Astaxanthin

Astaxanthin is a red-orange carotenoid antioxidant produced by microalgae and other organisms. Its conjugated molecular structure gives it strong antioxidant activity in laboratory systems, which has led to use in supplements and a smaller number of topical skincare products.

Reviews describe potential skin benefits involving oxidative stress, photoaging and inflammation, but topical formulation is challenging because astaxanthin is poorly water-soluble and chemically unstable. Human topical evidence remains limited, so delivery system and formulation quality matter considerably.