Cytotoxic activity and DNA binding of naphthalimide derivatives with amino acid and dichloroacetamide functionalizations

Synthesis and Biological Studies on (KLAKLAK)2-NH2 Analog Containing Unnatural Amino Acid β-Ala and Conjugates with Second Pharmacophore

(1) Background: Peptides are good candidates for anticancer drugs due to their natural existence in the body and lack of secondary effects. (KLAKLAK)2 is an antimicrobial peptide that also shows good anticancer properties. (2) Methods: The Solid Phase Peptide Synthesis (Fmoc-strategy) was used for the synthesis of target molecules, analogs of (KLAKLAK)2-NH2. The purity of all compounds was monitored by HPLC, and their structures were proven using mass spectrometry. Cytotoxicity and antiproliferative effects were studied using 3T3 NRU and MTT tests, respectively. For determination of antimicrobial activity, the disc-diffusion method was used. Hydrolytic stability at three pH values, which mimic the physiological pH in the body, was investigated by means of the HPLC technique. (3) Results: A good selective index against MCF-7 tumor cell lines, combined with good cytotoxicity and antiproliferative properties, was revealed for conjugates NphtG-(KLAKLAK)2-NH2 and Caf-(KLAKLAK)2-NH2. The same compounds showed very good antifungal properties and complete hydrolytic stability for 72 h. The compound Caf-(KLβ-AKLβ-AK)2-NH2 containing β-Ala in its structures exhibited good antimicrobial activity against Escherichia coli K12 407 and Bacillus subtilis 3562, in combination with very good antiproliferative and cytotoxic properties, as well as hydrolytic stability. (4) Conclusions: The obtained results reveal that all synthesized conjugates could be useful for medical practice as anticancer or antimicrobial agents.

Direct Amidation to Access 3-Amido-1,8-Naphthalimides Including Fluorescent Scriptaid Analogues as HDAC Inhibitors

Methodology to access fluorescent 3-amido-1,8-naphthalimides using direct Buchwald-Hartwig amidation is described. The protocol was successfully used to couple a number of substrates (including an alkylamide, an arylamide, a lactam and a carbamate) to 3-bromo-1,8-naphthalimide in good yield. To further exemplify the approach, a set of scriptaid analogues with amide substituents at the 3-position were prepared. The new compounds were more potent than scriptaid at a number of histone deacetylase (HDAC) isoforms including HDAC6. Activity was further confirmed in a whole cell tubulin deacetylation assay where the inhibitors were more active than the established HDAC6 selective inhibitor Tubastatin. The optical properties of these new, highly active, compounds make them amenable to cellular imaging studies and theranostic applications.

An endoplasmic reticulum targetable turn-on fluorescence probe for imaging application of carbon monoxide in living cells

Carbon monoxide (CO) is a significant mediator in regulating endoplasmic reticulum (ER) stress, and its level may play a potential role in the treatment of vascular diseases combined with ER stress. In-situ visualization of CO in the ER helps to elucidate its physiological and pathological mechanistic behavior. Herein, a novel CO fluorescent probe (Na-CM-ER) with ER-targeting characteristics was structured. Na-CM-ER with naphthalimide as a fluorescent group, under the trigger of CO, an ICT (Intramolecular Charge Transfer) mechanism was constructed by converting a nitro group to an amino group and showed dazzling green fluorescence. Na-CM-ER exhibited satisfactory response speed, selectivity, photo-stability and sensitivity to CO in vitro. Furthermore, biological imaging experiments demonstrated that Na-CM-ER could monitor the changes of exogenous/endogenous CO in living cells and possess an ER-targeting property. To sum up, we hope that Na-CM-ER can be as a serviceable molecular tool for imaging CO in cellular ER.

