丹酚酸B的水解动力学及降解机理01.docVIP

丹酚酸B的水解动力学及降解机理 摘要：目的 研究丹酚酸B的水解动力学特征和降解机理。方法 运用HPLC量分析丹酚酸B，运用LC-MS及NMR检测丹酚酸的水解产物，推测其降解途径。结果 丹酚酸B降解符合一级动力学特征，降解速率随缓冲盐浓度的增加pH-速率图是 “S”型曲线，在pH2.0时最为稳定 1H(13C)-NMR鉴定结果表明，丹参素、原儿茶醛、咖啡酸、丹酚酸E、紫草酸和紫草酸异构体Ⅰ等是丹酚酸B的降解产物初步推断了丹酚酸B的降解机理。 关键词：丹酚酸B；水解；动力学；降解机理； LC/MS (Hydrolysis Kinetics and Degradation Mechanismof Lithospermic Acid B Guo Yongxue，Zhang Hua，Dong Yuesheng，Xiu Zhilong* Department of Bioscience and Biotechnology,School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024,China ABSTRACT: OBJECTIVE To investigate the kinetics and mechanism of degradation of lithospermic acid B (LAB) in aqueous solution. METHODS High performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR) were employed. RESULTS The degradation follows pseudo-first-order kinetics under all experimental conditions. The results indicated that the degradation rate increased with the increase of buffer concentration and temperature. The pH-rate profile shows a characteristic S-shape, and the maximum stability was obtained at pH 2.0. Six degradation products including danshensu, protocatechuic aldehyde, caffeic acid, savianolic acid E, lithospermic acid and its isomer I were separated and identified by 1H(13C) NMR analysis. CONCLUSION The characters of kinetics and mechanism of degradation of LAB in aqueous solution were studied. The primary degradation pathway of LAB is proposed. KEY WORDS：Lithospermic acid B; Hydrolysis; Kinetics; Reaction mechanism; LC/MS 丹参是唇形科植物丹参(Salvia miltiorrhiza Bge.)的干燥根及根茎，是味传统中药，具有“袪瘀止痛，活血通经、清心除烦”等功效。丹酚酸B是丹参的主要水溶性成分，含量丰富（占干重的2-8%，约占丹参中总酚酸质量的54%），在抗氧化、清除自由基、保护心脑血管缺血再灌注损伤方面有较强的生物活性。从分子结构上看丹酚酸B是由两分子丹参素和一个分子咖啡酸二聚体以酯键缩合而成的低聚物，在水溶液中不稳定。王凤美等在研究样品处理方法对丹酚酸B的影响时发现用微沸的水提取丹酚酸B时，其含量先增大后降低。倪力军等在研究加热方式对缩合酚酸影响时，发现丹酚酸B对温度很敏感，加热方式不同，提取液中丹酚酸B的含量相差1倍以上。研究发现丹酚酸B不仅对温度敏感，还对pH敏感，丹酚酸B在pH2时比较稳定，在pH12时短时间内就迅速消失。曲桂武等研究了不同添加剂对水溶液中丹参酚酸B的影响，结果表明，酸性添加剂对溶液中丹酚酸B的保护作用明显好于碱性或中性添加剂,其中以抗坏血酸的保护效果最