**1. Introduction**

Since several decades, flavonoids have captured the attention of scientists worldwide. The popularity of flavonoids in the scientific world is due to their versatile applications, therapeutic uses and environmental significance. They are reported to possess several beneficial pharmacological effects. Based on published reports, flavonoids exist in eight different classes and they are more than 9000 in number. These classes include anthocyanins, anthocyanidins, lipophilic flavones and flavonols, flavone and flavonol glycosides, chalcones, dihydrochalcones and aurones, flavanones and dihydroflavonols [1, 2]. Anthocyanins occur in various parts of plants including flower petals, stems, leaves and fruits. They are polyphenolic pigments that range in colors from red to purple. Literature survey reveals the presence of more than 700 anthocyanin compounds [3, 4]. Anthocyanins have several phenyl groups in their structure and mostly occur in glycosylated form. When more than one sugar group is attached in the C-ring, they are classified as "anthocyanidins" [5]. The anthocyanidins are reported to be less stable than

anthocyanins [5]. The structural diversity of anthocyanins provides advantage to the chemical modifications that can be carried out. The most reported structural modifications on anthocyanins include acylation. Some studies report the bioavailability of anthocyanins to be low, except for cyanidin-3-glucoside which exhibits a bioavailability of about 12% [6]. Routine consumption of anthocyanins is reported to be beneficial in preventing cardiovascular, neurological and metabolic disorders [7]. They are not essential constituents of diet but can be easily supplemented through intake of fruits and vegetables. There are no dietary intake reference levels established for anthocyanins till date. However, institutes worldwide recommend the use of anthocyanins for promoting good health. Publications such as *Dietary Guidelines for Americans* have been published to create awareness among consumers about their health benefits [8]. A report published on the dietary intake of anthocyanins states that, on an average the female population has a higher intake of anthocyanins compared to males. There is variation also observed among individuals of various races/ethnicities in consumptions of anthocyanins. A report indicates that the intake of anthocyanins was found to be higher in white population compared to Hispanic and non-Hispanic other populations in the USA [9]. Traditionally, fruits especially berries have been recommended as rich sources of anthocyanins. Despite their long use in traditional medicine, the use of anthocyanins in western medicine is still awaited. With their increasing popularity, the application of anthocyanins as a substitute to synthetic colors in food products is gaining acceptance. In the current chapter, the chemistry, pre-clinical, clinical and pharmaceutical uses are discussed in detail. The natural sources of anthocyanins and their traditional medicinal uses are also discussed in detail.
