Pyrene Metabolites in the Hepatopancreas and Gut of the Isopod Porcellio Scaber, a New Biomarker for Polycyclic Aromatic Hydrocarbon Exposure in Terrestrial Ecosystems

Abstract

The object of this study was to investigate the formation of pyrene metabolites by the isopod Porcellio scaber as a possible tool in the environmental risk assessment of polycyclic aromatic hydrocarbon (PAH) exposure in terrestrial ecosystems. The formation of pyrene metabolites was studied after either pulse exposure to a single high dose, or prolonged exposure (14 d) to a lower dosage. Exposure studies were carried out with unlabeled or radiolabeled pyrene, ion pair chromatography was used for analysis, and reference conjugates were synthesized. We also measured pyrene metabolites in field-exposed animals, to explore their use as biomarkers of PAH exposure. Analysis of the hepatopancreas and gut of single isopods revealed the formation of five products, one of which was 1-hydroxypyrene. Four of the remaining products were identified as phase II metabolites of 1- hydroxypyrene, with UV absorption and fluorescence characteristics similar to that of pyrene. One metabolite was identified as pyrene-1-glucoside, which is in accordance with high rates of glucosidation, reported for these isopods. Another conjugate was identified as pyrene-1-sulfate. None of the metabolites coeluted with a pyrene-1-glucuronide reference obtained from fish bile. A fifth metabolite detected by on-line scintillation detection did not exhibit any absorption at 340 nm, possibly because one of the aromatic rings of pyrene had lost its aromatic character. Although pyrene is not known for its toxicity, it usually co-occurs with other PAHs that are transformed into toxic products. Investigating the metabolism of pyrene can provide information with regard to the biotransformation capacity of invertebrate species and uptake and elimination kinetics. Because pyrene is one of the most predominant PAHs in the environment, analysis of its metabolites provides an extra tool for the environmental risk assessment of ecosystems with regard to PAH exposure, bioavailability, and biotransformation.

Analysis of pyrene metabolites in marine snails by liquid chromatography using fluorescence and mass spectrometry detection

“…By collecting chromatograms at both of these wavelength pairs, the relative fluorescence response can be used as a tool for identifying PY metabolites in complex extracts, especially in the absence of a scanning fluorescence detector. When compared with 335/380, another commonly used wavelength pair [27][28][29]48,49], 235/388 also showed a significant increase in sensitivity. While low wavelength excitation did result in slightly more interference from fluorescent material in the matrix, the increase in sensitivity allowed for the detection of trace levels of PY metabolites in reference animals (Section 3.4) that was not possible with any other wavelength pair.…”

Soil ecotoxicology: state of the art and future directions

“…Van Gestel et al 2009). Isopods may be used for such biomarker studies (Köhler et al 1999, Stroomberg et al 1999, Stanek et al 2006, Drobne et al 2008, Lemos et al 2009), while also their potential of accumulating metals has been proposed as a suitable monitoring tool (‘woodlouse watch’ scheme) especially in metal-contaminated areas (Hopkin et al 1993). …”

Relationship between metabolism and bioaccumulation of benzo[α]pyrene in benthic invertebrates

“…Presented at the 23rd Annual Meeting, Society of Environmental Toxicology and Chemistry, Salt Lake City, Utah, USA November 16-20, 2002. olites most likely occurs through a combination of active elimination (e.g., excretion of water soluble conjugates) and passive elimination (e.g., parent PAH and some metabolites) [3,[12][13][14][15]. The little data that exist suggest that invertebrates tend to excrete metabolites more slowly than vertebrate species [6,11,16,17] Current results are conflicting on the degree to which PAH metabolism is inducible in marine invertebrates [3].…”