反式白藜芦醇热稳定性与光致异构化的高效液相色谱和液相色谱-电喷雾离子化质谱研究

Study on Thermostability and Photo-Isomerization of trans- Resveratrol by High Performance Liquid Chromatography and Liquid Chromatography-Electrospray Ionization-Mass Spectrometry

应用高效液相色谱(HPLC)及液相色谱 电喷雾离子化质谱(LC ESI MS)方法对反式白藜芦醇的长期热稳定性及光致顺反异构化反应进行了研究。色谱条件为:采用Hypersil ODS色谱柱分离,流动相为甲醇 0 05%三氟乙酸水溶液(体积比为60∶40)(用于HPLC分析)及甲醇 5mmol/L甲酸铵水溶液(含0 1%甲酸)(体积比为60∶40)(用于LC ESI MS分析),检测波长300nm,进样量20μL(HPLC)或10μL(LC ESI MS);质谱检测中设定为负离子模式。在4～40℃条件下的热稳定性研究表明,反式白藜芦醇溶液在冷藏条件下避光保存600h后,浓度没有明显下降。通过测定254及365nm紫外光照条件下不同光照时间各个化合物浓度的变化,研究了反式白藜芦醇的异构化和其余几个副反应的机理。根据实验结果推测,白藜芦醇的顺反异构化是通过一个p 几何状态完成的,而另外几个副反应则是通过自由基历程完成的。

The thermostability and photo-isomerization reaction mechanism of trans-resveratrol were studied by using high performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). A reversed-phase (Hypersil-)ODS column was used with the mobile phase consisting of 60/40 methanol-water, with addition of 0.05% trifluoroacetic acid for HPLC, and 0.1% formic acid and 5 (mmol/L) ammonium formate for LC-ESI-MS, at a flow rate of 0.5 (mL/min). Diode array detection was set at 300 nm and the injection volume was 20 or 10 μL. Mass spectrometric conditions were in the negative mode. The results of thermostability test under 4, 20 and 40 ℃ indicated that the concentration of trans-resveratrol, after storage for 600 h, was decreased slightly under 4 ℃, (decreased) by 5% under 20 ℃, and 10% under 40 ℃. In addition, the photo-isomerization (reaction) of trans- and cis-resveratrol under 254 nm and 365 nm UV irradiation was investigated by LC-ESI-MS, showing that the isomerization is based on p-status, and that some secondary (reactions) are radical induced.