Astaxanthin

Carotenoid from microalgae with the most potent antioxidant activity of any known carotenoid

Astaxanthin is a red carotenoid produced by the microalgae Haematococcus pluvialis — it is what gives salmon, flamingos, and shrimp their pink color. It is fat-soluble and accumulates in cell membranes where it spans the full bilayer, providing unusually comprehensive antioxidant protection.