Design, synthesis and bioactivity of novel naphthalimide-benzotriazole conjugates against A549 cells via targeting BCL2 G-quadruplex and inducing autophagy

AIMS

In this study, a series of novel naphthalimide-benzotriazole conjugates (1a-3c) based on 1, 8-naphthalimide as a core skeleton, aiming at G-quadruplexes, were designed and synthesized, and their anti-cancer activity and mechanism were studied.

MATERIALS AND METHODS

Using the CCK-8 assay, FRET melting, EMSA, CD, and molecular docking, intracellular assays, western blotting, immunofluorescence, and flow cytometry.

KEY FINDINGS

By the CCK-8 assay, it was found that the compound, 2-(3-(piperazin-1-yl)propyl)-6-(1H-benzo [d][1,2,3]triazol-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (3a), has better activity against A549 cells. Through extracellular assays, including FRET melting, EMSA, CD, and molecular docking, results showed that 3a selectively interacted with BCL2 G-quadruplex(es). Further studies by intracellular assays, including western blotting, immunofluorescence, flow cytometry, etc., verified that 3a mediated the death of A549 cells by two pathways: inhibition of the expression of the BCL2 gene, causing tumor cell apoptosis, and promotion of genetic instability, causing autophagy. This study suggests that the type of compounds, in particular, 3a, may be a potential molecule to explore for BCL2 G-quadruplex-targeted drugs against lung cancer.

SIGNIFICANCE

Our findings demonstrate that compound 3a as a BCL2 G-quadruplex ligand induces DNA damage, autophagy, and apoptosis in A549 cells. This study provides us with a type of lead compound as an anti-tumor drug.

N, Kumara K, Lokanath NK, Butcher RJ, Kumbar V, Bhat K. Copper(i) complexes with quinolone appended 1,8-naphthalimide conjugates: structural characterization, DNA and protein binding and cytotoxicity studies

Cytotoxicity, cellular uptake of copper(i) complexes containing 1,8-naphthalimide conjugates have been investigated.

Synthesis, structural characterization, protein binding, DNA cleavage and anticancer activity of fluorophore labelled copper(ii) complexes based on 1,8-naphthalimide conjugates

The synthesized copper complexes have good anticancer activity and induce an apoptotic mode of cell death.

Synthesis of naphthalimide derivatives with potential anticancer activity, their comparative ds- and G-quadruplex-DNA binding studies and related biological activities

Two new cytotoxic 1,8-naphthalimide derivatives have been synthesized and characterized. Their biological activities as cytotoxicity and antimicrobial activities and inhibitory activities against DNA-polymerase were evaluated. The interactions of compounds with double-stranded- and quadruple-DNA have been studied by UV-Vis, fluorescent intercalator displacement, competition dialysis, circular dichroism and the findings were compared with the parent naphthalimide and the other compounds. The results show that both compounds (1 and 2) and the parent compound NI have strong cytotoxic activities against Beas-2B, MCF-7, HepG2 and MDA-MB-231 cancer cell lines, antimicrobial activities against Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212 and inhibitory activities towards Taq-polymerase and transcriptase. These novel cationic compounds 1 and 2 can stabilize G-quadruplexes DNA according to thermal denaturation experiments, they change the 3D structure of the DNA (see details in CD experiments) and they exhibit different binding affinities for q-DNA and ds-DNA revealed by spectrophotometric titrations and competitive dialysis studies.

DNA G-quadruplexes binding and antitumor activity of palladium aryl oxime ligand complexes encapsulated in either albumin or algal cellulose nanoparticles

