C07C 229/74

Compounds containing amino and carboxyl groups bound to the same carbon skeleton having amino and carboxyl groups bound to carbon atoms of six-membered aromatic rings of the same carbon skeleton with amino and carboxyl groups bound to carbon atoms of six-membered aromatic rings being part of the same condensed ring system the carbon skeleton being further substituted by doubly-bound oxygen atoms the condensed ring system being formed by at least three rings, e.g. amino anthraquinone carboxylic acids