betacyanin

Betacyanin is a class of betalain pigments that impart red to violet colors to certain plants, most notably red beetroot (Beta vulgaris) and many species in the order Caryophyllales. Betacyanins are water-soluble pigments and form one of the two subdivisions of betalains, the other being betaxanthins, which are yellow to orange. Betacyanins are responsible for the characteristic red to purple hues in beet roots and related species, while betaxanthins provide complementary yellow-to-orange tones.

Chemically, betacyanins arise from the condensation of betalamic acid with cyclo-DOPA, yielding betacyanin molecules such as betanin, also known as betanidin-5-O-glucoside. Isobetanin is an epimer of betanin. Other betacyanins occur in various species, including gomphrenin and amaranthin, contributing to species-specific color profiles. Betalains are distinct from anthocyanins, as betalains—including betacyanins and betaxanthins—are produced via betalamic acid formation. The color of betacyanins is pH-dependent, typically red to purple under acidic conditions and fading under alkaline conditions; they are generally more stable in acidic environments and susceptible to degradation by heat and light.

Occurrence and use: Betacyanins occur in many Caryophyllales plants, including beets, amaranths, and certain cacti. They serve roles in plant coloration for pollinator attraction and may contribute to photoprotection. As natural colorants, betacyanins are used in foods and cosmetics, with stability influenced by pH, temperature, and light exposure. Extraction and analysis are commonly conducted by spectrophotometry and chromatography.