Synthesis and study of antiproliferative, antitopoisomerase II, DNA-intercalating and DNA-damaging activities of arylnaphthalimides

Exploring the Anticancer Potential of Phenolic nor-Triterpenes from Celastraceae Species

To explore new compounds with antitumour activity, fifteen phenolic nor-tripterpenes isolated from Celastraceae species, Maytenus jelskii, Maytenus cuzcoina, and Celastrus vulcanicola, have been studied. Their chemical structures were elucidated through spectroscopic and spectrometric techniques, resulting in the identification of three novel chemical compounds. Evaluation on human tumour cell lines (A549 and SW1573, non-small cell lung; HBL-100 and T-47D, breast; HeLa, cervix, and WiDr, colon) revealed that three compounds, named 6-oxo-pristimerol, demethyl-zeylasteral, and zeylasteral, exhibited significant activity (GI50 ranging from 0.45 to 8.6 µM) on at least five of the cell lines tested. Continuous live cell imaging identified apoptosis as the mode of action of selective cell killing in HeLa cells. Furthermore, their effect on a drug-sensitive Saccharomyces cerevisiae strain has been investigated to deepen on their mechanism of action. In dose-response growth curves, zeylasteral and 7α-hydroxy-blepharodol were markedly active. Additionally, halo assays were conducted to assess the involvement of oxidative stress and/or mitochondrial function in the anticancer profile, ruling out these modes of action for the active compounds. Finally, we also delve into the structure-activity relationship, providing insights into how the molecular structure of these compounds influences their biological activity. This comprehensive analysis enhances our understanding of the therapeutic potential of this triterpene type and underscores its relevance for further research in this field.

Synthesis of Structurally Related Coumarin Derivatives as Antiproliferative Agents

A library of structurally related coumarins was generated through synthesis reactions and chemical modification reactions to obtain derivatives with antiproliferative activity both in vivo and in vitro. Out of a total of 35 structurally related coumarin derivatives, seven of them showed inhibitory activity in in vitro tests against Taq DNA polymerase with IC₅₀ values lower than 250 μM. The derivatives 4-(chloromethyl)-5,7-dihydroxy-2H-chromen-2-one (2d) and 4-((acetylthio)methyl)-2-oxo-2H-chromen-7-yl acetate (3c) showed the most promising anti-polymerase activity with IC₅₀ values of 20.7 ± 2.10 and 48.25 ± 1.20 μM, respectively. Assays with tumor cell lines (HEK 293 and HCT-116) were carried out, and the derivative 4-(chloromethyl)-7,8-dihydroxy-2H-chromen-2-one (2c) was the most promising, with an IC₅₀ value of 8.47 μM and a selectivity index of 1.87. In addition, the derivatives were evaluated against Saccharomyces cerevisiae strains that report about common modes of actions, including DNA damage, that are expected for agents that cause replicative stress. The coumarin derivatives 7-(2-(oxiran-2-yl)ethoxy)-2H-chromen-2-one (5b) and 7-(3-(oxiran-2-yl)propoxy)-2H-chromen-2-one (5c) caused DNA damage in S. cerevisiae. The O-alkenylepoxy group stands out as that with the most important functionality within this family of 35 derivatives, presenting a very good profile as an antiproliferative scaffold. Finally, the in vitro antiretroviral capacity was tested through RT-PCR assays. Derivative 5c showed inhibitory activity below 150 μM with an IC₅₀ value of 134.22 ± 2.37 μM, highlighting the O-butylepoxy group as the functionalization responsible for the activity.

A simplified and easy-to-use HIP HOP assay provides insights into chalcone antifungal mechanisms of action

Elucidating the mechanism of action of an antifungal or cytotoxic compound is a time-consuming process. Yeast chemogenomic profiling provides a compelling solution to the problem but is experimentally complex. Here, we demonstrate the use of a highly simplified yeast chemical genetic assay comprising just 89 yeast deletion strains, each diagnostic for a specific mechanism of action. We use the assay to investigate the mechanism of action of two antifungal chalcone compounds, trans-chalcone and 4'-hydroxychalcone, and narrow down the mechanism to transcriptional stress. Crucially, the assay eliminates mechanisms of action such as topoisomerase I inhibition and membrane disruption that have been suggested for related chalcone compounds. We propose this simplified assay as a useful tool to rapidly identify common off-target mechanisms.

