Antioxidant capacity of individual and combined phenolic acids in a model system

Phenolic acids are plant food constituents that are associated with many health benefits and have potent antioxidant and free-radical scavenging properties that protect against oxidative damage to important biomolecules. Each phenolic acid has different antioxidant capacity depending on its structure, number of aromatic and hydroxyl groups and their distribution in the structure. In foodstuffs the composition on these bioactive compounds is complex. It is generally assumed that total antioxidant activity of a mixture is a sum of antioxidant activity of the components in a given sample. However, interactions between phenolic acids as well as other antioxidants can occur and they could be additive, synergistic or even antagonistic. In this study, individual antioxidant capacity of four major phenolic acids often found in fruits and vegetables (protocatechuic, caffeic, ferulic and gallic acid) were tested using two different in vitro assays - DPPH radical scavenging activity and cupric reducing antioxidant capacity (CUPRAC). Additionally, the presence of vitamin C and some vitamins from B- group was evaluated. The obtained results may assist in design of functional foods or designed nutraceuticals based on the antioxidant activity and synergistic or antagonist interactions between the components.