Chapter 4A - Antioxidant methods, in vitro and in vivo studies of phenolic acids

Abstract

Phenolic acids are common aromatic plant secondary metabolites with interesting biological roles, mainly antioxidant, antimicrobial, antimutagenic, anticancer, and antiproliferative properties. Although the role in plants is not yet been fully elucidated, phenolic acids are associated with plants’ growth regulation, photosynthesis, nutrient uptake, protein synthesis, enzyme activity, and allelopathy, besides having a protective role against herbivores and pathogens. Phenolic acids and their esters, especially hydroxycinnamic acid, hydroxybenzoic acid, chlorogenic acid, and caffeic acid, are known to present a strong antioxidant activity, which is associated with lower risk of chronic oxidative stress-related diseases like cardiovascular diseases and cancer. There are various factors affecting the antioxidant activity of phenolic acids, although one of the factors that most contributes for it is the number of hydroxyl groups of the molecule. This chapter mainly focuses the antioxidant activity of the main representatives of phenolic acids and extracts rich in phenolic acids, comparing the results achieved by different antioxidant methods. Results of both in vitro and in vivo assays as well as clinical assays will be discussed in order to conclude about the factors affecting the antioxidant capacity of the food extracts rich in phenolic acids and the potential of these compounds as antioxidants to be used successfully by food, pharmaceutical, and cosmetic industries.