Publications by authors named "Claudio Erratico"

27 Publications

  • Page 1 of 1

Allometric Scaling Approaches for Predicting Human Pharmacokinetic of a Locked Nucleic Acid Oligonucleotide Targeting Cancer-Associated miR-221.

Cancers (Basel) 2019 Dec 19;12(1). Epub 2019 Dec 19.

Department of Experimental and Clinical Medicine, Magna Graecia University, 88100 Catanzaro, Italy.

LNA-i-miR-221 is a novel phosphorothioate backbone 13-mer locked nucleic acid oligonucleotide-targeting microRNA-221 designed for the treatment of human malignancies. To understand the pharmacokinetic properties of this new agent, including unbound/total clearance, we investigated the LNA-i-miR-221 protein binding in three different species, including rat (Sprague-Dawley), monkey (Cynomolgus), and human. To this end, we generated a suitable ultrafiltration method to study the binding of LNA-i-miR-221 to plasma proteins. We identified that the fraction of LNA-i-miR-221 (at concentration of 1 and 10 µM) bound to rat, monkey, and human plasma proteins was high and ranged from 98.2 to 99.05%. This high protein binding of LNA-i-miR-221 to plasma proteins in all the species tested translates into a pharmacokinetic advantage by preventing rapid renal clearance. The integration of these results into multiple allometric interspecies scaling methods was then used to draw inferences about LNA-i-miR-221 pharmacokinetics in humans, thereby providing a framework for definition of safe starting and escalation doses and moving towards a first human clinical trial of LNA-i-miR-221.
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http://dx.doi.org/10.3390/cancers12010027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7017297PMC
December 2019

Mass spectrometric identification of in vitro-generated metabolites of two emerging organophosphate flame retardants: V6 and BDP.

Chemosphere 2018 Dec 3;212:1047-1057. Epub 2018 Sep 3.

Toxicological Centre, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium. Electronic address:

The aim of the present study was to investigate the in vitro metabolism of two emerging organophosphate flame retardants, namely tetrekis(2-chlorethyl)dichloroisopentyldiphosphate (V6) and bisphenol-A bis-diphenyl phosphate (BDP) in human liver microsomes (HLMs), HLM S9 fractions and in human serum. In particular, the role of cytochrome P450 (CYPs) enzymes and/or paraoxonases (PONs) in the formation of V6 and BDP phase I metabolites was studied. Mono-, di-hydroxylated and hydrolytic phase I metabolites of V6 were mainly formed by CYPs in HLMs, while hydrolytic and O-dealkylated phase I metabolites of BDP were generated by PONs mainly in serum experiments. Limited number of glucuronidated and sulfated phase II metabolites were also identified for the two chemicals. The activity of seven recombinant CYPs (rCYPs) including rCYP1A2, rCYP2B6, rCYP2C9, rCYP2C19, rCYP2D6, rCYP2E1 and rCYP3A4 in the in vitro phase I metabolism of V6 and BDP was investigated. The formation of V6 metabolites was catalyzed by several enzymes, especially rCYP1A2 that was responsible for the exclusive formation of two metabolites, one primary (M1) and its secondary metabolite (M9). For BDP, only one phase I metabolite (MM1) was catalyzed by the seven rCYPs. Collectively, these results indicate that CYPs have a predominant role in the metabolism of V6, while PONs have a predominant role in BDP in vitro metabolism. These results are a starting point for future studies involving the study of the toxicity, bioaccumulation and in vivo biomonitoring of V6 and BDP.
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http://dx.doi.org/10.1016/j.chemosphere.2018.08.142DOI Listing
December 2018

Case Study on Screening Emerging Pollutants in Urine and Nails.

Environ Sci Technol 2017 04 22;51(7):4046-4053. Epub 2017 Mar 22.

Flemish Institute for Technological Research (VITO NV) , Boeretang 200, 2400 Mol, Belgium.

Alternative plasticizers and flame retardants (FRs) have been introduced as replacements for banned or restricted chemicals, but much is still unknown about their metabolism and occurrence in humans. We identified the metabolites formed in vitro for four alternative plasticizers (acetyltributyl citrate (ATBC), bis(2-propylheptyl) phthalate (DPHP), bis(2-ethylhexyl) terephthalate (DEHTP), bis(2-ethylhexyl) adipate (DEHA)), and one FR (2,2-bis (chloromethyl)-propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate (V6)). Further, these compounds and their metabolites were investigated by LC/ESI-Orbitrap-MS in urine and finger nails collected from a Norwegian cohort. Primary and secondary ATBC metabolites had detection frequencies (% DF) in finger nails ranging from 46 to 95%. V6 was identified for the first time in finger nails, suggesting that this matrix may also indicate past exposure to FRs as well as alternative plasticizers. Two isomeric forms of DEHTP primary metabolite were highly detected in urine (97% DF) and identified in finger nails, while no DPHP metabolites were detected in vivo. Primary and secondary DEHA metabolites were identified in both matrices, and the relative proportion of the secondary metabolites was higher in urine than in finger nails; the opposite was observed for the primary metabolites. As many of the metabolites present in in vitro extracts were further identified in vivo in urine and finger nail samples, this suggests that in vitro assays can reliably mimic the in vivo processes. Finger nails may be a useful noninvasive matrix for human biomonitoring of specific organic contaminants, but further validation is needed.
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http://dx.doi.org/10.1021/acs.est.6b05661DOI Listing
April 2017

Stereoselective Metabolism of α-, β-, and γ-Hexabromocyclododecanes (HBCDs) by Human Liver Microsomes and CYP3A4.

Environ Sci Technol 2016 08 25;50(15):8263-73. Epub 2016 Jul 25.

Toxicological Center, University of Antwerp , Universiteitsplein 1, 2610 Wilrijk, Belgium.

