Metabolism of the pesticide metabolite 4-[U-14C]nitrophenol in Datura stramonium (L.) cell suspension culture : A model for processing of xenobiotic carbohydrate conjugates and formation of nonextractable residues

• Published in: Pesticide biochemistry and physiology Vol. 57; no. 2; pp. 109 - 118
• Main Authors: SCHMIDT, B, BREUER, J, THIEDE, B, SCHUPHAN, I
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier 01.02.1997
• Subjects: Agrochemicals products; Animal, plant and microbial ecology; Applied ecology; Biodegradation of pollutants; Biological and medical sciences; Biotechnology; cell suspension culture; Datura stramonium; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Environment and pollution; enzyme activity; Fundamental and applied biological sciences. Psychology; Generalities; Industrial applications and implications. Economical aspects; metabolism; metabolites; nitrophenols; pesticide residues; Phytopathology. Animal pests. Plant and forest protection; Pollution effects and side effects of agrochemicals on crop plants and forest trees. Other anthropogenic factors; Pollution effects. Side effects of agrochemicals; Cell culture; Metabolite; Datura stramonium; Biological model; Radioactive tracers; Suspension culture; Dicotyledones; Biotransformation; Angiospermae; Solanaceae; Labelled compound; Xenobiotic; Method study; Laboratory study; Ecotoxicology; Weed; Pollutant behavior; Pesticides; Phenol(4-nitro); Metabolism; Residue; Phenols; Environment; Spermatophyta; Experimental plant; Conjugated compound; Degradation product
• ISSN: 0048-3575
• DOI: 10.1006/pest.1997.2264

The biotransformation of the pesticide metabolite 4[U-14C]nitrophenol was studied in cell suspension cultures of Datura stramonium (L.), which were routinely subcultured every 9 or 10 days. In a standard metabolism experiment (48 hr of incubation) starting 7 days after subcultivation, the xenobiotic was found conjugated to its beta-glucoside (ca. 22% of applied 14C) and gentiobioside, Glc-beta-(1 leads to 6)-Glc-beta-4 nitrophenol (ca. 64%); about 7% of the parent remained unchanged. The conjugates were identified using TLC, HPLC, and their UV spectra. In contrast to previous, analogous studies with carrot, soybean, and wheat, a greater portion of nonextractable residues (11.2%) was detected. A time-course study (started 6 days after subcultivation for 96 hr) demonstrated that the disaccharide was formed from Glc-beta-4-nitrophenol, and that the major percentage of bound residues (7.1 of 12.2%) emerged in the last 72 hr of incubation. The data suggested this portion was due to a turnover of 4-nitrophenol conjugates. Two time-course experiments started directly after subcultivation and performed for 10 and 16 days confirmed that this turnover was confined to late rapid growth and stationary phases of the culture cycle. The main metabolite Glc-beta(1 leads to 6)-Glc-beta-4 nitrophenol proved to be only a temporary product which was degraded considerably (ca. 22%) during this period in favor of the beta-glucoside and nonextractable residues. According to these data, xenobiotic conjugates may be regarded as temporary storage products subject to turnover in the plant, as reported frequently for those of secondary compounds. The metabolic processes observed were attributed to differentiation processes possibly occurring especially during the stationary phase of the cell culture. In general, these are characterized by initiation of structural organization and increased cell aggregation and lignification and are known in particular for cell cultures of solanaceous species.