Selection of Natural Extracts for their Antioxidant Capacity by Using a Combination of In Vitro Assays

Abstract

Numerous different in vitro assays, labeled as “antioxidant assays,” are used intensively to predict the antioxidant capacity of phenolic compounds. Most of these methods give valuable information in terms of chemical reactivities but also present some weaknesses. It may be difficult to use them to predict antioxidant capacity in real conditions. Indeed, lipid oxidation is a complex reaction, with numerous paths and components, and antioxidant action can occur via a multitude of mechanisms, especially when different phases coexist in the lipid‐based formulation. Yet, correctly combining selected in vitro methods to extract complementary information with respect to antioxidant behaviors would be much better and will help reducing the gap between prediction and efficacy in the finished product. Thus, we hereby propose a methodology to evaluate the antioxidant properties of 12 selected natural polyphenolic extracts based on the appropriate combination of in vitro assays. The scores obtained with the DPPH test, the measure of the chelation capacity, the evaluation of antioxidants efficiency in emulsions (CAT and VESICAT assays), or in bulk oils were submitted to a statistical treatment. This analysis allowed a ranking on their global antioxidant capacities and the creation of clusters depending on their mechanisms of action and the type of media where the tests were performed.

High Metal Chelating Properties from Rapeseed Meal Proteins to Counteract Lipid Oxidation in Foods: Controlled Proteolysis and Characterization

“…This test was validated with phenolic compounds (gallic acid, chlorogenic acid, rosmarinic acid, etc.) or extracts, [ 31 ] taking Trolox as reference. To date, the method was not applied to peptide resources as antioxidants.…”