Yulian Zagranyarski

Background/Objectives: DNA-targeting small molecules that induce replication stress represent a promising strategy in anticancer drug development. 1,8-Naphthalimide (NI) derivatives are well-established DNA-intercalating agents, and heterocyclic annulation offers a rational approach to enhancing their potency and tumor selectivity. Here, we report the synthesis and biological evaluation of a novel series of benzofuran-containing naphthalimide derivatives, with particular focus on the lead dinitro-substituted compound 5d. Methods: Cytotoxic activity was assessed using the MTT assay in A549 (p53 wild-type), H1299 (p53-null), and MRC-5 cells. Long-term antiproliferative effects were evaluated by clonogenic survival assay. Cell cycle distribution was analyzed by propidium iodide staining and flow cytometry. Replication stress and DNA damage were quantified by EdU incorporation and γH2AX immunofluorescence, respectively. Apoptosis was assessed by Annexin V/PI staining and caspase-3/7 activation assay. p53 nuclear accumulation and autophagy induction were evaluated by immunofluorescence and Western blot, using LC3 as an autophagic marker. Results: All compounds exhibited cytotoxic activity in the nanomolar range, with 5d emerging as the most potent and selective. Clonogenic survival was significantly reduced, indicating durable suppression of proliferative capacity. Treatment with 5d induced G₁ arrest in A549 cells and the accumulation of H1299 cells in G₂/M, consistent with p53-dependent and p53-independent checkpoint activation, respectively. EdU incorporation was markedly reduced, while γH2AX intensity increased, collectively supporting a replication stress-driven mechanism of DNA damage. Apoptosis was confirmed by increased Annexin V-positive populations and caspase-3/7 activation. LC3 puncta formation and LC3-I/LC3-II conversion were increased, indicating LC3 processing and autophagosome accumulation consistent with the activation of autophagy-related processes. Conclusions: 5d induces a cellular phenotype consistent with replication stress, including reduced EdU incorporation, γH2AX accumulation, cell cycle arrest, and apoptotic cell death in a p53 status-dependent manner. These findings establish benzofuran-annulated naphthalimides as a promising scaffold for the development of anticancer agents that exploit replication stress vulnerabilities in tumor cells.

Intersystem crossing (ISC) efficiency is primarily governed by the magnitude of spin–orbit coupling, which is typically enhanced by heavy-atom effects and molecular symmetry effects. Recent studies have suggested that charge transfer and/or excitonic coupling between neighboring chromophore units, either covalently linked or spatially associated, can also play a key role in this process. Here, we demonstrate a molecular design strategy to enhance triplet generation based on excitonic coupling in covalently linked homodimers. A series of naphthalimide dimers bridged by chalcogen linkers (O, S, Se) was synthesized to systematically modulate interchromophoric electronic communication, probed by spectroscopic and theoretical investigation. Our results show that the oxygen-linked dimer (Napht₂[O]) exhibits minimal changes in absorption and emission spectra relative to the parent monomer. In contrast, Napht₂[S] and Napht₂[Se] dimers display pronounced excitonic signatures, accompanied by luminescence quenching and enhanced singlet oxygen generation, attributed to ISC enhancement. Time-dependent density functional theory calculations, combined with excitonic analysis based on transition density matrix, revealed how dimerization-induced modifications in excited-state character are crucial for maximizing ISC rates. Our findings demonstrate that increasing excitonic coupling through heavier chalcogen bridges can dramatically accelerate ISC in homodimers by inducing changes in excited-state character between singlet and triplet states, without invoking a full charge-separation step. Beyond these specific results, this work highlights excitonic coupling as a versatile handle for engineering ISC in molecular assemblies, opening new perspectives for the design of photoactive materials for optoelectronics, photocatalysis, and photodynamic applications.

The objective of this study was to design and evaluate π-extended 1,8-naphthalimide derivatives as photoinduced electron transfer (PET) optical sensors for protons and metal cations, with emphasis on the role of heterocyclic annulation and receptor–chromophore electronic matching. Benzofuran- and benzodioxin-annulated naphthalimides bearing either a dimethylaminoethyl receptor or a non-donating alkyl substituent at the imide nitrogen were synthesized using tailored synthetic strategies. Their photophysical properties were investigated by absorption and fluorescence spectroscopy, while sensing performance was evaluated by fluorescence titrations. Quantum chemistry calculations were employed to rationalize experimental observations. Benzofuran-annulated derivatives exhibit structured π–π* absorption bands and strong fluorescence, whereas introduction of the receptor induces efficient fluorescence quenching via reductive PET. Protonation or metal ion coordination suppresses PET and leads to pronounced fluorescence enhancement, particularly in the presence of Cu(II) and Sn(II). In contrast, benzodioxin-annulated derivatives display intramolecular charge-transfer absorption bands, large Stokes shifts, and low fluorescence quantum yields in polar media, resulting in a negligible sensing response. Computational results attribute this behavior to an unfavorable energy arrangement of the donor–acceptor orbitals. Overall, the study demonstrates that heterocyclic annulation critically governs the electronic structure and sensing performance of naphthalimide fluorophores, providing guidelines for the rational design of PET-based optical sensors.