Design, Synthesis, and Evaluation of Novel 3-Carboranyl-1,8-Naphthalimide Derivatives as Potential Anticancer Agents

We synthesized a series of novel 3-carboranyl-1,8-naphthalimide derivatives, mitonafide and pinafide analogs, using click chemistry, reductive amination and amidation reactions and investigated their in vitro effects on cytotoxicity, cell death, cell cycle, and the production of reactive oxygen species in a HepG2 cancer cell line. The analyses showed that modified naphthalic anhydrides and naphthalimides bearing ortho- or meta-carboranes exhibited diversified activity. Naphthalimides were more cytotoxic than naphthalic anhydrides, with the highest IC₅₀ value determined for compound 9 (3.10 µM). These compounds were capable of inducing cell cycle arrest at G0/G1 or G2M phase and promoting apoptosis, autophagy or ferroptosis. The most promising conjugate 35 caused strong apoptosis and induced ROS production, which was proven by the increased level of 2′-deoxy-8-oxoguanosine in DNA. The tested conjugates were found to be weak topoisomerase II inhibitors and classical DNA intercalators. Compounds 33, 34, and 36 fluorescently stained lysosomes in HepG2 cells. Additionally, we performed a similarity-based assessment of the property profile of the conjugates using the principal component analysis. The creation of an inhibitory profile and descriptor-based plane allowed forming a structure–activity landscape. Finally, a ligand-based comparative molecular field analysis was carried out to specify the (un)favorable structural modifications (pharmacophoric pattern) that are potentially important for the quantitative structure–activity relationship modeling of the carborane–naphthalimide conjugates.

New Thalidomide-Resembling Dicarboximides Target ABC50 Protein and Show Antileukemic and Immunomodulatory Activities

We identified novel dicarboximides that were selectively cytotoxic towards human leukemia cells. Using chemical and biological methods, we characterized the biological activity, identified cellular protein targets and defined the mechanism of action of the test dicarboximides. The reported IC₅₀ values (concentration required to reduce cell survival fraction to 50% of control) of selected dicarboximides were similar or lower than IC₅₀ of registered anticancer drugs, for example cytarabine, sorafenib, irinotecan. Test compounds induced apoptosis in chronic myelogenous (K562) and acute lymphoblastic (MOLT-4) leukemia cells by activation of receptor and mitochondrial apoptotic pathways and increased the expression of proapoptotic genes (BAX, NOXA, HTRA2, TNFRSF10B, ESRRBL1). Selected dicarboximides displayed immunomodulatory activity and downregulated IKZF1 and IKZF3 transcription factors in K562 and MOLT-4 leukemia cells. ATP-binding cassette protein 50 (ABC50) was identified as a target for dicarboximides. Cancer cells with knocked down ABC50 showed increased resistance to dicarboximides. Based on the structure of dicarboximides and thalidomide, novel proteolysis-targeting chimeras (PROTACs) were synthesized and used as tools to downregulate ABC50 in leukemia cells.

l,8-Naphthalimide based DNA intercalators and anticancer agents. A systematic review from 2007 to 2017

In this review, we describe a detailed investigation about the structural variations and relative activity of 1,8-naphthalimide based intercalators and anticancer agents. The 1,8-naphthalimides binds to the DNA via intercalation, and exert their antitumor activities through Topoisomerase I/II inhibition, photoinduced DNA damage or related mechanism. Here, our discussion focused on works published over the last ten years (2007-2017) related to therapeutic applications, in the order of cancer treatment followed by other properties of 1,8-naphthalimides. In preparing for this review, we considered that several seminal reviews have appeared over the last fifteen years and focused on closely related subjects, however, none of them is exhaustive.

