Naphthalimide–thiazoles as novel photonucleases: molecular design, synthesis, and evaluation

Convergent synthesis, kinetics insight and allosteric computational ascriptions of thiazole-(5-aryl)oxadiazole hybrids embraced with propanamides as alkaline phosphatase inhibitors

Considering the varied pharmacological prominence of thiazole and oxadiazole heterocyclic moieties, a unique series of bi-heterocyclic hybrids, 8a-h, was synthesized in a convergent manner. The structures of newly synthesized compounds were characterized by ¹H-NMR, ¹³C-NMR, and IR spectral studies. The structure-activity relationship of these compounds was predicted by examining their inhibitory effects against alkaline phosphatase, whereby all these molecules exhibited superb inhibitory potentials relative to the standard used. The kinetics mechanism was determined by Lineweaver-Burk plots which revealed that 8g inhibited the studied enzyme non-competitively by forming an enzyme-inhibitor complex. The inhibition constant K_i calculated from Dixon plots for this compound was 0.42 μM. The allosteric computational study was coherent with the experimental records and these ligands exhibited good binding energy values (kcal mol^-1). The hemolytic analysis revealed their mild cytotoxicity towards red blood cell membranes and hence, these molecules have potential to be nontoxic medicinal scaffolds for the treatment of alkaline phosphate-associated ailments.

Synthesis, Docking Study, Cytotoxicity, Antioxidant, and Anti-microbial Activities of Novel 2,4-Disubstituted Thiazoles Based on Phenothiazine

A series of novel 1,3-thiazole derivatives (5a-i) with a modified phenothiazine moiety were synthesized and tested against cancer cell line MCF-7 for their cytotoxicity. Most of them (5a-i) were less cytotoxic or had no activity against MCF-7 cancer cell line.

MATERIAL AND METHODS

The IC50 value of compound (4) was 33.84 μM. The compounds (5a-i) were also evaluated for antimicrobial activities, but no significant activity was observed. The antioxidant activity was conducted for target compounds (5a-i). The IC50 value of compound (5b) was 0.151mM.

RESULTS

The total amount of energy, ACE (atomic contact energy), energy of receptor (PDB: 5G5J), and ligand interaction of structure (4) were found to be 22.448 Kcal.mol-1 , -247.68, and -91.91 Kcal.mol-1, respectively. The structure (4) is well binded with the receptor because the values of binding energy, steric energy, and the number of hydrogen bondings are -91.91, 22.448 kcal.mol-1, and 2, respectively. It shows that structure (4) has good cytotoxicity with MCF-7 in vitro.

CONCLUSION

The increasing of docking ability of structures (5a-i) with the receptor is presented in increasing order as (5f)>(5e)>(5g)>(5a)>(5b)>(5d)>(5c)>(5i)>(5h). The structure bearing substitution as thiosemicarbazone (4), nitrogen heterocyclic (5f), halogen (5e), and azide (5g) showed good cytotoxicity activity in vitro.

Synthesis and Biological Evaluation of Novel 4,5,6,7-Tetrahydrobenzo[D]-Thiazol-2- Yl Derivatives Derived from Dimedone with Anti-Tumor, C-Met, Tyrosine Kinase and Pim-1 Inhibitions

BACKGROUND

Dimedone and thiazole moieties are privileged scaffolds (acting as primary pharmacophores) in many compounds that are useful to treat several diseases, mainly tropical infectious diseases. Thiazole derivatives are a very important class of compounds due to their wide range of pharmaceutical and therapeutic activities. On the other hand, dimedone is used to synthesize many therapeutically active compounds. Therefore, the combination of both moieties through a single molecule to produce heterocyclic compounds will produce excellent anticancer agents.

OBJECTIVE

The present work reports the synthesis of 47 new substances belonging to two classes of compounds: Dimedone and thiazoles, with the purpose of developing new drugs that present high specificity for tumor cells and low toxicity to the organism. To achieve this goal, our strategy was to synthesize a series of 4,5,6,7-tetrahydrobenzo[d]-thiazol-2-yl derivatives using the reaction of the 2-bromodimedone with cyanothioacetamide.

METHODS

The reaction of 2-bromodimedone with cyanothioacetamide gave the 4,5,6,7-tetrahydrobenzo[d]- thiazol-2-yl derivative 4. The reactivity of compound 4 towards some chemical reagents was observed to produce different heterocyclic derivatives.

RESULTS

A cytotoxic screening was performed to evaluate the performance of the new derivatives in six tumor cell lines. Thirteen compounds were shown to be promising toward the tumor cell lines which were further evaluated toward five tyrosine kinases.

CONCLUSION

The results of antitumor screening showed that many of the tested compounds were of high inhibition towards the tested cell lines. Compounds 6c, 8c, 11b, 11d, 13b, 14b, 15c, 15g, 21b, 21c, 20d and 21d were the most potent compounds toward c-Met kinase and PC-3 cell line. The most promising compounds 6c, 8c, 11b, 11d, 13b, 14b, 15c, 15g, 20c, 20d, 21b, 21c and 21d were further investigated against tyrosine kinase (c-Kit, Flt-3, VEGFR-2, EGFR, and PDGFR). Compounds 6c, 11b, 11d, 14b, 15c, and 20d were selected to examine their Pim-1 kinase inhibition activity the results revealed that compounds 11b, 11d and 15c had high activities.

