Anthraquinones, naphthohydroquinones and naphthohydroquinone dimers from Rubia cordifolia and their cytotoxic activity.

Further investigation of the roots of Rubia cordifolia resulted in the isolation of four new naphthohydroquinones and two naphthohydroquinone dimers, and one known naphthohydroquinone, one naphthoquinone, two anthraquinones and one naphthohydroquinone dimer. The structures of these compounds were established by various chemical and spectroscopic methods including two dimensional NMR techniques. Also, the isolated compounds were submitted to a bio-assay for cytotoxic and antitumor activity.