The interactions between two Pd complexes, designated as [Pd₃(C,N-(C₆H₄C(Cl) = NO)-4)₆] (complex 1) and [Pd₃(C₁₂H₈C = NO)₆] (complex 2), with the human telomeric G-quadruplex DNA, 5'-G₃(T₂AG₃)₃-3' (HTG21), were monitored using spectroscopic, biological, and molecular modeling studies. According to the UV-vis results, these complexes can strongly induce and stabilize G-quadruplex DNA structure with K_b1 = 4.5(±0.3) × 10⁶ M^-1 and K_b2 = 1.0(±0.2) × 10⁷ M^-1via groove mode in comparison with duplex DNA. The release mechanism of the Pd complexes from BSA nanoparticles followed a biphasic pattern unlike that of algal cellulose nanoparticles in vitro. In addition, the cytotoxicity of these complexes on MCF-7 cancer cells and PBMC normal cells was evaluated and compared with cisplatin under similar experimental conditions. Furthermore, to determine and verify the interaction mode of these compounds with G-quadruplex, the molecular docking technique was also performed. Our data clearly demonstrated that complex 2 had higher activity and cytotoxicity than that of complex 1 and could be further investigated in the future as a drug discovery platform.

Fluorescent organometallic rhodium(I) and ruthenium(II) metallodrugs with 4-ethylthio-1,8-naphthalimide ligands: Antiproliferative effects, cellular uptake and DNA-interaction

Fluorescent 4-ethylthio-1,8-naphthalimides containing rhodium(I) N-heterocyclic carbene (NHC) and ruthenium (II) NHC fragments were synthesised and evaluated for their antiproliferative effects, cellular uptake and DNA-binding activity. Both types of organometallics triggered ligand dependent efficient cytotoxic effects against tumor cells with the rhodium(I) NHC derivatives causing stronger effects than the ruthenium (II) NHC analogues. Antiproliferative effects could also be observed against several pathogenic Gram-positive bacterial strains, whereas the growth of Gram-negative bacteria was not substantially affected. Cellular uptake was confirmed by atomic absorption spectroscopy as well as by fluorescence microscopy indicating a general ligand dependent accumulation in the cells. An in-depth study on the interaction with DNA confirmed insertion of the naphthalimide moiety between the planar bases of B-DNA via an intercalation mechanism, as well as its stacking on top of the quartets of G-quadruplex structures. Furthermore, additional coordinative binding of the organometallic complexes to the model DNA base 9-ethylguanine could be detected. The studied compounds thus represent promising bioorganometallics featuring strong pharmacological effects in combination with excellent cellular imaging properties.

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.

Spectroscopy, electrochemistry and antiproliferative properties of Au(iii), Pt(ii) and Cu(ii) complexes bearing modified 2,2′:6′,2′′-terpyridine ligands

Impact of the metal centre and the substituent incorporated into a terpy framework.

Synthesis, G-quadruplex binding properties and cytotoxicity of naphthalimide–thiourea conjugates

The hydrogen bonding between a thiourea moiety and a G-quadruplex plays a crucial role in the sequence-specific DNA binding of naphthalimide–thiourea conjugates.

Targeting human telomeric and c-myc G-quadruplexes with alkynylplatinum(II) terpyridine complexes under molecular crowding conditions

The interactions between alkynylplatinum(II) terpyridine complexes 1-3 and the G-quadruplex DNA, including c-myc and telomeric quadruplex DNA, are investigated both in dilute solution and under molecular crowding conditions. The UV-vis absorption spectroscopy, circular dichroism and molecular docking studies suggest that 1-3 associate with telomeric and c-myc G-quadruplexes via groove binding, and electrostatic interactions. Experimental studies indicate that under molecular crowding conditions (in the presence of 40wt% PEG 200), 1-2 show weak affinity for c-myc, while 3 still displays high affinity and selectivity for c-myc. On the other hand, 1-3 act as efficient and selective ligand for telomeric quadruplex DNA under molecular crowding conditions. The complex 3 exhibits excellent cytotoxicity against A549, K562 and SGC-7901, with IC₅₀ values that are 35.0-fold, 10.0-fold, and 12.1-fold lower than the values of cisplatin under the same conditions, respectively.

A bimodal fluorescent and photocytotoxic naphthalene diimide for theranostic applications

We describe the bimodal activity of a water-soluble tetracationic naphthalene diimide as red light emitter for fluorescence imaging, including fluorescence-lifetime imaging, and singlet oxygen photosensitizer, inducing photocytotoxicity in cancer cells.