title: Dereplication of Natural Products Using GC-TOF Mass Spectrometry: Improved Metabolite Identification by Spectral Deconvolution Ratio Analysis.
abstract: Dereplication based on hyphenated techniques has been extensively applied in plant metabolomics, thereby avoiding re-isolation of known natural products. However, due to the complex nature of biological samples and their large concentration range, dereplication requires the use of chemometric tools to comprehensively extract information from the acquired data. In this work we developed a reliable GC-MS-based method for the identification of non-targeted plant metabolites by combining the Ratio Analysis of Mass Spectrometry deconvolution tool (RAMSY) with Automated Mass Spectral Deconvolution and Identification System software (AMDIS). Plants species from Solanaceae, Chrysobalanaceae and Euphorbiaceae were selected as model systems due to their molecular diversity, ethnopharmacological potential, and economical value. The samples were analyzed by GC-MS after methoximation and silylation reactions. Dereplication was initiated with the use of a factorial design of experiments to determine the best AMDIS configuration for each sample, considering linear retention indices and mass spectral data. A heuristic factor (CDF, compound detection factor) was developed and applied to the AMDIS results in order to decrease the false-positive rates. Despite the enhancement in deconvolution and peak identification, the empirical AMDIS method was not able to fully deconvolute all GC-peaks, leading to lowMFvalues and/or missing metabolites. RAMSY was applied as a complementary deconvolution method to AMDIS to peaks exhibiting substantial overlap, resulting in recovery of low-intensity co-eluted ions. The results from this combination of optimized AMDIS with RAMSY attested to the ability of this approach as an improved dereplication method for complex biological samples such as plant extracts.
authors.affiliation: Núcleo de Pesquisas em Produtos Naturais e Sintéticos, Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São PauloRibeirão Preto, Brazil; Núcleo de Bioensaios, Biossíntese e Ecofisiologia de Produtos Naturais, Departamento de Química Orgânica, Instituto de Química, Universidade Estadual Paulista UNESPAraraquara, Brazil.
authors.forename: Fausto
authors.initials: F
authors.lastname: Carnevale Neto
authors.affiliation: Núcleo de Bioensaios, Biossíntese e Ecofisiologia de Produtos Naturais, Departamento de Química Orgânica, Instituto de Química, Universidade Estadual Paulista UNESP Araraquara, Brazil.
authors.forename: Alan C
authors.initials: AC
authors.lastname: Pilon
authors.affiliation: Núcleo de Bioensaios, Biossíntese e Ecofisiologia de Produtos Naturais, Departamento de Química Orgânica, Instituto de Química, Universidade Estadual Paulista UNESP Araraquara, Brazil.
authors.forename: Denise M
authors.initials: DM
authors.lastname: Selegato
authors.affiliation: Núcleo de Bioensaios, Biossíntese e Ecofisiologia de Produtos Naturais, Departamento de Química Orgânica, Instituto de Química, Universidade Estadual Paulista UNESPAraraquara, Brazil; Centro de Imagens e Espectroscopia in vivo por Ressonância Magnética, Instituto de Física de São Carlos, Universidade de São PauloSão Carlos, Brazil.
authors.forename: Rafael T
authors.initials: RT
authors.lastname: Freire
authors.affiliation: Department of Anesthesiology and Pain Medicine, Northwest Metabolomics Research Center, University of WashingtonSeattle, WA, USA; Jiangxi Key Laboratory for Mass Spectrometry and Instrumentation, East China Institute of TechnologyNanchang, China.
authors.forename: Haiwei
authors.initials: H
authors.lastname: Gu
authors.affiliation: Department of Anesthesiology and Pain Medicine, Northwest Metabolomics Research Center, University of WashingtonSeattle, WA, USA; Public Health Sciences Division, Fred Hutchinson Cancer Research CenterSeattle, WA, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Raftery
authors.affiliation: Núcleo de Pesquisas em Produtos Naturais e Sintéticos, Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo Ribeirão Preto, Brazil.
authors.forename: Norberto P
authors.initials: NP
authors.lastname: Lopes
authors.affiliation: Núcleo de Bioensaios, Biossíntese e Ecofisiologia de Produtos Naturais, Departamento de Química Orgânica, Instituto de Química, Universidade Estadual Paulista UNESP Araraquara, Brazil.
authors.forename: Ian
authors.initials: I
authors.lastname: Castro-Gamboa
keywords: GC-MS; compound identification; peak deconvolution; plant metabolomics; ratio analysis