DNA Binding Ellipticine Analogues: Synthesis, Biological Evaluation, and Structure-Activity Relationships

Novel halogenated pyrido[2,3-a]carbazoles with enhanced aromaticity as potent anticancer and antioxidant agents: rational design and microwave assisted synthesis

Design and synthesis a series of pyrido[2,3-a]carbazoles for their anticancer and antioxidant activity.

New insights for the use of quercetin analogs in cancer treatment

AIM

Quercetin (Q1) is a flavonoid widely present in plants and endowed with several pharmacological properties mostly due to its antioxidant potential. Q1 shows anticancer activity and could be useful in cancer prevention. On the other hand, Q1 is poorly soluble in water and unstable in physiological systems, and its bioavailability is very low.

METHODS

A small set of Q1 derivatives (Q2-Q9) has been synthesized following opportunely modified chemical procedures previously reported. Anticancer activity has been evaluated by MTT assay. Human Topoisomerases inhibition has been performed by direct enzymatic assays. Apoptosis has been evaluated by TUNEL assay. ROS production and scavenging activity have been determined by immunofluorescence.

RESULTS

The anticancer profile of a small library of Q1 analogues, in which the OH groups were all or partially replaced with hydrophobic functional groups, has been evaluated. Two of the studied compounds demonstrated an interesting cytotoxic profile in two breast cancer models showing the capability to inhibit human Topoisomerases.

CONCLUSION

The studied compounds represent suitable leads for the development of innovative anticancer drugs. [Formula: see text].

Synthesis of hetero annulated isoxazolo-, pyrido- and pyrimido carbazoles: Screened for in vitro antitumor activity and structure activity relationships, a novel 2-amino-4-(3'-bromo-4'-methoxyphenyl)-8-chloro-11H-pyrimido[4,5-a]carbazole as an antitumor agent

Claisen-Schmidt condensation of 2,3,4,9-tetrahydro-1H-carbazol-1-one with 3-bromo-4-methoxy benzaldehyde afforded the 2-(3'-bromo-4'-methoxybenzylidene)-2,3,4,9-tetrahydro-1H-carbazol-1-one 3. Compound 3 was allowed to react with different organic reactants, hydroxylamine hydrochloride, malononitrile and guanidine nitrate through condensation cum cycloaddition reactions to afford a series of the respective novel hetero annulated carbazoles such as isoxazolo-, pyrido- and pyrimido carbazoles. The structures of the compounds were established by FT-IR, ¹H NMR, ¹³C NMR, X-ray diffraction and elemental analysis. The compounds have been screened for in vitro anti-tumor activity by MTT assay and displayed enviable selective growth inhibition on MCF-7 cell line compared to A-549 cell line. Apoptotic morphological changes in MCF-7 and A-549 cells were visualized using fluorescent microscopic technique. The preliminary structure activity relationships were also carried out. Data pointed out that among pyrimido carbazole compounds, 2-amino-4-(3'-bromo-4'-methoxyphenyl)-8-chloro-11H-pyrimido [4,5-a]carbazole could be exploited as an excellent therapeutic drug against cancer cell proliferation.

Determination of binding modes and binding constants for the complexes of 6H-pyrido[4,3-b]carbazole derivatives with DNA

The binding modes and binding constants for the complexes of forty types of pyridocarbazole derivatives 1-40 with double stranded DNAs (dsDNAs) were reported. The binding modes were determined by a combination of a deflection spectroscopy and orientation of the corresponding molecule in the DNA-based film with chain alignment. All of the compounds exhibited the intercalation-binding mode. Its binding constants K_a for the complexes, determined by quartz crystal microbalance (QCM), varied from 1.7×10⁵ to 4.5×10⁷M^-1 according to the substituents on the pyridocarbazole framework and the sequences of dsDNA. The binding constants K_a of pyridocarbazole derivatives possessing the 2-(ω-amino)alkyl group and 5-(ω-amino)alkylcarbamyl group were larger than those of the corresponding ω-ureido derivatives. These ω-amino compounds exhibited strong GC base-pair preference in complexation. The K_a values decreased with the increasing NaCl concentration. It was clarified by a molecular modeling that the framework of the 2-tethered ω-amino derivative was completely overlapped with the stacking GC base-pairs leading to the formation of the stable intercalative-complex, and that the framework of the 5-tethered ureido derivative was half overlapped leading to the formation of the unstable complex. Furthermore, there were good linear relationships between lnK_a and the relative stabilities S_rel of the complexes. Contrary to our expectation, there was no linear relationship between lnK_a and IC₅₀ against Sarcoma-180, NIH3T3, and HeLa S-3 cell lines.

