title: Changes in selenium speciation associated with increasing tissue concentrations of selenium in wheat grain.
abstract: Wheat (Triticum aestivum) collected in the Nawanshahr-Hoshiarpur Region (Punjab, India) showed the highest selenium concentrations ever recorded in cereal grains (29-185 microg g(-1)). There was a strong positive relationship between the selenium content in shoots and that in kernels, showing that grain selenium concentration can be predicted from that in the vegetative tissues of the plant. The identity and content of the selenocompounds in the grain samples and in wheat-based reference materials were investigated by HPLC-ICP-dynamic reaction cell-MS. Reversed-phase, cation exchange, and anion exchange HPLC were used to separate the selenium species after ultrasound-assisted enzymatic extraction with an ultrasonic probe. Selenomethionine and selenate accounted for 72-85% and 2-6% of the sum of the selenium species, respectively. The proportion of organic Se species varied with increasing Se content; namely, SeMet showed a relative reduction whereas the other organoselenium compounds increased up to 18-22% of the total chromatographed selenium. Se-methyl-selenocysteine was detected as a minor compound (0.2-0.5%) in high-Se wheat by both reversed-phase and cation exchange HPLC using retention time matching with the standard substance spiked to the sample extracts. Regular consumption of locally produced wheat-based food items may lead the population of the study area to an excessive intake of selenium. On the other hand, the large predominance of selenomethionine shows that local wheat can be a promising raw material for naturally enriched products to be used to supplement human and animal diets in low selenium areas.
authors.affiliation: Food and Veterinary Toxicology Unit, Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanita, Viale Regina Elena 299, Rome 00161, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cubadda
authors.forename: Federica
authors.initials: F
authors.lastname: Aureli
authors.forename: Silvia
authors.initials: S
authors.lastname: Ciardullo
authors.forename: Marilena
authors.initials: M
authors.lastname: D'Amato
authors.forename: Andrea
authors.initials: A
authors.lastname: Raggi
authors.forename: Raghunath
authors.initials: R
authors.lastname: Acharya
authors.forename: Ramana A V
authors.initials: RA
authors.lastname: Reddy
authors.forename: Nagaraja Tejo
authors.initials: NT
authors.lastname: Prakash
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002523:Edible Grain / Q000378:metabolism; D005433:Flour / Q000032:analysis; D020387:Food Chain; D006801:Humans; D007194:India; D013058:Mass Spectrometry; D012621:Seasons; D012643:Selenium / Q000172:deficiency / Q000378:metabolism* / Q000633:toxicity; D012645:Selenomethionine / Q000032:analysis / Q000302:isolation & purification; D013045:Species Specificity; D014908:Triticum / Q000378:metabolism*
chemical_list: D012645:Selenomethionine; D012643:Selenium