Phase II Glycosylation of Metronidazole in Tomato (Lycopersicum esculentum) and Basil (Ocimum basilicum): Implications for Plant-Mediated Transformation and Environmental Risk

Abstract

To investigate the uptake, physiological responses, and metabolism of metronidazole (MNZ), a widely used nitroimidazole antibiotic and emerging environmental contaminant, tomato (Lycopersicum esculentum) and basil (Ocimum basilicum) were selected as representative edible crops because of their agricultural relevance and contrasting physiological responses to environmental stress. The specimens were grown in MNZ-contaminated soil (250, 500, and 750 mg kg-1). Thin-layer chromatography coupled with densitometric analyses monitored MNZ uptake and metabolite formation, whereas ultra-high-performance liquid chromatography coupled with diode-array detection and tandem mass spectrometry analyses identified di- and triglycosylated MNZ derivatives, providing direct analytical evidence of plant-mediated phase II glycosylation. Tomato showed greater tolerance to MNZ exposure than basil. Although the bioconcentration (0.011 to 0.111) and translocation (0.14 to 0.49) factors of MNZ indicate low to moderate accumulation, the risk quotient values demonstrate high ecological risk (considering only the parent compound). Overall, these findings expand the current understanding of plant-mediated phase II transformation of MNZ and highlight the importance of considering transformation products, in addition to the parent compound, when evaluating their environmental fate and potential ecological impact in soil-plant systems.