Stainsfile - Orcein

Orcein

Structural formula Common name Orcein

Suggested name Orcein

Other names

C.I. number

C.I. name Natural red 28

Class Natural

Ionisation Acid

Solubility in water Poor

Solubility in ethanol Soluble

Absorption maximum

Colour Reddish brown

Empirical formula

Formula weight

Orcein was originally obtained from lichens, but is now made from orcinol by hydrogen peroxide oxidation with ammonia present. Several compounds have been identified as constituents of this dye, differing at the points R₁, R₂ and R₃ in the formula above. It is a standard method for the demonstration of elastic fibres, when it is applied in an acid, alcoholic solution. This same solution has recently been shown to be effective for staining the rough endoplasmic reticulum of hepatitis B infected liver cells, and it is now commonly used for that purpose.

Reference

Conn's Biological Stains
R. D. Lillie.
Williams & Wilkins, Baltimore, MD., U.S.A.

The Merck Index, 12 ed.
Susan Budavari, Ed.
Merck & Co., NJ, USA.

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Last updated March 1998


*Structural formula*	*Common name*	Orcein
	*Suggested name*	Orcein
	*Other names*
	*C.I. number*
	*C.I. name*	Natural red 28
	*Class*	Natural
	*Ionisation*	Acid
	*Solubility in water*	Poor
	*Solubility in ethanol*	Soluble
	*Absorption maximum*
	*Colour*	Reddish brown
	*Empirical formula*
	*Formula weight*

Orcein was originally obtained from lichens, but is now made from orcinol by hydrogen peroxide oxidation with ammonia present. Several compounds have been identified as constituents of this dye, differing at the points R₁, R₂ and R₃ in the formula above. It is a standard method for the demonstration of elastic fibres, when it is applied in an acid, alcoholic solution. This same solution has recently been shown to be effective for staining the rough endoplasmic reticulum of hepatitis B infected liver cells, and it is now commonly used for that purpose.