(-) Luteoskyrin and (+) Rugulosin are 2 hepatotoxic and carcinogenic anthraquinone-like pigments from Penicillia which contaminate rice and other foodstuffs. They inhibit in vivo and in vitro replication, transcription and DNA repair of Protocaryots and Eucaryots presumably by forming chelate-complexes with nucleic acids. In the present work, characterization, specificity and structure of binary polychelates (pigment-metal)n and ternary complexes (pigment-metal-nucleic acids) are successively reported: whereas, unspecific complex II with double-stranded polynucleotides is shown to result from simple adsorption of polychelate onto the double helix, complex I is specific for single-stranded DNA (or polypurine nucleotides) and results from electrostatic association of separate pigment-metal units with the polyphosphate chain. Additional stabilization is obtained by hydrophobic interaction between stacked aromatic moieties of pigment and purine units. A model of interaction is proposed for both complexes I and II.