The FRAP assay: Allowing students to assess the anti-oxidizing ability of green tea and more

Dietary sources of polyphenols receive significant public attention due to their many toted health benefits and speculated preventative medical applications. This stems from the reducing ability of polyphenolic compounds as it has been previously established that total reducing capacity can be linearly correlated to the antioxidant power of a material1. While undergraduate students are possibly aware of the potential benefits of antioxidants compounds found naturally in materials such as green teas and berries, they may not have yet considered the chemical mechanism of how these natural antioxidants function. Although the chemical mechanism by which natural materials act as antioxidants varies, many use polyphenol structures to perform these redox reactions2. Therefore, the antioxidizing power of various materials such as green tea leaves, coffee beans, and berries can be compared by quantifying the concentration of polyphenols in these materials3. Here, we have developed an experiment in which undergraduate organic chemistry students will use the “Ferric Reducing Ability of Plasma” assay (FRAP) to directly measure the reducing capacity of green tea leaves, and thus infer the antioxidant potential of natural antioxidants from dietary sources4. This experiment thus helps students gain an appreciation for the relevance and diversity of electrochemical reactions in natural materials, as well as introduces them to Green Chemistry principles. Students will use the FRAP assay to assess the viability of safe, natural, reducing agents4, which provide the potential to limit the use of more hazardous, environmentally damaging reducing agents) used in industry today