Effects of Acidic and Alkaline Treatments on Tannic Acid and Its Binding Property to Protein

Ro Osawa and Terence P. Walsh

Veterinary Service and Research, Lone Pine Koala Sanctuary, Fig Tree Pocket, Brisbane, Queensland 4069, Australia

Centre for Molecular Biotechnology, School of Life Science, Garden Point Campus, Queensland University of Technology, Brisbane, Queensland 4001, Australia


Effects of acidic and alkaline treatments on tannic acid (TA), one of the hydrolyzable tannins, and its to protein [bovine serum albumin (BSA)] were investigated. Dissociation of TA—BSA complexes was apparent in both highly acidic (pH <3) and ail/Aline (pH >7) treatments. TA dissociated from the complexes and pure TA was not significantly hydrolyzed in highly acidic (pH 1.0-3.0) media and retained its protein-binding property. TA did not seem to be hydrolyzed even with a more acidic treatment (in 1 M HCI, pH <0.5), although its protein-binding property was much reduced. The higher pH treatment (pH >6.5) faciliated the hydrolysis of TA, as judged by the release of its constituent gallic acid.