Raab Andrea, Ronzan Marilena, Feldmann Joerg
TESLA (Trace Element Speciation Laboratory), University of Aberdeen, Chemistry, Meston Walk, Aberdeen, Scotland AB243UE, UK.
Metallomics. 2017 Oct 18;9(10):1429-1438. doi: 10.1039/c7mt00098g.
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 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. The 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 sensitively to manipulations of sulphur fertilization than those compounds in the bulbs. In addition to known compounds (e.g. 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 a sulphur-specific detector and ESI-MS as a 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 the 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 dependent on sulphur fertilization.
大蒜（蒜）含有大量含硫（S）的小分子代谢产物，这些代谢产物对其味道和气味很重要，并且会因大蒜品种和生长条件而有所不同。本研究旨在通过使用HPLC-ICPMS/MS-ESI-MS/MS对大蒜根和鳞茎进行首次硫质量平衡分析，研究不同硫肥施用方式对低分子量含硫物种的影响。使用HPLC-ICP-MS/MS实现了对酸溶性含硫代谢产物的非物种特异性定量。为了鉴定这些化合物，使用了高分辨率ESI-MS（Orbitrap LTQ和q-TOF）。这些植物含有多达54种分离的含硫化合物，约占大蒜中总硫含量的80%。大蒜的根和鳞茎含有相同的化合物，但数量和比例不一定相同。根中的含硫代谢产物对硫肥施用的反应比鳞茎中的那些化合物更敏感。除了已知化合物（如γ-谷氨酰-S-1-丙烯基半胱氨酸）外，我们还能够鉴定并部分定量31种化合物。还首次鉴定并定量了三种尚未描述的含硫化合物。推测的结构被指定为S-1-丙烯基巯基谷胱甘肽、S-2-丙烯基巯基谷胱甘肽、含S-烯丙基/丙烯基的PC-2和2-氨基-3-[(2-羧丙基)硫基]丙酸的氧化形式。将ICP-MS/MS作为硫特异性检测器和ESI-MS作为分子检测器并行使用，无需物种特异性标准即可简化含硫代谢产物的鉴定和定量。这种非靶向分析方法实现了质量平衡分析，并鉴定了迄今为止未鉴定的有机硫化合物的存在。实验表明，硫肥施用方式不影响硫形态，但根中一些含硫化合物的浓度取决于硫肥施用情况。
