Structure−Activity Relationships in a Series of Substituted Indolocarbazoles:  Topoisomerase I and Protein Kinase C Inhibition and Antitumoral and Antimicrobial Properties

Abstract

A series of compounds structurally related to staurosporine, rebeccamycin, and corresponding aglycones was synthesized, and their activities toward protein kinase C and topoisomerases I and II were tested together with their in vitro antitumor efficiency against murine B16 melanoma and P388 leukemia cells. Their antimicrobial activities were also examined against a Gram-negative bacterium (Escherichia coli), a yeast (Candida albicans), and three Gram-positive bacteria (Bacillus cereus, Streptomyces chartreusis, and Streptomyces griseus). To avoid side effects expected with protein kinase C inhibitors, we introduced substitution on the maleimide nitrogen and/or a sugar moiety linked to one of the indole nitrogens to obtain specific inhibitors of topoisomerase I with minimal activities on protein kinase C. As expected, these structures were inefficient on topoisomerase II, and some of them exhibited a strong activity against topoisomerase I. Generally, dechlorinated compounds were found to be more active than chlorinated analogues against both purified topoisomerase I and protein kinase C. On the other hand, opposite results were obtained in the cell antiproliferative assays. These results suggest lack of cell membrane permeability in the absence of the chlorine residue or cleavage of carbon-chlorine bonds inside the cell.

Recognition of Specific Sequences in DNA by a Topoisomerase I Inhibitor Derived from the Antitumor Drug Rebeccamycin

“…The syntheses of the indolocarbazole R-3 and its aglycone derivative, R-4, have been reported previously (Rodrigues-Pereira et al, 1996). In the dry state, the drugs were stored in a desiccator in the dark at 4°.…”

“…We found that the presence of chlorine on the indolocarbazole chromophore (as in rebeccamycin) significantly reduces the effect on topoisomerase I, whereas the substituents on the maleimido function and the functional group on the nonindolic moiety can be varied without loss of activity. In addition, we showed that the methoxyglucose residue attached to the chromophore plays a determinant role in facilitating interaction of the drug with DNA/topoisomerase I complexes (Bailly et al, 1997;Rodrigues-Pereira et al, 1996). However, the exact mechanism of interaction between these compounds and DNA with or without topoisomerase I remains unclear and poorly documented.…”

Enhanced Binding to DNA and Topoisomerase I Inhibition by an Analog of the Antitumor Antibiotic Rebeccamycin Containing an Amino Sugar Residue

“…Considerable interest has been devoted by our laboratories to the study of correlations between the molecular structure and biochemical and/or biological activities of indolocarbazole drugs to obtain information at the molecular level that may be relevant to the proper design of chemotherapeutically more effective drugs (Rodrigues-Pereira et al, 1996;Anizon et al, 1997Anizon et al, , 1998Bailly et al, 1997Bailly et al, , 1998aPrudhomme, 1997;Moreau et al, 1998 ). The present approach has been centered on the addition of an amine group at position 2Ј (modifications at 3Ј and 4Ј positions currently are being investigated).…”

“…Indolocarbazoles linked to the carbohydrate via a ␤-glycoside linkage are potent inhibitors of topoisomerase I, whereas the ␣-analogs completely failed to inhibit the enzyme, most likely as a result of their greatly reduced affinity for DNA. Both the chemical nature and the isomeric form of the sugar residue are essential to the interaction with DNA and to the biological activity (for the structure-activity relationships, see Rodrigues-Pereira et al, 1996;Anizon et al, 1997Anizon et al, , 1998Bailly et al, 1997Bailly et al, , 1998aPrudhomme, 1997;Moreau et al, 1998).…”

“…P388 murine leukemia cells were incubated at 37°C for 96 h in the presence of various concentrations of drug and evaluated for viability by neutral red staining as described previously (Rodrigues-Pereira et al, 1996). The concentrations of drugs giving 50% of growth inhibition (IC 50 ) were determined.…”