Determination of 9-hydroxyellipticine by redox colorimetry.

The chemical reactions involved in the decomposition of 9-hydroxyellipticine (9-OH-E), an anticancer agent, in polar solvents is explained. The reactions, which involve the formation of 9-oxo-ellipticine and the addition of a nucleophilic acid on the C10 site of the heterocyclic system, have been used to measure 9-OH-E quantitatively by colorimetry in solution and by reflection on paper surfaces. A method for the stabilization of 9-OH-E in polar solvents is proposed.