Urinary and Faecal Excretion of Phenanthrene and Phenanthrols by Rats Following Oral, Intraperitoneal, or Intrapulmonary Application

The expression of cytochrome P-450 and cytochrome P-450 reductase genes in the simultaneous transformation of corticosteroids and phenanthrene byCunninghamella elegans

The expression of cytochrome P-450 and cytochrome P-450 reductase (CPR) genes in the conterminous biotransformation of corticosteroids and PAHs was studied in Cunninghamella elegans 1785/21Gp. We had previously used this strain as a microbial eucaryotic model for studying the relationship between mammalian steroid hydroxylation and the metabolization of PAHs. We reported that cytochrome P-450 reductase is involved in the biotransformaton of cortexolone and phenanthrene. RT-PCR and Northern blotting analyses indicated that the cytochrome P-450 and CPR genes appear to be inducible by both steroids and PAHs. The expression of the cytochrome P-450 gene was increased ninefold and the expression of the CPR gene increased 6.4-fold in cultures with cortexolone and/or phenanthrene in comparison with controls. We conclude that the increase in cytochrome P-450 gene expression was accompanied by an increase in cytochrome P-450 enzymatic activity levels.

Occupational exposure to polycyclic aromatic hydrocarbons in German industries: association between exogenous exposure and urinary metabolites and its modulation by enzyme polymorphisms

A cross-sectional study was conducted in 170 German workers exposed to polycyclic aromatic hydrocarbons (PAH) to investigate the role of 11 polymorphisms of CYP1A1, CYP1A2, CYP1B1, CYP3A4, EPHX1, GSTM1, GSTT1, and GSTP1 in the association between occupational exposure to PAH and urinary PAH metabolites. Polymorphisms were genotyped with real-time PCR. Exposure to 16 PAH was measured by personal air sampling. Urinary concentrations of 1-hydroxypyrene (1-OHP) and the sum of 1-, 2+9-, 3-, and 4-hydroxyphenanthrenes (OHPhe) were determined post-shift. Urinary 1-OHP and OHPhe correlated significantly with exogenous pyrene (Spearman r=0.52, p<0.0001) and phenanthrene (Spearman r=0.72, p<0.0001), respectively. ANCOVA was applied to investigate potential predictors of the metabolite levels. Current smoking and type of industry turned out to be predictors of 1-OHP but not of OHPhe. CYP1A1 3801TC carriers showed 1.6-fold higher OHPhe levels than 3801TT carriers (p=0.03). EPHX1 113HH was associated with higher and 139RR with lower metabolite levels when compared with the corresponding reference genotypes (113YY; 139HH). In comparison to GSTP1 114AA, carriers of the V allele had 1.5-fold higher 1-OHP (p=0.03) and 2-fold higher OHPhe concentrations (p=0.001). OHPhe turned out to be also a suitable biomarker of occupational PAH exposure. The association with ambient PAH exposure and the influence of polymorphisms was more pronounced for OHPhe.

Biomonitoring of polycyclic aromatic hydrocarbons in human urine

Measurement of polycyclic aromatic hydrocarbons (PAH) metabolites in human urine is the method of choice to determine occupational and/or environmental exposure of an individual to PAH, in particular, when multiple routes of exposure have to be taken into account. Requirements for methods of biomonitoring PAH metabolites in urine are presented. Studies using 1-hydroxypyrene or phenanthrene metabolites including its phenols and dihydrodiols are summarized. The role of these PAH metabolites as established biomarkers and also more recent developments of PAH biomonitoring are discussed.

Initial oxidative and subsequent conjugative metabolites produced during the metabolism of phenanthrene by fungi

Three filamentous fungi were examined for the ability to biotransform phenanthrene to oxidative (phase I) and conjugative (phase II) metabolites. Phenanthrene metabolites were purified by high-performance liquid chromatography (HPLC) and identified by UV/visible absorption, mass, and 1H NMR spectra. Aspergillus niger ATCC 6275, Syncephalastrum racemosum UT-70, and Cunninghamella elegans ATCC 9245 initially transformed [9-(14)C]phenanthrene to produce metabolites at the 9,10-, 1,2-, and 3,4-positions. Subsequently, sulfate conjugates of phase I metabolites were formed by A. niger, S. racemosum, and C. elegans. Minor glucuronide conjugates of 9-phenanthrol and phenanthrene trans-9, 10-dihydrodiol were formed by S. racemosum and A. niger, respectively. In addition, C. elegans produced the glucose conjugates 1-phenanthryl beta-D-glucopyranoside and 2-hydroxy-1-phenanthryl beta-D-glucopyranoside, a novel metabolite. [9-(14)C]Phenanthrene metabolites were not detected in organic extracts from biotransformation experiments with the yeasts, Candida lipolytica 37-1, Candida tropicalis ATCC 32113, and Candida maltosa R-42.

Biomonitoring of polycyclic aromatic hydrocarbons in highly exposed coke plant workers by measurement of urinary phenanthrene and pyrene metabolites (phenols and dihydrodiols)

A filter combination consisting of an impregnated glass fibre and a control filter was used for the collection of air samples in which gaseous and particulate polycyclic aromatic hydrocarbons (PAHs) were determined. To estimate the loss of lower boiling PAHs, d10-phenanthrene was applied as internal standard. A simple, well-producible method for the determination of 1-, 2-, 3-, 4- and 9-hydroxyphenanthrene, 1,2-, 3,4- and 9,10-dihydroxydihydrophenanthrene, 1-hydroxypyrene and 1,2-dihydroxy-1,2-dihydropyrene is described. By means of personal air samplers the exposure to PAHs of four coke plant employees working at different locations was measured over 4 days. Simultaneously the 24-h urine was collected and stored frozen until analysed. The main excretion product of pyrene is a 1-hydroxypyrene conjugate, whereas phenanthrene is excreted predominantly as dihydrodiol conjugate. As expected, workers on the battery topside were exposed the most and accordingly excreted by far the highest amounts of PAHs. Up to 34.0 micrograms phenanthrol conjugates (total of all isomeric phenols) and 195.5 micrograms dihydrodiol conjugates (total of all isomeric dihydrodiols) were excreted in the 24-h urine (mean of 4 days). The metabolite profiles of five isomeric phenanthrene phenols and three isomeric dihydrodiols exhibited only small percentage variations within one individual whereas significant interindividual differences were observed. These findings may indicate a genetically determined enzyme pattern responsible for the metabolic conversion of PAHs.