syanidin

Syanidin is a plant pigment in the class of anthocyanidins, more commonly spelled cyanidin. It is a water-soluble flavonoid that contributes red to magenta hues in many fruits, vegetables, and flowers. In plants it exists primarily as glycosides, known as cyanidin glycosides (for example, cyanidin-3-O-glucoside), which result from attachment of sugar moieties to the aglycone cyanidin.

Occurrence and biosynthesis: Cyanidin is widespread in the plant kingdom, especially in red onions, raspberries, blackberries, blueberries, and red cabbage. It is produced via the flavonoid branch of the phenylpropanoid pathway, following the conversion of chalcone to flavanones and through subsequent steps to the anthocyanidin cyanidin. Glycosylation, acylation, and methylation yield various cyanidin derivatives.

Properties and behavior: As a pigment, cyanidin is pH-sensitive; it typically appears red in acidic conditions and can appear purple or blue at higher pH. It is relatively unstable to light, heat, and oxidation, which affects its color and concentration in foods and plants. In foods, cyanidin derivatives contribute to color stability and appeal; they are also studied for potential antioxidant activity.

Uses and safety: Cyanidin-containing extracts and purified compounds are used as natural colorants and are evaluated for health effects. In many jurisdictions, cyanidin glycosides occur naturally in foods and are considered safe as components of a normal diet.

Notes: The spelling "syanidin" is uncommon and may reflect a typographical error for cyanidin.