Background/Objectives: The development of small-molecule agents that selectively target DNA replication remains a central strategy in anticancer drug discovery. In this study, we report the biological characterization of a novel 6-nitro-benzodioxin-naphthalimide (NI) derivative (compound 5a), evaluated as a potential DNA-targeted anticancer lead. Methods/Results: The antiproliferative activity of 5a was assessed in a small panel of human lung carcinoma cell models (A549, H1299) and a non-malignant control (MRC-5), revealing pronounced cytotoxic effects in tumor cells, accompanied by favorable selectivity indices. Mechanistic investigations demonstrated that treatment with 5a results in strong inhibition of DNA synthesis, as evidenced by a marked reduction in EdU incorporation and a robust induction of the DNA damage marker γH2AX. These effects were associated with cell-cycle perturbations characterized by accumulation in G₁ and G₂/M phases, followed by activation of apoptotic pathways. Importantly, clonogenic survival assays confirmed that even transient exposure to 5a leads to a sustained loss of proliferative capacity, indicating irreversible long-term cellular damage. These results support a replication stress-driven mechanism of action for compound 5a, consistent with interference in DNA-associated processes during S phase. Conclusions: While the precise molecular initiating event remains to be elucidated, the observed biological profile positions 5a as a promising DNA-targeted lead structure with potential for further pharmaceutical optimization. These findings provide a solid foundation for the continued development of naphthalimide-based compounds as anticancer agents within a pharmaceutically relevant framework.

Aquaporin 1 (AQP1) is a transmembrane protein that acts as a highly selective channel for the rapid passage of water across cell membranes, driven by osmotic gradients. The narrowest part of the water channel pore—the selectivity filter (SF)—plays a key role in ensuring selective and efficient water transport. In this study, density functional theory (DFT) at the M062X/6-311+G(d,p) level was used to identify the preferred position of the water molecule(s) inside the SF and to elucidate the forces that lead to its displacement during permeation. A systematic scan along the pore axis identified a well-defined energy minimum where a single water molecule was optimally stabilized by hydrogen bonds with SF residues. A second water molecule was introduced to study how the incoming water affects the translocation of the first water molecule. The resulting energy and force profiles reveal that the approaching water molecule gradually pushes the bound water forward, ultimately occupying its favorable binding site. These results provide an atomistic description of the positioning and displacement of water molecules in SF and offer a quantitative view of the fundamental interactions that govern water transport in AQPs.

A new synthetic strategy for the functionalization of the 1,8-naphthalimide core with weak nucleophiles was developed and is presented herein. By selection of the appropriate base and reaction temperature, access to difluoro, dialkoxy (including with a fused dioxa ring), and mixed fluoro-alkoky and alkoxy-hydroxy derivatives was achieved. All of the reactions proceed rapidly on a gram scale, affording the target products in a high yield (80-97%) and purity from inexpensive, commercially available starting compounds and reagents.

In recent years, bipolar organic electrode materials have gained recognition as competitive alternatives to inorganic materials due to their unique multielectron redox mechanism for energy storage. In this study, we examined the mechanism of redox reactions in naphthalimide (NI) derivatives when used as electrodes in lithium half-cells with ionic liquid electrolytes. The NI derivatives consist of three building fragments: an aromatic naphthalene core, N-alkylated imide unit, and a peri-dichalcogenide bridge. The integration of electrochemical and microscopic methods with DFT calculations facilitates the delineation of the role of each fragment in the oxidation and reduction reactions of NI derivatives. It is found that the peri-dichalcogenide bridge is mainly involved in the oxidation of NI derivatives above 3.9 V, the charge compensation being achieved by electrolyte TFSI⁻ counter-ions. The reduction of NI derivatives with two Li⁺ ions is mainly due to the participation of the chalcogenide bridge, while after interaction with the next two Li⁺ ions, the imide fragment and the naphthalene moiety contribute equally to the reduction. Based on the leading role of the peri-dichalcogenide bridge, the redox properties of NI derivatives are effectively controlled by the gradual replacement of S with Se and Te atoms in the bridge. To improve the electronic conductivity of NIs, composites with rGO are also synthesized by a simple procedure of mechanical mixing in a centrifugal mixer. The composites rGO/NIs display a good storage performance, the best being the Se-containing analogue.

In the search for bipolar organic materials as electrodes in rechargeable batteries, we report peri-diselenolo-substituted 1,8-naphthalimides (NIs).

A general protocol for the synthesis of 3,4-dihalogen substituted 1,8-naphthalimides is proposed, starting from available and cheap 1,8-naphthalic anhydride. The reported new compounds have only bromine or chlorine atoms as substituents, in contrast to the known iodo-containing analogues. This is an advantage in possible aryl nucleophilic substitution or cross-coupling modifications, making them interesting and important building-block molecules in naphthalimide chemistry. Although the procedure includes five synthetic steps, they are quick and straightforward. The overall yields are relatively high (48–62%), and only one column of chromatographic purification is needed. All the reactions were carried out on a multigram scale to allow the target building-block compounds to be obtained in sufficient amounts for further derivatizations.

This communication reports a reliable one-pot synthetic protocol for preparation on a multigram scale of 3-bromo- and 3,4-dibromo-6-nitro-1,8-naphthalic anhydride from commercially available and economical 1,8-naphthalic anhydride. The synthetic steps used were nitration and selective bromination in sulfuric acid at room temperature. The reaction takes place under mild conditions and is completely controllable depending on the equivalents of the brominating reagent used. Both anhydrides are powerful building blocks in naphthalimide chemistry. In addition, their imides and esters were also synthesized.