Astaxanthin (3,3’-dihydroxy-beta,beta-carotene-
4,4’-dione) belongs to the xanthophyll subclass of
carotenoids. It has oxygen in its molecular structure,
which sets it apart from beta-carotene and
other molecules of the carotene subclass.5 The
astaxanthin molecule has an extended shape, with
a polar structure at either end of the molecule and
a nonpolar zone in the middle (Figure 1). The polar
structures are ionone rings that have potent
capacity for quenching free radicals or other
oxidants, primarily in an aqueous environment,
but possibly also in the absence of water