Synthesis of Triphenylethylene-Naphthalimide Conjugates as topoisomerase-IIα inhibitor and HSA binder

Column Chromatography-Free Synthesis of Spirooxindole and Spiroindanone-Based Naphthalimides as Potent c-MYC G4 Stabilizers and HSA Binders for Elevating Anticancer Potential

G-quadruplex (G4) DNA plays a pivotal regulatory role in fundamental biological processes, integral for governing cellular functions such as replication, transcription, and repair in living cells. Within cancer cells, G4 DNA exerts an impact on the expression of crucial genes such as c-MYC, effectively repressing its activity when structured within its promoter region. Therefore, employing molecular scaffolds to target these structures offers an attractive strategy for altering their functions. In our pursuit of potent and selective G-quadruplex binders, herein we report a series of spironaphthalimide-pyrrolidine analogues that demonstrate the ability to stabilize c-MYC G4 formation and subsequently inhibit c-MYC expression. These analogues are evaluated for their anticancer activity against 60 human cancer cell lines at 10 μM. The most potent analogues 8j and 21c underwent additional testing at five dose concentrations (10-4-10-8 M) where low MG-MID GI50 values are observed for both the analogues 8j (9.98 μM) and 21c (2.49 μM). To correlate with the antiproliferative activity, the mechanism is explored in vitro by performing Pu27 DNA binding studies through multispectroscopic techniques, and the results are compared with Pu22, human telomere, and calf thymus DNA. Additionally, insights from molecular docking suggested stacking over the G-tetrad of G4 structures of both analogues, with quantum mechanical studies further reinforcing the rationale for the stability of this quadruplex secondary structure. The analogues are also evaluated for their binding affinity to human serum albumin, revealing their robust capability to effectively bind and potentially facilitate targeted delivery to specific sites. Amidst the abundance of G4s across the human genome, the above findings underscore the significance of spiro analogues, with potent multitargeting anticancer attributes, marking a transformative leap forward in G4-ligand innovation, promising frontiers in the quest for effective anticancer modalities.

Selective Recognition of Oncogene Promoter C-Myc G-Quadruplex: Design, Synthesis, and In Vitro Evaluation of Naphthalimide and Imidazo[1,2-a]pyrazines for Their Anticancer Activity

c-Myc is a transcription factor that is overexpressed in most human cancers. Despite its challenging nature, we have developed a series of naphthalimide-imidazopyrazine conjugates to target c-Myc. The library of synthesized derivatives was tested for their anticancer activity against a nine-panel of cancer cell lines. Compound 8eb showed excellent cytotoxicity against all the tested cancer cell lines, with the range of growth inhibition from -98.79% to 96.62% at a single-dose concentration of 10-5 M. Further, 8eb was employed for a 5-dose assay against the same cancer cell lines, which showed efficacy at varying concentrations with an MG-MID GI50 value of 2.61 μM. Biophysical studies were performed to explore the interaction of 8eb with c-Myc Pu27 over ct-DNA, oncogene promotor Pu22, and human telomere, with a binding constant value of 1.3 × 107 M-1. Additionally, experiments were performed to get insights into the interaction mechanism between 8eb and the c-Myc oncogene promoter. A molecular docking study unveiled the stacking of the compound with G4 DNA through groove binding, where very few reports are available, with a favorable binding energy of -9.2 kcal/mol. Moreover, the pharmacokinetic study and HOMO-LUMO energy gap analysis underscored the potency of the active candidate. The compound's binding ability toward HSA was also assessed, where results suggested effective binding of the compound to HSA, revealing its potential for easy delivery to the target site. The above findings suggested that these newly synthesized candidates with potent anticancer activity offer a promising avenue as G4 DNA c-Myc stabilizers.

