RIKEN tandem mass spectral database (ReSpect) for phytochemicals: A plant-specific MS/MS-based data resource and database

TLDR

Fragment pattern analysis of tandem mass spectrometry has long been used to structurally characterize metabolites. The authors aim to build a plant‑specific MS/MS database that narrows complex phytochemical structures to candidate structures. ReSpect contains 3,595 metabolites (76 % from literature, 24 % from authentic standards) and offers a web‑based fragment search using only m/z values, with confidence levels assigned by an MS/MS fragmentation association rule; a case study on Lotus japonicus untargeted data demonstrated its use. In the case study, unknown metabolites were successfully reduced to putative structures through the ReSpect website.

Abstract

The fragment pattern analysis of tandem mass spectrometry (MS/MS) has long been used for the structural characterization of metabolites. The construction of a plant-specific MS/MS data resource and database will enable complex phytochemical structures to be narrowed down to candidate structures. Therefore, a web-based database of MS/MS data pertaining to phytochemicals was developed and named ReSpect (RIKEN tandem mass spectral database). Of the 3595 metabolites in ReSpect, 76% were derived from 163 literature reports, whereas the rest was obtained from authentic standards. As a main web application of ReSpect, a fragment search was established based on only the m/z values of query data and records. The confidence levels of the annotations were managed using the MS/MS fragmentation association rule, which is an algorithm for discovering common fragmentations in MS/MS data. Using this data resource and database, a case study was conducted for the annotation of untargeted MS/MS data that were selected after quantitative trait locus analysis of the accessions (Gifu and Miyakojima) of a model legume Lotus japonicus. In the case study, unknown metabolites were successfully narrowed down to putative structures in the website.