Copyright information:Taken from "Biosynthesis of Antitumoral and Bactericidal Sanguinarine"Journal of Biomedicine and Biotechnology 2006;2006():-.Published online 1 Mar 2006PMCID:PMC1559923. One of the best targets for testing interaction of a drug with its receptor is DNA. Antitumor antibiotics are known to act at the DNA level. Due to DNA's helical and relatively stable conformation in solution, DNA-drug complexes can conveniently be studied by high-resolution NMR-spectroscopy.