Nucleic acids, coplanarity

In 1984, Giibble et al. reported for the first time a novel l,10-bis-(6-methyl-5H-benzo[fc]carbazol-ll-yl)decane (469) which has potential bifunctional nucleic acid intercalating properties (406). To function as anti-tumor active drugs, one of the most important cytostatic mechanisms of action of coplanar annelated polycyclic compounds is their intercalation with DNA (405). Ten years later, Kucklander et al. studied a series of 5H-benzo[ 7]carbazole quinone derivatives for their cytotoxic activity against colon and lung cancer cells, and found that the heteroannelated 5H-benzo[ 7]carbazole quinone derivative 470 was the most active among the various analogs (407) (Scheme 4.2). 

J. Leszczynski, Are the Amino Groups in the Nucleic Acid Bases Coplanar with the Molecular Rings Ab Initio HF/6-31G and MP2/6-31G Studies. Int. J. Quantum Chem. 19, 43-55 (1992)... 

A nucleic acid gives more than 40 well-defined absorption bands in the IR spectrum (300-4000 cm region). For elucidating the nature of the normal vibrations of a nucleic acid, it is helpful to examine the effects of base composition on the vibrational frequencies, as well as the intensity and anisotropy of the IR absorption. Three of the four natural bases of a DNA (adenine, guanine, and cytosine) have an amino group w hich is considered to be nearly coplanar, because the purine or pyrimidine rings have aromatic character and the C—N bonds have some double-bond character. 

The coplanarity of benzo[ajpyrene and many carcinogenic polycyclic hydrocarbons is of interest. It has been suggested that this flat structure allows intercalation of the hydrocarbon within the DNA molecule, thereby facilitating reaction of the intermediate with the nucleic acid. 

Leszczynski, J. (1992). Are the amino groups in the nucleic acid bases coplanar with the molecular... 

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