Assessment of antioxidant capacity of natural products

It is now widely accepted that oxidative stress induced by reactive oxygen and nitrogen species is involved in the pathogenesis of various diseases such as atherosclerosis and cardiovascular disease and consequently the role of antioxidants in the prevention and treatment of diseases has received much attention of scientists, clinicians and general public. However, most of the large clinical intervention trials of antioxidants and meta-analysis of the data from these large studies do not show beneficial evidence with regard to cardiovascular outcomes. In order to understand the role of antioxidants, it is essential to elucidate the action and capacity of antioxidants. In this article, the assessment of antioxidant capacity is reviewed and the methods for assessment of natural antioxidant capacity are discussed.