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首页> 外文期刊>Journal of Agricultural and Food Chemistry >Kinetics of light-induced cis-trans isomerization of four piperines and their levels in ground black peppers as determined by HPLC and LC/MS
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Kinetics of light-induced cis-trans isomerization of four piperines and their levels in ground black peppers as determined by HPLC and LC/MS

机译：HPLC和LC / MS测定的四种胡椒碱的光诱导顺式异构化动力学及其在黑胡椒中的含量

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摘要

The pungent compounds piperine and isomers thereof, secondary metabolites present in black and white pepper fruit, undergo light-induced isomerizations. To facilitate studies in this area, an HPLC method has been developed for analysis and isolation of the following four possible piperine-derived photoinduced isomers: piperine, isopiperine, chavicine, and isochavicine. The limits of detection (LOD) estimated from calibration plots were similar to 15-30 ng for each isomer. Reproducibilities of the analyses were excellent, and recoveries of spiked samples were as follows (average +/- SD; n = 3): chavicine, 98.4 +/- 2.1%; isopiperine, 96.2 +/- 3.2%; piperine, 104 +/- 3.8%; isochavicine, 98.9 +/- 3.0%. To determine the kinetics of these isomerizations, fluorescent light, sunlight, and UV radiation at 254 nm was used to induce cis-trans geometric isomerization as a function of light intensities and time of exposure determined with the aid of high-performance liquid chromatography (HPLC) and liquid chromatography with diode array UV detection-mass spectrometry (LC-DAD/MS). HPLC was also used to determine the distribution of the isomers in four commercial ground black pepper products used as spices in culinary practice. Isomerization increased with light intensities and time of exposure and leveled off at the so-called photostationary phases. The piperine levels of the four products were quite similar, ranging (in wt %) from 10.17 to 11.68. The amounts of the other three isomers ranged from 0.01 to 0.07 of the total for chavicine; from 0.15 to 0.23 for isopiperine; and from 0.37 to 0.42 for isochavicine. The results establish the utility of the HPLC method for simultaneous analysis of the four isomers both in pure form and in black pepper extracts. The dietary significance of the results is discussed.
机译：辛辣化合物胡椒碱及其异构体（存在于黑胡椒和白胡椒果实中的次生代谢产物）会经历光诱导的异构化。为了促进该领域的研究，已经开发了一种HPLC方法来分析和分离以下四种可能的胡椒碱衍生的光诱导异构体：胡椒碱，异胡椒碱，查维汀和异丁卡因。根据校准图估算的检测限（LOD）类似于每种异构体的15-30 ng。分析的重现性极好，加标样品的回收率如下（平均值+/- SD; n = 3）：查维因98.4 +/- 2.1％;异胡椒碱，96.2 +/- 3.2％;胡椒碱，​​104 +/- 3.8％;异丁卡因，98.9 +/- 3.0％。为了确定这些异构化的动力学，使用254 nm的荧光，日光和UV辐射根据光强度和曝光时间来诱导顺反几何异构化，借助高效液相色谱（HPLC）测定）液相色谱和二极管阵列紫外检测质谱（LC-DAD / MS）。 HPLC还用于确定在烹饪实践中用作香料的四种商品黑胡椒产品中异构体的分布。异构化随着光强度和曝光时间的增加而增加，并在所谓的光固定相处趋于平稳。四种产品的胡椒碱含量非常相似，以重量％计为10.17至11.68。其他三种异构体的含量在查维因总量的0.01到0.07之间。异胡椒碱从0.15到0.23;异丁卡因从0.37至0.42。结果建立了HPLC方法的实用性，可同时分析纯形式和黑胡椒提取物中的四种异构体。讨论了结果的饮食意义。

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