Liquid chromatography–mass spectrometry (LC–MS): a powerful combination for selenium speciation in garlic (Allium sativum)
- 25 January 2006
- journal article
- research article
- Published by Springer Science and Business Media LLC in Analytical and Bioanalytical Chemistry
- Vol. 384 (5), 1196-1206
- https://doi.org/10.1007/s00216-005-0272-6
Abstract
Liquid chromatography (LC) hyphenated with both elemental and molecular mass spectrometry has been used for Se speciation in Se-enriched garlic. Different species were separated by ion-pair liquid chromatography–inductively coupled plasma mass spectrometry (LC–ICP–MS) after hot-water extraction. They were identified by on-line reversed-phase liquid chromatography–electrospray ionization tandem mass spectrometry (RPLC–ESI–MS–MS). Se-methionine and Se-methylselenocysteine were determined by monitoring their product ions. Another compound, γ-glutamyl-Se-methylselenocysteine, shown to be the most abundant form of Se in the garlic, was determined without any additional sample pre-treatment after extraction and without the need for a synthesized standard. Product ions for this dipeptide were detected by LC–ESI–MS–MS for three isotopes of Se—78 Se, 80Se: and 82Se. The method was extended to the species extracted during in-vitro gastrointestinal digestion. Because both Se-methylselenocysteine and γ-glutamyl-Se-methylselenocysteine have anticarcinogenic properties, their extractability and stability during human digestion are very important. Garlic was also treated with saliva, to enable detection and analysis of species extracted during mastication. Detailed information on the extractability of selenium species by both simulated gastric and intestinal fluid are given, and variation of the distribution of Se among the different species with time is discussed. Although the main species in garlic is the dipeptide γ-glutamyl-Se-methylselenocysteine, Se-methylselenocysteine is the main compound present in the extracts after treatment with gastrointestinal fluids. Two more, so far unknown compounds were observed in the chromatogram. The extracted species and their transformations were analysed by combining LC–ICP–MS and LC–ESI–MS–MS. In both the simulated gastric and intestinal digests, Se-methionine, Se-methylselenocysteine, and γ-glutamyl-Se-methylselenocysteine could be determined by LC–ESI–MS–MS by measuring their typical product ions.Keywords
This publication has 24 references indexed in Scilit:
- Identification of water-soluble gamma-glutamyl-Se-methylselenocysteine in yeast-based selenium supplements by reversed-phase HPLC with ICP-MS and electrospray tandem MS detectionJournal of Analytical Atomic Spectrometry, 2005
- Selenium speciation analysis of selenium-enriched supplements by HPLC with ultrasonic nebulisation ICP-MS and electrospray MS/MS detectionJournal of Analytical Atomic Spectrometry, 2004
- SPME for on-line volatile organo-selenium speciationJournal of Analytical Atomic Spectrometry, 2003
- Identification of the principal selenium compounds in selenium-enriched natural sample extracts by ion-pair liquid chromatography with inductively coupled plasma- and electrospray ionization-mass spectrometric detectionAnalytical Communications, 1999
- Selenium-enriched garlic inhibits the early stage but not the late stage of mammary carcinogenesisCarcinogenesis: Integrative Cancer Research, 1996
- Effect of an aqueous extract of selenium-enriched garlic on in vitro markers and in vivo efficacy in cancer preventionCarcinogenesis: Integrative Cancer Research, 1996
- Allium chemistry: Natural abundance of organoselenium compounds from garlic, onion and related plants and in human garlic breathPure and Applied Chemistry, 1996
- Allium Chemistry: Identification of Natural Abundance Organoselenium Compounds in Human Breath after Ingestion of Garlic Using Gas Chromatography with Atomic Emission DetectionJournal of Agricultural and Food Chemistry, 1995
- Allium chemistry: Identification of natural abundance organoselenium volatiles from garlic, elephant garlic, onion, and Chinese chive using headspace gas chromatography with atomic emission detectionJournal of Agricultural and Food Chemistry, 1994
- Bioavailability of selenium from selenium‐enriched garlicNutrition and Cancer, 1993