Tannic Acid as an Ion Channel Modulator: An Understanding of Its Pharmacological Spectrum

Tannic acid (TA) is a polyphenol present in many plant foods and beverages such as green tea and wines. As a food additive, it has been recognized by Food and Drug Administration as generally safe. As a candidate drug, its pharmacological effects cover a wide spectrum, ranging from antibacterial, anticancer, cardioprotection to neuroprotection. TA has been shown to modulate a number of ion channels such as Ca²⁺-activated Cl^- channels (CaCC), voltage-gated K⁺ (Kv) channels and transient receptor potential (TRP) channels, producing effects such as analgesia, antihypertensive effects and reduction of airway hypersensitivity. In this review we focus on how ion channel modulation by TA may account for the pharmacological effects of TA in various cells and organ systems. Further emphasis should be paid to factors, such as dosage and routes of administration, before the pharmacological actions of TA could be translated into therapeutic applications.