Anthocyanin

Anthocyanins are water-soluble flavonoid pigments responsible for red, purple, and blue colors in many plants — including the violet and deep-purple hues of certain cannabis cultivars (e.g., "Purple Urkle," "GDP" phenotypes). Structurally they are glycosides of anthocyanidins (cyanidin, delphinidin, pelargonidin, peonidin, petunidin, malvidin). Their expression in cannabis is genetically determined but also pH- and temperature-modulated: cooler nighttime temperatures during late flowering enhance anthocyanin accumulation in bracts and leaves. Color shifts red → purple → blue as vacuolar pH rises. Anthocyanins have well-documented antioxidant activity in food chemistry but have not been demonstrated to contribute meaningfully to the pharmacology of inhaled or ingested cannabis — they are largely cosmetic markers of genetics and growing conditions. → See also: Flavonoid.