Antioxidant or pro-oxidant? The effects of boron compounds on Saccharomyces cerevisiae BY4741 strain.

Boron is one of the most important elements with its indisputable biological importance and widespread use. The most studied derivatives of the boron element are boric acid and its salts. In this article, we searched the effects of boric acid and its lithium salt, lithium metaborate, on enzymatic defense system, cell damage, and cell surface morphology of Saccharomyces cerevisiae BY4741 strain. It was found that while all studied concentrations of boric acid showed toxicity against the yeast, even the highest studied concentration of lithium metaborate could not effectively inhibit cell viability. In addition, we observed reverse effect of lithium metaborate depend on its concentration on yeast cell proliferation and metabolic activity. As a defense mechanism, superoxide dismutase and glutathione S-transferase activities were significantly induced in yeast cells treated with boric acid. But these inductions could not protect cells from boric acid induced lipid peroxidation. It was determined that glutathione S-transferase was the only enzyme induced after lithium metaborate treatment. Finally, we visualized the signs of features of necrotic and early apoptotic mechanisms in yeast cells treated with boric acid and lithium metaborate, respectively, which should be investigated with further studies.