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In our pursuit of developing novel analogs of anthracyclines with enhanced antitumor efficacy and safety, we have designed a synthesis scheme for 4,11-dihydroxy-5,10-dioxocyclopenta[ b ]anthracene-2-carboxamides. These newly synthesized compounds exhibit remarkable antiproliferative potency against various mammalian tumor cell lines, including those expressing activated mechanisms of multidrug resistance. The structure of the diamine moiety in the carboxamide side chain emerges as a critical determinant for anticancer activity and interaction with key targets such as DNA, topoisomerase 1, and ROS induction. Notably, the introduced modification to the doxorubicin structure results in significantly increased lipophilicity, cellular uptake, and preferential distribution in lysosomes. Consequently, while maintaining an impact on anthracyclines targets, these novel derivatives also demonstrate the potential to induce cytotoxicity through pathways associated with lysosomes. In summary, derivatives of cyclic diamines, particularly 3-aminopyrrolidine, can be considered a superior choice compared to aminosugars for incorporation into natural and semi-synthetic anthracyclines or new anthraquinone derivatives, aiming to circumvent efflux-mediated drug resistance. [Display omitted] • • New cyclopentane-fused anthraquinone derivatives have been designed and synthesized. • • Selected compounds have strong antiproliferative potency and circumvent Pgp-mediated efflux. • • Derivative 9 has increased lipophilicity and faster cellular uptake than doxorubicin. • • Terminal amino group in the side chain is crucial for DNA binding and Top1 inhibition. [ABSTRACT FROM AUTHOR]

Abstract Derivatives of the anthraquinone (anthracene-9,10-dione) such as doxorubicin, mitoxantrone and others have proved great clinical efficacy for decades. Currently the search in this exceptionally productive chemical class is aimed at optimization of antitumor properties including circumvention of drug resistance. Previously we have reported that heteroarene-fused anthraquinones fused to a 5-membered heterocyclic ring are advantageous in killing drug resistant tumor cells. Herein we present the synthesis and antitumor properties of a series of new anthra[2,3- b ]furan-2-carboxamides. Vast majority of new derivatives were similarly cytotoxic to wild type tumor cell lines and their isogenic sublines with P-glycoprotein overexpression and/or p53 inactivation. Comparison of structurally close derivatives varying in their position relative to the furan moiety, that is, furan-3-carboxamide 1 vs furan-2-carboxamides 5 and 6 , revealed fundamental differences in the cytotoxicity profiles, formation of drug-DNA complexes, efficacy of topoisomerase 1 inhibition and mechanisms of tumor cell death. Together with previous SAR data on the role of individual substituents, these results provide evidence that regioisomerization of anthra[2,3- b ]furancarboxamides generates the practically perspective derivatives whose properties may vary significantly. Graphical abstract Image 1 Highlights • A series of new anthra[2,3- b ]furan-2-carboxamides was synthesized and evaluated. • Individual compounds were potent against wild type and drug resistant tumor cells. • Anthra[2,3- b ]furan-2-carboxamides inhibit topoisomerase 1-mediated DNA unwinding and induce apoptosis. • Position of the carboxamide moiety is important for antitumor properties. [ABSTRACT FROM AUTHOR]

Abstract Here, a combined molecular modelling methodology was used to identify the binding mode of 4,11-bis((2-guanidinoethyl)amino)anthra[2,3- b ]thiophene-5,10-dione (1), a previously reported G4 ligand. After calculating the optimal interaction parameters 1 with the target, two series of tri-armed ligands based on furan- or thiophene-fused anthraquinone scaffolds were designed and synthesized. The new compounds bearing an additional side chain at the 2-position of the heterocycle and the 4,11-side chains with different spacer lengths and structures of terminal groups demonstrated much stronger affinity for telomeric G4 (4–15 times) versus the parental ligand. Moreover, the specificity to the quadruplex over duplex DNA was significantly improved (up to 75 times) when the 3-guanidinopropyl side chain was introduced at the 2-position of the heterocycle ring. All tri-armed ligands demonstrated modest antiproliferative potency, which is likely due to low intracellular penetration. Nevertheless, this work shows how computer-aided rational design of new potent compounds can be used for targeted anticancer therapy. Graphical abstract Image 1 Highlights • Molecular modelling was applied for rational design of new G-quadruplex ligands. • Two series of G4 ligands were designed and synthesized. • Additional side "arm" provides stronger stabilization of telomeric quadruplex. • Modifications significantly improves specificity to the G4 over duplex DNA. • Compounds inhibit growth of cancer cells at micromolar concentrations. [ABSTRACT FROM AUTHOR]

