Synthesis and Biological Activity of a New Indenoisoquinoline Copper Derivative as a Topoisomerase I Inhibitor.

Topoisomerases are interesting targets in cancer chemotherapy. Here, we describe the design and synthesis of a novel copper(II) indenoisoquinoline complex, WN198. The new organometallic compound exhibits a cytotoxic effect on five adenocarcinoma cell lines (MCF-7, MDA-MB-231, HeLa, HT-29, and DU-145) with the lowest IC50 (0.37 ± 0.04 µM) for the triple-negative MDA-MB-231 breast cancer cell line. Below 5 µM, WN198 was ineffective on non-tumorigenic epithelial breast MCF-10A cells and Xenopus oocyte G2/M transition or embryonic development. Moreover, cancer cell lines showed autophagy markers including Beclin-1 accumulation and LC3-II formation. The DNA interaction of this new compound was evaluated and the dose-dependent topoisomerase I activity starting at 1 µM was confirmed using in vitro tests and has intercalation properties into DNA shown by melting curves and fluorescence measurements. Molecular modeling showed that the main interaction occurs with the aromatic ring but copper stabilizes the molecule before binding and so can putatively increase the potency as well. In this way, copper-derived indenoisoquinoline topoisomerase I inhibitor WN198 is a promising antitumorigenic agent for the development of future DNA-damaging treatments.

A Novel Copper(II) Indenoisoquinoline Complex Inhibits Topoisomerase I, Induces G2 Phase Arrest, and Autophagy in Three Adenocarcinomas.

Topoisomerases, targets of inhibitors used in chemotherapy, induce DNA breaks accumulation leading to cancer cell death. A newly synthesized copper(II) indenoisoquinoline complex WN197 exhibits a cytotoxic effect below 0.5 µM, on MDA-MB-231, HeLa, and HT-29 cells. At low doses, WN197 inhibits topoisomerase I. At higher doses, it inhibits topoisomerase IIα and IIß, and displays DNA intercalation properties. DNA damage is detected by the presence of γH2AX. The activation of the DNA Damage Response (DDR) occurs through the phosphorylation of ATM/ATR, Chk1/2 kinases, and the increase of p21, a p53 target. WN197 induces a G2 phase arrest characterized by the unphosphorylated form of histone H3, the accumulation of phosphorylated Cdk1, and an association of Cdc25C with 14.3.3. Cancer cells die by autophagy with Beclin-1 accumulation, LC3-II formation, p62 degradation, and RAPTOR phosphorylation in the mTOR complex. Finally, WN197 by inhibiting topoisomerase I at low concentration with high efficiency is a promising agent for the development of future DNA damaging chemotherapies.

Copper Complexes as Anticancer Agents Targeting Topoisomerases I and II.

Organometallics, such as copper compounds, are cancer chemotherapeutics used alone or in combination with other drugs. One small group of copper complexes exerts an effective inhibitory action on topoisomerases, which participate in the regulation of DNA topology. Copper complexes inhibitors of topoisomerases 1 and 2 work by different molecular mechanisms, analyzed herein. They allow genesis of DNA breaks after the formation of a ternary complex, or act in a catalytic mode, often display DNA intercalative properties and ROS production, and sometimes display dual effects. These amplified actions have repercussions on the cell cycle checkpoints and death effectors. Copper complexes of topoisomerase inhibitors are analyzed in a broader synthetic view and in the context of cancer cell mutations. Finally, new emerging treatment aspects are depicted to encourage the expansion of this family of highly active anticancer drugs and to expend their use in clinical trials and future cancer therapy.

Visible-Light-Driven CarboxyLic Amine Protocol (CLAP) for the Synthesis of 2-Substituted Piperazines under Batch and Flow Conditions.

Piperazines are privileged scaffolds in medicinal chemistry. Disclosed herein is a visible-light-promoted decarboxylative annulation protocol between a glycine-based diamine and various aldehydes to access 2-aryl, 2-heteroaryl, as well as 2-alkyl piperazines. The iridium-based complex [Ir(ppy)2(dtbpy)]PF6 and carbazolyl dicyanobenzene 4CzIPN were found to be the photocatalysts of choice to efficiently perform the transformation under mild conditions, whether in batch or in continuous mode.

Effects of Ferrocenyl 4-(Imino)-1,4-Dihydro-quinolines on Xenopus laevis Prophase I - Arrested Oocytes: Survival and Hormonal-Induced M-Phase Entry.

