Hydrophilic interaction liquid chromatography with tandem mass spectrometry for the determination of underivatized dencichine (beta-N-oxalyl-L-alpha,beta-diaminopropionic acid) in Panax medicinal plant species

Dencichine (beta-N-oxalyl-L-alpha,beta-diaminopropionic acid) is a haemostatic agent present in important Chinese medicinal herbs such as Panax notoginseng, as well as other Panax species. It is also a reported neurotoxic agent found in Lathyrus sativus (grass pea seed). A selective analytical method incorporating hydrophilic interaction chromatography with positive electrospray ionization tandem mass spectrometry (HILIC/ESI-MS/MS), for the analysis of dencichine in Panax plant species, was developed. Using multiple reaction monitoring (MRM) mode, underivatized dencichine, a small and highly polar compound, was selectively detected and quantified. The contents of dencichine in raw and steamed Panax notoginseng roots, 11 pairs of raw and steamed P. notoginseng herbal products, Panax ginseng roots, and Panax quinquefolium roots, were analyzed and compared. Optimal sensitivity of 0.3 ppm (detection limit) and 1.5 ppm (quantification limit) was achieved. The method was rapid (< or =5 min), with the HILIC peak eluting at about 1 min. Steamed P. notoginseng samples were found to contain less dencichine than the corresponding raw samples, and there were also differences among the three Panax species; raw P. ginseng and P. quinquefolium contained less dencichine than the raw P. notoginseng species. This rapid and specific method may be applied to the quantification of dencichine in complex medicinal plants and their products.