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Comparison of the Biotransformation of the 14 C‐Labelled Insecticide Carbaryl by Non‐Transformed and Human CYP1A1‐, CYP1A2‐, and CYP3A4‐Transgenic Cell Cultures of Nicotiana tabacum
Author(s) -
Schmidt Burkhard,
Faymonville Tanja,
Gembé Eva,
Joußen Nicole,
Schuphan Ingolf
Publication year - 2006
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200690091
Subject(s) - carbaryl , biotransformation , cyp1a2 , chemistry , metabolite , cytochrome p450 , transformation (genetics) , cyp3a4 , biochemistry , chromatography , enzyme , pesticide , biology , gene , agronomy
Transgenic tobacco‐cell‐suspension cultures expressing separately the human cytochrome P450 monooxygenases CYP1A1, CYP1A2, and CYP3A4 were utilized to study the biotransformation of the 14 C‐labelled insecticide carbaryl (=naphthalen‐1‐yl methylcarbamate). The resulting data were compared to similar data from the corresponding non‐transformed (NT) tobacco‐cell culture and commercially available membrane preparations ( Bactosomes ® ) of genetically modified bacteria separately containing the same human P450s. A rapid conversion rate of carbaryl was observed with the CYP1A1 and CYP1A2 cells, where only 49.7 and 0.2% of applied carbaryl (1 mg/l), respectively, remained after 24 h, as compared to 77.7% in the non‐transformed culture. Unexpectedly, the corresponding results obtained from the CYP3A4 cultures were not definite. With 25 mg/l of carbaryl and 96 h of incubation, it was proven that the insecticide is also substrate of CYP3A4. This finding was supported by GC/EI‐MS analysis of the primary metabolite pattern produced by the isozyme. This consisted of naphthalene‐1‐ol, N ‐(hydroxymethyl)carbaryl, 4‐hydroxycarbaryl, and 5‐hydroxycarbaryl, whereas the main product in non‐transformed cells was N ‐(hydroxymethyl)carbaryl. Data obtained from the CYP1A1, CYP1A2, or CYP3A4 Bactosomes ® agreed with those of the P450‐transgenic tobacco cells. Problems with GC/EI‐MS analysis of carbaryl and its metabolites are discussed.