Abstract
Garlic (A. sativum) contains a large number of small sulphur (S)-containing metabolites, which are important for its taste and smell and vary with A. sativum variety and growth conditions. This study was designed to investigate the influence of different sulphur-fertilization regimes on the low molecular weight S-species by attempting the first sulphur mass balance in A. sativum roots and bulbs using HPLC-ICPMS/MS-ESI-MS/MS. Species unspecific quantification of acid soluble S-containing metabolites was achieved using HPLC-ICP-MS/MS. For identification of the compounds high resolution ESI-MS (Orbitrap LTQ and q-TOF) was used. The plants contained up to 54 separated sulphur-containing compounds, which constitute about 80 % of the total sulphur present in A. sativum. Roots and bulbs of A.sativum contained the same compounds, but not necessarily the same amounts and proportions. The S-containing metabolites in the roots reacted more sensitive to manipulations of sulphur fertilization than those compounds in the bulbs. In addition to known compounds (eg. γ-glutamyl-S-1-propenylcysteine) we were able to identify and partially quantify 31 compounds. Three as yet undescribed S-containing compounds were also identified and quantified for the first time. Putative structures were assigned to the oxidised forms of S-1-propenylmercaptoglutathione, S-2-propenylmercaptoglutathione, S-allyl/propenyl-containing PC-2 and 2-amino-3-[(2-carboxypropyl)sulfanyl]propanoic acid. The parallel use of ICP-MS/MS as sulphur-specific detector and ESI-MS as molecular detector simplifies the identification and quantification of sulphur containing metabolites without species specific standards. This non-target analysis approach enables a mass balance approach and identifies the occurrence of so far unidentified organosulphur compounds. The experiments showed that the sulphur-fertilization regime does not influence sulphur-speciation, but the concentration of some S-containing compounds in roots is depending on the sulphur fertilization.
Original language | English |
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Pages (from-to) | 1429-1438 |
Number of pages | 10 |
Journal | Metallomics |
Volume | 9 |
Issue number | 10 |
Early online date | 7 Sept 2017 |
DOIs | |
Publication status | Published - 1 Oct 2017 |