Multifaceted properties of 1,4-dimethylcarbazoles: Focus on trimethoxybenzamide and trimethoxyphenylurea derivatives as novel human topoisomerase II inhibitors

Natural or synthetic carbazole derivatives have recently attracted the attention of the scientific world because of their multiple biological activity, leading to an increase of designed, synthesized and studied analogues. In this paper, four 1,4-dimethylcarbazole derivatives, analogues of Ellipticine, have been investigated for their ability to block cancer cells growth, with low effects on the proliferation of normal cells. DNA topoisomerases inhibition assays, docking simulations, stability studies and effects on a membrane model are reported. Particularly, compounds 2 and 3 have been found thermally stable and able to inhibit, strongly and selectively, the human DNA topoisomerase II. These properties confer a good and broad antitumoral activity in vitro, with very low cytotoxic effect on the proliferation of normal cell lines and without damaging, in contrast with Ellipticine, the cell membrane model. The presented outcomes set the most active compounds as good candidates for pre-clinical studies useful in cancer treatment.

New trans dichloro (triphenylphosphine)platinum(II) complexes containing N-(butyl),N-(arylmethyl)amino ligands: Synthesis, cytotoxicity and mechanism of action

Some new platinum(II) complexes have been prepared, of general formula trans-[PtCl2(PPh3){NH(Bu)CH2Ar}], where the dimension of the Ar residue in the secondary amines has been varied from small phenyl to large pyrenyl group. The obtained complexes, tested in vitro towards a panel of human tumor cell lines showed an interesting antiproliferative effect on both cisplatin-sensitive and -resistant cells. For the most cytotoxic derivative 2a the investigation on the mechanism of action highlighted the ability to induce apoptosis on resistant cells and interestingly, to inhibit the catalytic activity of topoisomerase II.

Cell Cycle Arrest and Induction of Apoptosis in Colon Adenocarcinoma Cells by a DNA Intercalative Quinoline Derivative, 4-Morpholinopyrimido [4',5':4,5] Selenolo (2,3-b) Quinoline

Circular dichroism, topological studies, molecular docking, absorbance, and fluorescence spectral titrations were employed to study the interaction of 4-morpholinopyrimido [4',5':4,5] selenolo (2,3-b) quinoline (MPSQ) with DNA. The association constants of MPSQ-DNA interactions were of the order of 10(4) M(-1). Melting temperature, topological, and docking studies confirmed that the mode of interaction was by intercalation with preference to d(GpC)-d(CpG) site of DNA. Cytotoxicity studies showed the MPSQ-induced dose-dependent inhibitory effect on the proliferation of different cancer cells. Colon adenocarcinoma (COLO 205) cells are more sensitive among the cell lines tested, with an IC50 value of 15 μM. Flow cytometry revealed that MPSQ affects the cell cycle progression by arresting at G2M phase. Further, Annexin V staining, mitochondrial membrane potential assay, and caspase-3 activity assay confirmed that MPSQ leads to mitochondria-mediated apoptotic cell death in COLO 205 cells.

Synthesis, in vitro antimicrobial and cytotoxic activities of new carbazole derivatives of ursolic acid

A series of new carbazole derivatives of ursolic acid were designed and synthesized in an attempt to develop potent antimicrobial or antitumor agents. Their structures were confirmed by using IR, HRMS and (1)H NMR analysis. All the synthesized compounds were evaluated for their antimicrobial activity against four bacterial and three fungal strains using serial dilution method. Compounds 3a, 3b, 4a, 4b and 5a-f exhibited significant antibacterial activity against at least one tested bacteria with MIC values of 3.9-15.6μg/ml. In addition, the in vitro cytotoxicity of these compounds were also assayed against two human tumor cell lines (SMMC-7721 and HepG2) using MTT colorimetric method. From the results, compounds 5a-e and 5h displayed pronounced cytotoxic activity with IC50 values below 10μM. Specially, compound 5e was found to be the most potent compound with IC50 values of 1.08±0.22 and 1.26±0.17μM against SMMC-7721 and HepG2 cells, respectively, comparable to those of doxorubicin. In addition, compound 5e showed reduced cytotoxicity against noncancerous LO2 cells with IC50 value of 5.75±0.48μM.

Synthesis and in vitro antitumor activity of novel 2-alkyl-5-methoxycarbonyl-11-methyl-6H-pyrido[4,3-b]carbazol-2-ium and 2-alkylellipticin-2-ium chloride derivatives

Twenty-one types of novel ellipticine derivatives and pyridocarbazoles (5-methoxycarbonyl-11-methyl-6H-pyrido[4,3-b]carbazoles) with a nitrosourea moiety, linked by an oxydiethylene unit at the 2 position, were synthesized, and their cytotoxicity against HeLa S-3 cells was evaluated. Some of these new compounds exhibited potent antitumor activity by comparison with that of ellipticine.

