Metabolic syndrome (MS) is the association of three or more pathologies among which obesity, hypertension, insulin resistance, dyslipidemia, and diabetes are included. It causes oxidative stress (OS) and renal dysfunction. Hibiscus sabdariffa L. (HSL) is a source of natural antioxidants that may control the renal damage caused by the MS. The objective of this work was to evaluate the effect of a 2% HSL infusion on renal function in a MS rat model induced by the administration of 30% sucrose in drinking water. 24 male Wistar rats were divided into 3 groups: Control rats, MS rats and MS + HSL rats. MS rats had increased body weight, systolic blood pressure, triglycerides, insulin, HOMA index, and leptin (p ≤ 0.04). Renal function was impaired by an increase in perfusion pressure in the isolated and perfused kidney, albuminuria (p ≤ 0.03), and by a decrease in clearance of creatinine (p ≤ 0.04). The activity of some antioxidant enzymes including the superoxide dismutase isoforms, peroxidases, glutathione peroxidase, glutathione-S-transferase was decreased (p ≤ 0.05). Lipoperoxidation and carbonylation were increased (p ≤ 0.001). The nitrates/nitrites ratio, total antioxidant capacity, glutathione levels and vitamin C were decreased (p ≤ 0.03). The treatment with 2% HSL reversed these alterations. The results suggest that the treatment with 2% HSL infusion protects renal function through its natural antioxidants which favor an improved renal vascular response. The infusion contributes to the increase in the glomerular filtration rate, by promoting an increase in the enzymatic and non-enzymatic antioxidant systems leading to a decrease in OS and reestablishing the normal renal function.

Hibiscus sabdariffa L. (HSL) has high amounts of antioxidants and many beneficial effects in several pathologies. However, few studies describe the possible harmful effects of high concentrations of HSL. Here we evaluate the effect of excessive and chronic consumption of infusions with different percentages of HSL on some oxidative stress markers in serum, and the possible association with inflammation and increased systolic blood pressure (SBP), in healthy rats. A total of 32 male Wistar rats were used to form 4 groups with 8 animals each. Group 1 control (drinking tap water), group 2, 3 and 4, drinking water supplemented with 15, 30 and 60 g/L of HSL calyxes respectively. SBP was evaluated and determinations in serum of the NO₃⁻/NO₂⁻ ratio, glutathione (GSH), total antioxidant capacity (TAC), selenium (Se), TNF-α, IL-1α/IL-1F1, IL-1β, IL-10, extracellular superoxide dismutase (EcSOD), thioredoxin reductase (TrxR) and glutathione peroxidase (GPx) activities, were evaluated. The SBP (p = 0.01), GPx activity, GSH, TAC, Se, TNF-α and EcSOD activities (p ≤ 0.001) and IL-1α/IL-1F1, IL-1β, TrxR and NO₃⁻/NO₂⁻ (p ≤ 0.05), were increased but IL-10 (p < 0.001) was decreased in rats that consumed the 3 and 6% HSL infusions. The excessive and chronic consumption of HSL may increase the TAC that could lead to a proinflammatory state which is associated with hypertension.

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.

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 which can overload the antioxidant system. Twenty-one Wistar rats were divided into three groups: G1: rats that consumed 6% HSL infusion for one month (HSL + 6 %), G2: rats that consumed 6 % HSL infusion for one month and were then given natural water for another month (HSL ± 6%), and G3: rats with natural drinking water (C). Renal vascular resistance (RVR) was evaluated through the responses to norepinephrine (Ne), acetylcholine (Ach), O2–, H2O2 and ONOO–. The activity of antioxidant enzymes and oxidative stress markers were evaluated in the kidney. RVR was increase by Ne and H2O2 (p=0.03), but it was decreased by Ach, O2–and ONOO– (p=0.01). GSH/GSSG and nitrates/nitrites, the total antioxidant capacity, and the activities of SOD, catalase, peroxidases, GPx, GR, glucose-6-phosphate, and the Nrf2 expression were increased (p≤0.04). However, thiol groups, adenochrome, and glutathione-S-transferase were decreased (p=0.01) in the G1 vs. G2 and G3. Excessive consumption antioxidants provided by 6 % HSL infusion results in RS contributing to decrease ROS.

SARS-CoV-2 is an obligatory intracellular pathogen that requires a lipid bilayer membrane for its transport to build its nucleocapsid envelope and fuse with the host cell. The biological membranes are constituted by phospholipids (PLs), and vitamin E (Vit E) protects them from oxidative stress (OS). The aim of this study was to demonstrate if treatment with Vit E restores the modified profile of the FA in PLs in serum from patients with coronavirus disease-19 (COVID-19). We evaluated Vit E, total fatty acids (TFAs), fatty acids of the phospholipids (FAPLs), total phospholipids (TPLs), 8-isoprostane, thromboxane B₂ (TXB₂), prostaglandins (PGE₂ and 6-keto-PGF1_α), interleukin-6 (IL-6), and C-reactive protein (CRP) in serum from 22 COVID-19 patients before and after treatment with Vit E and compared the values with those from 23 healthy subjects (HSs). COVID-19 patients showed a decrease in Vit E, TPLs, FAPLs, and TFAs in serum in comparison to HSs (p ≤ 0.01), and Vit E treatment restored their levels (p ≤ 0.04). Likewise, there was an increase in IL-6 and CRP in COVID-19 patients in comparison with HSs (p ≤ 0.001), and treatment with Vit E decreased their levels (p ≤ 0.001). Treatment with Vit E as monotherapy can contribute to restoring the modified FA profile of the PLs in the SARS-CoV-2 infection, and this leads to a decrease in lipid peroxidation, OS, and the inflammatory process.

Ingestion of Hibiscus sabdariffa L. (HSL) provides antioxidants with beneficial effects for several pathologies, with underlying oxidative stress. However excessive, chronic consumption of the antioxidant-rich diet with HSL in healthy rats induces reductive stress (RS) with damaging effects. The aim of this study was to evaluate if the consumption of an infusion of 6% HSL for two months alters the function and structure of the myocardium. 24 male Wistar rats were divided into three groups: Control (C), HLS infusion at 6% for two months (HSL 6%), and a washout group that received HSL 6 % for two months followed by two months of natural water (HSL ± 6%). Myocardial performance during ischemia-reperfusion (I/R) was evaluated by using the isolated Langendorff heart model, accompanied by surface electrocardiography and histopathological analysis. Chronic 6% HSL intake increased systolic pressure (p≤0.03), elevated coronary vascular resistance, depressed mechanical performance, led to bradycardia, and critical, extended asystolic/sinus pauses. Histopathology showed dense, permanent networks of interstitial and perivascular collagen encapsulating the hypertrophied cardiomyocytes. Therefore, the overload of antioxidant molecules provided by the HSL infusion leads to RS that increases myocardial interstitial fibrosis and disrupts coronary compliance and intercellular electrical coupling, leaving the heart vulnerable to ischemic stress.