Analysis of dihydroindole‐type alkaloids in Strychnos nux‐vomica unprocessed and processed seeds by high‐performance liquid chromatography coupled with diode array detection and mass spectrometry

The ripened seeds of Strychnos nux-vomica L. have been extensively used as herbal medicines in Asian countries. Dihydroindole-type alkaloids are not only the active constituents but also the toxicants in Strychnos. However, the simultaneous determination of these alkaloids in both crude and processed Semen Strychni is still lacking. The present study represents the first quantitation and relative quantitation assay of 12 dihydroindole-type alkaloids in Strychnos nux-vomica unprocessed and sand-processed seeds using high-performance liquid chromatography coupled with diode array detection and mass spectrometry. The relative concentration of ten alkaloids was calculated by semi-quantification using the internal standard and their amounts in unprocessed and detoxified Semen Strychni were compared. We report here for the first time the significant increase of the two alkaloids, 19-N-methyl-strychnine, and 2,3-dimethoxy-19-N-methyl-strychnine, during the processing of Semen Strychni. Our study provides new insight into the true complexity of seed processing procedure and valuable information for assessing the efficacy and safety for clinical applications of Semen Strychni-containing drugs.