Anthocyanins are water-soluble flavonoid pigments responsible for red, purple, and blue coloration in fruits, vegetables, and flowers. Cyanidin-3-glucoside (C3G) is among the most abundant, occurring in berries, grapes, red cabbage, and purple corn. It features a flavylium cation core with a glucose moiety at the 3-position. C3G exhibits strong antioxidant activity via radical scavenging and metal chelation. Color shifts with pH: red at pH <3, purple at pH 4-6, blue at pH >7 due to structural transformations between flavylium, quinoidal base, and carbinol forms. Used as natural colorant E163; researched for anti-inflammatory, antidiabetic, and cardioprotective effects via Nrf2 pathway activation. Thermally labile and light-sensitive, degrading during processing.