Synthesis of a 3,4-Disubstituted 1,8-Naphthalimide-Based DNA Intercalator for Direct Imaging of Legionella pneumophila

The development of organic molecules to target nucleic acid is an active area of research at the interface of chemistry and biochemistry, which involves DNA binding, nuclear imaging, and antitumor studies. These molecules bind with DNA through covalent interactions, electrostatic interactions, or intercalation. However, they are less permeable to membrane, and they have a significant cytotoxicity, which limits their application under in vivo conditions. In the present work, various mono- and disubstituted 1,8-naphthalimides-based derivatives (S-12, S-13, S-15, and S-21) have been synthesized and characterized through various spectroscopic techniques. Among these, 3-amino-4-bromo-1,8-naphthalimide (S-15) was found to have an attractive water solubility and act as a nuclear imaging agent. The spectroscopic absorption and emission data showed that S-15 has a strong affinity for salmon sperm DNA with a binding constant of 6.61 × 10⁴ M^-1, and the ratiometric fluorescence intensity (I ₄₈₉/I ₅₅₂) of S-15 has a linear relationship in the 0-50 μM range of DNA concentrations. It intercalates with DNA through the hydrophobic planar naphthalimide core as confirmed through cyclic voltammetry, circular dichroism, ¹H NMR titration, and thermal denaturation studies. Positively charged amine groups also participate in H-bonding with the bases and backbone of DNA. The S-15 intercalator showed a large Stokes shift and photostability, which made it attractive for direct imaging of Legionella pneumophila, without the need for a prior membrane permeabilization.

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.

Dihydroindeno[1,2-b]pyrroles: new Al3+selective off–on chemosensors for bio-imaging in living HepG2 cells

An approach for the expeditious synthesis of a new Al³⁺-selective turn-on dihydroindeno[1,2-b]pyrrole probe under environmentally benevolent conditions and its bio-imaging studies on HepG2 cell.

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.

Design, Synthesis, and Proticity Inclined Conformational Modulation in a Highly Fluorescent Bichromophoric Naphthalimide Derivative: Hint Directed from RICT Perspective

The present study embodies design, in silico DNA interaction, synthesis of benzothiazole containing naphthalimide derivative, 2-(6-chlorobenzo[d]thiazol-2-yl)-1H-benzo[de] isoquinoline-1,3(2H)-dione (CBIQD) along with its systematic photophysics, solvatochromic behavior, and solvation dynamics using an experimental and theoretical spectroscopic approach. Steady-state dual emission and biexponential fluorescence decay reveals the formation of two different excited species. Ground- and excited-state optimized geometry and the potential-energy curve obtained from DFT and TD-DFT calculation ascertained the existence of nonplanar and planar conformation. When the solvent polarity is changed from nonpolar to protic polar, the feebly emissive emission band highly intensifies probably due to the reversal of n, π*-π, π* emissive state along with consequent modulation of their energy gap that is induced by H-bonding. Excluding nonpolar solvents, in all other solvents, the Stokes shift correlates linearly with orientation polarizability, whereas in water, the story remains intriguing. With photoexcitation, intermolecular H-bonding stimulates the pyramidalization tendency of imide "N" with subsequent conformational change of GS nonplanar geometry to a coplanar one through acceptor rehybridization generating a rehybridized intramolecular charge transfer (RICT) state that caused a dramatic fluorescence upsurge. This allosteric modulation is promoted by excited-state H-bonding dynamics especially in strong H-bond donor water. A close interplay between preferential solvation and the proximity effect is evident in the emission behavior in a benzene (Bn)-ethanol (EtOH) binary mixture. Molecular docking analysis delineates considerable noncovalent sandwiched π-π stacking interactions of CBIQD with the pyrimidine rings as well as with imidazole rings of dG 6 and dG 2 base pairs of B-DNA double helix, which probably suffices the design strategy adopted. Overall, a strategic design to synthesize a highly fluorescent and potential bioactive agent is executed to revolutionize the fluorophore field due its enormous progressive importance in biochemical applications.

Shedding light on the photostability of two intermolecular charge-transfer complexes between highly fluorescent bis-1,8-naphthalimide dyes and some π-acceptors: a spectroscopic study in solution and solid states

Given the great importance of the various uses of 1,8-naphthalimides in the trends of biology, medicine and industry, the current study focused on extending the scope of these dyes by introducing some of their charge-transfer (CT) complexes. For this purpose, two highly fluorescent bis-1,8-naphthalimide dyes and their complexes with some π-acceptors have been synthesized and characterized spectroscopically. The π-acceptors include picric acid (PA), chloranilic acid (CLA), tetracyanoquinodimethane (TCNQ) and dichlorodicyanobenzoquinone (DDQ). The molecular structure, spectroscopic and fluorescence properties as well as the binding modes were deduced from IR, UV-vis and (1)H NMR spectral studies. The binding ratio of complexation was determined to be 1:1 according to the elemental analyses and photometric titrations. It has been found that the order of acceptance ability for the different acceptors is TCNQ>DDQ>CLA>PA. The photostability of 1,8-naphthalimide dye as a donor and its charge-transfer complex doped in polymethyl methacrylate/PMMA were exposed to UV-Vis radiation and the change in the absorption spectra was achieved at different times during irradiation period.

