龙眼核多酚提取工艺的正交试验优化及其分离纯化与结构表征

采用正交试验设计优化龙眼核多酚的提取条件。在单因素试验的基础上，以乙醇体积分数、料液比、提取时间、提取温度为自变量，以龙眼核多酚提取量为考察指标，经过四因素三水平正交试验得出龙眼核多酚提取的最佳工艺条件：乙醇体积分数40%、料液比1∶20（g/mL）、提取温度70 ℃、提取时间90 min。在该条件下龙眼核多酚提取量为36.15 mg/g。通过对4 种树脂静态吸附及解吸性能的比较，确定D3520型树脂为龙眼核多酚分离纯化的理想树脂，洗脱剂乙醇体积分数为40%时，树脂对多酚的解吸率最高。采用傅里叶变换离子回旋共振质谱（Fouriertransform ion cyclotron resonance mass spectrometry，FT-ICR-MS）对龙眼核多酚结构进行初步分析，结果表明，龙眼核多酚主要成分为以鞣花酸及其衍生物为主的小分子质量水解单宁。通过核磁共振、紫外光谱和红外光谱对FT-ICR-MS中2 种丰度很高的物质进行分析，确定其分别为鞣花酸和(S)-flavogallonic acid，后者为鞣花酸的衍生物。

Separation and Purification of Phenols from Longan (Dimocarpus longan Lour.) Seeds and Their Structural Analysis

Orthogonal array design was used to optimize the extraction conditions for phenols from longan (Dimocarpus
longan Lour.) seeds by evaluating the effect of four crucial variables including alcohol concentration, solid-to-solvent ratio,
extraction temperature and extraction time on the yield of phenols. The optimum conditions were determined as follows:
ethanol concentration 40%, solid-to-solvent ratio 1:20 (g/mL), extraction temperature 70 ℃, and extraction time 90 min.
Under these conditions, the maximum yield of phenols of 36.15 mg/g was obtained. D3520 resin was selected to purify
longan seed phenols by comparing static absorption and dynamic desorption capacity of four macroporous resins, and
40% ethanol was chosen as the best elution solvent. The structural properties of longan seed phenols were preliminarily
analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), and the results showed that longan
seed phenols were mainly composed of hydrolyzable tannins with small molecular weights, such as ellagic acid and its
derivatives. Ellagic acid and (S)-flavogallonic acid were confirmed as two abundant compounds from longan seeds by NMR,
UV spectroscopy and IR spectroscopy. (S)-Flavogallonic was identified as a derivative of ellagic acid.