Exposure of marine mussels to diclofenac: modulation of prostaglandin biosynthesis

Human pharmaceuticals, such as nonsteroidal anti-inflammatory drugs (NSAIDs), are an emerging threat to marine organisms. NSAIDs act through inhibition of cyclooxygenase (COX) conversion of arachidonic acid into prostaglandins. One experiment was carried out whereby marine mussels were exposed for 72 h to 1 and 100 μg/L diclofenac (DCF). A specific and sensitive method using liquid chromatography high-resolution tandem mass spectrometry was developed to quantify DCF in mussel tissues. The developed method could also clearly identify and quantify COX products, i.e., prostaglandin levels, and be used to assess their modulation following DCF exposure. Prostaglandin-D2 (PGD2) was always found below the detection limit (20 μg/kg dry weight (dw)). Basal prostaglandin-E2 (PGE2) concentrations ranged from below the detection limit to 202 μg/kg dw. Exposure of 100 μg/L resulted in a significant reduction in PGE2 levels, whereas a downward trend was observed at 1 μg/L exposure. No difference was observed for prostaglandin-F2α (PGF2α) levels between controls and exposed organisms.