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.