高效液相色谱法研究白藜芦醇光致异构化动力学与平衡常数

反式白藜芦醇有多种生理活性，自然资源丰富，但存在光不稳定现象。以光致异构平衡对照品溶液，采用高效液相色谱建立了同时测定顺、反异构体浓度的方法。方法学考察显示符合含量测定要求，反式异构体在1.5~60 μ mol/L、顺式异构体在1.5~55 μ mol/L范围内线性关系良好，R²均达0.999。将该方法应用于研究光致异构化动力学及平衡常数，结果显示反式白藜芦醇在室温避光条件下中性、偏酸性及乙醇介质中稳定；25 ℃时在50%（v/v）乙醇介质中的光异构平衡常数为11.7±0.3。以光致异构平衡液制作标准曲线的策略简单方便，具有可操作性；反式白藜芦醇的稳定性与介质有关，在pH < 7的溶液中光致异构化为一级反应。

Determination of the kinetics of photo-isomerization and equilibrium constant of resveratrol by high performance liquid chromatography

Trans-resveratrol (C₁₄H₁₂O₃, 5-(4-hydroxystyryl)benzene-1, 3-diol), with a variety of physiological activities and abundant sources, shows instability to light irradiation. The control solution was balanced by photo-isomerization and high performance liquid chromatography (HPLC) method was developed for the simultaneous determination of trans-resveratrol and cis-resveratrol. The methodology study showed good linear correlations (R²=0.999) in the range of 1.5-60 μ mol/L of trans-resveratrol and 1.5-55 μ mol/L of cis-resveratrol which conforms to the request of content determination. The method was used to study the kinetics and equilibrium constant of photo-isomerization. The results showed that trans-resveratrol protected from light was stable in neutral, weak acid and ethanol media at room temperature. The photo-isomerization equilibrium constant was 11.7±0.3 at 25 ℃ in dilute ethanol solution. The method of making the standard curve by photo-isomerization equilibrium solution is simple, convenient and practicable. The stability of trans-resveratrol is related to the medium. When pH value is less than 7, the photo-isomerization is a first order reaction.