Xenopus oocytes were used as cellular and molecular sentinels to assess the effects of a new class of organometallic compounds called ferrocenyl dihydroquinolines that have been developed as potential anti-cancer agents. One ferrocenyl dihydroquinoline compound exerted deleterious effects on oocyte survival after 48 h of incubation at 100 µM. Two ferrocenyl dihydroquinoline compounds had an inhibitory effect on the resumption of progesterone induced oocyte meiosis, compared to controls without ferrocenyl groups. In these inhibited oocytes, no MPF (Cdk1/cyclin B) activity was detected by western blot analysis as shown by the lack of phosphorylation of histone H3. The dephosphorylation of the inhibitory Y15 residue of Cdk1 occurred but cyclin B was degraded. Moreover, two apoptotic death markers, the active caspase 3 and the phosphorylated histone H2, were detected. Only 7-chloro-1-ferrocenylmethyl-4-(phenylylimino)-1,4-dihydroquinoline (8) did not show any toxicity and allowed the assembly of a histologically normal metaphase II meiotic spindle while inhibiting the proliferation of cancer cell lines with a low IC50, suggesting that this compound appears suitable as an antimitotic agent.

Reductive Amination/Cyclization of Methyl Levulinate with Aspartic Acid: Towards Renewable Polyesters with a Pendant Lactam Unit.

Environmental regulation and depletion of fossil resources are boosting the search for new polymeric materials produced from biomass. Here, the synthesis of a new diester bearing a pendant lactam unit from methyl levulinate and aspartic acid is reported. The palladium-catalyzed reductive amination/cyclization sequence was carefully optimized to afford the diacid with high yield (>95 %). In a second step, the compound was esterified to give the corresponding diester. The latter monomer was copolymerized with α-ω linear diols, yielding polyesters with molecular weights up to 20.5 kg mol-1 .

Synthesis and biological activity of ferrocenyl indeno[1,2-c]isoquinolines as topoisomerase II inhibitors.

Three series of indeno[1,2-c]isoquinolines bearing a ferrocenyl entity were synthesized and evaluated for DNA interaction, topoisomerase I and II inhibition, and cytotoxicity against breast human cancer cell lines. In the first and second series, the ferrocenyl scaffold was inserted as a linker between the two nitrogen atoms. In the last series, it was introduced at the end of the carbon chain. The present study showed that the ferrocenyl entity enhanced the topoisomerase II inhibition. Most compounds showed a potent growth inhibitory effect on MDA-MB-231 cell line with the IC50 in µM range.

Synthesis and in vitro antiplasmodial activity of ferrocenyl aminoquinoline derivatives.

The aim of this study was to synthesize a series of ferrocenyl 4-aminoquinolines and to evaluate their activities against Plasmodium falciparum F32 (chloroquine-sensitive) and FCB1 and K1 (chloroquino-resistant). Some of the ferrocenyl compounds exhibited in vitro antiplasmodial activity in the nM range. In particular, (1R,4R)-N1-(7-chloroquinolin-4-yl)-N4-(ferrocenylmethyl)-N4-methylcyclohexane-1,4-diamine 17 presented the lowest IC50 value (26 nM) against CQ-resistant strains.

Enantioselective organocatalytic partial transfer hydrogenation of lactone-fused quinolines.

The first enantioselective synthesis of 4-aza-podophyllotoxin derivatives by partial transfer hydrogenation of lactone-fused quinolines was achieved using a chiral Brønsted acid catalyst. This reaction was extended to a large scope of substrates with good yields and enantioselectivities.

Synthesis and antimycobacterial activity of a series of ferrocenyl derivatives.

In this work we reported the synthesis and evaluation of Mycobacterium tuberculosis activities in vitro of a series of twenty five ferrocenyl derivatives: ferrocenyl amides derived from nicotinamide and pyrazinamide, ferrocenyl pyridinyl, quinolyl and acridinylhydrazones. In particular ferrocenyl acylhydrazones 7 and 8 and ferrocenylquinoxaline amide 57 showed interesting antimycobacterial activities.

Synthesis and antitubercular activity of ferrocenyl diaminoalcohols and diamines.

A total of 21 ferrocenyl and benzyl diaminoalcohols and diamines were synthesized and evaluated against Mycobacterium tuberculosis H37Rv. Interestingly, ferrocenyl diamines exhibit better activities than ferrocenyl diaminoalcohols.

Probing the role of the covalent linkage of ferrocene into a chloroquine template.

A new therapeutic approach to malaria led to the discovery of ferroquine (FQ, SR97276). To assess the importance of the linkage of the ferrocenyl group to a 4-aminoquinoline scaffold, two series of 4-aminoquinolines, structurally related to FQ, were synthesized. Evaluation of antimalarial activity, physicochemical parameters, and the beta-hematin inhibition property indicate that the ferrocene moiety has to be covalently flanked by a 4-aminoquinoline and an alkylamine. Current data reinforced our choice of FQ as a drug candidate.