Synthesis, Antitumor and Antibacterial Studies of New Shortened Analogues of (KLAKLAK)2-NH2 and Their Conjugates Containing Unnatural Amino Acids

(1) Background: (KLAKLAK)2 is a representative of the antimicrobial peptide group which also shows good anticancer properties. (2) Methods: Herein, we report synthesis using SPPS and characterization by HPLC/MS of a series of shortened analogues of (KLAKLAK)2. They contain single sequence KLAKLAK as C-terminal amides. In addition, substitution of some natural amino acids with unnatural β-Ala and nor-Leu is realized. In addition, these structures are conjugated with second pharmacophore with well proven anticancer properties 1,8-naphthalimide or caffeic acid. Cytotoxicity, antiproliferative effect and antimicrobial activity of newly synthesized structures were studied. (3) Results: The obtained experimental results reveal significant selective index for substances with common chemical structure KLβAKLβAK-NH2. The antibacterial properties of newly synthesized analogues at two different concentrations 10 μM and 20 μM, were tested against Gram-negative microorganisms Escherichia coli K12 407. Only two of the studied compounds KLAKLAK-NH2 and the one conjugated with second pharmacophore 1,8-naphthalimide and unnatural amino acid nor-Leu showed moderate activity against tested strains at concentration of 20 μM. (4) Conclusions: The obtained results reveal that the introducing of 1,8-naphthalimideGly- and Caf- increase the cytotoxicity and antiproliferative activity of the peptides but not their selectivity. Only two compounds KLAKLAK-NH2 and 1,8-naphthalimideGKnLAKnLAK-NH2 show moderate activity against Escherichia coli K12 at low concentration of 20μM.

Synthesis, Characterization, Quantum-Chemical Calculations and Cytotoxic Activity of 1,8-Naphthalimide Derivatives with Non-Protein Amino Acids

BACKGROUND

The 1,8-Naphthalimides constitute an important class of biologically active, DNAbinding compounds. There are no available data on the synthesis of 1,8-naphthalimide derivatives with nonprotein amino acids and their biological activity. The aim of this paper was to determine the synthesis, structural characterization and cytotoxic activity of new 1-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)cycloalkane-1- carboxylic acids with 5-, 6-, 7-, 8- and 12-membered rings as well as 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)- yl)adamantane-2-carboxylic acid and 1-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)-1,2,3,4-tetrahydronaphthalene- 1-carboxylic acid.

METHODS

The target compounds were obtained by an interaction of 1,8-naphthalic anhydride with a series of non-protein amino acids. The optimized geometry and harmonic vibrational frequencies have been calculated by DFT employing B3LYP functional using 6-31G(d,p) basis set. An ab initio (MP2 and Hartee-Fock) and DFT (different functionals) using several basis sets have been applied for NMR calculations. The cytotoxic effects of the synthesized compounds are assessed against two human tumor cell lines, namely K-562 (chronic myeloid leukemia) and HUT-78 (cutaneous T-cell lymphoma) after 72 h exposure, using the MTT-dye reduction assay. The apoptogenic effects and the ability to modulate the NFκB-signaling pathways were determined using commercially available ELISA kits.

RESULTS

All compounds inhibited the growth of malignant cells at micromolar concentrations whereby compound 4b (1-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)cyclohexane-1-carboxylic acid) demonstrated superior activity in both cell lines with IC50 values comparable to those of the reference anticancer drug melphalan.

CONCLUSION

New 1,8-naphthalimide derivatives with non-protein amino acids were successfully synthesized. Quantum-chemical calculations were performed to elucidate the structure of the newly synthesized compounds. There is a proper alignment between theoretical and experimental results. The cytotoxicity of the synthesized products against two human tumor cell lines, namely K-562 and HUT-78 was evaluated. All compounds inhibited the growth of malignant cells at micromolar concentrations. The pharmacodynamics evaluation of compound 4b showed that its cytotoxicity is mediated by induction of apoptosis and inhibition of NFκB-signaling.

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.

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.

Synthesis, in vitro evaluation and DNA interaction studies of N-allyl naphthalimide analogues as anticancer agents

A novel series of 2-allyl-6-substituted-benzo[de]isquinoline-1,3-diones has been synthesized and evaluated for their in vitro antitumor activities and DNA intercalation.