This is the first study investigating the in vitro metabolism of α-, β-, and γ-hexabromocyclododecane (HBCD) stereoisomers in humans and providing semiquantitative metabolism data. Human liver microsomes were incubated with individual racemic mixtures and with individual stereoisomers of α-, β-, and γ-HBCDs, the hydroxylated metabolites formed were analyzed by liquid chromatography-tandem mass spectrometry, and the value of the intrinsic in vitro clearance (Clint,vitro) was calculated. Several mono- and dihydroxylated metabolites of α-, β-, and γ-HBCDs were formed, with mono-OH-HBCDs being the major metabolites. No stereoisomerization of any of the six α-, β-, and γ-HBCD isomers catalyzed by cytochrome P450 (CYP) enzymes occurred. The value of Clint,vitro of α-HBCDs was significantly lower than that of β-HBCDs, which, in turn, was significantly lower than that of γ-HBCDs (p < 0.05). Such differences were explained by the significantly lower values of Clint,vitro of each α-HBCD stereoisomer than those of the β- and γ-HBCD stereoisomers. In addition, significantly lower values of Clint,vitro of the (-) over the (+)α- and β-HBCD stereoisomers, but not γ-HBCDs, were obtained. Our data offer a possible explanation of the enrichment of α-HBCDs over β- and γ-HBCDs on the one hand and, on the other hand, of (-)α-HBCDs over (+)α-HBCDs previously reported in human samples. It also offers information about the mechanism resulting in such enrichments, the stereoisomer-selective metabolism of α-, β-, and γ-HBCDs catalyzed by CYPs with the lack of stereoisomerization.
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http://dx.doi.org/10.1021/acs.est.6b01059DOI Listing
August 2016

Oxidative metabolism of BDE-47, BDE-99, and HBCDs by cat liver microsomes: Implications of cats as sentinel species to monitor human exposure to environmental pollutants.

Chemosphere 2016 May 15;151:30-6. Epub 2016 Mar 15.

Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium. Electronic address:

The in vitro oxidative metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and individual α-, β- and γ-hexabromocyclododecane (HBCD) isomers catalyzed by cytochrome P450 (CYP) enzymes was screened using cat liver microsomes (CLMs). Six hydroxylated metabolites, namely 4-hydroxy-2,2',3,4'-tetrabromodiphenyl ether (4-OH-BDE-42), 3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (3-OH-BDE-47), 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE-47), 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47), 4'-hydroxy-2,2',4,5'- tetrabromodiphenyl ether (4'-OH-BDE-49), and 2'-hydroxy-2,3',4,4'-tetrabromodiphenyl ether (2'-OH-BDE-66), were identified and quantified after incubation of BDE-47. A di-OH-tetra-BDE was also found as metabolite of BDE-47 with CLMs. 5-OH-BDE-47 was the major metabolite formed. Five hydroxylated metabolites (3'-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (3'-OH-BDE-99), 5'-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (5'-OH-BDE-99), 6-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (6-OH-BDE-99), 6'-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (6'-OH-BDE-99), and 4'-hydroxy-2,2',4,5,5'-pentabromodiphenyl ether (4'-OH-BDE-101) were formed from BDE-99 incubated with CLMs. Concentrations of BDE-99 metabolites were lower than those of BDE-47. Four or more mono-hydroxylated HBCD (OH-HBCDs), four or more di-hydroxylated HBCD (di-OH-HBCDs), five or more mono-hydroxylated pentabromocyclododecanes (OH-PBCDs), and five or more di-hydroxylated pentabromocyclododecenes (di-OH-PBCDs) were detected after incubation of α-, β-, or γ-HBCD with CLMs. No diastereoisomeric or enantiomeric enzymatic isomerisation was observed incubating α-, β- or γ-HBCD with CLMs. Collectively, our data suggest that (i) BDE-47 is metabolized at a faster rate than BDE-99 by CLMs, (ii) OH-HBCDs are the major hydroxylated metabolites of α-, β- and γ-HBCD produced by CLMs, and (iii) the oxidative metabolism of BDE-47 and BDE-99 is different by cat and human liver microsomes. This suggests that cats are not a suitable sentinel to represent internal exposure of PBDEs for humans, but is likely a promising sentinel for internal HBCDs exposure for humans.
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http://dx.doi.org/10.1016/j.chemosphere.2016.02.054DOI Listing
May 2016

In vitro metabolism of BDE-47, BDE-99, and α-, β-, γ-HBCD isomers by chicken liver microsomes.

Environ Res 2015 Nov 24;143(Pt A):221-8. Epub 2015 Oct 24.

Toxicological Centre, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium. Electronic address:

The in vitro oxidative metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and the individual α-, β- and γ-hexabromocyclododecane (HBCD) isomers catalyzed by cytochrome P450 (CYP) enzymes was studied using chicken liver microsomes (CLMs). Metabolites were identified using a liquid chromatography-tandem mass spectrometry method and authentic standards for the oxidative metabolites of BDE-47 and BDE-99. Six hydroxylated tetra-BDEs, namely 4-hydroxy-2,2',3,4'-tetrabromodiphenyl ether (4-OH-BDE-42), 3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (3-OH-BDE-47), 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE-47), 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47), 4'-hydroxy-2,2',4,5'- tetrabromodiphenyl ether (4'-OH-BDE-49), and 2'-hydroxy-2,3',4,4'-tetrabromodiphenyl ether (2'-OH-BDE-66), were identified and quantified after incubation of BDE-47 with CLMs. 4'-OH-BDE-49 was the major metabolite formed. Three hydroxylated penta-BDEs (5'-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (5'-OH-BDE-99), 6'-hydroxy-2,2',4,4',5- pentabromodiphenyl ether (6'-OH-BDE-99), and 4'-hydroxy-2,2',4,5,5'-pentabromodiphenyl ether, 4'-OH-BDE-101, were formed incubating BDE-99 with CLMs. Concentrations of BDE-99 metabolites were lower than those of BDE-47. More than four mono-hydroxylated HBCD (OH-HBCD), more than four di-hydroxylated HBCD (di-OH-HBCD), more than five mono-hydroxylated pentabromocyclododecenes (OH-PBCD), and more than five di-hydroxylated pentabromocyclododecenes (di-OH-PBCD) were detected when α-, β-, or γ-HBCD were individually incubated with CLMs. Response values (the ratio between the peak areas of the target compound and its internal standard) for OH-HBCD were 1-3 orders of magnitude higher than those for OH-PBCD, di-OH-HBCD, and di-OH-PBCD, suggesting that OH-HBCD might be the major metabolites of α-, β- and γ-HBCD produced by CLMs. No diastereoisomeric or enantiomeric bioisomerisation was observed incubating α-, β- or γ-HBCD with CLMs. Collectively, our data suggest that (i) BDE-47 is metabolized at a faster rate than BDE-99 by CLMs, (ii) OH-HBCD are the major hydroxylated metabolites of α-, β- and γ-HBCD produced by CLMs and (iii) the diastereoisomeric or enantiomeric bioisomerisation of α-, β- and γ-HBCD is not mediated by chicken CYP enzymes.
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http://dx.doi.org/10.1016/j.envres.2015.10.023DOI Listing
November 2015

Identification of in vitro metabolites of ethylphenidate by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

J Pharm Biomed Anal 2016 Jan 23;117:474-84. Epub 2015 Oct 23.

Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk-Antwerp, Belgium. Electronic address:

Ethylphenidate is a new potent synthetic psychoactive drug, structurally related to methylphenidate. Using human liver microsomes and cytosol, we have investigated for the first time the Phase-I and Phase-II in vitro metabolism of ethylphenidate. The structure of the metabolites was elucidated by hybrid quadrupole time-of-flight mass spectrometry. Overall, seven Phase-I, but no Phase-II metabolites were detected. Ethylphenidate underwent hydroxylation forming two primary mono-hydroxylated metabolites and, subsequently, dehydration and ring opening with an additional hydroxylation, forming secondary metabolites. The involvement of different human cytochrome P450 (CYP) enzymes in the formation of ethylphenidate metabolites was investigated using a panel of human recombinant CYPs (rCYPs). rCYP2C19 was the most active recombinant enzyme involved in the formation of all seven ethylphenidate metabolites detected, although other rCYPs (rCYP1A2, rCYP2B6, rCYPC9, rCYP2D6, and rCYP3A4, but not rCYP2E1) played a role in the metabolism of ethylphenidate. All metabolites identified in the present study can be considered as potential specific biomarkers of ethylphenidate in toxicological studies. Additionally, ritalinic acid and methylphenidate were formed by non-enzymatic hydrolysis and trans-esterification, and, therefore, they cannot be considered as (oxidative) metabolites of ethylphenidate. The presence of methylphenidate and ritalinic acid cannot be exclusively associated to the use of ethylphenidate, since methylphenidate is a drug itself and ritanilic acid can be formed from both ethylphenidate and methylphenidate.
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http://dx.doi.org/10.1016/j.jpba.2015.09.029DOI Listing
January 2016

Liquid chromatography-quadrupole time-of-flight mass spectrometry for screening in vitro drug metabolites in humans: investigation on seven phenethylamine-based designer drugs.

J Pharm Biomed Anal 2015 Oct 12;114:355-75. Epub 2015 Jun 12.

Toxicological Center, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.

Phenethylamine-based designer drugs are prevalent within the new psychoactive substance market. Characterisation of their metabolites is important in order to identify suitable biomarkers which can be used for better monitoring their consumption. Careful design of in vitro metabolism experiments using subcellular liver fractions will assist in obtaining reliable outcomes for such purposes. The objective of this study was to stepwise investigate the in vitro human metabolism of seven phenethylamine-based designer drugs using individual families of enzymes. This included para-methoxyamphetamine, para-methoxymethamphetamine, 4-methylthioamphetamine, N-methyl-benzodioxolylbutanamine, benzodioxolylbutanamine, 5-(2-aminopropyl) benzofuran and 6-(2-aminopropyl) benzofuran. Identification and structural elucidation of the metabolites was performed using liquid chromatography-quadrupole-time-of-flight mass spectrometry. The targeted drugs were mainly metabolised by cytochrome P450 enzymes via O-dealkylation as the major pathway, followed by N-dealkylation, oxidation of unsubstituted C atoms and deamination (to a small extent). These drugs were largely free from Phase II metabolism. Only a limited number of metabolites were found which was consistent with the existing literature for other phenethylamine-based drugs. Also, the metabolism of most of the targeted drugs progressed at slow rate. The reproducibility of the identified metabolites was assessed through examining formation patterns using different incubation times, substrate and enzyme concentrations. Completion of the work has led to a set of metabolites which are representative for specific detection of these drugs in intoxicated individuals and also for meaningful evaluation of their use in communities by wastewater-based drug epidemiology.
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http://dx.doi.org/10.1016/j.jpba.2015.06.016DOI Listing
October 2015

In vitro Phase I and Phase II metabolism of α-pyrrolidinovalerophenone (α-PVP), methylenedioxypyrovalerone (MDPV) and methedrone by human liver microsomes and human liver cytosol.

Anal Bioanal Chem 2015 Jul 27;407(19):5803-16. Epub 2015 May 27.

Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Antwerp, Belgium.

The aim of the present study was to identify the in vitro Phase I and Phase II metabolites of three new psychoactive substances: α-pyrrolidinovalerophenone (α-PVP), methylenedioxypyrovalerone (MDPV), and methedrone, using human liver microsomes and human liver cytosol. Accurate-mass spectra of metabolites were obtained using liquid chromatography-quadrupole time-of-flight mass spectrometry. Six Phase I metabolites of α-PVP were identified, which were formed involving reduction, hydroxylation, and pyrrolidine ring opening reactions. The lactam compound was the major metabolite observed for α-PVP. Two glucuronidated metabolites of α-PVP, not reported in previous in vitro studies, were further identified. MDPV was transformed into 10 Phase I metabolites involving reduction, hydroxylation, and loss of the pyrrolidine ring. Also, six glucuronidated and two sulphated metabolites were detected. The major metabolite of MDPV was the catechol metabolite. Methedrone was transformed into five Phase I metabolites, involving N- and O-demethylation, hydroxylation, and reduction of the ketone group. Three metabolites of methedrone are reported for the first time. In addition, the contribution of individual human CYP enzymes in the formation of the detected metabolites was investigated.
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http://dx.doi.org/10.1007/s00216-015-8763-6DOI Listing
July 2015

Regioselective Versatility of Monooxygenase Reactions Catalyzed by CYP2B6 and CYP3A4: Examples with Single Substrates.

Adv Exp Med Biol 2015 ;851:131-49

Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T1Z3, Canada.

Hepatic microsomal cytochrome P450 (CYP) enzymes have broad and overlapping substrate specificity and catalyze a variety of monooxygenase reactions, including aliphatic and aromatic hydroxylations, N-hydroxylations, oxygenations of heteroatoms (N, S, P and I), alkene and arene epoxidations, dehalogenations, dehydrogenations and N-, O- and S-dealkylations. Individual CYP enzymes typically catalyze the oxidative metabolism of a common substrate in a regioselective and stereoselective manner. In addition, different CYP enzymes often utilize different monooxygenase reactions when oxidizing a common substrate. This review examines various oxidative reactions catalyzed by a CYP enzyme acting on a single substrate. In the first example, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a halogenated aromatic environmental contaminant, was oxidatively biotransformed by human CYP2B6. Nine different metabolites of BDE-47 were produced by CYP2B6 via monooxygenase reactions that included aromatic hydroxylation, with and without an NIH-shift, dealkylation and debromination. In the second example, lithocholic acid (3α-hydroxy-5β-cholan-24-oic acid), an endogenous bile acid, served as a substrate for human CYP3A4 and yielded five different metabolites via aliphatic hydroxylation and dehydrogenation reactions.
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http://dx.doi.org/10.1007/978-3-319-16009-2_5DOI Listing
October 2015

Human hydroxylated metabolites of BDE-47 and BDE-99 are glucuronidated and sulfated in vitro.

