Anthocyanins

Anthocyanins are water-soluble plant pigments from the flavonoid family. They give blueberries, blackcurrants, red cabbage, purple rice and hibiscus their red, purple and blue tones, and they appear in cosmetics as part of botanical extracts rather than as isolated single molecules.

In laboratory testing anthocyanins behave as antioxidants, meaning they can help neutralise free radicals. That is why extracts rich in them are marketed within antioxidant serums and masks, usually alongside better-studied ingredients such as vitamin C or vitamin E. Evidence for what a topical botanical extract does on human skin is far thinner than the laboratory data, so treat the antioxidant framing as supportive rather than as a replacement for daily sunscreen.

Anthocyanins are also pH-sensitive, shifting colour between acidic and alkaline conditions, and they degrade with light and heat — one reason such products are often packaged opaquely. Botanical extracts carry their own sensitisation potential, so patch test if your skin reacts easily.