Antosyanidiineja

Antosyanidiineja (anthocyanidins) are a class of water-soluble polyphenolic compounds that act as the aglycone forms of anthocyanins, the pigments responsible for red, purple and blue colors in many fruits, flowers and leaves. Structurally they are flavonoids based on a flavylium cation skeleton; they typically exist in plants as glycosylated derivatives (anthocyanins) after attachment of sugar moieties, but as aglycones they are anthocyanidins such as pelargonidin, cyanidin, delphinidin, petunidin, peonidin and malvidin.

Biosynthesis occurs via the phenylpropanoid pathway, with enzymes including chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, dihydroflavonol 4-reductase, and anthocyanidin synthase. They are subsequently glycosylated to form anthocyanins, which are the more stable storage forms in plant tissues.

Color expression in plants depends on several factors, including pH, metal ion complexation, and co-pigmentation with other phenolics. Anthocyanidins are comparatively less stable than their glycosylated counterparts and can degrade under light, heat, or alkaline conditions, often forming chalcones or quinones.

Ecological and practical significance: anthocyanidins contribute to the vivid coloration of flowers and fruit, which can influence pollinator attraction and seed dispersal. They are also studied for potential antioxidant activity. In research and industry, anthocyanidin content is typically analyzed by chromatography, either directly or as part of hydrolyzed anthocyanins, to assess pigment composition and quality.