Structural annotation and discovery of toxic cyclopeptides and their analogues in lethal mushroom Amanita and Lepiota species using UPLC-HRMS and molecular networking strategy

Foodborne poisoning caused by the cyclopeptide toxins-producing mushroom species seriously endangers human life health. In recent years discovery of new cyclopeptides is getting more attention not only for their toxicity but also for their specific bioactivity. In this study, a combined strategy using liquid chromatography tandem high resolution mass spectrometry and the feature-based molecular networking analysis was established to identify the known cyclopeptide toxins and discover new cyclopeptides in the cyclopeptide toxins-producing mushroom species. The specific fragmentation behaviors of the known cyclopeptide toxins were systematically annotated. Four new phallotoxin analogues were identified for the first time, the chemical structures of which were completely deduced. Moreover, the chemical profiles of the toxic cyclopeptides in lethal mushroom Amanita and Lepiota species were investigated by the self-built cyclopeptides database. The developed strategy could be utilized as a useful tool for identifying the cyclopeptide toxins-induced food poisoning, as well as aid in the discovery of more unknown cyclopeptides.