液固色谱法分离番茄红素异构体

Isolation of Geometrical Isomers of Lycopene Using Liquid-Solid Chromatography

采用Nucleosil300 5正相色谱柱,将3根色谱柱串联后对番茄红素异构体进行了色谱分离。全反式番茄红素通过与标准样保留时间的比较进行定性判断,顺式异构体的定性判断以特征紫外吸收和DB/DⅡ值(在362nm处的吸收强度与最大吸收峰吸收强度的比值)作为依据。番茄红素的顺反异构体均以全反式番茄红素的标准样作为外标进行定量计算。对5个样品的分析结果显示,新鲜番茄中反式番茄红素的比例最高,为96 38%;番茄酱中反式结构的番茄红素占10 83%。3种番茄红素产品中顺反异构体的比例各不相同,以1%番茄红素油树脂中反式结构含量最低,只有37 65%,其顺式异构体的种类也最多。该实验结果为进一步研究番茄红素异构体的物化性质和生理活性打下了基础。

A normal phase high performance liquid chromatographic method, using three columns in series, was used to separate the geometrical isomers of lycopene. The results showed a better performance for isomer separation than reversedphase high performance liquid chromatography (RPHPLC). Five samples were measured, including tomato, tomato paste, tomato oleoresin and other two products of lycopene. The identities of alltrans lycopene peaks were assigned based on retention time and absorbance spectra obtained by the photodiode array detector by comparing with standard. The isomers were identified by their absorbance spectra and DB/DⅡ ratios, the value of the absorbance at the cispeak(362 nm) divided by the absorbance at the maximum wavelength. Alltrans lycopene was quantified by determining peak areas in the HPLC chromatograms calibrated against known amounts of alltrans standard. The contents of cisisomers were calculated using alltrans standard for the cisisomer standards are unavailable. Alltrans lycopene was the predominant geometrical isomer in all the samples, whose contents varied from 9638% of fresh tomato to 3765% of 01% tomato oleoresin. The results indicate that during the processing of tomatos and extraction of lycopene, alltrans lycopene underwent isomerization, which increased the portions of cisisomers.