Assessment of Plasmodium falciparum resistance to ferroquine (SSR97193) in field isolates and in W2 strain under pressure.

BACKGROUND: Ferroquine (FQ), or SSR97193, is a novel antimalarial drug currently in phase I clinical trials. FQ is a unique organometallic compound designed to overcome the chloroquine (CQ) resistance problem. FQ revealed to be equally active on CQ-sensitive and CQ-resistant Plasmodium falciparum laboratory strains and field isolates. FQ is also curative on rodent malaria parasites. As FQ will be tested in patients, the potential for resistance to this drug was evaluated. METHODS: The relationship between CQ-resistant transporter gene genotype and susceptibility to FQ were studied in 33 Cambodian P. falciparum field isolates previously studied for their in vitro response to CQ. In parallel, the ability of the CQ-resistant strain W2, to become resistant to FQ under drug pressure was assessed. RESULTS: The IC50 values for FQ in field isolates were found to be unrelated to mutations occurring in the P. falciparum chloroquine resistance transporter (PfCRT) or to the level of expression of the corresponding mRNA. In vitro, under a drug pressure of 100 nM of FQ, transient survival was observed in only one of two experiments. CONCLUSION: Field isolates studies and experimental drug pressure experiments showed that FQ overcomes CQ resistance, which reinforces the potential of this compound as a new antimalarial drug.

In vitro metabolism of ferroquine (SSR97193) in animal and human hepatic models and antimalarial activity of major metabolites on Plasmodium falciparum.

Ferroquine (SSR97193) has been shown to be a promising antimalarial, both on laboratory clones and on field isolates. So far, no resistance was documented in Plasmodium falciparum. In the present work, the metabolic pathway of ferroquine, based on experiments using animal and human hepatic models, is proposed. Ferroquine is metabolized mainly via an oxidative pathway into the major metabolite mono-N-demethyl ferroquine and then into di-N,N-demethyl ferroquine. Some other minor metabolic pathways were also identified. Cytochrome P450 isoforms 2C9, 2C19, and 3A4 and, possibly in some patients, isoform 2D6, are mainly involved in ferroquine oxidation. The metabolites were synthesized and tested against the 3D7 (chloroquine-sensitive) and W2 (chloroquine-resistant) P. falciparum strains. According to the results, the activity of the two main metabolites decreased compared with that of ferroquine; however, the activity of the mono-N-demethyl derivative is significantly higher than that of chloroquine on both strains, and the di-N-demethyl derivative remains more active than chloroquine on the chloroquine-resistant strain. These results further support the potential use of ferroquine against human malaria.

Synthesis and in vitro activities of ferrocenic aminohydroxynaphthoquinones against Toxoplasma gondii and Plasmodium falciparum.

Fourteen ferrocenyl aminohydroxynaphthoquinones, analogues of atovaquone, were synthesized from the hydroxynaphthoquinone core. These novel atovaquone derivatives were tested for their in vitro activity against two apicomplexan parasites of medical importance, Toxoplasma gondii and Plasmodium falciparum, including resistant strains to atovaquone (T. gondii) and chloroquine (P. falciparum). Three of these ferrocenic atovaquone derivatives composed of the hydroxynaphthoquinone core plus an amino-ferrocenic group and an aliphatic chain with 6-8 carbon atoms were found to be significantly active against T. gondii. Moreover, these novel compounds were also effective against the atovaquone-resistant strain of T. gondii (Ato(R)).

Synthesis and antimycobacterial activity of ferrocenyl ethambutol analogues and ferrocenyl diamines.

A new series of ferrocenyl diamino alcohols and diamines were synthesized and their inhibitory potencies were probed with Mycobacterium tuberculosis. Interestingly, ferrocenyl diamines 6a and b display significant activities against M. tuberculosis H37Rv.

Synthesis and chloroquine-enhancing activity of Na-deacetyl-ferrocenoyl-strychnobrasiline.

Several strychnobrasiline derivatives have been synthesized to overcome the lack of in vivo reversal activity of the parent compound. In the present study, N(a)-deacetyl-ferrocenoyl-strychnobrasiline was synthesized by condensing N(a)-deacetyl-strychnobrasiline with ferrocenic acid previously treated with oxalyl chloride. While the in vitro antiplasmodial activity of the test compound (IC(50)=4.83 microg/mL) was increased 15-fold compared to that of strychnobrasiline, and the in vitro enhancing activity was found to be similar to that of the parent compound, the compound was devoid of any in vivo potentiating effect, and an antagonistic effect was even observed at higher doses. Based on the overall results on the hemisynthesis of strychnobrasiline derivatives for better reversal activity, this strategy has appeared to be of little value for useful drugs.