The synthesis, physicochemical properties, and biological activities of a series of novel spiro cyclopropyl compounds, modeled on the potent antitumor antibiotic CC-1065 (1), are described. Many of these synthetic analogues are significantly more effective than 1 against murine tumors. In particular, compound 27 exhibits high activity and potency. Structure-activity analysis supports a molecular mechanism for biological action involving hydrophobic interaction of the drug with DNA and acid-catalyzed alkylation of DNA.
In an extensive analysis of the antiviral and interferon-induction structure-activity relationship of 6-arylpyrimidinones we found that modifications at positions 1-4 of the pyrimidine ring resulted in a loss of activity. However, we uncovered interesting hypotensive and antiinflammatory activity with a series of N-substituted analogues, the results of which we report herein.
The binding of the antitumor drug CC-1065 has been studied with nuclear magnetic resonance (NMR) spectroscopy. This study involves two parts, the elucidation of the covalent binding site of the drug to DNA and a detailed investigation of the noncovalent interactions of CC-1065 with a DNA fragment through analysis of 2D NOE (NOESY) experiments. A CC-1065-DNA adduct was prepared, and an adenine adduct was released upon heating. NMR (1H and 13C) analysis of the adduct shows that the drug binds to N3 of adenine by reaction of its cyclopropyl group. The reaction pathway and product formed were determined by analysis of the 13C DEPT spectra. An octamer duplex, d(CGATTAGC.GCTAATCG), was synthesized and used in the interaction study of CC-1065 and the oligomer. The duplex and the drug-octamer complex were both analyzed by 2D spectroscopy (COSY, NOESY). The relative intensity of the NOEs observed between the drug (CC-1065) and the octamer duplex shows conclusively that the drug is located in the minor groove, covalently attached to N3 of adenine 6 and positioned from the 3'----5' end in relation to strand A [d(CGATTA6GC)]. A mechanism for drug binding and stabilization can be inferred from the NOE data and model-building studies.
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