Biotransformation of [ ring ‐U‐ 14 C]atrazine to dealkylated and hydroxylated metabolites in cell‐suspension cultures

Summary The biconversion of [ 14 C]atrazine to deaikyt‐ated and hydroxylated products was studied in heteroirophic cell‐suspension cultures of carrot ( Daucus caroia L.), Agrostemma githago L. (corn cockle). Digitalis purpurea L. (purple foxglove), soyabean ( Giycine max L. Merr; four different cultivars). Datura stramonium L. (thorn‐apple) and wheat ( Tritician aestivum L.). During 48 h of incubation, the herbicide was biotransformed by all species; turnovers yields differed considerably and were between 10.1% and 88.0% of applied 14 C. Differences were also observed among the soyabean cultivars (10.1‐73.5%). Hydroxy‐atrazine, de‐ethyl‐, deisopropyl‐ and de‐ethyt‐deisopropylatrazine formed in the cultures were identified by thin‐layer chromatography (tlc) (co‐chromatography with reference compounds); deaikyiated metabolites were also proved by gas chromatography–mass spectrometry (gc–ms). In addition, highly polar transformation products emerged that were not identified. Portions of non‐extractable residues were below 5% (one soyabean cultivar: 8.9%). Atrazine was metabolized by the cells, mainly to its dealkylated derivatives and hydroxyatrazine (totals of 9.4‐54, 5%), whereas portions of highly polar products were lower (0.1‐26.1%). Exceptions were A. githago (26.0 and 33.6%, respectively) and D, purpurea (4.5 and 25.2% respectively). Thus, plants generally contribute to the environmental degradation of atrazine.