and metabolism by Cyperus alternifolius and Lemna gibba [90] were investigated.
As already discussed shortly, a targeted approach for metabolite detection is always
somewhat biased, as unexpected conjugates might be overlooked. Macherius et al.
provided a sophisticated workflow for the identification of triclosan-related plant
metabolites in horseradish [56]. They recorded HR-MS spectra for both treated and
untreated horseradish hairy root tissue, whereby abundant metabolites were simply
detected by comparing base peak chromatograms from both series. For less abundant
conjugates, they subjected the data to data filtering and multivariate statistics
(principal component analysis). Another work worth mentioning employing novel
instrumentation for metabolite detection and (at least tentative) identification was
published by Seyer et al. [90]. Here the interaction of several UV filters commonly
employed in sunscreen agents with two water-borne plants (Lemna gibba and
Cyperus alternifolius) was investigated. The use of DTIM-HR-MS provided an
increased amount of data available for metabolite structure proposal.
5 Conclusions and Perspectives
In particular within the last 10 years, interest in the uptake and metabolization of
pharmaceuticals by plants has faced increasing interest, leading to a series of
publications in this field. There are several driving forces for conducting such
studies. The first category are basic studies, mainly devoted to the identification of
metabolites originating from drugs or personal care products formed in plants,
ideally allowing to propose a (tentative) metabolic pathway. Second, when investigating edible plants (where uptake of xenobiotics via the use of reclaimed waters for
irrigation is of particular interest), drugs and their metabolites might affect their use
for food and feed. Third, there is research focusing on the potential of certain plants
(such as Typha spp. [65], Typha angustifolia/latifolia [80], Phragmites australis
[69], or Lemna gibba [77]) for phytoremediation of contaminated land.
Regarding current and future trends related to this scientific field, there are a
number of promising developments that either can already be seen or imagined for
the years coming. Climate change and with it the need for employing reclaimed
waters in agriculture are an increasingly important factor within many countries. As
a consequence, plants used for production of food and feed might be affected by
xenobiotics (and their metabolites) taken up from irrigation water. For this reason,
there is a high probability that research in this field will face growing importance.
Whereas the determination of the parent drugs in food and feed at the required trace
level was already accomplished [16], for the corresponding metabolites, methods for
their detection and even more their quantitation in edible plants definitely need to be
substantially improved [25].
To achieve these improvements, advances need to be made in all analytical steps.
These include new approaches for extraction and preconcentration of the metabolites
of interest and finally optimization of HPLC-MS
(n) analysis. The final goal of these
efforts should be to achieve comparable standards as already accomplished in the
Analytical Approaches for the Determination and Identification of Drug. . .
517
As already discussed shortly, a targeted approach for metabolite detection is always
somewhat biased, as unexpected conjugates might be overlooked. Macherius et al.
provided a sophisticated workflow for the identification of triclosan-related plant
metabolites in horseradish [56]. They recorded HR-MS spectra for both treated and
untreated horseradish hairy root tissue, whereby abundant metabolites were simply
detected by comparing base peak chromatograms from both series. For less abundant
conjugates, they subjected the data to data filtering and multivariate statistics
(principal component analysis). Another work worth mentioning employing novel
instrumentation for metabolite detection and (at least tentative) identification was
published by Seyer et al. [90]. Here the interaction of several UV filters commonly
employed in sunscreen agents with two water-borne plants (Lemna gibba and
Cyperus alternifolius) was investigated. The use of DTIM-HR-MS provided an
increased amount of data available for metabolite structure proposal.
5 Conclusions and Perspectives
In particular within the last 10 years, interest in the uptake and metabolization of
pharmaceuticals by plants has faced increasing interest, leading to a series of
publications in this field. There are several driving forces for conducting such
studies. The first category are basic studies, mainly devoted to the identification of
metabolites originating from drugs or personal care products formed in plants,
ideally allowing to propose a (tentative) metabolic pathway. Second, when investigating edible plants (where uptake of xenobiotics via the use of reclaimed waters for
irrigation is of particular interest), drugs and their metabolites might affect their use
for food and feed. Third, there is research focusing on the potential of certain plants
(such as Typha spp. [65], Typha angustifolia/latifolia [80], Phragmites australis
[69], or Lemna gibba [77]) for phytoremediation of contaminated land.
Regarding current and future trends related to this scientific field, there are a
number of promising developments that either can already be seen or imagined for
the years coming. Climate change and with it the need for employing reclaimed
waters in agriculture are an increasingly important factor within many countries. As
a consequence, plants used for production of food and feed might be affected by
xenobiotics (and their metabolites) taken up from irrigation water. For this reason,
there is a high probability that research in this field will face growing importance.
Whereas the determination of the parent drugs in food and feed at the required trace
level was already accomplished [16], for the corresponding metabolites, methods for
their detection and even more their quantitation in edible plants definitely need to be
substantially improved [25].
To achieve these improvements, advances need to be made in all analytical steps.
These include new approaches for extraction and preconcentration of the metabolites
of interest and finally optimization of HPLC-MS
(n) analysis. The final goal of these
efforts should be to achieve comparable standards as already accomplished in the
Analytical Approaches for the Determination and Identification of Drug. . .
517