Antioxidant and pro-oxidant challenge of tannic acid in mussel hemocytes exposed to cadmium.

The present study investigates the antioxidant and pro-oxidant behavior of tannic acid (TA) in hemocytes of mussel Mytilus galloprovincialis, in the presence or the absence of cadmium (Cd). TA at concentrations up to 20 μM, primarily found to be no toxic (in terms of cell viability, superoxide anions, nitric oxide and lipid peroxidation products currently estimated), significantly diminished the cytotoxic and oxidative effects induced by the metal (50 and/or 100 μM) in all cases. On the other hand, higher concentrations of TA (40 and 60 μM) were toxic, thus enhancing Cd-mediated cytotoxic and oxidative effects. The present study showed TA beneficiary properties in hemocytes of mussels, at least at low concentrations, while TA at concentrations higher than 20 μM could serve as an excellent oxidized substrate, thus enhancing toxic effects either alone or with the presence of micromolar concentrations of non transition metals, such as Cd.