang
中科院分区：
文献类型：
--
作者：
Guohua Yao;Shuju Guo;WEN-JIE Yu;M. Muhammad;Jianguo Liu;Qing Huang
虾青素（AST）是一种广泛存在于水生动物体内的叶黄素类胡萝卜素，具有抗氧化、抗炎、降血压、抗糖尿病等多种生理功能。虾青素具有三种光学异构体，包括一对对映体（3S，3 'S和3R，3 'R）和内消旋形式（3R，3 'S）。不同的光学异构体在多种生理功能上存在差异。传统上，高效液相色谱法（HPLC）可用于区分这些异构体。本工作中，我们发现拉曼光谱可以用来区分这三种光学异构体。由于三种异构体在1190 cm-1和1215 cm-1处的两个拉曼谱带的强度不同。DFT计算被执行并用于分析频谱差异。计算结果表明，这些手性异构体的结构并不严格镜像对称，从而导致它们的拉曼光谱的差异。利用拉曼光谱可以区分全反式虾青素的三种光学异构体。DFT计算的光谱被用来解释为什么光学异构体在1190和1215 cm-1的拉曼带是不同的。确定了三种光学异构体的结构参数。
Astaxanthin (AST) is a xanthophyll carotenoid widely distributed in aquatic animals, which has many physiological functions such as antioxidant, anti-inflammatory, anti-hypertensive and anti-diabetic activities. Astaxanthin has three optical isomers, including a pair of enantiomers (3S,3 ‘S and 3R,3 ‘R) and a meso form (3R,3 ‘S). Different optical isomers have differences in a variety of physiological functions. Traditionally, High Performance Liquid Chromatography (HPLC) can be used to distinguish these isomers. In this work, it’s found that Raman spectroscopy can be employed to distinguish the three optical isomers. Because the intensities of two Raman bands at 1190 cm-1 and 1215 cm-1 of three isomers are different. DFT calculations are performed and used to analyze the spectral differences. The calculation results show that the structures of these chiral isomers are not strictly mirror-symmetrical to each other, which leads to the difference in their Raman spectra. Highlights Raman spectroscopy can be utilized to distinguish three optical isomers of all-trans astaxanthin. The DFT-calculated spectrum is used to explain why the Raman bands of optical isomers at 1190 and 1215 cm-1 are different. The structural parameters of the three optical isomers have been identified.