Project Title: Structure and Toxicity: Alkyl-PAH Derivatives
Research Topic/Project description: Shirin's research is a collaborative Biology-Chemistry project in fish toxicology. The thesis concerns the relationship between chemical structure and toxicity to fish embryos for aromatic hydrocarbons that have been hydroxylated during the process of excretion.
Polycyclic Aromatic hydrocarbons (PAHs) are lipophilic environmental contaminants with petrogenic, biogenic, and pyrogenic sources. Alkyl-PAHs predominate in crude oils and can also be found downstream of pulp and paper mills. Studies suggest that some alkyl-PAHs such as retene (7-isopropyl-1-methylphenanthrene) are more toxic than their un-alkylated parent PAH. Previous work in our lab points to a link between the enzymatic metabolism of alkyl-PAHs such as alkyl phenanthrenes (APs), the resulting generation of oxy-PAH metabolites in the form of ring (phenols) and chain hydroxylated (benzylic alcohols) derivatives, and the increased prevalence of toxicity in early life stages (ELS) of fish. It remains unclear whether this metabolic toxicity enhancement is attributed to the byproducts of metabolism such as reactive oxygen species (ROS) and reactive intermediates, or the metabolites themselves. While the introduction of oxygen increases the polarity of the compound as a first step in excretion, early work suggests these derivatives to be more toxic than their un-substituted counterparts. The main objective of this research is to estimate the potential role of these oxy-alkyl-PAH derivatives in PAH metabolism and toxicity. This project involves assessment of the chronic toxicity of a series of ring and chain hydroxylated AP derivatives to the ELS of Japanese Medaka, comparing their effects with one another and their un-substituted parent compound.
The results will have a great relevance to assessing the risks of oil spills to fish reproduction.
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