W9 PM Residual Oil and its Effects
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 339-340

(SAR-1117-860889) A method for selective extraction of CYP1A inducing components in Alaskan North Slope crude oil.

SARAVANABHAVAN, G¹, KHAN, C², HODSON, P², BROWN, R¹, ¹ Department of Chemistry and School of Environmental Studies, Queens University, Kingston, Ontario, Canada² Department of Biology and School of Environmental Studies, Queens University, Kingston, Ontario, Canada

ABSTRACT- In recent times, several scientific reports have been published concerning the toxicity of crude oil to the early life stages of aquatic organisms. Crude oil contains a wide variety of chemical compounds whose relative toxicities are generally unknown. In several instances, the toxicity of metabolites has been found to be more severe than that of parent compounds. Hence the activation of the CYP450 enzyme system is considered as an important indicator of toxicity. Earlier studies from our group have shown that the exposure of trout (Oncorhynchus mykiss) to ANS crude oil and its sub-fractions (coal tar and wax fractions) showed higher CYP1A induction. The ′coal tar′ fraction is rich in PAHs and also contains a considerable amount of waxes. The ′wax′ fraction predominantly contains asphaltenes and waxes, but also some PAHs. The PAHs present in these fractions are considered to be responsible for CYP1A induction. To test this hypothesis, we have developed a low temperature solvent extraction method to isolate the PAHs from other components. Operating parameters of the method such as the choice of the solvent, volume, and extraction temperature were optimized for this study. Extraction of the coal tar used acetone for the precipitation of wax components. The wax fraction was extracted with pentane to isolate PAHs while precipitating asphaltenes. The CYP1A induction of the extract was potent, which correlated with the high PAH content. The wax or asphaltene residues did not induce CYP1A appreciably. The PAHs in the extracts were further fractionated using semi-preparative HPLC on a silica column into five fractions, based on the number of rings in the PAH structure. Results of CYP1A induction studies on these fractions and the detailed chemical analysis will be reported.

Key words: CYP1A induction, polycyclic aromatic hydrocarbons, wax precipitation, acetone extraction