Alteration of the aortic vascular reactivity associated to excessive consumption of Hibiscus sabdariffa Linnaeus: Preliminary findings

The moderate production of reactive oxidative species (ROS) is important because ROS act as second messengers. However, their depletion through the over-activity of the antioxidant system may lead to reductive stress (RS) which is characterized by an increase in reducing equivalents and an elevation of some components of the antioxidant system disturbing redox homeostasis. Hibiscus sabdariffa Linnaeus (HSL) is a plant with antioxidant properties that provides compounds that favor the antioxidant system. However, excess chronic consumption could lead to the over expression of the antioxidant enzymatic system, and this could contribute to decrease ROS. Therefore, the objective of this study was to evaluate the alteration of the vascular reactivity associated to excessive and chronic consumption of HSL infusions at different percentages. 40 male Wistar rats were divided into 4 groups. 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. The systolic blood pressure (SBP), vascular reactivity, morphological changes, and different components of the enzymatic antioxidant system were evaluated in the thoracic aorta by spectrophotometry. We also determined glucose-6-phosphate dehydrogenase (G6PD), glutathione-S-transferase (GST), thioredoxin-reductase (TrxR), glutathione peroxidase (GPx) and glutathione reductase (GR) and some markers of the non-enzimatic system such as the NO(3)(−)/NO(2)(−)ratio, glutathione (GSH), selenium, thiols, lipoperoxidation (LPO), and 3-nitrityrosine (3-NT). Vasoconstriction was increased and vasorelaxation was decreased. These alterations were reversed by O(2)(−) and H(2)O(2). There was an increase in the wall thickness and elastic fibers (p = 0.004 and p = 0.02, respectively) and in G6PD, GPX, TrxR (p = 0.02, p = 0.03, and p = 0.01 respectively). LPO, GSH (p = 0.01), and selenium (p = 0.04) were decreased. There was a decrease in thiols (p < 0.001), 3-NT (p = 0.04) and GST (p = 0.0005) in rats that received the infusion at 3 and 6%. The excess antioxidants provided by the HSL infusions at 3% and 6% modified vascular reactivity, increasing the enzymatic antioxidant system, and depleting ROS.