insoluble residues in the cell wall (bound residues) [80] chapter “Metabolism of
Pharmaceuticals in Plants and their Associated Microbiota”. Several studies showed
that this detoxification mechanism is also applicable for the metabolization of
pharmaceuticals in plants [84–86]. The metabolization of particular pharmaceuticals
can be differentially pronounced in plant tissues. Therefore, the metabolization of
the anticonvulsant carbamazepine was noticeably higher in shoots than in roots,
which might suggest a higher metabolism occurring in the leaves. However, one
should bear in mind the fast translocation and the subsequent higher concentration of
carbamazepine in shoots compared to roots [10]. Supporting this hypothesis, the
phase
I
and
phase
II
metabolites
4
0 -OH
diclofenac,
4-Oglucopyranosyloxydiclofenac and 4-OH-glutathionyl-diclofenac were present in
much higher concentrations in roots than shoots of cattail. These conjugates all
originated from diclofenac, a pharmaceutical known to accumulate in roots rather
than to be translocated to shoots [84]. In light of current literature, it is also possible
that partially metabolized compounds, at least after phase I reactions, or even as
conjugates can be translocated in plants via the vascular tissue [87, 88]. Nonetheless,
Fig. 3 The metabolic cascade of the green liver concept implies three phases for the fate of
herbicides and foreign compounds in plants. It can be assumed that pharmaceuticals follow the
same routes. While many compounds are finally bound to cell wall material to form insoluble
residues, other xenobiotics may be stored in the vacuole as “soluble residues” and undergo further
metabolism (adapted from [83])
Uptake and Translocation of Pharmaceuticals in Plants:. . .
115
Pharmaceuticals in Plants and their Associated Microbiota”. Several studies showed
that this detoxification mechanism is also applicable for the metabolization of
pharmaceuticals in plants [84–86]. The metabolization of particular pharmaceuticals
can be differentially pronounced in plant tissues. Therefore, the metabolization of
the anticonvulsant carbamazepine was noticeably higher in shoots than in roots,
which might suggest a higher metabolism occurring in the leaves. However, one
should bear in mind the fast translocation and the subsequent higher concentration of
carbamazepine in shoots compared to roots [10]. Supporting this hypothesis, the
phase
I
and
phase
II
metabolites
4
0 -OH
diclofenac,
4-Oglucopyranosyloxydiclofenac and 4-OH-glutathionyl-diclofenac were present in
much higher concentrations in roots than shoots of cattail. These conjugates all
originated from diclofenac, a pharmaceutical known to accumulate in roots rather
than to be translocated to shoots [84]. In light of current literature, it is also possible
that partially metabolized compounds, at least after phase I reactions, or even as
conjugates can be translocated in plants via the vascular tissue [87, 88]. Nonetheless,
Fig. 3 The metabolic cascade of the green liver concept implies three phases for the fate of
herbicides and foreign compounds in plants. It can be assumed that pharmaceuticals follow the
same routes. While many compounds are finally bound to cell wall material to form insoluble
residues, other xenobiotics may be stored in the vacuole as “soluble residues” and undergo further
metabolism (adapted from [83])
Uptake and Translocation of Pharmaceuticals in Plants:. . .
115