Enzymatically enriching naringenin with hydroxylated and/or methoxylated phenolic compounds

The demand for supplementary dietary antioxidants is increasing as their role in preventing oxidative stress is becoming clearer. This study was therefore aimed at investigating the possibility of coupling simple phenolic molecules rich in hydroxyl groups and/or methoxyl groups onto naringenin by using laccases in order to enhance its antioxidant activity. In all cases, up to two catechol, guaiacol, ferulic and sinapic acid molecules were covalently coupled onto naringenin. The type of solvent used had an impact of coupling efficiencies with highest yields obtained for ethyl acetate when compared to methanol and acetonitrile. Proposed coupling structures predominantly showed a C–C bonding except for sinapic acid which was bound through 4-O-5 coupling. Indeed an increase in hydroxyl groups and/or methoxyl groups, which may positively influence antioxidant activities, was inferred from the chromatographic and mass data.