Unveiling Hidden Aconitum Alkaloids in a Poisoning-Implicated Tincture by Untargeted Screening and Molecular Networking

Aconitum poisoning is a major public health concern in East Asia, and remains difficult to diagnose when the causative toxins are not covered by routine targeted assays. In a poisoning incident that occurred in 2018, 15 individuals were affected, including five fatalities, after accidentally consuming a medicinal tincture during a shared meal. The comprehensive alkaloid profile of the tincture implicated in the poisoning was achieved through the integration of targeted analysis, molecular networking, and untargeted screening based on ultra-high performance liquid chromatography coupled to time-of-flight mass spectrometry, aiming to clarify the causative agents. Targeted quantitative analysis detected nine alkaloids derived from Aconitum plants, confirming the presence of Aconitum ingredients in the medicinal tincture. However, these alkaloids were either present at low concentrations or exhibited low toxicity, and thus were not the principal causative agents of this poisoning incident. Molecular networking revealed additional hidden diester-diterpenoid alkaloids (DDAs) and monoester-diterpenoid alkaloids (MDAs) that were undetected by targeted analysis. Untargeted screening identified 58 Aconitum alkaloids, including 15 DDAs, 17 MDAs, 17 amino-diterpenoid alkaloids (ADAs), 2 C20-diterpenoid alkaloids, and seven unclassified alkaloids. The three most abundant alkaloids were structurally identified as pseudoaconitine, 8-deacetylpseudoaconitine, and 3′-methoxyacoforestinine, and were identified as the main causative agents of this poisoning. To our knowledge, this is the first detection of these alkaloids in Aconitum poisoning in China. These findings demonstrate that integrated targeted and untargeted toxicological analysis can identify undocumented toxins in poisoning events of unknown origin and clarify the chemical etiology of unusual Aconitum poisoning.