Departamento de Química, CP19081, Universidade Federal do Paraná, CEP 81531-990, Curitiba-PR, Brazil.
Phytochem Anal. 2012 Mar-Apr;23(2):143-51. doi: 10.1002/pca.1335. Epub 2011 Aug 2.
Uncaria tomentosa ("cat's claw") is widely used for the treatment of some infectious and inflammatory diseases. Oxindole alkaloids are regarded as the most important components responsible for the biological activities attributed to the plant. Their analysis require efficient sample preparation and suitable reference standards but few are commercially available.
To develop and validate a HPLC analytical method for oxindole alkaloids in Uncaria tomentosa with emphasis on sample preparation.
Factorial experimental designs were used for the optimisation of both sample preparation and chromatographic separation. The optimised sample preparation involved extraction with aqueous ethanol, and the granulometry of the powdered plant material significantly influenced extraction yields. Mitraphylline was used as a calibration reference for the determination of total alkaloids.
The method was fully validated and showed good selectivity, linearity (r² ≥ 0.9996), accuracy (≥ 96%) and precision (RSD < 2.4%). Detection and quantification limits for mitraphylline were 0.8 and 2.4 ppm, respectively.
The optimised chromatographic method, using organic buffer in the mobile phase, provided baseline separation of tetracyclic and pentacyclic alkaloids in the samples. Calibration using mitraphylline provided more accurate estimates of total alkaloid content when compared to other available reference alkaloids.
钩藤（“猫爪”）被广泛用于治疗一些传染病和炎症性疾病。吲哚生物碱被认为是赋予该植物生物活性的最重要成分。其分析需要有效的样品制备和合适的参考标准，但很少有商业上可获得的。
建立和验证一种高效液相色谱法分析钩藤中的吲哚生物碱，重点是样品制备。
采用析因实验设计对样品制备和色谱分离进行优化。优化的样品制备包括用水乙醇提取，粉末状植物材料的粒度对提取产率有显著影响。一叶萩碱被用作总生物碱测定的校准参考。
该方法经过充分验证，具有良好的选择性、线性（r²≥0.9996）、准确性（≥96%）和精密度（RSD<2.4%）。一叶萩碱的检测限和定量限分别为 0.8 和 2.4ppm。
优化的色谱方法，在流动相中使用有机缓冲液，提供了样品中四环和五环生物碱的基线分离。与其他可用的参考生物碱相比，使用一叶萩碱进行校准可以更准确地估计总生物碱含量。
