2 research outputs found
Zearalenone-16‑<i>O</i>‑glucoside: A New Masked Mycotoxin
This paper reports the identification
of a barley UDP-glucosyltransferase,
HvUGT14077, which is able to convert the estrogenic Fusarium mycotoxin zearalenone into a near-equimolar
mixture of the known masked mycotoxin zearalenone-14-<i>O</i>-β-glucoside and a new glucose conjugate, zearalenone-16-<i>O</i>-β-glucoside. Biocatalytical production using engineered
yeast expressing the <i>HvUGT14077</i> gene allowed structural
elucidation of this compound. The purified zearalenone-16-<i>O</i>-β-glucoside was used as an analytical calibrant
in zearalenone metabolization experiments. This study confirmed the
formation of this new masked mycotoxin in barley seedlings as well
as in wheat and Brachypodium distachyon cell suspension cultures. In barley roots, up to 18-fold higher
levels of zearalenone-16-<i>O</i>-β-glucoside compared
to the known zearalenone-14-<i>O</i>-β-glucoside were
found. Incubation of zearalenone-16-<i>O</i>-β-glucoside
with human fecal slurry showed that this conjugate can also be hydrolyzed
rapidly by intestinal bacteria, converting the glucoside back to the
parental mycotoxin. Consequently, it should be considered as an additional
masked form of zearalenone with potential relevance for food safety
Untargeted Profiling of Tracer-Derived Metabolites Using Stable Isotopic Labeling and Fast Polarity-Switching LC–ESI-HRMS
An untargeted metabolomics workflow
for the detection of metabolites
derived from endogenous or exogenous tracer substances is presented.
To this end, a recently developed stable isotope-assisted LC–HRMS-based
metabolomics workflow for the global annotation of biological samples
has been further developed and extended. For untargeted detection
of metabolites arising from labeled tracer substances, isotope pattern
recognition has been adjusted to account for nonlabeled moieties conjugated
to the native and labeled tracer molecules. Furthermore, the workflow
has been extended by (i) an optional ion intensity ratio check, (ii)
the automated combination of positive and negative ionization mode
mass spectra derived from fast polarity switching, and (iii) metabolic
feature annotation. These extensions enable the automated, unbiased,
and global detection of tracer-derived metabolites in complex biological
samples. The workflow is demonstrated with the metabolism of <sup>13</sup>C<sub>9</sub>-phenylalanine in wheat cell suspension cultures
in the presence of the mycotoxin deoxynivalenol (DON). In total, 341
metabolic features (150 in positive and 191 in negative ionization
mode) corresponding to 139 metabolites were detected. The benefit
of fast polarity switching was evident, with 32 and 58 of these metabolites
having exclusively been detected in the positive and negative modes,
respectively. Moreover, for 19 of the remaining 49 phenylalanine-derived
metabolites, the assignment of ion species and, thus, molecular weight
was possible only by the use of complementary features of the two
ion polarity modes. Statistical evaluation showed that treatment with
DON increased or decreased the abundances of many detected metabolites