orcein
orcein
A variable mixture of several compounds isolated from lichens, the eight most abundant being α-aminoorcein, α-hydroxyorcein, β-aminoorcein, γ-aminoorcein, β-hydroxyorcein, γ-hydroxyorcein, β-aminoorceimine and β-aminoorceimine (all are phenoxazine-based). It is used for the demonstration of elastic fibres as well as to stain the rough endoplasmic reticulum of hepatitis B infected liver cells.