Tannic Acid: Specific Form of Tannins in Cancer Chemoprevention and Therapy-Old and New Applications

Abstract

Purpose of Review: This short review is aimed at providing an updated and comprehensive report on tannic acid biological activities and molecular mechanisms of action most important for cancer prevention and adjuvant therapy. Recent Findings: Tannic acid (TA), a mixture of digallic acid esters of glucose, is a common ingredient of many foods. The early studies of its anti-mutagenic and anti-tumorigenic activity were mostly demonstrated in the mouse skin model. This activity has been explained by its ability to inhibit carcinogens activation, as well as antioxidant and anti-inflammatory properties. Recently, the cell cycle arrest, apoptosis induction, reduced rate of proliferation, and cell migration and adhesion of several cancer cell lines as a result of TA treatment were described. The underlining mechanisms include modulation of signaling pathways such as EGFR/Jak2/STATs, or inhibition of PKM2 glycolytic enzyme. Moreover, epithelial-to-mesenchymal transition prevention and decrease of cancer stem cells formation by TA were also reported. Besides, TA was found to be potent chemosensitizer overcoming multidrug resistance. Eventually, its specific physicochemical features were found useful for generation of drug-loaded nanoparticles. Summary: TA was shown to be a very versatile molecule with possible application not only in cancer prophylaxis, as was initially thought, but also in adjuvant cancer therapy. The latter may refer to chemosensitization and its application as a part of drug delivery systems. More studies are required to better explore this subject. In addition, the effect of TA on normal cells and its bioavailability have to better characterized.