Effects of ecologically relevant concentrations of Boral® 500 SC, Glifosato® Biocarb, and a blend of both herbicides on markers of metabolism, stress, and nutritional condition factors in bullfrog tadpoles.

The aim of this study was to verify the effects of the isolated forms of Boral® SC 500, Glifosato® Biocarb herbicides, and a blend of both herbicides on metabolism and oxidative balance markers of Rana catesbeiana tadpoles and on their nutritional condition. Groups of tadpoles were divided into different treatments: control (no herbicides), Boral® 500 SC (sulfentrazone: 130 μg/L), Glifosato® Biocarb (glyphosate: 234 μg/L), and a blend of both herbicides. After 7 days, the liver, caudal muscle, and blood samples were taken to subsequently perform the biomarkers determination by spectrophotometry. The intestinal condition factor increased in animals exposed to glyphosate and herbicide blends, suggesting a hyperphagic effect. This hypothesis was confirmed by the rise of triglycerides and circulating very low-density lipoprotein (VLDL). There was a significant increase in the levels of uric acid in tadpoles exposed to the herbicide blend. Corticosterone levels reduced significantly in animals exposed to glyphosate and the herbicide blend. Oxidative stress markers had a tissue-dependent response. In the liver, glutathione S-transferase increased, and superoxide dismutase and catalase decreased in animals exposed to sulfentrazone and glyphosate. Lipoperoxidation was reduced in the glyphosate treatment. In the caudal muscle, superoxide dismutase and catalase activities were maintained, and there was a decline in the levels of glutathione S-transferase and TBARS only in the blend group.