Toxicol Lett 2015 Jul 5;236(2):98-109. Epub 2015 May 5.

Toxicological Center, University of Antwerp, Universiteitsplein 1, Wilrijk, Belgium.

Polybrominated diphenyl ethers (PBDEs) were used worldwide as additive flame retardants and are classified as persistent, bioaccumulable and toxic environmental pollutants. In humans, the hydroxylated metabolites of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) formed in vitro have also been detected in vivo. To further characterize the metabolism of BDE-47 and BDE-99 and to identify candidate markers for monitoring the human exposure to PBDEs using non-invasive approaches, glucuronidation and sulfation of hydroxylated metabolites of BDE-47 and BDE-99 were investigated using human liver microsomes and cytoplasm, respectively. The formed Phase II metabolites were analyzed by liquid chromatography-tandem mass spectrometry using a novel approach to develop analytical methods in absence of authentic standards. All available standards for hydroxylated metabolites of BDE-47 and BDE-99 were glucuronidated and sulfated, showing that glucuronidation and sulfation are part of the metabolism pathway of BDE-47 and BDE-99 in vitro. The major glucuronidated and sulfated analogs of hydroxylated metabolites of BDE-47 were (a) 2,4-DBP-Gluc and 5-Gluc-BDE-47, and (b) 2'-Sulf-BDE-28, 4-Sulf-BDE-42 and 3-Sulf-BDE-47, respectively. The major glucuronidated and sulfated analogs of hydroxylated metabolites of BDE-99 were (a) 2,4,5-TBP-Gluc and 6'-Gluc-BDE-99, and (b) 3'-Sulf-BDE-99 and 5'-Sulf-BDE-99, respectively. Apparent Km values associated with the formation of sulfated metabolites of BDE-47 and BDE-99 were ten times lower than those of the corresponding glucuronidated metabolites, suggesting that sulfated rather than glucuronidated metabolites of OH-PBDEs might be used as markers of human exposure to PBDEs using a non-invasive approach based on urine sample collection.
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http://dx.doi.org/10.1016/j.toxlet.2015.05.003DOI Listing
July 2015

In vitro and in vivo human metabolism of the synthetic cannabinoid AB-CHMINACA.

Drug Test Anal 2015 Oct 12;7(10):866-76. Epub 2015 Apr 12.

Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk-Antwerp, Belgium.

N-[(1S)-1-(aminocarbonyl)-2-methylpropyl]-1-(cyclohexylmethyl)-1H-indazole-3-carboxamide (AB-CHMINACA) is a recently introduced synthetic cannabinoid. At present, no information is available about in vitro or in vivo human metabolism of AB-CHMINACA. Therefore, biomonitoring studies to screen AB-CHMINACA consumption lack any information about the potential biomarkers (e.g. metabolites) to target. To bridge this gap, we investigated the in vitro metabolism of AB-CHMINACA using human liver microsomes (HLMs). Formation of AB-CHMINACA metabolites was monitored using liquid chromatography coupled to time-of-flight mass spectrometry. Twenty-six metabolites of AB-CHMINACA were detected including seven mono-hydroxylated and six di-hydroxylated metabolites and a metabolite resulting from N-dealkylation of AB-CHMINACA, all produced by cytochrome P450 (CYP) enzymes. Two carboxylated metabolites, likely produced by amidase enzymes, and five glucuronidated metabolites were also formed. Five mono-hydroxylated and one carboxylated metabolite were likely the major metabolites detected. The involvement of individual CYPs in the formation of AB-CHMINACA metabolites was tested using a panel of seven human recombinant CYPs (rCYPs). All the hydroxylated AB-CHMINACA metabolites produced by HLMs were also produced by the rCYPs tested, among which rCYP3A4 was the most active enzyme. Most of the in vitro metabolites of AB-CHMINACA were also present in urine obtained from an AB-CHMINACA user, therefore showing the reliability of the results obtained using the in vitro metabolism experiments conducted to predict AB-CHMINACA in vivo metabolism. The AB-CHMINACA metabolites to target in biomonitoring studies using urine samples are now reliably identified and can be used for routine analysis.
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http://dx.doi.org/10.1002/dta.1796DOI Listing
October 2015

Levels of PBDEs in plasma of juvenile starlings (Sturnus vulgaris) from British Columbia, Canada and assessment of PBDE metabolism by avian liver microsomes.

Sci Total Environ 2015 Jun 3;518-519:31-7. Epub 2015 Mar 3.

Environment Canada, 5421 Robertson Road, Delta, British Columbia, Canada. Electronic address:

In this study, the levels of polybrominated diphenyl ethers (PBDEs), HO-PBDEs, and bromophenols were monitored in starling chick plasma samples collected in Delta (British Columbia, Canada) close to the Vancouver municipal landfill and in Glen Valley, a rural area in British Columbia. The in vitro formation of hydroxylated metabolites of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) was also investigated using starling chick liver microsomes. Total PBDE plasma levels were approximately 60 times higher in starling chicks from Delta than from Glen Valley, suggesting that the Delta site is a major source of PBDEs for the local population of starlings and that PBDEs previously measured in starling eggs are bioavailable to chicks. In both locations, BDE-47 and BDE-99 were the two major congeners present at similar concentrations, suggesting contamination with the Penta-BDE mixture. Among the several possible hydroxylated metabolites of PBDEs monitored in starling plasma, only 2,4,5-tribromophenol was detected and its levels did not exceed 18±7 pg/mL. Also, several hydroxylated metabolites of BDE-47 and BDE-99 were formed by starling chick liver microsomes, but in low amounts. Therefore, our data consistently suggest that oxidative metabolism of PBDEs in starling chicks proceeds at low rate in vivo and in vitro. In conclusion, the landfill located in Delta is a relevant source of bioavailable PBDEs for the local starling population. Because of the limited ability of starling chicks to metabolize PBDEs, these compounds are likely to bioaccumulate in starlings over time. The possible toxicological implications of PBDEs bioaccumulation in starlings are currently unknown and require further research.
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http://dx.doi.org/10.1016/j.scitotenv.2014.12.102DOI Listing
June 2015

In vitro biotransformation of tris(2-butoxyethyl) phosphate (TBOEP) in human liver and serum.

