Brazilin & Brazilein
Brazilin is a natural dye which is extracted from the heartwood of South American trees Caesalpinia echinata and Haematoxylon brasiletto, and is closely related to the more well known hematoxylin, from which it differs by having one less hydroxyl group. It's oxidation to brazilein is analogous to that dye, as is the way it forms lakes with mordants, usually aluminum or iron, although others have been suggested. The tissue component most frequently demonstrated is nuclear chromatin, which it stains red. It has not gained the popularity of the similar hematoxylin, as it can be replaced with other, more easily available red dyes.
Anatech has suggested it as a substitute for nuclear fast red, because of difficulties with supply of that dye. They suggest that brazilin may be substituted for hematoxylin in hemalum formulae, but that the amount of dye used should be doubled. They also note that brazilin must be oxidised to brazilein with sodium iodate for the solutions to stain properly. Likely the same amount of sodium iodate would be required as for hematoxylin.
There is an interesting article on brazilin and hematoxylin at Wayne's Word. The article describes how logwood dyes were introduced to Europe, and how they resulted in the creation of two countries.
Like hematoxylin, brazilin has not been completely synthesized.
R. D. Lillie.
Conn's Biological Stains
Williams & Wilkins, Baltimore, MD., U.S.A.
Morsingh, F., and Robinson, R., (1970)
The synthesis of brazilin and haematoxylin
Tetrahedron, v. 26, p. 281,