Identification of toxic products of anthracene photomodification in simulated sunlight

Abstract

Currently, the evidence of a rapid photomodification of anthracene under sunlight resulting in enhanced toxicity exists; however, the chemical causes of toxicity are still unknown. The present study aimed at filling this gap by irradiation of an anthracene suspension with simulated sunlight and subsequent effect-directed fractionation and analysis of toxic products with respect to the inhibition of bacterial energy metabolism of Vibrio fischeri, reproduction of the green algae Scenedesmus vacuolatus, and genotoxicity in the umuC test. Algal toxicity of anthracene was hardly modified by irradiation prior to testing and distributed over all fractions with emphasis on the fractions containing anthracene-9,10-dione and a photometabolite suggested to be 10-hydroxyanthrone. Bacterial toxicity and genotoxicity in contrast emerged only when anthracene was irradiated. Anthracene-1,4-dione, a so-far-unknown trace photometabolite, was identified as a very potent toxicant dominating the toxicity of photomodified anthracene to V. fischeri. In genotoxic fractions, 1-hydroxyanthracene-9,10-dione and 1,4-dihydroxyanthracene-9,10-dione were identified and confirmed as genotoxicants. The results stress the potential of effect-directed analysis approaches in contrast to mere chemical analysis in studies aiming at toxicologically relevant photomodified substances.

Effect-directed analysis: a promising tool for the identification of organic toxicants in complex mixtures?

“…Appropriate alternatives applied for genotoxicity identification are the umu-test on the basis of the activation of the SOS DNA repair system in Salmonella typhimurium TA1535/pSK1002 [68,111,112] and the Mutatox assay using a dark mutant strain of Vibrio fischeri [36,77]. Both are promising approaches with respect to high-throughput analysis even if the discriminating power is lower than that of the multi-strain Ames approach.…”

“…The recording of ultraviolet (UV) absorption spectra after separation by HPLC is also a powerful tool for the identification of compounds with noncharacteristic mass spectra such as many polyaromatic compounds [13,86]. Functional groups of analytes may be identified by recording infrared absorption spectra [13,112].…”

“…Extensive studies of photomodification of anthracene have been performed in the past, but only EDA was able to identify the metabolites causing the toxicity of photomodified anthracene including anthracene-1,4-dione, a previously unknown photomodification product of very high toxicity to Vibrio fischeri [112]. Thus, anthracene-1,4-dione was identified as one of the few specifically acting toxicants to Vibrio fischeri, even if the mode of action remains to be analysed.…”

Wirkungsorientierte Analytik komplexer Mischungen Erfahrungen aus der Umwelt- und Ökotoxikologie für die Lebensmitteluntersuchung

“…Im Falle polyaromatischer Verbindungen liefern UV-Absorptionsspektren wichtige Informationen über das aromatische Grundgerüst (Holmborn et al, 1984;Brack und Schirmer, 2003). Funktionelle Gruppen lassen sich durch den Einsatz von IR-Absorptionsspektren gewinnen (Brack et al, 2003a;Holmborn et al, 1984).…”

Photoproducts of carminic acid formed by a composite from Manihot dulcis waste

“…Incidentally, authors reported observing a higher toxicity after the biodegradation of CA than before the microbiological treatment of effluent (Arroyo-Figueroa et al, 2011). The fact that hydroxylated anthraquinones have presented significant toxicity is important because these compounds can be photoproducts of CA (Brack et al, 2003). This fact makes the identification of the compounds produced during the degradation of CA necessary.…”