Oxidative stress in the hydrophilic medium of algae and invertebrates

The harmful effects of the reactive species may be due to the increase in their steady state concentration either by the enhancement of their production rates and/or the decrease of their consumption rate by antioxidant activity. The ascorbyl radical (A^? ) can be considered as a final product of radical oxidative transformations of ascorbate (AH^-). The ratio A^? content/AH^- content (A^? /AH^-) has been widely used as an interesting tool to estimate mild to moderate oxidative transformations, providing a quick and simple method of diagnosis of stress in the hydrophilic cellular medium. The aim of this work was to summarize studies on the cellular oxidative condition in algae and invertebrates by assessing the A^? /AH^- ratio under environmentally changing conditions. The use of indices of oxidative stress increasingly sensitive and, somewhat more specific, can bring a new light to the still unknown world of oxidative responses in marine organisms