ACTA FAC MED NAISS 2011;28(4):219-224

Original article

UDC:543.544.5:577.587.2

HPLC-DAD Study of Gallic Acid Autoxidation in Alkaline Aqueous Solutions and the Influence of Mg(II) Ion

Goran Nikolić, Aleksandar Veselinović, Žarko Mitić, Slavoljub Živanović

University of Niš, Faculty of Medicine, Department of Chemistry, Niš, Serbia


summary

High performance liquid chromatography with diode array detection (HPLC -DAD) was used to study the autoxidation of gallic acid in alkaline aqueous solutions and the influence of Mg(II) ion on this process. At pH 10, one main autoxidation product was determined, and based on the data obtained in this study its structure was proposed to some kind of gallic acid dimer. Among the minor products, the compound with characteristics similar to ellagic acid was detected. Chromatographic analysis of gallic acid autoxidation at pH 8.5 in the presence of Mg(II) ion indicated that reaction rate decreased. At the same time the mechanism of reaction(s) also changed, which was indicated by the formation of different autoxidation products. These findings may provide better insight into various actions of gallic acid in biological systems since Mg(II) ions are ubiquitous in all living cells.

Key words: autoxidation, gallic acid, HPLC, Mg(II) ion