Pyrazole analogs of the staurosporine aglycon K252c were recently described as potent inhibitors of the three Pim protein kinase isoforms. To evaluate the impact of the introduction of a sugar moiety on the biological activities of this heterocyclic scaffold, four new glucosylated pyrazole analogs of K252c were synthesized. Their biological evaluation demonstrated that most active compounds 11 and 19 substituted by a β- d -glucosyl moiety at N12 or N13 positions exhibited antiproliferative activities toward HCT116 cells. [ABSTRACT FROM AUTHOR]

A series of 4-aminomethyl derivatives of heliomycin 1 was prepared using the Mannich reaction. The modification significantly improved aqueous solubility of the initially poorly soluble antibiotic. Testing the antiproliferative efficacy revealed a potent activity of heliomycin as well as its new derivatives on a panel of mammalian tumor cells including drug resistant variants. In contrast to 1 the new derivatives 7a , 7l , 7p generated a high level of ROS associated with induction of apoptosis in T24 bladder cancer cells. Introduction of 4-aminomethyl moiety increased the affinity to DNA and the ability to inhibit topoisomerase 1 making 7p the most promising candidate for further preclinical evaluation. Thus, aminomethylation is the first-in-class successful transformation of the antibiotic 1 resulting in an improved water solubility of derivatives and promising properties in search of novel anticancer drug candidates. [ABSTRACT FROM AUTHOR]

A derivative of the staurosporine aglycon (K252c), in which the lactam ring was replaced by a pyrazole moiety, was synthesized. The resulting indolopyrazolocarbazole ( 3 ) inhibited Pim isoforms 1–3 whereas it did not impair the activity of two known targets of K252c, protein kinase C isoforms α and γ. Compound 3 exhibited moderate cytotoxic activity toward human leukemia and colon carcinoma cell lines (K562 and HCT116), strongly suggesting that this new scaffold deserves further investigations for treatment of malignancies associated with Pim activity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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)-1 H -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. [ABSTRACT FROM AUTHOR]

Novel generations of antitumor anthraquinones are expected to be advantageous over the conventional chemotherapeutic agents. Previous structure–activity relationship studies demonstrated an importance of the positively charged side chains conjugated to anthra[2,3- b ]thiophene-5,10-dione scaffolds. Exploring a role of individual side chain moieties in binding to the duplex and G-quadruplex DNA, modulation of telomerase and topoisomerase I activities, intracellular accumulation and cytostatic potency, we herein analyzed a series of reported and newly synthesized guanidine-containing derivatives of anthra[2,3- b ]thiophene-5,10-dione. We found that the number of cationic side chains (namely, two) is critical for a tight interaction with human telomeric G-quadruplex (TelQ). Along with a larger drug–TelQ association constant, the telomerase attenuation by anthrathiophenediones with two basic groups in the side chains was more pronounced than by the analogs bearing one basic group. For mono-guanidinated compounds the substituent with the amino group in the side chain provided better TelQ affinity than the methylamine residue. The intracellular uptake of the mono-guanidino derivative with two side chains was >2-fold higher than the respective value for the bis(guanidino) derivative. This difference can explain a lower antiproliferative potency of bis(guanidine) containing compounds. Thus, the modifications of side chains of anthra[2,3- b ]thiophene-5,10-dione differently modulated drug–target interactions and cellular effects. Nevertheless, the selected compound 11-(3-aminopropylamino)-4-(2-guanidinoethylamino)anthra[2,3- b ]thiophene-5,10-dione 13 demonstrated a high affinity to TelQ and the ability to stabilize the quadruplex structure. These properties were paralleled by reasonable potency of 13 as a telomerase/topoisomerase I inhibitor and an antiproliferative agent. These results indicate that the structural elements of anthra[2,3- b ]thiophene-5,10-dione derivatives can be balanced to yield a candidate for further preclinical study. [ABSTRACT FROM AUTHOR]

Abstract: A series of DNA aptamers bearing triazole internucleotide linkages that bind to thrombin was synthesized. The novel aptamers are structurally analogous to the well-known thrombin-inhibiting G-quadruplexes TBA15 and TBA31. The secondary structure stability, binding affinity for thrombin and anticoagulant effects of the triazole-modified aptamers were measured. A modification in the central loop of the aptamer quadruplex resulted in increased nuclease resistance and an inhibition efficiency similar to that of TBA15. The likely aptamer-thrombin binding mode was determined by molecular dynamics simulations. Due to their relatively high activity and the increased resistance to nuclease digestion imparted by the triazole internucleotide linkages, the novel aptamers are a promising alternative to known DNA-based anticoagulant agents. [Copyright &y& Elsevier]

