Development and pharmaceutical evaluation of the anticancer Anthrafuran/Cavitron complex, a prototypic parenteral drug formulation.

To improve the water solubility of the anticancer drug candidate LCTA-2034 (A1), we investigated the formation of complexes of this anthrax[2,3-b]furan congener with the solubilizing 2-hydroxypropyl derivative of ß-cyclodextrin HP-ßCD (Cavitron®). The interaction of A1 with HP-ßCD resulted in the inclusion complex A1/HP-ßCD in 1:1 stoichiometry. The A1/HP-ßCD complex was used to develop a prototype of a lyophilised drug formulation with enhanced (>10-fold) aqueous solubility than A1 and a long-term stability. The use of HP-ßCD decreased the acute toxicity of A1 by >30%. The A1/HP-ßCD drug formulation as well as A1 in equal doses (5×30mg/kg) to increase the lifespan by up to 140% for mice with i.p. transplanted P388 leukaemia. Furthermore, the A1/HP-ßCD formulation demonstrated a significant and reliable antitumor efficacy in a Р388/ADR drug resistant leukaemia and B16/F10 melanoma, proving a perspective of investigations of toxicology, biodistribution and pharmacokinetics.

Discovery of antitumor anthra[2,3-b]furan-3-carboxamides: Optimization of synthesis and evaluation of antitumor properties.

Anthraquinones and their analogues, in particular heteroarene-fused anthracendiones, are prospective scaffolds for new compounds with improved antitumor characteristics. We herein report the use of a 'scaffold hopping' approach for the replacement of the core structure in the previously discovered hit compound naphtho[2,3-f]indole-5,10-dione 2 with an alternative anthra[2,3-b]furan-5,10-dione scaffold. Among 13 newly synthesized derivatives the majority of 4,11-dihydroxy-2-methyl-5,10-dioxoanthra[2,3-b]furan-3-carboxamides demonstrated a high antiproliferative potency against a panel of wild type and drug resistant tumor cell lines, a property superior over the reference drug doxorubicin or lead naphtho[2,3-f]indole-5,10-dione 2. At low micromolar concentrations the selected derivative of (R)-3-aminopyrrolidine 3c and its stereoisomer (S)-3-aminopyrrolidine 3d caused an apoptotic cell death preceded by an arrest in the G2/M phase. Studies of intracellular targets showed that 3c and 3d formed stable intercalative complexes with the duplex DNA as determined by spectral analysis and molecular docking. Both 3c and 3d attenuated topoisomerase 1 and 2 mediated unwinding of the supercoiled DNA via a mechanism different from conventional DNA-enzyme tertiary complex formation. Furthermore, 3d decreased the activity of selected human protein kinases in vitro, indicating multiple targeting by the new chemotype. Finally, 3d demonstrated an antitumor activity in a model of murine intraperitoneally transplanted P388 leukemia, achieving the increase of animal life span up to 262% at tolerable doses. Altogether, the 'scaffold hopping' demonstrated its productivity for obtaining new perspective antitumor drug candidates.

Synthesis and evaluation of new antitumor 3-aminomethyl-4,11-dihydroxynaphtho[2,3-f]indole-5,10-diones.

A series of new 3-aminomethyl-4,11-dihydroxynaphtho[2,3-f]indole-5,10-diones 6-13 bearing the cyclic diamine in the position 3 of the indole ring was synthesized. The majority of new compounds demonstrated a superior cytotoxicity than doxorubicin against a panel of mammalian tumor cells with determinants of altered drug response, that is, Pgp expression or p53 inactivation. For naphtho[2,3-f]indole-5,10-diones 6-9 bearing 3-aminopyrrolidine in the side chains, the ability to bind double-stranded DNA and inhibit topoisomerases 1 and 2 mediated relaxation of supercoiled DNA were demonstrated. Only one isomer, (R)-4,11-dihydroxy-3-((pyrrolidin-3-ylamino)methyl)-1H-naphtho[2,3-f]indole-5,10-dione (7) induced the formation of specific DNA cleavage products similar to the known topoisomerase 1 inhibitors camptothecin and indenoisoquinoline MJ-III-65, suggesting a role of the structure of the side chain of 3-aminomethylnaphtho[2,3-f]indole-5,10-diones in interaction with the target. Compound 7 demonstrated an antitumor activity in mice with P388 leukemia transplants whereas its enantiomer 6 was inactive. Thus, 3-aminomethyl derivatives of 4,11-dihydroxynaphtho[2,3-f]indole-5,10-dione emerge as a new prospective chemotype for the search of antitumor agents.