Bio-fortification and isotopic labelling of Se metabolites in onions and carrots following foliar application of Se and ⁷⁷Se

TY - JOUR

T1 - Bio-fortification and isotopic labelling of Se metabolites in onions and carrots following foliar application of Se and 77Se

AU - Kápolna, Emese

AU - Laursen, Kristian Holst

AU - Husted, Søren

AU - Larsen, Erik Huusfeldt

PY - 2012/8/1

Y1 - 2012/8/1

N2 - The aims were to bio-fortify onions by foliar application of selenium (Se) and to intrinsically label bioactive Se-metabolites in onion and carrot by enriched, stable 77Se for use in human physiological studies. Onion bulbs and leaves were enriched in Se by repeated foliar spraying of 10 or 100 μg Se ml -1 solutions of sodium selenite (Se(IV)) or sodium selenate (Se(VI)). ICP-MS analysis of onion leaves and bulbs showed that the Se concentration was enhanced by up to a factor of approximately 50 and 200 in bulbs and leaves, respectively. HPLC-ICP-MS analysis of proteolytic plant extracts showed that foliar application of Se(IV) gave rise to bio-synthesis of a higher fraction of the desired organic Se species and was better tolerated by the plants than Se(VI). Based on these findings onions and carrots were bio-fortified by foliar application of a solution of 77Se(IV) that was enriched to 99.7% as 77Se. The 77Se- labelled metabolites in onions were predominantly γ-glutamyl- 77Se- selenomethyl-selenocysteine (γ-glu-Me 77SeCys), 77Se-methylselenocysteine (Me 77SeCys) and 77Se-selenomethionine ( 77SeMet). Furthermore, we report here for the first time the finding in carrots of the bioactive Me 77SeCys, the identity of which was verified by HPLC-ESI-MS/MS.

AB - The aims were to bio-fortify onions by foliar application of selenium (Se) and to intrinsically label bioactive Se-metabolites in onion and carrot by enriched, stable 77Se for use in human physiological studies. Onion bulbs and leaves were enriched in Se by repeated foliar spraying of 10 or 100 μg Se ml -1 solutions of sodium selenite (Se(IV)) or sodium selenate (Se(VI)). ICP-MS analysis of onion leaves and bulbs showed that the Se concentration was enhanced by up to a factor of approximately 50 and 200 in bulbs and leaves, respectively. HPLC-ICP-MS analysis of proteolytic plant extracts showed that foliar application of Se(IV) gave rise to bio-synthesis of a higher fraction of the desired organic Se species and was better tolerated by the plants than Se(VI). Based on these findings onions and carrots were bio-fortified by foliar application of a solution of 77Se(IV) that was enriched to 99.7% as 77Se. The 77Se- labelled metabolites in onions were predominantly γ-glutamyl- 77Se- selenomethyl-selenocysteine (γ-glu-Me 77SeCys), 77Se-methylselenocysteine (Me 77SeCys) and 77Se-selenomethionine ( 77SeMet). Furthermore, we report here for the first time the finding in carrots of the bioactive Me 77SeCys, the identity of which was verified by HPLC-ESI-MS/MS.

U2 - 10.1016/j.foodchem.2012.01.043

DO - 10.1016/j.foodchem.2012.01.043

M3 - Journal article

SN - 0308-8146

VL - 133

SP - 650

EP - 657

JO - Food Chemistry

JF - Food Chemistry

IS - 3

ER -