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.