UPLC-MS based metabolomics study on Senecio scandens and S. vulgaris: an approach for the differentiation of two Senecio herbs with similar morphology but different toxicity

Pyrrolizidine alkaloids show significant hepatotoxicity as they can bind to DNA or proteins after being activated in liver. Senecio vulgaris L., like many Compositae herbs containing pyrrolizidine alkaloids, was reported to have great hepatotoxicity. However, Senicio scandens Buch.-Ham., from the same genus, which was also used as a herb and documented in China Pharmacopoeia published in 2010, hardly showed any side effects or relevant toxicity. In the present study, we conducted the metabolomics study using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) to obtain the different metabolic profiles of the two Senecio herbs. In addition, principle component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA) were introduced for the multivariate analysis, and MS/MS was applied to the identification of target alkaloid markers which contributed most to the established models. As a result, ten pyrrolizidine alkaloids, including adonifoline, senecionine, senecionine N-oxide, retrorsine, retrorsine N-oxide and seneciphylline, were selected and identified. Among them, adonifoline was found to be a specific marker for S. scandens while senecionine and its N-oxidative were characteristic markers for S. vulgaris. Furthermore, the hepatotoxicity studies in vivo and in vitro showed that senecionine had more potent toxicity (LD50, 57.3 mg/kg; IC50, 5.41 μM) than that of adonifonine (LD50, 163.3 mg/kg; IC50, 49.91 μM). Taken together, the present study provides not only better understanding of the different toxicity between the two Senecio herbs containing pyrrolizidine alkaloids but also a reference method, which can be applied to other genetically closed species with similar morphology but different toxicity.