Benzoxazinoid phytochemicals, abundant in rye bread, are taken up in humans. Analytical method for plasma metabolites is highly needed

Benzoxanoids (BXs) were identified for the first time in young cereal plants in 1957 and in medicinal plants in 1969. In 2008 our lab discovered that BXs are present in mature cereal grains and in food/feed based on cereal whole grains [1]. We showed that BXs are taken up in pigs, rats and humans [2]–[4], and that they appear in prostate tissue of humans consuming rye bread [5]. The aim of this study was to develop a method for identification and quantification of human phase 1 and phase 2 metabolites in plasma. The method included an initial protein precipitation step of the plasma with the purpose of reducing the matrix interference. The chromatographic analysis of BXs and their metabolites in the remaining extract was performed in LC-MS/MS. Pure standards were unavailable for most of the phase 2 metabolites. Phase 2 metabolites are present in much higher amounts in urine than in plasma. Thus urine metabolites of BXs for which structures could be assigned using data dependent acquisition were isolated and used for verification of MS/MS signals in plasma extracts. The isolation of approx 10 µg of each compound was done with consecutive HLB and mixed mode SPE’s (Oasis, Waters) exploiting the variety of polarity and acidity of the metabolites. Glucuronide and sulphate metabolites of paracetamol were used as standards for semi-quantification due to their structural similarity and commercial availability.

• References

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