title: Pre-analytical method for NMR-based grape metabolic fingerprinting and chemometrics.
abstract: Although metabolomics aims at profiling all the metabolites in organisms, data quality is quite dependent on the pre-analytical methods employed. In order to evaluate current methods, different pre-analytical methods were compared and used for the metabolic profiling of grapevine as a model plant. Five grape cultivars from Portugal in combination with chemometrics were analyzed in this study. A common extraction method with deuterated water and methanol was found effective in the case of amino acids, organic acids, and sugars. For secondary metabolites like phenolics, solid phase extraction with C-18 cartridges showed good results. Principal component analysis, in combination with NMR spectroscopy, was applied and showed clear distinction among the cultivars. Primary metabolites such as choline, sucrose, and leucine were found discriminating for 'Alvarinho', while elevated levels of alanine, valine, and acetate were found in 'Arinto' (white varieties). Among the red cultivars, higher signals for citrate and GABA in 'Touriga Nacional', succinate and fumarate in 'Aragonês', and malate, ascorbate, fructose and glucose in 'Trincadeira', were observed. Based on the phenolic profile, 'Arinto' was found with higher levels of phenolics as compared to 'Alvarinho'. 'Trincadeira' showed lowest phenolics content while higher levels of flavonoids and phenylpropanoids were found in 'Aragonês' and 'Touriga Nacional', respectively. It is shown that the metabolite composition of the extract is highly affected by the extraction procedure and this consideration has to be taken in account for metabolomics studies.
authors: Natural Products Laboratory, Institute of Biology, Leiden University, 2300 RA Leiden, The Netherlands.
authors: Kashif
authors: K
authors: Ali
authors: Federica
authors: F
authors: Maltese
authors: Ana Margarida
authors: AM
authors: Fortes
authors: Maria Salomé
authors: MS
authors: Pais
authors: Robert
authors: R
authors: Verpoorte
authors: Young Hae
authors: YH
authors: Choi
mesh_terms: D000596:Amino Acids / Q000032:analysis / Q000302:isolation & purification; D003998:Dicarboxylic Acids / Q000032:analysis / Q000302:isolation & purification; D005419:Flavonoids / Q000032:analysis / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D055442:Metabolome; D055432:Metabolomics / Q000379:methods; D009005:Monosaccharides / Q000032:analysis / Q000302:isolation & purification; D010636:Phenols / Q000032:analysis / Q000302:isolation & purification; D025341:Principal Component Analysis; D052616:Solid Phase Extraction / Q000379:methods; D027843:Vitis / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D003998:Dicarboxylic Acids; D005419:Flavonoids; D009005:Monosaccharides; D010636:Phenols