The effects of varying the substituent and DNA sequence on the stability of 4-substituted DNA-naphthalimide complexes

DNA duplexes are stabilized by many interactions, one of which is stacking interactions between the nucleic acid bases. These interactions are useful for designing small molecules that bind to DNA. Naphthalimide intercalators have been shown to be valuable anti-cancer agents that stack between the DNA bases and exhibit stabilizing effects. There is a continued need to design intercalators that will exhibit these stabilizing effects while being more selective toward DNA binding. This work investigates 4-substituted naphthalimides with varying functional groups and their interactions with nucleic acid duplexes. Mode of binding was determined via wavelength scans, circular dichroism, and viscosity measurements. Optical melting experiments were used to measure the absorbance of the sample as a function of temperature. The T_m values derived from the DNA duplexes were subtracted from the T_m values derived from the DNA-intercalator complexes, resulting in ΔT_m values. The ΔT_m values demonstrated that the substituents on the intercalator affect the stability of the DNA-intercalator complex. From the results of this study and comparison to results from previous work, we conclude that the substituent type and position on the core intercalator molecule affect the stability of the complex it forms with DNA.

Novel Naphthalimide Derivatives as Selective G-Quadruplex DNA Binders

A new derivate of 4-bromo-1,8-naphthalic anhydride and its quaternized analogue have been prepared and characterized. The interactions of both derivatives with human telomere quadruplex-DNA and ds-DNA have been comparatively studied by UV-visible (UV-Vis), fluorescent intercalator displacement assays, competition dialysis, circular dichroism (CD), agarose gel electrophoresis, and polyacrylamide gel electrophoresis. The results show that both derivatives can stabilize G-quadruplexes DNA, and they show different binding affinities for G-quadruplexes-DNA and ds-DNA. All spectroscopic studies have shown that the derivatives have a modest selectivity for G-quadruplex versus ds-DNA.

A novel triazolonaphthalimide induces apoptosis and inhibits tumor growth by targeting DNA and DNA-associated processes

DNA and DNA-associated processes have been classes of the most important targets of chemotherapeutic drugs. As classic DNA intercalators and topoisomerase inhibitors, naphthalimides have been extensively investigated as potential anti-cancer drugs. We recently synthesized a novel series of triazolonaphthalimides with excellent anti-cancer activities. In the present study, one of the most potent triazolonaphthalimides, LSS-11, was investigated. LSS-11 bound to DNA in vitro and in cell mainly by minor groove binding and significantly increased the stability of DNA, which could be fundamental for the biological activities of LSS-11. In addition to inhibiting DNA topoisomerase II-catalyzed decatenation of knotted circulated DNA, LSS-11 dramatically inhibited DNA replication mediated by polymerase chain reaction and isothermal helicase-dependent amplification, as well as the expression of luciferase driven by a minimal TA promoter in cell. Furthermore, LSS-11 exhibited strong cytotoxicity in selected human colon cancer cell lines by inducing cell cycle arrest and apoptosis, which was accompanied by DNA damage response. Finally, LSS-11 potently inhibited the growth of S180 murine sarcoma and SW480 human colorectal cancer xenografts in vivo without significant major toxicities. These results suggest that LSS-11 deserves further research and development as a novel anti-cancer agent, and provided new understandings of mechanisms by which LSS-11 inhibited multiple DNA-associated processes and tumor growth.