Facile synthesis of 5H-benzo[b]carbazol-6-yl ketones via sequential reaction of Cu-catalyzed Friedel–Crafts alkylation, iodine-promoted cyclization, nucleophilic substitution and aromatization

A convenient method to access 5H-benzo[b]carbazol-6-yl ketones from indoles and 2-(2-(alkynyl)benzylidene)malonates has been developed.

Novel Nitrobenzazolo[3,2-a]quinolinium Salts Induce Cell Death through a Mechanism Involving DNA Damage, Cell Cycle Changes, and Mitochondrial Permeabilization

This study reports the capacity of three nitro substituted benzazolo[3,2-a]quinolinium salts NBQs: NBQ 95 (NSC-763304), NBQ 38 (NSC 763305), and NBQ 97 (NSC-763306) as potential antitumor agents. NBQ's are unnatural alkaloids possessing a positive charge that could facilitate interaction with cell organelles. The anticancer activities of these compounds were evaluated through the National Cancer Institute (NCI) 60 cell line screening which represents diverse histologies. The screening was performed at 10 µM on all cell lines. Results from the NCI screening indicated cytotoxicity activity on six cell lines. In order to explore a possible mechanism of action, a detailed biological activity study of NBQ 95 and NBQ 38 was performed on A431 human epidermoid carcinoma cells to determine an apoptotic pathway involving, cell cycle changes, DNA fragmentation, mutations, mitochondrial membrane permeabilization and caspases activation. DNA fragmentation, cell cycle effects, mutagenesis, mitochondrial permeabilization and activation of caspases were determined by fluorimetry and differential imaging. Our data showed that A431 growth was inhibited with an average IC50 of 30 µM. In terms of the mechanism, these compounds interacted with DNA causing fragmentation and cell cycle arrest at sub G0/G1 stage. Mutagenesis was higher for NBQ 38 and moderate for NBQ 95 Mitochon-drial permeabilization was observed with NBQ 38 and slightly for NBQ 95. Both compounds caused activation of Caspases 3 and 7 suggesting an apoptotic cell death pathway through an intrinsic mechanism. This study reports evidence of the toxicity of these novel compounds with overlapping structural and mechanistic similarities to ellipticine, a known anti-tumor compound.

Novel rhein analogues as potential anticancer agents

Two series of rhein analogues were synthesized with modification at the 3-position. Their cytotoxicities were evaluated using an MTT assay. Among all the compounds synthesized, one compound showed the best potency, with an IC(50) value of 2.7 μM against the HeLa cell line and 0.6 μM against the MOLT4 cell line.

L-Proline anchored multicomponent synthesis of novel pyrido[2,3-a]carbazoles; investigation of in vitro antimicrobial, antioxidant, cytotoxicity and structure activity relationship studies

The newly synthesized pyrido[2,3-a]carbazoles were prepared in good yields by multicomponent reactions under L-proline as promoter and structurally characterized. Few compounds showed significant activity toward both gram-positive, gram-negative bacterial strains. All compounds exerted negative efficacy for antifungal activity except compounds 5f and 7f which showed moderate activity. All compounds showed weak to moderate capacity for scavenging DPPH. The cytotoxicity was evaluated by Sulforhodamine B assay against A-549, B16F10, HCT-15, SKMel2 and SKOV3 cell lines and compared with standard drug cisplatin. Compound 5f outperformed cisplatin against A-549, HCT-15, SKMel2 and B16F10 cell lines. Compound 5e outranged cisplatin against A-549, HCT-15, and SKMel2 cell lines. 5b outperformed cisplatin specifically against B16F10. The preliminary structure activity relationships were carried out.

Synthesis and antiproliferative activity of oxazinocarbazole and N,N-bis(carbazolylmethyl)amine derivatives

The synthesis, structure elucidation and antitumoral activity of novel heterocyclic compounds containing a carbazole nucleus are reported. Oxazinocarbazoles were synthesized by application of the Mannich reaction to the corresponding hydroxylated derivatives leading to 41 new molecules. Their cytotoxic activity was evaluated against various human tumor cell lines including three leukemic cell lines: CEM and Jurkat (type T), Raji (type B); breast cancer cell line (MCF-7); colorectal cancer cell line (Caco-2). A primary screening at 100 microM allowed the selection of the 10 most active compounds, which showed an antiproliferative activity on all the cell lines. A dose-effect study between 12.5 and 100 microM sorted two compounds with a significant activity: 5t and 7e against leukemic cell lines CEM, Jurkat and Raji with IC50 values around 12 microM.