Deciphering Binding Potential of Naphthalimide-Coumarin Conjugate with c-MYC G-Quadruplex for Developing Anticancer Agents: A Spectroscopic and Molecular Modeling Approach

It has been well accumulated that G-quadruplex (G4-DNA) has great anticancer relevance, and various heterocyclic moieties have been synthesized and examined as potent G4-DNA binders with promising anticancer activity. Here, we have synthesized a series of naphthalimide-triazole-coumarin conjugates by substituting various amines and further examine their anticancer activity against 60 human cancer cell lines at 10 μM. One and five dose concentration results reveal low values of MG-MID GI50 for compounds including 8a (3.18 μM), 8b (13.11 μM), 8e (7.68 μM) and 8f (1.75 μM). Further cell apoptosis manifests that all compounds can induce cell apoptosis in cancer cells by stabilizing the c-MYC promoter G-quadruplex. Therefore, the G-quadruplex-mediated pathway may be responsible for the apoptosis that these naphthalimide-coumarin compounds caused in cancer cells. Therefore, multispectroscopic techniques are employed to evaluate the binding of molecules with c-MYC G4-DNA where all four molecules readily bind to G4-DNA and stabilize it with a high binding constant, leading to inhibition of cancer cells and apoptosis of cancer cells. Binding studies toward ct-DNA disclose that these compounds do not interact with ds-DNA and thus selectively target G4-DNA to exert their anticancer activity. All the active compounds have greater affinity toward Human Serum Albumin (HSA) and can readily bind with HSA with a binding constant of 12 × 104 M-1 (8a), 13.0 × 104 M-1 (8b), 14.2 × 104 M-1 (8e), 16.3 × 104 M-1 (8f). Thus, the results disclose that inhibition and killing of cancer cells by these derivatives feasibly occur due to their ability to interact with c-MYC G-quadruplex forming promoters and their high affinity toward HSA unfold potent anticancer agents and can be taken further for clinical trials.

Investigating the Serum Albumin Binding Behavior of Naphthalimide Based Fluorophore Conjugates: Spectroscopic and Molecular Docking Approach

In the present study, naphthalimide-pyrazole-benzothiazole based fluorescent analogs were synthesized by substituting different primary and secondary amines on the naphthalimide nucleus and were evaluated for their sensitivity and selectivity towards serum albumin. Among various synthesized analogues compound 25 showed the most significant change with serum albumin and was further studied for selective detection and mode of interaction with serum albumin. Here, we compared the binding interaction of fluorescent probe 25 for variation/detection of two 76 % structurally resembling proteins HSA and BSA, by spectroscopic experiments. The compound shows more selectivity for HSA and BSA with a higher binding constant and evident visible change in the emission spectra of two serum albumins among different bioanalytes. The mode of interaction of 25 with human serum albumin and bovine serum albumin was investigated by FT-IR, circular dichroism, and DLS techniques to find out the change in the microenvironment and variation in the structure of serum albumin proteins. Higher binding affinity and specific selectivity of 25 with a limit of detection of 0.69 μM and 1.4 μM towards HSA and BSA compared to other bioanalytes make it a significant fluorescent probe for quantitatively detecting serum albumins at the very early stage of many fatal diseases.

Engineered Artesunate-Naphthalimide Hybrid Dual Drug for Synergistic Multimodal Therapy against Experimental Murine Lymphoma

Lymphoma can effectively be treated with a chemotherapy regimen that is associated with adverse side effects due to increasing drug resistance, so there is an emergent need for alternative small-molecule inhibitors to overcome the resistance that occurs in lymphoma management and overall increase the prognosis rate. A new series of substituted naphthalimide moieties conjugated via ester and amide linkages with artesunate were designed, synthesized, and characterized. In addition to the conjugates, to further achieve a theranostic molecule, FITC was incorporated via a multistep synthesis process. DNA binding studies of these selected derivatives by ultraviolet-visible (UV-vis), fluorescence spectroscopy, intercalating dye (EtBr, acridine orange)-DNA competitive assay, and minor groove binding dye Hoechst 33342-DNA competitive assay suggested that the synthesized novel molecules intercalated between the two strands of DNA due to its naphthalimide moiety and its counterpart artesunate binds with the minor groove of DNA. Napthalimide-artesunate conjugates inhibit the growth of lymphoma and induce apoptosis, including ready incorporation and reduction in cell viability. The remodeled drug has a significant tumoricidal effect against solid DL tumors developed in BALB/c mice in a dose-dependent manner. The novel drug appears to inhibit metastasis and increase the survival of the treated animals compared with untreated littermates.