Impaired Renal Function Due to Reductive Stress Is Associated with Excessive Consumption of Hibiscus sabdariffa...

Reductive stress (RS) results from the overactivity of the enzymatic and non-enzymatic antioxidant systems and from excess antioxidant agents that neutralize reactive oxygen species. Hibiscus sabdariffa Linnaeus (HSL) is a natural source of antioxidant molecules that can overload the antioxidant system. Twenty-one Wistar rats were divided into three groups: group 1 (G) G1: rats that consumed a 6% HSL infusion for one month (HSL + 6%), G2: rats that consumed a 6% HSL infusion for one month and were then given natural water for another month (HSL ± 6%), and G3: rats with natural drinking water. Renal vascular resistance (RVR) was evaluated through their responses to norepinephrine (Ne), acetylcholine (Ach), super oxide (O₂^-), hydrogen peroxide (H₂O₂)_, and peroxynitrite (ONOO^-). The activity of antioxidant enzymes and oxidative stress markers was evaluated. RVR was increased by Ne and H₂O₂ (p = 0.03), but it was decreased by Ach, O₂^-, and ONOO^- (p = 0.01). The reduced glutathione / oxidized glutathione (GSH/GSSG) ratio and nitrates/nitrites ratio, the total antioxidant capacity, the activities of superoxide dismutase, catalase, peroxidases, glutathione peroxidase, glutathione reductase, glucose-6-phosphate, and the expression of phosphorylated NrF2 were increased (p ≤ 0.04). However, the thiol groups, adenochrome, and glutathione-S-transferase were decreased (p = 0.01) in G1 vs. G2 and G3. The excessive consumption of antioxidants provided by a 6% HSL infusion results in RS contributing to a decrease in ROS.