Hematein

Hematein or haematin is an oxidized derivative of haematoxylin, used in staining.

Hematein exhibits indicator-like properties, being blue and less soluble in aqueous alkaline conditions, and red and more soluble in alcoholic acidic conditions. In acidic conditions, hematein binds to lysine residues of nuclear histones by linkage via a metallic ion mordant like Fe(III) or Al(III) salts, forming lakes or colored complexes (dye-mordant-tissue complexes), the color of which will depend on the salt used. Aluminium salt lakes are usually colored blue white while ferric salt lakes are colored blue-black.

Structures that stain with hematein are called basophilic. The basophilic structures are usually the ones containing nucleic acids, such as the ribosomes and the chromatin-rich cell nucleus, and the cytoplasmatic regions rich in RNA.

References