molecules. Plants, algae, and other lower animals from our agroecosystems have
similar receptor and metabolic enzymatic systems and can be affected by the release
of pharmaceuticals in reclaimed wastewater.
Plants have evolved very sophisticated detoxification systems including a battery
of xenobiotic-metabolizing enzymes to form metabolites of different nature. Some of
them are similar to those in humans and animals, but there are several plant-specific
ones. Therefore, it is necessary to address the metabolism in crop plants and soil
because the parent compounds along their metabolites can enter the food chain. In
some cases, these may have higher toxicity than the original molecule, thereby
threatening ecosystems [2]. Identification of harmful metabolites in edible vegetables (formed or not in plants) should be addressed to prevent exposure of humans to
hazardous compounds derived from drugs. In this context, information obtained by
mass spectrometry (MS) is of special relevance. New available equipment and
techniques have increased the sensitivity of non-target analyses, resulting in a
relevant number of new molecules and metabolites identified in our agroecosystems.
This information is necessary if we want to provide safe and healthy food whose
production involves the use of reclaimed wastewater. Phytoremediation is another
field where the identification of metabolites is important. Nature-based solutions
(NBS) are commonly implemented to treat secondary wastewater effluents as a
polishing step [3]. Even small communities may have only one wastewater treatment
plant based on lagoon systems before finally disposing of the effluent into the
environment. In these cases, monitoring of pharmaceuticals and their transformation
products from the raw wastewater entering the treatment plant to the effluent
discharged back into nature is necessary. Therefore, knowing what happens between
these two points, i.e., in the rhizosphere and in the plant, can help determine whether
a treatment is efficient or not and to implement corrective actions. Here, the aim is to
check that plants can absorb, accumulate, and immobilize drugs and their transformation products, eliminating the risk to the environment and the trophic chain.
This chapter attempts to give a description of the mechanisms of pharmaceutical
metabolism in plants which depend strongly on their physicochemical properties and
the interactions with plant-associated bacteria. Similarities between human and plant
metabolism are discussed, following some examples of metabolites recently identified in plant tissues. The use of models to study metabolism of pharmaceuticals in
plants is also discussed. As the plant microbiome plays an important role in
xenobiotic metabolism, degradation of pharmaceuticals can be modulated using
techniques based on holobiontic approaches. Hence, the impact of several pharmaceuticals on plant microbial communities and the cooperative metabolism of pharmaceuticals by plants and their microbiome are presented.
2 Human Drug-Metabolizing Enzymes
As an innate defense mechanism against potentially harmful agents that may have
entered the organism through ingestion, inhalation, or dermal exposure, enzymatic
detoxification pathways are in place to aid in removing undesired substances from
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A. Sauvêtre et al.
similar receptor and metabolic enzymatic systems and can be affected by the release
of pharmaceuticals in reclaimed wastewater.
Plants have evolved very sophisticated detoxification systems including a battery
of xenobiotic-metabolizing enzymes to form metabolites of different nature. Some of
them are similar to those in humans and animals, but there are several plant-specific
ones. Therefore, it is necessary to address the metabolism in crop plants and soil
because the parent compounds along their metabolites can enter the food chain. In
some cases, these may have higher toxicity than the original molecule, thereby
threatening ecosystems [2]. Identification of harmful metabolites in edible vegetables (formed or not in plants) should be addressed to prevent exposure of humans to
hazardous compounds derived from drugs. In this context, information obtained by
mass spectrometry (MS) is of special relevance. New available equipment and
techniques have increased the sensitivity of non-target analyses, resulting in a
relevant number of new molecules and metabolites identified in our agroecosystems.
This information is necessary if we want to provide safe and healthy food whose
production involves the use of reclaimed wastewater. Phytoremediation is another
field where the identification of metabolites is important. Nature-based solutions
(NBS) are commonly implemented to treat secondary wastewater effluents as a
polishing step [3]. Even small communities may have only one wastewater treatment
plant based on lagoon systems before finally disposing of the effluent into the
environment. In these cases, monitoring of pharmaceuticals and their transformation
products from the raw wastewater entering the treatment plant to the effluent
discharged back into nature is necessary. Therefore, knowing what happens between
these two points, i.e., in the rhizosphere and in the plant, can help determine whether
a treatment is efficient or not and to implement corrective actions. Here, the aim is to
check that plants can absorb, accumulate, and immobilize drugs and their transformation products, eliminating the risk to the environment and the trophic chain.
This chapter attempts to give a description of the mechanisms of pharmaceutical
metabolism in plants which depend strongly on their physicochemical properties and
the interactions with plant-associated bacteria. Similarities between human and plant
metabolism are discussed, following some examples of metabolites recently identified in plant tissues. The use of models to study metabolism of pharmaceuticals in
plants is also discussed. As the plant microbiome plays an important role in
xenobiotic metabolism, degradation of pharmaceuticals can be modulated using
techniques based on holobiontic approaches. Hence, the impact of several pharmaceuticals on plant microbial communities and the cooperative metabolism of pharmaceuticals by plants and their microbiome are presented.
2 Human Drug-Metabolizing Enzymes
As an innate defense mechanism against potentially harmful agents that may have
entered the organism through ingestion, inhalation, or dermal exposure, enzymatic
detoxification pathways are in place to aid in removing undesired substances from
224
A. Sauvêtre et al.