Xiangdong Wei and Li-June Ming*

Department of Chemistry and
Institute for Biomolecular Science
University of South Florida
Tampa, Florida 33620-5250
USA
 
Abstract
 The antibiotic streptonigrin (SN) produced by Streptomyces flocculus is a metal-dependent potent antitumor agent.  Optical and ¹H NMR techniques have been applied to the study of a few metal complexes (Co²⁺, Fe²⁺, and Yb³⁺) of this antitumor antibiotic.  The hyperfine-shifted ¹H NMR signals of these paramagnetic complexes are fully assigned by means of NMR relaxation, EXSY, and COSY techniques.  These studies reveal that SN binds transition metal and lanthanide ions and form stable metal-drug complexes, with the metal located at the quinolinequinone-pycolinate sites.  This configuration requires a ~180º twist of the C2—C2’ bond in the crystal structure of the drug.  The hyperfine-shifted ¹H NMR signals of the Co²⁺-SN complex are significantly changed upon addition of calf thymus DNA or poly[dA-dT], indicating direct binding of Co2+-SN complex with DNA.

(Read more about streptonigrin.)
 
(Read an introduction about metal complexes of the antitumor antibiotics anthracyclines.)