Study of the interaction of the antimalarial drug cinchonine with nucleic acids by Raman spectroscopy

Resonance Raman and Raman spectra were obtained for cinchonine (C19H22N2O), which belongs to the group of four most important, biologically active alkaloids of Cinchona tree bark. The UV resonance Raman and Raman spectra of cinchonine mixed with poly(dA-dT)(2), poly(dG-dC)(2) and calf thymus DNA were also measured. A new cinchonine band of wavenumber 1374 cm(-1) (a constituent peak of the band of wavenumber 1369 cm(-1)) was observed as a characteristic feature of cinchonine-DNA interaction, The shift of the PO2- stretching vibration of DNA towards lower wavenumbers indicates coulombic interactions with cinchonine. These observations suggest that the cinchonine cation is bonded to the minor groove with the quinoline part protruding into the major groove of DNA.