Improved method for the determination of oxindole alkaloids in Uncaria tomentosa by high performance liquid chromatography

This Paper describes an improved HPLC method for the determination of penta cyclic: oxindole alkaloids in Uncaria tomentosa (Cat's Claw). Six of the is omeric compounds could be baseline separated at room temperature within les s than 30 min by using 3 mum C-18 column material and a mobile phase consis ting of 10 mM phosphate buffer at pH 7.0 and acetonitrile. At a wavelength of 245 nm all standard compounds could be detected at concentrations as low as 0.63 mug/ml. Different samples of U. tomentosa bark and market products containing Cat's Claw were extracted with a modified procedure ensuring th e integrity of the alkaloids and analyzed successfully. The results indicat ed accuracy and consistency of the new method, and showed variations in the total alkaloid content in products from 0.156 to 0.962 %.