Anthaquinone dyes are derived from anthracene:
They have the general formula:
The general formula shows the chromophore to be a quinoid ring. This class of dyes may have either hydroxyl groups or amino groups attached to the general structure. Those that have hydroxyl groups (hydroxyanthraquinones) are the more numerous for histological purposes, and include the mordant dyes alizarin and alizarin red S, both used to demonstrate calcium. Also represented is anthracene blue SWR, a substitute for hematoxylin. Dyes having amino groups (aminoanthraquinones) are less common, but include nuclear fast red, a mordant dye useful for staining nuclei red.
R. D. Lillie.
Conn's Biological Stains
Williams & Wilkins, Baltimore, MD., U.S.A.