Annotated molecular networks of precursor ions acquired by tandem MS/MS for ethyl acetate extract of Penicillium crustosum

The ethyl acetate extract of P. crustosum was analyzed by UHPLC-HRMS/MS in positive (PI) and negative (NI) ionization modes, MS/MS spectra of all detected features were recorded by data dependent analysis (DDA). Feature-based molecular networks of both modes were built to arrange the precursor into clusters based on MS2 similarity. The precursor masses and their associated MS2 spectra were matched against experimental data from GNPS as well as predicted spectra obtained by in silico MS2 fragmentation database (ISDB-DNP). For each node of the MN, possible structure candidates were listed according to MS2 similarity (initial rank) up to a maximum of top 50 structures reported to occur in fungi. To increase the level of confidence in annotation, a reweighting step based on taxonomy was performed. It takes into consideration the matching with the biological source reported in DNP at level of species > genus > family, resulting in a maximum of top 5 candidates (final rank) for each annotated node.