- indirubinA substance isomeric with, and resembling, indigo blue; a component of Tyrian purple
- ruberythrinic acidAn acid extracted from madder root; a yellow crystalline substance from which alizarin is obtained.
- rubificreddening, making red.
- rubrocurcuminA red dye formed by the reaction of curcumin with borates in the presence of oxalic acid.
- xerocomorubinA pigment found in Boletales fungi; the oxidized form of isoxerocomic acid.