Neuroprotective effects of tannic acid in the postischemic brain via direct chelation of Zn²⁺

Abstract

Tannic acid (TA) is a polyphenolic compound that exerts protective effects under pathological conditions. The diverse mechanisms of TA can exert beneficial anti-oxidative, anti-inflammatory, and anti-cancer effects. Herein, we reported that TA affords robust neuroprotection in an animal model of stroke (transient middle cerebral artery occlusion; tMCAO) and exhibits Zn 2+ -chelating and anti-oxidative effects in primary cortical neurons. Following tMCAO induction, intravenous administration of TA (5 mg/kg) suppressed infarct formation by 32.9 ± 16.2% when compared with tMCAO control animals, improving neurological deficits and motor function. We compared the chelation activity under several ionic conditions and observed that TA showed better Zn 2+ chelation than Cu 2+ . Furthermore, TA markedly decreased lactate dehydrogenase release following acute Zn 2+ treatment and subsequently reduced the expression of p67 (a cytosolic component of NADPH oxidase), indicating the potential mechanism underlying TA-mediated Zn 2+ chelation and anti-oxidative effects in primary cortical neurons. These findings suggest that anti-Zn 2+ toxicity and anti-oxidative effects participate in the TA-mediated neuroprotective effects in the postischemic brain.

Anti-Inflammatory, Antioxidant, and Neuroprotective Effects of Polyphenols—Polyphenols as an Element of Diet Therapy in Depressive Disorders

“…Tannins, which are phenolic compounds commonly found in fruits, vegetables, herbs, and tea, have antioxidant properties and neuroprotective effects involving the prevention of the accumulation of nitrites, inhibition of the expression and activity of heme oxygenase 1 (HO-1), and a reduction in the degradation of poly glycohydrolase (ADP-ribose) (PARP) [285]. Tannic acid showed a strong neuroprotective effect in an animal model of stroke (transient occlusion of the middle cerebral artery; tMCAO), as well as Zn 2+ chelating and antioxidant activity in primary cortical neurons of Sprague-Dawley rats [286]. In addition, tannic acid may soothe brain tissue damage caused by chronic exposure to heavy metals, including Cd, aluminum (Al), and Pb, due to its strong antioxidant and metal chelating properties [71,96,287].…”

Biomass-Based Ferric Tannate Hydrogel with a Photothermal Conversion Function for Solar Water Evaporation

“…32,33 Due to the triphylene groups in the TA structure, TA can be chelated with several kinds of metal ions (Fe 3+ , Cu 2+ , and so on) and can also form a metal−polyphenol REDOX system that is used as an activator of free-radical polymerization that can improve the polymerization rate significantly. 34 The photothermal conversion performance of ferric tannate (TA-Fe 3+ ), which is a chelate of TA and Fe(III), has been confirmed, which has potential application in photothermal therapy, photothermal sterilization, and solar water evaporation. 35,36 Herein, a double-network (DN) TA-Fe 3+ /SA-Fe 3+ /PAM (TFSFP) hydrogel was synthesized and characterized as an SWE.…”

“…Tannic acid (TA) as a kind of natural plant polyphenol can be obtained from a variety of plants with the characteristics of an antioxidant, adhesion, biocompatibility, and so on, which has been widely used in medicine and food engineering. , Due to the triphylene groups in the TA structure, TA can be chelated with several kinds of metal ions (Fe 3+ , Cu 2+ , and so on) and can also form a metal–polyphenol REDOX system that is used as an activator of free-radical polymerization that can improve the polymerization rate significantly . The photothermal conversion performance of ferric tannate (TA-Fe 3+ ), which is a chelate of TA and Fe­(III), has been confirmed, which has potential application in photothermal therapy, photothermal sterilization, and solar water evaporation. , …”