Toxicol Appl Pharmacol 2015 Apr 11;284(2):246-53. Epub 2015 Feb 11.

Toxicological Center, Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium. Electronic address:

Tris(2-butoxyethyl) phosphate (TBOEP) is a plasticizer present in indoor dust, reaching levels of several micrograms per gram. Such levels could lead to significant daily exposure of adults and children. Currently, no toxicokinetic data are available to estimate TBOEP clearance in humans after uptake and therefore, one objective of this study was to investigate intrinsic clearance of TBOEP by human liver microsome (HLM) and serum enzymes. Another objective was to generate information to identify and prioritize several metabolites of TBOEP for investigation of human exposure by biomonitoring. 1D and 2D-NMR methodologies were successfully applied on a mixture of the metabolites to confirm the structure of 3-HO-TBOEP (bis(2-butoxyethyl) 3-hydroxyl-2-butoxyethyl phosphate) and to tentatively assign structures to 1-HO-TBOEP and 2-HO-TBOEP. HO-TBOEP isomers and bis(2-butoxyethyl) phosphate (BBOEP), bis(2-butoxyethyl) hydroxyethyl phosphate (BBOEHEP) were further monitored by liquid chromatography-tandem mass spectrometry. Rates of formation of BBOEHEP and HO-TBOEP metabolites by liver enzymes were best described by the Michaelis-Menten model. Apparent Km values for BBOEHEP, 3-HO-TBOEP, and sum of 1- and 2-HO-TBOEP isomer formation were 152, 197 and 148μM, respectively. Apparent Vmax values for the formation of BBOEHEP, 3-HO-TBOEP, and the sum of 1- and 2-HO-TBOEP isomers were 2560, 643, and 254pmol/min/mg protein, respectively. No detectable formation of BBOEP occurred with liver or serum enzymes. Our findings indicate that intrinsic clearance of TBOEP is mainly catalyzed by oxidative enzymes in the liver and that its major in vitro metabolite is BBOEHEP. These findings can be applied in human biomonitoring studies and risk assessment.
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http://dx.doi.org/10.1016/j.taap.2015.01.021DOI Listing
April 2015

In vitro metabolism of 2-ethylhexyldiphenyl phosphate (EHDPHP) by human liver microsomes.

Toxicol Lett 2015 Jan 11;232(1):203-12. Epub 2014 Nov 11.

Toxicological Center, University of Antwerp, Universiteitsplein 1, Antwerp, Wilrijk 2610, Belgium.

2-ethylhexyl diphenyl phosphate (EHDPHP) is used as flame retardant and plasticizer additive in a variety of consumer products. Since EHDPHP is toxic to aquatic organisms and has been detected in environmental samples, concerns about human exposure and toxicity are emerging. With the aim of identifying human-specific metabolites, the biotransformation of EHDPHP was investigated using human liver microsomes. Using an in silico program (Meteor) for the prediction of metabolites, untargeted screening tools (agilent Mass Hunter) and a suitable analysis platform based on ultra-high performance liquid chromatography (UPLC) and quadrupole time-of-flight high resolution mass spectrometer (QTOF-MS), for the first time a wide variety of phases-I and II metabolites of EHDPHP were identified. Mono- and di-hydroxylated metabolites, keto metabolites, mixed keto and hydroxylated metabolites and diphenyl phosphate were the major phase-I metabolites of EHDPHP. Glucuronidated metabolites of phase-I metabolites of EHDPHP were also formed by human liver microsomes. Using these results, we propose a general metabolism pathway for EHDPHP in humans and a number of candidate biomarkers for assessing the human exposure to this ubiquitous phosphate flame retardant and plasticizer in future biomonitoring studies. Furthermore, we provide a template analytical approach based on the combination of untargeted and targeted screening and UPLC-QTOF-MS analysis suitable for use in future metabolism studies.
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http://dx.doi.org/10.1016/j.toxlet.2014.11.007DOI Listing
January 2015

Human biomonitoring of emerging pollutants through non-invasive matrices: state of the art and future potential.

Anal Bioanal Chem 2014 Jul 15;406(17):4063-88. Epub 2014 May 15.

Flemish Institute for Technological Research (VITO NV), Boeretang 200, 2400, Mol, Belgium,

Human biomonitoring (HBM) is a scientific technique that allows us to assess whether and to what extent environmental pollutants enter humans. We review here the current HBM efforts for organophosphate esters, emerging flame retardants, perfluoroalkyl substances, and phthalate esters. Use of some of these chemicals has already been banned or restricted; they are regularly detected in the environment, wildlife, and human matrices. Traditionally, blood and urine collection have been widely used as sampling methods. New non-invasive approaches (e.g., saliva, hair, nails) are emerging as valid alternatives since they offer advantages with respect to sampling, handling, and ethical aspects, while ensuring similar reliability and sensitivity. Nevertheless, the identification of biomarkers of exposure is often difficult because chemicals may be metabolized in the human body. For many of the above-mentioned compounds, the mechanisms of the favorable metabolization pathways have not been unraveled, but research on important metabolites that could be used as biomarkers of exposure is growing. This review summarizes the state of the art regarding human exposure to, (non-invasive) HBM of, and metabolism of major organophosphate esters, emerging flame retardants, perfluoroalkyl substances, and phthalate esters currently detected in the environment.
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http://dx.doi.org/10.1007/s00216-014-7748-1DOI Listing
July 2014

First insights in the metabolism of phosphate flame retardants and plasticizers using human liver fractions.

Toxicol Lett 2013 Oct 27;223(1):9-15. Epub 2013 Aug 27.

Toxicological Center, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Wilrijk, Belgium.

Phosphate flame retardants and plasticizers (PFRs) are additives used in a wide range of polymers. Important representatives, such as tris(2-butoxyethyl) phosphate (TBOEP), triphenyl phosphate (TPHP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), have been found in the indoor environment at high levels. Biotransformation of these PFRs needs to be investigated because it can be a major determinant of their bioavailability and toxicity in humans. TBOEP, TPHP, TCEP, TCIPP and TDCIPP were incubated with human liver S9 fraction and microsomes. Supernatants were analyzed using a liquid chromatography coupled to a quadrupole-time-of-flight mass spectrometer. Chromatograms were scanned for the presence of Phase-I and Phase-II metabolites and tentatively identified based on mass accuracy of the molecular formula, isotopic pattern, and MS/MS spectra. The two major metabolites of TBOEP were products of O-dealkylation and of hydroxylation, respectively. TPHP was mainly transformed to its diester metabolite by O-dearylation and to a hydroxylated metabolite. TCEP was poorly metabolized into its diester and a product of oxidative dehalogenation. The major metabolite of TCIPP was a product of oxidative dehalogenation. TDCIPP was mainly transformed into its diester and a glutathione S-conjugate. The metabolites identified in the present study are candidate biomarkers for future human biomonitoring studies.
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http://dx.doi.org/10.1016/j.toxlet.2013.08.012DOI Listing
October 2013

Biotransformation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by human liver microsomes: identification of cytochrome P450 2B6 as the major enzyme involved.

