Shi Shuyun, Zhao Yu, Zhou Honghao, Zhang Yuping, Jiang Xinyu, Huang Kelong
School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
J Chromatogr A. 2008 Oct 31;1209(1-2):145-52. doi: 10.1016/j.chroma.2008.09.004. Epub 2008 Sep 5.
Taraxacum mongolicum was a traditional Chinese medicine for the treatment of inflammatory disorders and viral infectious diseases. Furthermore, fresh leaves of T. mongolicum have been used by local people as vegetable food in Northern China. An on-line rapid screening method, high-performance liquid chromatography-diode array detection-radical-scavenging detection-electrospray ionization mass spectrometry (HPLC-DAD-RSD-ESI-MS) system, has been developed for the separation and identification of radical scavengers from the methanolic extract of T. mongolicum. In addition, the detected antioxidants were isolated directly by preparative HPLC (PHPLC) and Sephadex LH-20, then the purified compounds were sampled to off-line nuclear magnetic resonance (NMR) spectrometer to acquire NMR spectra. The structure of the active compounds was elucidated by ultraviolet (UV), ESI-MS and NMR spectral data. Thirty-two radical-scavenging compounds including sixteen flavonoid derivatives, ten phenylpropanoid derivatives and six benzoic acid derivatives were screened, isolated and identified. Among them, seventeen compounds including three new compounds were first isolated from Taraxacum genus by our group. Caffeic acid (6), isoetin-7-O-beta-d-glucopyranosyl-2'-O-alpha-l-arabinopyranoside (9), isoetin-7-O-beta-d-glucopyranosyl-2'-O-alpha-d-glucopyranoside (10) and isoetin-7-O-beta-d-glucopyranosyl-2'-O-beta-d-xyloypyranoside (12) were found to be the major metabolites in T. mongolicum based on their relative peaks in the HPLC chromatogram. Antioxidant activity of three new compounds was assessed for their scavenging capacity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, and all of them showed potent activity.
蒲公英是一种用于治疗炎症性疾病和病毒感染性疾病的传统中药。此外，在中国北方，当地人将新鲜的蒲公英叶作为蔬菜食用。已开发出一种在线快速筛选方法，即高效液相色谱-二极管阵列检测-自由基清除检测-电喷雾电离质谱（HPLC-DAD-RSD-ESI-MS）系统，用于从蒲公英甲醇提取物中分离和鉴定自由基清除剂。此外，通过制备型高效液相色谱（PHPLC）和葡聚糖凝胶LH-20直接分离检测到的抗氧化剂，然后将纯化后的化合物进样到离线核磁共振（NMR）光谱仪中获取NMR光谱。通过紫外（UV）、ESI-MS和NMR光谱数据阐明了活性化合物的结构。筛选、分离并鉴定了32种自由基清除化合物，包括16种黄酮类衍生物、10种苯丙素类衍生物和6种苯甲酸类衍生物。其中，包括3种新化合物在内的17种化合物首次被本研究团队从蒲公英属植物中分离得到。基于它们在HPLC色谱图中的相对峰面积，发现咖啡酸（6）、异荭草素-7-O-β-D-吡喃葡萄糖基-2'-O-α-L-阿拉伯吡喃糖苷（9）、异荭草素-7-O-β-D-吡喃葡萄糖基-2'-O-α-D-吡喃葡萄糖苷（10）和异荭草素-7-O-β-D-吡喃葡萄糖基-2'-O-β-D-木糖吡喃糖苷（12）是蒲公英中的主要代谢产物。评估了3种新化合物对2,2-二苯基-1-苦基肼（DPPH）自由基的清除能力，结果表明它们均具有较强的活性。
