Metwork: a web server for natural products anticipation.

Motivation The annotation of natural products and more generally small molecules is one of the major drawbacks in untargeted mass spectrometry analysis. Molecular networking has emerged as a structured way to organize and mine data from untargeted tandem mass spectrometry (MS/MS) experiments. Despite the great potential of this tool, the annotation is usually performed manually by the expert as only few spectral libraries are available. Results Herein we propose a web server of in silico metabolization of metabolites that represents a full implementation of the metabolome consistency concept. The workflow is based on MS/MS data, organized in molecular network using the Global Natural Products Social Molecular Networking (GNPS) platform, a collaborative library of reactions and a MS/MS spectra prediction module. Having one node identified in the molecular network, the server generates putative structures and predict the associated MS/MS spectra when the exact mass is detected in the network. A similarity comparison between the MS/MS spectra is then performed in order to annotate the node. Availability and implementation The web server is available at: https://metwork.pharmacie.parisdescartes.fr.