Antioxidant potential of hydroxycinnamic acid glycoside esters.

Hydroxycinnamic acids are natural antioxidants found in fruits, vegetables, and cereals. In this study, the antioxidant activity of various types of hydroxycinnamoyl glycoside esters that mimic the structure of polymeric carbohydrates was studied in different model systems prone to oxidation, namely, liposomes and emulsions. In addition, radical scavenging activity against the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was tested. It was found that the esterification in the primary hydroxyl group of the glycoside resulted in the improved radical scavenging activity of both sinapoyl and feruloyl glycosides compared to conjugation to the secondary hydroxyl group. Increased activity was also observed, particularly in the case of feruloyl glucosides in inhibiting the oxidation of liposomes emulsions. The results showed that sinapic and ferulic acid glycoside esters were as effective or more efficient antioxidants than their free forms. In conclusion, the strength of their antioxidant effect depends on the nature of conjugation.