Pellati Federica, Benvenuti Stefania, Magro Lara, Melegari Michele, Soragni Fabrizia
Department of Pharmaceutical Sciences, University of Modena and Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy.
J Pharm Biomed Anal. 2004 Apr 16;35(2):289-301. doi: 10.1016/S0731-7085(03)00645-9.
The aim of this study was to set up and validate an RP-LC method with DAD-detection to quantify caffeic acid derivatives in various Echinacea spp. Samples were extracted with 80% methanol. The analyses were carried out on a Lichrospher RP-18 column (125 mm x 4 mm i.d., 5 microm), with a mobile phase gradient, which increases the acetonitrile level in a phosphoric acid solution (0.1%). The flow rate was 1.5 ml/min. Detection was set at 330 nm. This method allowed the identification and quantification of caftaric acid, chlorogenic acid, caffeic acid, cynarin, echinacoside and cichoric acid in Echinacea roots and derivatives. The total phenolic content was 10.49 mg/g for E. angustifolia, 17.83 mg/g for E. pallida and 23.23 mg/g for E. purpurea. Among Echinacea commercial herbal medicines, a certain variability in the concentrations of phenolic compounds was observed. The radical scavenging activity of Echinacea methanolic extracts was evaluated in vitro with a spectrophotometric method based on the reduction of an alcoholic 2,2-diphenyl-1-picrylhydrazyl (DPPH*) radical solution at 517 nm in the presence of a hydrogen donating antioxidant. As for pure compounds, echinacoside had the highest capacity to quench DPPH* radicals (EC50 = 6.6 microM), while caftaric acid had the lowest (EC50 = 20.5 microM). The average EC50 values for E. purpurea, E. pallida and E. angustifolia were 134, 167 and 231 microg/ml, respectively. The radical scavenging activity of Echinacea root extracts reflected their phenolic composition. The results indicate that Echinacea roots and derivatives are a good source of natural antioxidants and could be used to prevent free-radical-induced deleterious effects.
本研究的目的是建立并验证一种采用二极管阵列检测的反相液相色谱法，用于定量测定不同紫锥菊属植物中的咖啡酸衍生物。样品用80%甲醇提取。分析在Lichrospher RP - 18柱（125 mm×4 mm内径，5微米）上进行，采用流动相梯度，即在磷酸溶液（0.1%）中增加乙腈含量。流速为1.5 ml/min。检测波长设定为330 nm。该方法可对紫锥菊属植物根及衍生物中的咖啡酰苹果酸、绿原酸、咖啡酸、洋蓟素、紫锥菊苷和菊苣酸进行鉴定和定量。狭叶紫锥菊的总酚含量为10.49 mg/g，淡紫松果菊为17.83 mg/g，紫松果菊为23.23 mg/g。在紫锥菊商业草药中，观察到酚类化合物浓度存在一定差异。采用分光光度法，基于在供氢抗氧化剂存在下，在517 nm处还原乙醇中的2,2 - 二苯基 - 1 - 苦基肼自由基（DPPH*）溶液，对紫锥菊甲醇提取物的自由基清除活性进行体外评估。对于纯化合物，紫锥菊苷淬灭DPPH*自由基的能力最强（EC50 = 6.6 microM），而咖啡酰苹果酸最低（EC50 = 20.5 microM）。紫松果菊、淡紫松果菊和狭叶紫锥菊的平均EC50值分别为134、167和231 microg/ml。紫锥菊根提取物的自由基清除活性反映了其酚类成分。结果表明，紫锥菊根及衍生物是天然抗氧化剂的良好来源，可用于预防自由基引起的有害影响。
