Analysis and Antioxidant Capacity of Anthocyanin Pigments. Part I: General Considerations Concerning Polyphenols and Flavonoids

Many epidemiological studies have shown the benefits of a diet rich in fruit and vegetables to human health and for the prevention of various diseases associated with oxidative stress, such as cancer and cardiovascular diseases. Anthocyanins, natural pigments belonging to the group of flavonoids, are common components of the human diet, as they are present in many foods, fruits, and vegetables, especially in berries. Their use as colorants has considerable interest because of their coloring properties. Moreover, they have an antioxidant activity. Various adverse effects on health have frequently been attributed to synthetic antioxidants. For these reasons, currently, there is a trend towards relying on antioxidants derived from natural products. The efficacy of anthocyanins as antioxidants depends, to a large extent, upon their chemical structure. They act as antioxidants both in the foodstuffs in which they are found and in the organism after intake of these foods. With this in mind, an introduction to polyphenols is made with emphasis on their role as secondary metabolites, classification, and health relevance. Flavonoid intake, biological activities, databases, classification and structure, distribution, and dietary sources are then considered. Aspects of anthocyanin concerning its early history and chemical structure, color, and intake are dealt with in the second part of the series. The extraction and analysis of anthocyanin pigments and their antioxidant power, paying special attention to the oxidation process, will be the subject of the third part. Bioavailability and metabolism of anthocyanic pigments, the methods used for measuring the antioxidant activity of anthocyanins, and the influence of anthocyanins on the antioxidant activity of wine will finally be covered in the fourth part. The present review intends to reflect the interdisciplinary nature of the research that is currently carried out in this prolific area. Key research articles and reviews are mainly referenced, and we apologize to those researchers whose work is not cited directly by us.