The studied hypothesis is that glyphosate (GLY) can affect the oxidative balance in the hydrophilic intracellular medium in non-target Chlorella vulgaris cells. Analytical GLY (5 μM) and a commercial product (RUP) (5 μM) supplementation, did not affect the growth profile. Neither in latent (Lag) nor in exponential (Exp) phase of development, there were significant differences in the cellular abundance, evaluated as cell number, after the supplementation with GLY or RUP. The ascorbyl (A•) content was significantly increased in the presence of GLY or RUP, in Lag and Exp phase of growth. No changes were observed in stationary (St) phase after supplementation with either GLY or RUP. Ascorbate (AH-) content was decreased by 30% in Exp phase of development the presence of RUP. In St phase of the development both, the administration of either GLY or RUP decreased the antioxidant content by 34 and 37%, respectively. The supplementation with GLY and RUP lead to a significant 5- and 10-fold increase in Exp phase, respectively in the A•/AH-content ratio, assessed as a damage/protection ratio in the hydrophilic fraction of the cells, as compared to controls. Neither GLY nor RUP affected the ratio in cells in St phase of development. The data presented here showed experimental evidence that suggested that oxidative balance in the hydrophilic environment is affected by GLY, even at the low to medium concentrations currently used. The effect seems as reversible either because of the magnitude of the herbicide-dependent damage or the antioxidant activity activated.
Keywords: Antioxidant; Ascorbyl/ascorbate ratio; Chlorella vulgaris; Glyphosate; Oxidative stress.
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