Enzymatic modification of 2,6-dimethoxyphenol for the synthesis of dimers with high antioxidant capacity

Abstract

2,6-Dimethoxyphenol is a phenolic compound that is extensively used for the measurement of laccase activity, but is often not exploited for its potential as an antioxidant compound. Since laccase can be used to modify phenolic antioxidants as a way of improving their activities, the present study investigated the laccase-mediated oxidation of 2,6-dimethoxyphenol in biphasic or homogenous aqueous-organic media for the production of compounds with higher antioxidant capacity than the starting substrate. The main product was a dimer (m/z 305.0672), which was further characterized as a symmetrical C-C linked 3,3’,5,5’-tetramethoxy biphenyl-4,4’-diol. In the monophasic system, the dimer was preferentially formed when acetone was used as co34 solvent, while in the biphasic system, formation of the dimer increased as the concentration of ethyl acetate was increased from 50 to 90 %. The dimer showed higher antioxidant capacity than the substrate (≈ 2×) as demonstrated by standard antioxidant assays (DPPH and FRAP). These results demonstrate that a product of the laccase-catalysed oxidation of 2,6-dimethoxyphenol can find useful application as a bioactive compound.