The anthraquinone scaffold has long been known as a source of efficacious antitumor drugs. In particular, the various chemical modifications of the side chains in this scaffold have yielded the compounds potent for the wild type tumor cells, their counterparts with molecular determinants of altered drug response, as well as in vivo settings. Further exploring the chemotype of anticancer heteroarene-fused anthraquinones, we herein demonstrate that derivative of anthra[2,3- b ]thiophene-2-carboxamide, (compound 8) is highly potent against a panel of human tumor cell lines and their drug resistant variants. Treatment with submicromolar or low micromolar concentrations of 8 for only 30 min was sufficient to trigger lethal damage of K562 chronic myelogenous leukemia cells. Compound 8 (2.5 μM, 3–6 h) induced an apoptotic cell death as determined by concomitant activation of caspases 3 and 9, cleavage of poly(ADP-ribose) polymerase, increase of Annexin V/propidium iodide double stained cells, DNA fragmentation (subG1 fraction) and a decrease of mitochondrial membrane potential. Neither a significant interaction with double stranded DNA nor strong inhibition of the DNA dependent enzyme topoisomerase 1 by 8 were detectable in cell free systems. Laser scanning confocal microscopy revealed that some amount of 8 was detectable in mitochondria as early as 5 min after the addition to the cells; exposure for 1 h caused significant morphological changes and clustering of mitochondria. The bioisosteric analog 2 in which the thiophene ring was replaced with furan was less active although the patterns of cytotoxicity of both derivatives were similar. These results point at the specific role of the sulfur atom in the antitumor properties of carboxamide derivatives of heteroarene-fused anthraquinone. [Display omitted] • A series of anthra[2,3- b ]thiophene-2-carboxamides were synthesized and evaluated. • A submicromolar cytotoxicity of compound 8 for wild type and drug resistant cells. • Compound 8 induces rapid cell death via organelle but not DNA targeting. [ABSTRACT FROM AUTHOR]

Heteroarene-fused anthraquinone derivatives represent a class of perspective anticancer drug candidates capable of targeting multiple vital processes including drug resistance. Taking advantage of previously demonstrated potential of amide derivatives of heteroarene-fused anthraquinones, we herein dissected the role of the heterocyclic core in antitumor properties. A new series of naphtho[2,3- f indole-3- and anthra[2,3- b thiophene-3-carboxamides was synthesized via coupling the respective acids with cyclic diamines. New compounds demonstrated a submicromolar antiproliferative potency close to doxorubicin (Dox) against five tumor cell lines of various tissue origin. In contrast to Dox , the new compounds were similarly cytotoxic for HCT116 colon carcinoma cells (wild type p53) and their isogenic p53 knockout counterparts. Modification of the heterocyclic core changed the targeting properties: the best-in-series naphtho[2,3- f indole-3-carboxamide 8 formed more affine complexes with DNA duplex than furan and thiophene analogs, a property that can be translated into a stronger inhibition of topoisomerase 1 mediated DNA unwinding. At tolerable doses the water soluble derivative 8 significantly inhibited tumor growth (up to 79%) and increased the lifespan (153%) of mice bearing P388 lymphoma transplants. Together with better solubility for parenteral administration and well tolerance by animals of the indole derivative 8 indicates prospects for further search of new antitumor drug candidates among the heteroarene-fused anthraquinones. Image 1 • A series of new anthrathiophene-3- and naphthoindole-3-carboxamides was synthesized. • Selected compounds were potent against wild type and drug resistant tumor cells. • Compound 8 binds DNA in vitro , inhibits topoisomerase 1 and induces apoptosis. • Antitumor potency in vivo demonstrates a prospect for lead optimization. [ABSTRACT FROM AUTHOR]

• New pyrrolocarbazole-imidazobenzimidazole conjugates were prepared. • Compounds 3 , 6 and 13 exhibited sub-micromolar Pim-1 inhibitory potencies. • Conjugation could enhance the antiproliferative potency of conjugates. New pyrrolocarbazole-imidazobenzimidazole conjugates were prepared and evaluated for their inhibitory potencies toward Pim-1 kinase, DNA binding and antiproliferative activities against human tumor cell lines. The results demonstrated that conjugation of pyrrolocarbazole Pim inhibitors with imidazobenzimidazole derivatives could enhance the antiproliferative potency of conjugates compared to the derived compounds. [ABSTRACT FROM AUTHOR]