Microwave-assisted synthesis of novel non-peripherally substituted metallophthalocyanines and their sensing behaviour for a broad range of Lewis bases

The synthesis of novel, symmetrical, tetrasubstituted metallophthalocyanines (cobalt, zinc, and manganese) bearing four 2-(4-methyl-1,3-thiazol-5-yl)ethoxy units is reported.

Synthesis and photophysical evaluation of a pyridinium 4-amino-1,8-naphthalimide derivative that upon intercalation displays preference for AT-rich double-stranded DNA

The synthesis, characterisation and solid state crystal structure of a cationic 4-amino-1,8-naphthalimide derivative (1) are described. The photophysical properties of 1 are shown to vary with the solvent polarity and H-bonding ability. The fluorescence of 1 is enhanced and blue-shifted in its 1:1 complex with 5'-adenosine-monophosphate while it is partially quenched and red-shifted in its complex with 5'-guanosine-monophosphate. Linear and circular dichroism measurements show that 1 binds to double-stranded DNA by intercalation. Comparative UV-visible and fluorescence studies with double stranded synthetic polynucleotides poly(dA-dT)(2) and poly(dG-dC)(2) show that 1 binds much more strongly to the AT polymer; 1 also has a strong preference for A-T rich sequences in natural DNA. Thermal denaturation measurements also reveal a much greater stabilisation of the double-stranded poly(dA-dT)(2) than of natural DNA.

Synthesis and antimicrobial activity of some novel 4-(1H-benz[d]imidazol-2yl)-1,3-thiazol-2-amines

A new series of novel 4-(1H-benz[d]imidazol-2yl)-1,3-thiazol-2-amines 5a-d and 4-(1H-benz[d]imidazol-2yl)-3-alkyl-2,3-dihydro-1,3-thiazol-2-amine 8a-d has been synthesized by the cyclocondensation of 2-acetyl benzimidiazoles 4a-d and 2-bromo-1-(1-alkyl-1H-benzo[d]imidazol-2-yl)-1-ethanone 7a-d with thiourea respectively, and evaluated for their antibacterial and antifungal activity against clinical isolates of Gram-positive and Gram-negative bacteria. Some of these hybrids in these series exhibited antibacterial activity comparable to standard Streptomycin and Benzyl penicillin and antifungal activity against Fluconazole. All the newly synthesized compounds were characterized by their spectral data and further used to estimate their ability towards antimicrobial activity.

Molecular design, chemical synthesis, and biological evaluation of ‘4-1’ pentacyclic aryl/heteroaryl-imidazonaphthalimides

A novel series of '4-1' pentacyclic naphthalimides, where the chromophore consists of a naphthalimide moiety, fused to an imidazole ring containing an unfused aryl or heteroaryl ring, were synthesized and evaluated for in vitro antitumor activity. In general, the new derivatives showed an improved cytotoxic activity over amonafide. DNA binding experiments supported that this class of compounds behaves as effective DNA-intercalating agents.

Design, synthesis, and antitumor evaluation of novel acenaphtho[1,2-b]pyrrole-carboxylic acid esters with amino chain substitution

8-Oxo-8H-acenaphtho[1,2-b]pyrrole-9-carboxylic acid esters and derivatives were prepared and evaluated for cytotoxicity against A549 and P388 cell lines. Based on a novel chromophore precursor 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile 1, the very insoluble 1 was converted to more soluble esters 5 and a series of 3-amino derivatives from 5 were obtained by mild S(N)Ar(H) reaction between 5 and various amines. The biological evaluation indicated that methyl esters 5a are the most cytotoxic with IC(50) values of 0.45 and 0.80 microM (against A549 and P388, respectively) among the parent esters 5a-5f, but 3-amino derivatives 4b and 4c of 5f with bromine showed the highest activity (with IC(50) values of 0.019-0.60 microM) among the 3-amino derivatives.

Novel thiazonaphthalimides as efficient antitumor and DNA photocleaving agents: Effects of intercalation, side chains, and substituent groups

A series of novel antitumor and DNA photocleaving agents was designed and synthesized by fusing a (substituted) thiazole ring to the naphthalimide skeletons. C1, the most active compound against A549, was about 30-fold more cytotoxic than the compound amonafide. A1, the most active compound against P388, was about 6-fold more cytotoxic than amonafide. C2, the most efficient DNA intercalator, showed the strongest DNA photocleaving activity via superoxide anion produced under UV light at 360 nm.