May 22, 2009
Author(s): Paul Novotny , Nicole Haubrich , Luther McDonald , Michael Cochran , Julia Serdula , Wade Jeffrey , Pamela P. Vaughan
Photochemically produced reactive oxygen species (ROS) were quantified for three quinones: 2,3-dichloro-napthoquinone (dichlone), tetrachloro-benzoquinone (chloranil) and sodium anthraquinone-2-sulfonate (AQ2S). When exposed to light, chloranil (10 µM) produced 0.045 nM/s H2O2 and 0.15 nM/s superoxide; AQ2S (20 µM) showed 0.057 nM/s H2O2 and 0.05 nM/s superoxide production; dichlone (20 µM) produced 0.10 nM/s H2O2 with no superoxide formation occurring in the light. In the dark, dichlone produced 0.06 nM/s H2O2. Of the three quinones studied, only chloranil was found to produce hydroxyl radical at a rate of 1.63 nM/s. The relative toxicity of each compound was determined using 3H-leucine incorporation as a measure of bacterial growth in seawater and in samples containing Pseudomonas aeruginosa. For seawater, dichlone showed greatest toxicity in the dark with AQ2S showing greatest toxicity when exposed to light. AQ2S showed greatest stability in the light while pre-irradiation of chloranil and dichlone showed decreased toxicity compared to untreated samples.