不同茶类中黄酮醇苷酸水解条件的优化及酸水解前后3种黄酮醇含量的测定

Optimization of the acid hydrolysis conditions of flavonoid glycosides in different teas and determination for the content of 3 kinds of flavonols before and after acid hydrolysis

中文关键词:  茶叶  黄酮醇  黄酮醇苷  酸水解  高效液相色谱法

英文关键词:tea  flavonols  flavonoid glycosides  acid hydrolysis  high performance liquid chromatography

中文摘要:

      目的 建立高效液相色谱法(high performance liquid chromatography, HPLC)同时测定不同茶类中黄酮醇的含量, 并优化茶叶中黄酮醇苷酸水解成黄酮醇(杨梅素、槲皮素、山柰酚)的条件。方法 样品经70%甲醇水(V:V)提取后, 用盐酸(16%)-甲醇溶液进行酸水解, 再经乙酸乙酯萃取、浓缩、复溶至相同体积; 酸水解前后的样品溶液均用HPLC对黄酮醇进行定量分析并用超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)对黄酮醇苷进行定性分析。结果 3种黄酮醇在3.125~100.000 μg/mL的浓度范围内具有良好的线性关系(r2≥0.9976), 优化后的方法的重复性、稳定性、精密度较好(相对标准偏差不大于0.04%)。六大茶类中黄酮醇苷的最佳酸水解条件为: 水解时间为1 h、水解温度为80 ℃、盐酸(16%)-甲醇溶液最佳比例为1:2 (V:V)。结论 本研究优化了茶叶中黄酮醇苷酸水解的条件, 并建立HPLC测定了六大茶类酸水解前后黄酮醇的含量。该方法处理简单、结果准确可靠, 适用于茶叶中黄酮醇及其苷类物质的分析。

英文摘要:

      Objective To establish a method for the simultaneous determination of flavonols in different teas by high performance liquid chromatography (HPLC), and optimize the conditions for the hydrolysis of flavonoid glycosides into flavonols (myricetin, quercetin and kaempferol). Methods The sample was extracted with 70% methanol water (V:V), acid hydrolyzed with hydrochloric acid (16%)-methanol solution, and then extracted, concentrated and redissolved with ethyl acetate to the same volume; the sample solutions before and after acid hydrolysis were quantitatively analyzed by HPLC, and the flavonoid glycosides were qualitatively analyzed by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Results Three kinds of flavonols had good linear relationships (r2≥0.9976) within the concentration range of 3.125?100.000 μg/mL, and the repeatability, stability and precision of the optimized method were good (the relative standard deviations were no more than 0.04%). The optimum acid hydrolysis conditions of flavonoid glycosides in 6 kinds of teas were as follows: Hydrolysis time was 1 h, hydrolysis temperature was 80 ℃, hydrochloric acid (16%)-methanol solution was 1:2 (V:V). Conclusion In this study, the conditions of acid hydrolysis of flavonoid glycosides in tea were optimized, and HPLC was established to determine the content of flavonol before and after acid hydrolysis of 6 kinds of tea. The method is simple, accurate and reliable, and is suitable for the analysis of flavonol and its glycosides in tea.