Study on the interaction between the 1,4,5,8-naphthalene diimide-spermine conjugate (NDIS) and DNA using a spectroscopic approach and molecular docking

The interaction of herring sperm DNA with the 1,4,5,8-naphthalene diimide-spermine conjugate (NDIS) was studied by UV/vis absorption, fluorescence and CD spectroscopic methods. Compared with the 1,8-naphthalimide-spermidine conjugate (NIS), the values of KSV (quenching constant) and Kb (binding constant) of NDIS were larger, and the hypochromic effect in the UV/vis spectra and the quenching effect in the fluorescence of NDIS were more significant. The interaction mode between NDIS and DNA was mainly groove binding. The fluorescence experiments at varying temperatures showed that the binding process of NDIS and DNA was static, as both hydrogen bonds and hydrophobic forces played a major role in the binding of NDIS and DNA. The CD spectrum indicated that NDIS caused a conformational change, like the B to A-DNA transition, and the tests using KI and NaCl and 1H NMR spectroscopy indicated that NDIS was not a classical DNA inserter. All the results demonstrated that both the polyamine side chain and the aromatic rings affect the process of NDIS binding to DNA, which is thus obviously different from that of NIS. The conclusion was confirmed by the in silico molecular docking experiments.

1,8-Naphthalimide: A Potent DNA Intercalator and Target for Cancer Therapy

The poor pharmacokinetics, side effects and particularly the rapid emergence of drug resistance compromise the efficiency of clinically used anticancer drugs. Therefore, the discovery of novel and effective drugs is still an extremely primary mission. Naphthalimide family is one of the highly active anticancer drug based upon effective intercalator with DNA. In this article, we review the discovery and development of 1,8-naphthalimide moiety, and, especially, pay much attention to the structural modifications and structure activity relationships. The review demonstrates how modulation of the moiety affecting naphthalimide compound for DNA binding that is achieved to afford a profile of antitumor activity. The DNA binding of imide and ring substitution at naphthalimide, bisnaphthalimide, naphthalimide-metal complexes is achieved by molecular recognition through intercalation mode. Thus, this synthetic/natural small molecule can act as a drug when activation or inhibition of DNA function, is required to cure or control the cancer disease. The present study is a review of the advances in 1,8-naphthalimide-related research, with a focus on how such derivatives are intercalated into DNA for their anticancer activities.

Synthesis and biological evaluation of naphthoquinone-coumarin conjugates as topoisomerase II inhibitors

Based on previous Topoisomerase II docking studies of naphthoquinone derivatives, a series of naphthoquinone-coumarin conjugates was synthesized through a multicomponent reaction from aromatic aldehydes, 4-hydroxycoumarin and 2-hydroxynaphthoquinone. The hybrid structures were evaluated against the α isoform of human topoisomerase II (hTopoIIα), Escherichia coli DNA Gyrase and E. coli Topoisomerase I. All tested compounds inhibited the hTopoIIα-mediated relaxation of negatively supercoiled circular DNA in the low micromolar range. This inhibition was specific since neither DNA Gyrase nor Topoisomerase I were affected. Cleavage assays pointed out that naphthoquinone-coumarins act by catalytically inhibiting hTopoIIα. ATPase assays and molecular docking studies further pointed out that the mode of action is related to the hTopoIIα ATP-binding site.

Spectroscopic study on the interaction between naphthalimide-polyamine conjugates and DNA

The interaction of naphthalimide-polyamine conjugates with herring sperm DNA was studied by UV/vis absorption and fluorescent spectra under physiological conditions (pH=7.4). The observed spectral quenching of compounds by DNA and the displacement of EB from DNA-EB complex by compounds indicated that these naphthalimide-polyamine conjugates could intercalate into the DNA base pairs. The UV test also showed that these compounds caused the conformational alteration of DNA. Further caloric fluorescent tests revealed that the quenching mechanism was a static type, which Ksv of 1-DNA, 2-DNA and 1-DNA-EB, 2-DNA-EB 3-DNA-EB was 1.208×10(4), 7.792×10(3) and 1.712×10(4), 1.287×10(4), 2.874×10(4), respectively, at room temperature. The obtained quenching constant, binding constant and thermodynamic parameters suggested that binding strength was associated with substituted groups on naphthalene backbone, and the type of interaction force included mainly hydrogen bonding and weak van der Waals. The binding process was mainly driven by hydrogen bond and van der Waals. Additionally, the effect of NaCl on compounds-DNA interaction provided further evidence that their interaction modes were dependent on substituted groups.