Library Enabling Annotation of Botanical Natural Products (LEAFBot): An Open-Access Library of Mass Spectrometry Fragmentation Spectra for Plant Metabolites

Many existing mass spectral libraries focus on human or microbially derived molecules. Few plant-specific MS2 databases exist, making annotation of botanical samples difficult. To fill this gap in mass spectrometry data availability, the Library Enabling Annotation of Botanical Natural Products (LEAFBot) was constructed. Using a flow injection mass spectrometry method that allowed for rapid throughput data collection, the MS2 spectra of >300 pure botanical secondary metabolites were experimentally measured and complied into a single library housed in the Global Natural Products Social Molecular Networking (GNPS) spectral database. Of these compounds, over 20% were not present in the existing GNPS database, and 11% were not present in any of three main mass spectral databases (GNPS, Metlin, and MassBank). Additionally, LEAFBot contains a wider range of adducts compared to other plant-based mass spectral libraries, enabling more effective annotation of unknown features. The LEAFBot database represents a new resource to the mass spectrometry and metabolomics community seeking to characterize plant-based samples. The possibility of searching against a taxonomically specific library decreases the likelihood of false positives in database searches, and the ease of adding new spectra, following procedures outlined herein, will enable community-lead expansion of the database.