Quality evaluation of Radix Stemonae through simultaneous quantification of bioactive alkaloids by high-performance...

A high-performance liquid chromatography coupled with diode array detection and evaporative light scattering detection (HPLC-DAD-ELSD) method was developed to simultaneously quantify six major bioactive alkaloids belonging to different structure types in Radix Stemonae, Bai-Bu in Chinese, a traditionally used antitussive and insecticidal medicinal material in China and other countries of Southeast Asia. Diode array detector (DAD) with the wavelengths at 307 and 260 nm was used to monitor the conjugated system of protostemonine (2) and maistemonine (4), respectively, whereas evaporative light scattering detector (ELSD) was employed to detect croomine (1), stemoninine (3), neotuberostemonine (5) and tuberostemonine (6), the other four analytes with no or poor chromophores. The assay was validated to be sensitive, precise and accurate, with a detection limit of 3.64-0.04 microg/mL depending on the individual analytes. The overall intra- and inter-day variations were less than 9.3%, and the overall recoveries higher than 91.2%, respectively. The correlation coefficients of the calibration curves were better than 0.996 for all analytes. The newly established method was successfully utilized to determine six major components in the genuine sources of Radix Stemonae: Stemona japonica, S. sessilifolia and S. tuberosa. Significant variations of contents of these components were demonstrated in samples of these three species. This simple, rapid, low-cost and reliable method is suitable for the routine quality control of herbal medicines containing bioactive components with different structure types such as Radix Stemonae.