Anthocyanins are water soluble pigments found in most species in the plant kingdom. These secondary metabolites belong to the chemical class of the flavonoids and consist of more than 400 compounds differing in number and types of sugars bound to a variety of phenolic moieties. The term anthocyanin is originated from the Greek;anthos meaning flower and kianos meaning blue . They are responsible for red, blue and violet colors of the plant kingdom. For example anthocyanins are responsible for the bright red skins of radishes, the red skin of potatoes, and the dark skin of eggplants. Blackberries, red and black raspberries, blueberries, cherries, currants, concord and other red grapes, pomegranate, ripe gooseberries and cranberries all contain anthocyanins. The composition of anthocyanins strongly depends on the vegetal species and, within them, on their varieties and cultivation conditions.
Anthocyanins in plants mainly have three functions, namely as absorbers of harmful radiation, as transport vehicles for monosaccharides and as osmotic adjusters during periods of drought and low temperatures. In general, anthocyanins are believed to increase the antioxidant response against biotic and abiotic stress factors.
Apart from their physiological roles in plants, anthocyanins are regarded as important components in human nutrition, which is supported by numerous studies that report a high positive correlation of fruit or vegetable pigment content and antioxidant capacities.
In addition to the anecdotal use of anthocyanins and anthocyanin –rich plants in traditional medicine, modern laboratories have demonstrated the potent anti-inflammatory, antioxidant and antimicrobial effects of these molecules. A plethora of studies have been published with regards to their possible use in the prevention of many chronic diseases such as neurological and cardiovascular diseases, diabetes, and cancer, among others.
Although anthocyanins are generally believed to display an array of beneficial actions on human health and wellbeing, the critical examination of their exact mechanism of action, the specific radical-scavenging capabilities of the different anthocyanins, as well as well-designed clinical trials are still crucial for establishing their actual role in human health.
Anthocyanins blood concentration is critical for their nutritional benefit; their absorption rate from foods is typically below 1%, and depends also on food matrix and processing.