Discovery of N-Acyl Amino Acids and Novel Related N-, O-Acyl Lipids by Integrating Molecular Networking and an Extended In Silico Spectral Library

Research on novel bioactive lipids has garnered increasing interest. Although lipids can be identified by searching mass spectral libraries, the discovery of novel lipids remains challenging as the query spectra of such lipids are not included in libraries. In this study, we propose a strategy to discover novel carboxylic acid-containing acyl lipids by integrating molecular networking with an extended in silico spectral library. Derivatization was performed to improve the response of this method. The tandem mass spectrometry spectra enriched by derivatization facilitated the formation of molecular networking and 244 nodes were annotated. We constructed consensus spectra for these annotations based on molecular networking and developed an extended in silico spectral library based on these consensus spectra. The spectral library included 6879 in silico molecules covering 12,179 spectra. Using this integration strategy, 653 acyl lipids were discovered. Among these, O-acyl lactic acids and N-lactoyl amino acid-conjugated lipids were annotated as novel acyl lipids. Compared with conventional methods, our proposed method allows for the discovery of novel acyl lipids, and extended in silico libraries significantly increase the size of the spectral library.