Inhibition of pyrene biotransformation by piperonyl butoxide and identification of two pyrene derivatives in Lumbriculus variegatus (Oligochaeta)

Abstract

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.

Bioconcentration, biotransformation and elimination of pyrene in the arctic crustacean Gammarus setosus (Amphipoda) at two temperatures

“…(4) was obtained for the total body burden concentrations (r 2 = 0.90 283 and 0.88 for 2 and 8 ºC treatments, respectively). This resulted in a good estimation of k u to 284 start working with the model described by equations(1)(2)(3).…”

“…They were calculated by fitting the experimental data during the depuration 227 phase to the equations (6-7) 228 ln C total = ln C total,0 -k d ·t (6) 229 ln C p = ln C p, 0 -k dp ·t (7) 230 Based on the results found for k dp and k d , the variables k ep and k m were then calculated with The variables from equations (1)(2)(3)(4) and BCFs were compared following Bailer et al (2000).…”

Sex pheromone component produced by microbial associates of the forest pestMegaplatypus mutatus

“…Filamentous secretion reactions are usually mediated by monooxygenase enzymes that belong to the cytochrome P450 system (van den Brink et al., ). An indirect method for studying the activity of P450 enzymes is by using piperonyl butoxide (PBO), which acts as inhibitor of these enzymes and allows for the determination of P450‐dependancy of a chemical reaction (Carrasco Navarro et al., ). In this context, we incubated the reaction mixture of fungus cultures and sulcatol with PBO to rule out any P450 or mixed function oxidase (MFO) role in the oxidation of sulcatol to sulcatone.…”

Bioaccumulation and Biotransformation of Triclosan and Galaxolide in the Freshwater Oligochaete Limnodrilus hoffmeisteri in a Water/Sediment Microcosm

“…However, little to no research has been performed to investigate their degradation under more ecologically realistic conditions, such as water/sediment systems in the presence of oligochaete worms that may efficiently biotransform organic contaminants. For example, Lumbriculus variegatus (Oligochaeta) was reported to biotransform pyrene into 1-hydroxypyrene …”