Chem Res Toxicol 2013 May 11;26(5):721-31. Epub 2013 Apr 11.

Faculty of Pharmaceutical Sciences, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z3.

Polybrominated diphenyl ethers (PBDEs) were widely used flame retardants that have become persistent environmental pollutants. In the present study, we investigated the in vitro oxidative metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a major PBDE detected in human tissue and environmental samples. Biotransformation of BDE-47 by pooled and individual human liver microsomes and by human recombinant cytochrome P450 (P450) enzymes was assessed using a liquid chromatography/tandem mass spectrometry-based method. Of the nine hydroxylated metabolites of BDE-47 produced by human liver microsomes, seven metabolites were identified using authentic standards. A monohydroxy-tetrabrominated and a dihydroxy-tetrabrominated metabolite remain unidentified. Kinetic analysis of the rates of metabolite formation revealed that the major metabolites were 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE-47), 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47), and possibly the unidentified monohydroxy-tetrabrominated metabolite. Among the human recombinant P450 enzymes tested, P450 2B6 was the most active enzyme in the formation of the hydroxylated metabolites of BDE-47. Moreover, the formation of all metabolites of BDE-47 by pooled human liver microsomes was inhibited by a P450 2B6-specific antibody and was highly correlated with P450 2B6-mediated activity in single donor liver microsomes indicating that P450 2B6 was the major P450 responsible for the biotransformation of BDE-47. Additional experiments involving the incubation of liver microsomes with individual monohydroxy-tetrabrominated metabolites in place of BDE-47 demonstrated that 2,4-dibromophenol was a product of BDE-47 and several primary metabolites, but the dihydroxy-tetrabrominated metabolite was not formed by sequential hydroxylation of any of the monohydroxy-tetrabrominated metabolites tested. The present study provides a comprehensive characterization of the oxidative metabolism of BDE-47 by human liver microsomes and P450 2B6.
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http://dx.doi.org/10.1021/tx300522uDOI Listing
May 2013

Oxidative metabolism of BDE-99 by human liver microsomes: predominant role of CYP2B6.

Toxicol Sci 2012 Oct 27;129(2):280-92. Epub 2012 Jun 27.

The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.

Hydroxylated polybrominated diphenyl ethers (PBDEs) have been found in human serum, suggesting that they are formed by in vivo oxidative metabolism of PBDEs. However, the biotransformation of 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), a major PBDE detected in human tissue and environmental samples, is poorly understood. In the present study, the oxidative metabolism of BDE-99 was assessed using pooled and single-donor human liver microsomes, a panel of human recombinant cytochrome P450 (CYP) enzymes, and CYP-specific antibodies. Hydroxylated metabolites were quantified using a liquid chromatography/tandem mass spectrometry-based method. In total, 10 hydroxylated metabolites of BDE-99 were produced by human liver microsomes. Six metabolites were identified as 2,4,5-tribromophenol (2,4,5-TBP), 4-OH-BDE-90, 5'-OH-BDE-99, 6'-OH-BDE-99, 4'-OH-BDE-101, and 2-OH-BDE-123 using authentic standards. Three monohydroxy- and one dihydroxy-pentabrominated metabolites were unidentified. Rates of formation of the three major metabolites (2,4,5-TBP, 5'-OH-BDE-99, and 4'-OH-BDE-101) by human liver microsomes ranged from 24.4 to 44.8 pmol/min/mg protein. Additional experiments demonstrated that the dihydroxylated metabolite was a primary metabolite of BDE-99 and was not produced by hydroxylation of a monohydroxy metabolite. Among the panel of recombinant CYP enzymes tested, formation of all 10 hydroxylated metabolites was catalyzed solely by CYP2B6. A combined approach using antibodies to CYP2B6 and single-donor liver microsomes expressing a wide range of CYP2B6 levels confirmed that CYP2B6 was responsible for the biotransformation of BDE-99. Collectively, the results show that the oxidative metabolism of BDE-99 by human liver microsomes is catalyzed solely by CYP2B6 and is an important determinant of the toxicity and bioaccumulation of BDE-99 in humans.
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http://dx.doi.org/10.1093/toxsci/kfs215DOI Listing
October 2012

Comparative oxidative metabolism of BDE-47 and BDE-99 by rat hepatic microsomes.

Toxicol Sci 2011 Sep 14;123(1):37-47. Epub 2011 Jun 14.

Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.

Polybrominated diphenyl ethers (PBDEs) are flame-retardant chemicals that have become ubiquitous environmental pollutants. 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) and 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) are among the most prevalent PBDEs detected in humans, wildlife, and abiotic environmental matrices. The purpose of this study was to investigate the oxidative metabolism of BDE-47 and BDE-99 in rat hepatic microsomes by comparing metabolite formation rates, kinetic parameters associated with metabolite formation, and the effects of prototypical cytochrome P450 (CYP) inducers. The CYP enzymes involved were also identified. Incubation of BDE-47 with hepatic microsomes from phenobarbital-treated rats generated a total of five hydroxylated (OH-BDE) metabolites, among which 4'-hydroxy-2,2',4,5'-tetrabromodiphenyl ether (4'-OH-BDE-49) and 3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (3-OH-BDE-47) were the major metabolites, as identified using authentic standards and quantified by liquid chromatography/mass spectrometry. Incubations of BDE-99 with hepatic microsomes from dexamethasone-treated rats produced a total of seven hydroxylated metabolites, among which 4-hydroxy-2,2',3,4',5-pentabromodiphenyl ether (4-OH-BDE-90) and 6'-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (6'-OH-BDE-99) were the major metabolites. Although the overall rate of oxidative metabolism of BDE-99 by hepatic microsomes was greater than that of BDE-47, para-hydroxylation involving a National Institutes of Health shift mechanism represented a major metabolic pathway for both PBDE congeners. Among the rat recombinant CYP enzymes tested, CYP2A2 and CYP3A1 were the most active in BDE-47 and BDE-99 metabolism, respectively. However, CYP1A1 exhibited the highest activity for 4'-OH-BDE-49 and 6'-OH-BDE-99 formation, and CYP3A1 exhibited the highest activity for 3-OH-BDE-47 and 4-OH-BDE-90 formation. Collectively, the results demonstrate that oxidative metabolism of BDE-47 and BDE-99 is mediated by distinct but overlapping sets of CYP enzymes and represents a key process that determines the bioaccumulation of BDE-47 and BDE-99 in mammals.
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http://dx.doi.org/10.1093/toxsci/kfr155DOI Listing
September 2011

Validation of a novel in vitro assay using ultra performance liquid chromatography-mass spectrometry (UPLC/MS) to detect and quantify hydroxylated metabolites of BDE-99 in rat liver microsomes.

