Cyanidin

Cyanidin is an organic compound in the anthocyanidin subgroup of flavonoids, a large family of plant pigments ^[4]. In plants it rarely occurs as the free pigment; instead it is usually found bound to one or more sugars, forming water-soluble glycosides known as anthocyanins, among them cyanidin-3-glucoside (chrysanthemin), cyanidin-3-galactoside, and cyanidin-3-rutinoside ^[3]. As a flavylium-type molecule, cyanidin carries a positive charge and changes color with pH, appearing red under acidic conditions and shifting toward purple and blue as acidity falls, a property that lets anthocyanins serve as natural pH indicators ^[4].

Cyanidin and its glycosides are among the most common anthocyanins in the human diet ^[1]. They concentrate in the skins and seeds of many berries, including blackberry, blueberry, bilberry, cherry, chokeberry, elderberry, cranberry, and raspberry, and also occur in red grapes, red cabbage, red onion, plums, and apples ^[3]. In black raspberry, for instance, cyanidin rutinosides make up the bulk of the fruit's anthocyanins and its principal phenolic antioxidants ^[3].

Diets rich in anthocyanins have been linked in observational studies with lower risk of cardiovascular disease and other conditions, and cyanidin glycosides are frequently cited as representative dietary anthocyanins ^[1]. Their absorption follows an unusual pattern; anthocyanins can be taken up in both the stomach and the intestine, undergo extensive first-pass metabolism, and circulate largely as phenolic acid metabolites, while much of the intact pigment reaches the large intestine to be transformed by gut microbes ^[1]. These metabolites and breakdown products are thought to carry much of any resulting health effect ^[1]. In laboratory screening, cyanidin stood out among plant polyphenols as a strong activator of the enzyme sirtuin 6 (SIRT6), a target of interest in metabolism, DNA repair, and aging research ^[2].

Cyanidin-based pigments are also central to the color of red wine, where they and related anthocyanins are extracted from grape skins and undergo further reactions during fermentation and aging ^[4]. In the European food-additive system, anthocyanin colorants are grouped under the E number E163, with cyanidin corresponding to E163a, and are used as natural coloring agents. Cyanidin is not a drug and is consumed mainly as an ordinary constituent of fruits, vegetables, and their extracts, including berry supplements ^[1].

As a food-derived pigment it has a strong safety record and is generally well tolerated. Concentrated supplements have less long-term data, but no major toxicity is reported. Very high intakes could theoretically upset the stomach, and quality of extracts varies.