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Inhibition of pyrene biotransformation by piperonyl butoxide and identification of two pyrene derivatives in Lumbriculus variegatus (Oligochaeta)
Author(s) -
Carrasco Navarro Víctor,
Brozinski JennyMaria,
Leppänen Matti T.,
Honkanen Jani O.,
Kronberg Leif,
Kukkonen Jussi V.K.
Publication year - 2011
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.485
Subject(s) - biotransformation , pyrene , chemistry , bioaccumulation , piperonyl butoxide , metabolite , chromatography , environmental chemistry , hydroxylation , biochemistry , toxicity , enzyme , organic chemistry
Using the freshwater annelid Lumbriculus variegatus (Oligochaeta), the presence of cytochrome P450 (CYP) isozymes was investigated by analyzing metabolites of the polycyclic aromatic hydrocarbon (PAH) pyrene in treatments with and without the CYP inhibitor piperonyl butoxide (PBO). The results show a low biotransformation capability of L. variegatus (7% of total pyrene body burden as metabolites at 168 h). Addition of PBO resulted in a significant reduction of metabolites, suggesting the presence of a CYP in L. variegatus . Besides 1‐hydroxypyrene, three peaks representing unknown metabolites were detected in LC‐FLD (liquid chromatography with fluorescence detection) chromatograms of L. variegatus . Deconjugations showed that sulfonation and glucosidation are involved in the formation of these unknowns. Further studies with the time of flight mass analyzer provided the identification of the glucose‐sulfate conjugate of 1‐hydroxypyrene. The same metabolites were detected in the solvent‐nonextractable fraction by incubation of the tissue residues with proteinase K, suggesting that part of these metabolites are bound to proteins. Overall, the slow biotransformation of pyrene by L. variegatus (involving CYP) supports the use of this species in standard bioaccumulation tests; however, the tissue‐bound metabolite fraction described in the current study deserves further investigation for its toxicity and availability to upper trophic levels through diet. Environ. Toxicol. Chem. 2011; 30:1069–1078. © 2011 SETAC