J Chromatogr B Analyt Technol Biomed Life Sci 2010 Jun 24;878(19):1562-8. Epub 2010 Apr 24.

Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, British Columbia V6T 1Z3, Canada.

The purpose of this study was to develop and validate an ultra performance liquid chromatography-mass spectrometry (UPLC/MS) method to investigate the hepatic oxidative metabolism of 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), a widely used flame retardant and ubiquitous environmental contaminant. Hydroxylated metabolites were extracted using liquid-to-liquid extraction, resolved on a C18 column with gradient elution and detected by mass spectrometry in single ion recording mode using electrospray negative ionization. The assay was validated for linearity, accuracy, precision, limit of quantification, range and recovery. Calibration curves were linear (R2 > or = 0.98) over a concentration range of 0.010-1.0 microM for 4-OH-2,2',3,4',5-pentabromodiphenyl ether (4-OH-BDE-90), 5'-OH-2,2',4,4',5-pentabromodiphenyl ether (5'-OH-BDE-99) and 6'-OH-2,2',4,4',5-pentabromodiphenyl ether (6'-OH-BDE-99), and a concentration range of 0.0625-12.5 microM for 2,4,5-tribromophenol (2,4,5-TBP). Inter- and intra-day accuracy values ranged from -2.0% to 6.0% and from -7.7% to 7.3%, respectively, and inter- and intra-day precision values ranged from 2.0% to 8.5% and from 2.2% to 8.6% (n=6), respectively. The limits of quantification were 0.010 microM for 4-OH-BDE-90, 5'-OH-BDE-99 and 6'-OH-BDE-99, and 0.0625 microM for 2,4,5-TBP. Recovery values ranged between 85 and 100% for the four analytes. The validated analytical method was applied to identify and quantify hydroxy BDE-99 metabolites formed in vitro. Incubation of BDE-99 with rat liver microsomes yielded 4-OH-BDE-90 and 6'-OH-BDE-99 as major metabolites and 5'-OH-BDE-99 and 2,4,5-TBP as minor metabolites. To our knowledge, this is the first validated UPLC/MS method to quantify hydroxylated metabolites of PBDEs without the need of derivatization.
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http://dx.doi.org/10.1016/j.jchromb.2010.04.014DOI Listing
June 2010

Polybrominated diphenyl ethers (PBDEs) in gammarids, caddisflies, and bed sediments of the lowland River Po.

Bull Environ Contam Toxicol 2009 Feb 14;82(2):200-5. Epub 2008 Nov 14.

Water Research Institute-National Council of Research, Milan, Italy.

Polybrominated diphenyl ethers (PBDEs) were investigated in sediments and invertebrates (gammarids and caddisflies) collected in the River Po, upstream and downstream from a polluted tributary. Besides a diffuse contamination by penta-BDE technical mixture, the river sediments identified the tributary as an important source to the main river of decabromodiphenyl ether (BDE-209), which peaked to 64 microg/g (OC) in the downstream stretch. At 10 km downstream from the tributary, a higher bioavailability was evident than at 22 km, and small gammarids accumulated at two/three times the levels of PBDEs found in large gammarids. The congener profiles of sediments and invertebrates were dominated by BDE-47, BDE-99 and BDE-209.
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http://dx.doi.org/10.1007/s00128-008-9605-4DOI Listing
February 2009

Estrogenicity profile and estrogenic compounds determined in river sediments by chemical analysis, ELISA and yeast assays.

Chemosphere 2008 Oct 16;73(7):1078-89. Epub 2008 Sep 16.

Water Research Institute, National Council of Research, Brugherio (Milan), Italy.

An effects-directed strategy was applied to bed sediments of a polluted tributary in order to isolate and identify the major estrogenic chemicals it discharges into the River Po, the principal Italian watercourse. Sediment extract was concentrated by solid phase extraction and then fractioned into 10 fractions by reversed phase high performance liquid chromatography (RP-HPLC). Estrogenic activity of whole extract and fractions were determined using a recombinant yeast assay containing the human estrogen receptor (YES). The 10 fractions and whole extract were analysed for target compounds, e.g. estrone (E1), 17beta-estradiol (E2), estriol (E3), 4-nonylphenol (NP), 4-tert-octylphenol (t-OP), bisphenol A (BPA), using both liquid chromatography-tandem mass spectrometry (LC-MS/MS) and non-competitive enzyme-linked immunosorbent assays (ELISA). The YES assay determined high estrogenic activity in whole sediment (15.6 ng/g EE2 equivalents), and positive results for fractions nr 1, 2, 6, 7 and 8. E1, E3 and NP were the main estrogenic chemicals, however, other unidentified compounds contributed to sediment estrogenicity, particularly for polar fractions nr 1 and 2. A GC-MS screening performed in scan mode identified other potential contributors such as phthalates (DBP, BBP), and OP isomers. A next sampling campaign extended to other tributaries and receiving stretches of the River Po confirmed E1, E3 and NP as major estrogenic chemicals potentially threatening other sites of the main river. In general, target compound ELISAs have been shown to be suitable tools for a rapid screening of wide areas or large numbers of environmental samples for estrogenic risk. The potential for interferences suggests however to use cautiously the concentration values obtained from some of the immunoassays.
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http://dx.doi.org/10.1016/j.chemosphere.2008.07.057DOI Listing
October 2008

Vitellogenin as a biomarker for estrogenic effects in brown trout, Salmo trutta: laboratory and field investigations.

Environ Toxicol Chem 2008 Nov;27(11):2387-96

Institute of Biology, 55, Campusvej, DK-5230 Odense M, Denmark.

