Redox-active and DNA-binding coordination complexes of clotrimazole

DNA interactions of anticancer mononuclear Cu2+, Co2+, Zn2+, and Ni2+ complexes with the biologically active ligand clotrimazole (clotri) are reported. To fully characterize DNA binding modes for these complexes of the formulae [M(clotri)2Cl2]·nH2O (1–4), [M(clotri)2Br2]·nH2O (5,6), [M(clotri)3NO3]NO3·nH2O (9), and [M(clotri)3(NO3)2] (10), circular dichroism (CD) and linear dichroism (LD) spectroscopy, UV melting experiments, atomic force microscopy (AFM) and ethidium bromide (EtBr) displacement methods were used. Results indicate mixed electrostatic interactions, possibly through groove binding, that result in accretion and coiling of DNA. Electrochemical studies indicate that the Cu2+ complex 9 readily reduces to the reactive-oxygen-species-generating Cu+, which oxidatively damages DNA. There is a subtle correlation between log P values, calculated electrostatic potentials, and cytotoxicity of the complexes. The extent of cell-nucleus DNA-metal adduct formation in the HeLa cervix-uterine carcinoma cell line does not necessarily correlate with cytotoxicity, indicating that the nature of DNA lesions may be crucial to activity

Chemical synthesis and cytotoxicity of dihydroxylated cyclopentenone analogues of neocarzinostatin chromophore

Compounds containing the naphthoate moiety of Neocarzinostatin chromophore or 2-hydroxynaphthoate have been synthesized and evaluated for cytotoxic activity against a leukemia cell line and a small panel of human-tumor cell lines. Those compounds containing a cyclopentenone moiety were active, with the carbonyl group being essential for biological activity

Characterization of a Human Colorectal Carcinoma Cell Line with Acquired Resistance to Flavopiridol

ABSTRACT Flavopiridol is a broad-spectrum inhibitor of cyclin-dependent kinases (cdks) and represents the first in this anticancer class to enter clinical trials. In anticipation of the likelihood that, as with other cancer drugs, acquired resistance may limit the drug's efficacy, an acquired resistance model has been established by in vitro drug exposure of the human colon carcinoma cell line HCT116. This stably resistant line, possessing 8-fold resistance to flavopiridol, showed a lack of cross-resistance to the anticancer agents etoposide, doxorubicin, paclitaxel, topotecan, and cisplatin, and notably to other chemical classes of cdk inhibitors: the aminopurines roscovitine and purvalanol A, 9-nitropaullone, and hymenialdisine. Resistance did not seem to be related to differences in the levels of multidrug resistance drug efflux proteins, P-glycoprotein, and MRP1. Moreover, there were no changes in overall drug accumulation between the resistant and sensitive cell lines. Flavopiridol induced cell cycle arrest, apoptosis, and inhibition of retinoblastoma gene product phosphorylation on serine 780 in both parental and resistant lines, but the latter required 8-fold higher concentrations to achieve these effects. Cyclin E protein levels and cyclin E-associated kinase activity were increased in the resistant line, suggesting that overexpression of cyclin E may be the mechanism of resistance to flavopiridol. However, transfection of cyclin E to increase expression of this protein did not result in an increase in resistance to flavopiridol. Thus, up-regulation of cyclin E alone does not seem to cause resistance to this cdk inhibitor

An expeditious synthesis of cytotoxic pyrroloisoquinoline derivatives.

A number of pyrroloisoquinolines have been prepared by reaction of 5-nitroisoquinoline with vinylmagnesium bromide followed by N-alkylation with the appropriate 2-chloro-N,N-dialkylethylamine. Their cytotoxicity was evaluated in a number of ovarian cell lines and compared to their analogous isomeric pyrroloquinolines. Two of the new compounds, 7c and 7d, are selective toward the A2780 cisplatin-resistant line. (C) 2002 Elsevier Science B.V. All rights reserved

A New Ring-Forming Methodology for the Synthesis of Bioactive Pyrroloquinoline Derivatives

A new, efficient, two-step method for the synthesis of bioactive pyrroloquinolines is described. Readily available nitroquinolines, bearing the nitro moiety in the carbocyclic ring, are treated with 4-chlorophenoxyacetonitrile in the presence of potassium tert-butoxide/THF to give the analogous vicarious nucleophilic substitution products (5, 8 and 11). These, in turn, are subjected to catalytic hydrogenation to produce 1H-pyrrolo[2,3-f]quinoline (6), 3H-pyrrolo[3,2-f]quinoline (9) and 1H-pyrrolo[3,2-h]quinoline (12) in good yields and relatively short reaction times. The differential activity of two N-alkylated 1H-pyrrolo[2,3-f]quinolines (1) in cisplatin resistant cell lines compared to the corresponding parent lines suggests that these might be useful leads for developing agents for use in drug resistant diseases

Novel Approaches to Polynuclear Platinum Pro-Drugs. Selective Release of Cytotoxic Platinum−Spermidine Species through Hydrolytic Cleavage of Carbamates

BBR3464 is a novel trinuclear platinum drug currently in Phase II clinical trials. Polyamine-bridged dinuclear platinum compounds as represented by [{trans-Pt(NH_3)_2Cl}_2-μ-spermidine-N^1,N^8]Cl_3 (1) are highly interesting second-generation analogues of BBR3464 because the hydrogen-bonding and electrostatic contributions of the central platinum−amine group in BBR3464 are replicated by the free, noncoordinated “central” quaternary nitrogens of the linear polyamine linker while the presence of two separate Pt−Cl bonds maintains the bifunctional binding mode on the DNA adducts. Preclinical investigations confirm the potency of these species with cytotoxicity in the nanomolar range. This remarkable potency results in a relatively narrow therapeutic index. To enhance the therapeutic index of these drugs, we investigated the potential for “pro-drug” delivery of less toxic and better tolerated derivatives such as the compounds [{trans-Pt(NH_3)_2Cl}_2-μ-N^4-R-spermidine-N_1,N_8]Cl_2 where N^4-R represents BOC (tert-butyl), CBz (benzyl), and Fmoc (fluorenylmethyl) carbamate blocking groups, 2−4, respectively. The bulky Fmoc derivative showed evidence for conformational isomers by ^1H NMR spectroscopy due to the inequivalence of the two n-propyl and n-butyl side chains of the spermidine moiety. The rate constants for hydrolysis and release of 1 were calculated. Release of cytotoxic 1 at physiologically relevant pH followed the order 4 > 2 > 3. The calculated values for 4 (pH 5, 6.0(±3.9) × 10^(-10) s^(-1); pH 6, 6.5(±0.2) × 10^(-9) s^(-1); pH 7, 6.0(±0.2) × 10^(-8) s^(-1); pH 8, 1.6(±0.1) × 10^(-7) s^(-1)) show a more pronounced pH dependence compared to 2 (pH 5, 4.6(±0.1) × 10^(-8) s^(-1; pH 6, 4.2(±0.1) × 10^(-8) s^(-1); pH 7, 3.2(±0.1) × 10-8 s-1). Preliminary biological assays of cellular uptake and cytotoxicity confirm the utility of the pro-drug concept. While blocked-polyamine compounds such as 2−4 are, in general, 2−3 orders of magnitude less cytotoxic than 1, there is significant cell type variability. Specifically, the Fmoc derivative 4 showed significantly enhanced cytotoxicity warranting further study of the pro-drug concept for greater selectivity and/or oral delivery