The sensitivity of juvenile brown trout towards estrogenic chemicals (17beta-estradiol [E2], estrone [E1], 17alpha-ethinylestradiol [EE2], 4-tert-octylphenol [OP], and n-butylparaben [BP]) was tested in laboratory experiments with plasma and liver vitellogenin concentrations as endpoints. Vitellogenin concentrations were also assessed in juvenile brown trout collected in streams affected by agricultural runoff and discharges from scattered houses in the open land. In the laboratory, juvenile brown trout were exposed to the chemicals in flow-through tanks for 7 to 12 d and concentration-response relationships for the induction of vitellogenin synthesis were obtained. The actual exposure concentrations were determined by liquid chromatography-mass spectrometry. The median plasma vitellogenin concentration in first year control brown trout reared in recirculated groundwater was 165 ng/ml with 783 ng/ml as the highest value. The median effective concentration (EC50) values for vitellogenin induction (based on plasma concentrations) were 3.7 ng EE2/L, 15 ng E2/L, 88 ng E1/L, 68 microg BP/L, and 7 microg OP/L. Median effective concentrations derived from liver vitellogenin concentrations were similar. The 166 brown trout caught in the field were mainly first and second year fish and a few third year fish. Plasma vitellogenin concentrations were below 1000 ng/L in 146 of the fish, between 1000 ng/L and 4234 ng/L in 19 fish and 5.3 x 10(6) ng/L in one male fish. Vitellogenin concentrations did not differ between first and second year fish, but were elevated in third year fish. The data may indicate that juvenile (<2 years) trout with plasma vitellogenin concentrations above 1000 ng/ml have had their vitellogenin synthesis induced by exposure to estrogens in the environment. Plasma and liver vitellogenin concentrations were closely correlated in brown trout with elevated vitellogenin concentrations. It is noteworthy, however, that exposure to synthetic estrogens (EE2, BP, and OP) resulted in higher liver concentrations (for the same plasma concentration) than exposure to the natural estrogens E1 and E2.
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http://dx.doi.org/10.1897/08-148.1DOI Listing
November 2008

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in 0+ juvenile cyprinids and sediments of the Po River.

Arch Environ Contam Toxicol 2008 Aug 23;55(2):282-94. Epub 2008 Jan 23.

Water Research Institute, National Council of Research, via della Mornera 25, 20047, Brugherio, (Milan), Italy.

PBDE and PCB content has been determined in 0+ bleak (Cyprinus alburnus), nase (Chondrostoma soetta), gudgeon (Cyprinus gobio), chub (Cyprinus cephalus), and barbel (Barbus sp.) as well as in bed sediments sampled from the River Po upstream and downstream of the confluence of a tributary draining a highly industrialized and urbanized subbasin. Both groups of chemicals were present at higher levels in fish and sediments downstream from the confluence. In addition, whole-body concentrations of PBDEs and PCBs were different among species despite the young specimen age. The fact that PBDEs and PCBs were higher in benthivorous versus planktivorous fish, as well as in carnivorous versus herbivorous species, suggests that feeding behavior is a major controlling factor that may help differentiate the accumulation levels of 0+ juveniles. Of the five species, the pelagic/planktivorous cyprinid bleak (C. alburnus) showed the lowest concentrations (111 ng PBDE/g lipid weight [l.w.], 2016 ng PCB/g l.w.), whereas the benthic dweller and feeder barbel (Barbus sp.) had the highest concentrations of both groups of chemicals (259 ng PBDE/g l.w., 4785 ng PCB/g l.w.). The rank order of species contamination was essentially stable upstream and downstream from the tributary, and the congener contribution of PBDEs was also similar. In general, BDE-47 was the dominant congener, followed by BDE-100, -154, -153, and -28. BDE-209 dominated the PBDE congener profiles of sediments but was not found in any fish sample. Conversely, an unidentified hexa-BDE congener, which was not detected in sediments, was found in all fish species. The levels of PBDEs and PCBs determined in adult goby (Padogobius martensii), a small demersal predator also examined in the same river stretches, provided additional useful insights with which to interpret results.
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http://dx.doi.org/10.1007/s00244-007-9130-1DOI Listing
August 2008

Assessment of the environmental significance of heavy metal pollution in surficial sediments of the River Po.

Chemosphere 2007 Jun 20;68(4):761-8. Epub 2007 Feb 20.

Balaton Limnological Research Institute of the Hungarian Academy of Sciences, P.O. Box 35, H-8237 Tihany, Hungary.

The magnitude and ecological relevance of metal pollution of the middle Po river deriving from the River Lambro tributary was investigated by applying different (complementary) sediment quality assessment approaches: (1) comparisons of concentrations with regional reference data, and (2) comparisons with consensus-based sediment quality guidelines (SQGs), as well as by investigations of the partitioning patterns of target heavy metals (Cd, Cu, Ni, Pb, Zn). Total metal concentrations in the surficial sediments revealed significant pollution inputs on the whole river stretch investigated, with a distinct peak at the inlet of the River Lambro. Based on the geoaccumulation index of target heavy metals, the middle reach of River Po has to be considered as moderately polluted with Cd (1
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http://dx.doi.org/10.1016/j.chemosphere.2006.12.099DOI Listing
June 2007

The accumulation levels of PAHs, PCBs and DDTs are related in an inverse way to the size of a benthic amphipod (Echinogammarus stammeri Karaman) in the River Po.

Sci Total Environ 2007 Feb 26;373(1):131-45. Epub 2006 Dec 26.

Water Research Institute CNR, Via della Mornera 25, 20047 Brugherio (Milan), Italy.

The accumulation of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and DDTs were investigated in gammarids captured at three sites along the middle River Po; the first was located upstream and the other two were at increasing distances downstream of the confluence of a polluted tributary, the River Lambro. Using a GC-MS technique, the levels of PCBs, PAHs and DDTs were determined separately in large and small gammarids as well as in the fine fraction of sediment samples collected along the sites of capture. Results confirm the River Lambro as a source of these chemicals to the River Po, and show that bioaccumulation differences exist between small and large individuals, the former being more contaminated particularly by PCBs and DDTs. This is likely the result of several interacting factors such as contaminant bioavailability, gammarid-size effects on kinetic parameters and feeding selectivity. The bioaccumulation patterns of PCBs and DDTs, and their higher biota-sediment accumulation factors (BSAF), are consistent with chemical properties and suggest a dietary disequilibrium found only 10 km downstream from the tributary, and in smaller amphipods. Present results show that gammarids may represent an additional source of contaminants, particularly of chlorinated compounds, to the many organisms feeding on them, with a higher risk for those which prey selectively on smaller gammarids.
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http://dx.doi.org/10.1016/j.scitotenv.2006.11.006DOI Listing
February 2007
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