Novel diarylated tacrine derivatives: Synthesis, characterization, anticancer, antiepileptic, antibacterial, and antifungal activities

In this study, our goal was to synthesize novel aryl tacrine derivatives and assess their potential as anticancer, antibacterial agents, and enzyme inhibitors. We adopted a two-step approach, initiating with the synthesis of dibromotacrine derivatives 3 and 4 through the Friedlander reaction. These intermediates underwent further transformation into diarylated tacrine derivatives 3a-e and 4a-e using a Suzuki-Miyaura cross-coupling reaction. Thorough characterization of these novel diarylated tacrines was achieved using various spectroscopic techniques. Our findings highlighted the potent anticancer effects of these innovative compounds across a range of cancer cell lines, including lung, gynecologic, bone, colon, and breast cancers, while demonstrating low cytotoxicity against normal cells. Notably, these compounds surpassed the control drug, 5-Fluorouracil, in terms of antiproliferative activity in numerous cancer cell lines. Moreover, our investigation included an analysis of the inhibitory properties of these novel compounds against various microorganisms and cytosolic carbonic anhydrase enzymes. The results suggest their potential for further exploration as cancer-specific, enzyme inhibitory, and antibacterial therapeutic agents. Notably, four compounds, namely, 5,7-bis(4-(methylthio)phenyl)tacrine (3d), 5,7-bis(4-(trifluoromethoxy)phenyl)tacrine (3e), 2,4-bis(4-(trifluoromethoxy)phenyl)-7,8,9,10-tetrahydro-6H-cyclohepta[b]quinolin-11-amine (4e), and 6,8-dibromotacrine (3), emerged as the most promising candidates for preclinical studies.

The anticancer potentials of substituted indeno[1,2-b]quinoline amines against HT29 and SW620: Experimental and in silico approach

Purpose:

This study aimed at the determination of the antiproliferative and cytotoxic activities of recently prepared indeno [1,2-b]quinoline amines against colon carcinoma, HT29 and SW620 cell lines by using cell proliferation and cytotoxicity assays.

Methods:

In vitro inhibition of cell proliferation of indenoquinoline derivatives was determined with an MTT cell proliferation assay. On the other hand, their cell cytotoxicities and apoptotic potential were investigated by LDH cytotoxicity and DNA laddering assays. Moreover, molecular docking studies were performed between the compounds and PDB ID: 1OLG and 4LVT target proteins using virtual scanning techniques.

Results:

Most of the compounds (1, 3, and 7-9) exhibit much more potent antiproliferative activity than positive controls against HT29 and SW620 cell lines (IC50 values 1.1 - 4.1 µg/mL) and show slightly toxic properties (percent cytotoxicity 9.8% to 33.5%) to cells compared to positive control. On the other hand, it was determined that effective compounds 1, 2, 3 and 9 stimulated apoptosis on HT29 and SW620. Moreover, the anticancer effect of the recent indeno[1,2-b]quinoline amine derivatives was investigated with the help of molecular docking simulations for their pharmacokinetics. The molecular docking results displayed that mono bromo (1-3) and phenyl (7-9) substituted indeno [1,2-b]quinoline amines interact with mutated p53 and protein Blc-2 residues with hydrogen bonding and polar interactions, respectively.

Conclusion:

As a result, the preliminary experimental data and in silico studies indicated that the mono-substituted indenoquinoline amine derivatives, especially 1, 3, and 7-9, exhibit effective pharmacological properties.

Design, synthesis, DFT calculations, molecular docking and antimicrobial activities of novel cobalt, chromium metal complexes of heterocyclic moiety-based 1,3,4-oxadiazole derivatives

A Schiff base, 5-(4-methylphenyl)-4-[(pyridin-2-ylmethylidene)amino]-4H-1,2,4-oxadiazole as a bidentate ligand has been synthesized by the reaction between the 4-amino-5-(4-methylphenyl)-4H-1,3,4-oxadiazole and aromatic aldehyde. The Schiff base reacted with CoCl₃·6H₂O and CrCl₃·6H₂O in ethanol to yield 1,3,4-oxadiazole complexes. The structures of synthesized ligand and their complexes have been established on the basis of their IR, Mass and ¹H-NMR spectra. Electronic and geometric structures of both cobalt and chromium complexes were investigated by density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) calculations. DFT-based reactivity calculations estimated the studied system as strong electrophile and/or strong nucleophile in polar organic reactions. Moreover, most reactive sites were predicted theoretically based on the delocalized and localized indexes. The nature of Ligand-Metal chemical bonding is discussed in terms of the natural bond orbital (NBO) and QTAIM analysis. Accordingly, the metal ions such as cobalt and chromium are bidentate coordinated with the Schiff base by nitrogen atoms of imine function and pyridine, to form stable complexes. Furthermore, the chromium ions have an affinity superior to the cobalt ions towards Schiff base ligand. In addition, the results of the antibacterial activity in-vitro show that the metal complexation confers an increase in the antibacterial activity of the complexed ligand compared to the free ligand against both Gram-positive and Gram-negative bacteria with broad spectrum activity. In silico molecular docking studies of the ligands and their complexes were applied to describe the probable binding modes into the active site of Escherichia coli (E. coli) FabH and Salmonella typhimurium LT2 neuraminidase (STNA) receptors. The increase in biological activity could be attributed to the high stability of the complexes and strong affinities to bacterial enzyme receptors.Communicated by Ramaswamy H. Sarma.

High-Performance Material for the Effective Removal of Uranyl Ion from Solution: Computationally Supported Experimental Studies

Adsorption is a widely used method for pollution removal and for the recovery of valuable species. In recent years, the use of metal-organic compounds among the adsorbents used in adsorption studies has increased. In this study, the performance of the water-insoluble Fe complex as a metal organic framework (MOF-Fe-Ta) of water-soluble tannic acid, which is not used as an adsorbent in uranium recovery and removal, was investigated. For the characterization of the new synthesized material, Fourier transform infrared, scanning electron microscopy, and X-ray diffraction analyses were performed. The changes in the adsorption process based on various parameters were investigated and discussed. The point of zero charges value of the adsorbent was found as 5.52. It was noticed that the adsorption increases as the pH increases. Analyzing the effect of concentration on adsorption, we determined which model explained the adsorption better. The monolayer capacity of the adsorbent determined in light of the Langmuir model was reported as 0.347 mol kg^-1. The Freundlich constant, namely the β value obtained in the Freundlich model, which is a measure of surface heterogeneity, was found to be 0.434, and the E_DR value, which was found from the Dubinin-Raduskevich model and accepted as a measure of adsorption energy, was 10.3 kJ mol^-1. The adsorption was kinetically explained by the pseudo-second-order model and the adsorption rate constant was reported as 0.15 mol^-1 kg min^-1. The effect of temperature on adsorption was studied; it was emphasized that adsorption was energy consuming, that is, endothermic and ΔH was found as 7.56 kJ mol^-1. The entropy of adsorption was positive as 69.3 J mol^-1 K^-1. As expected, the Gibbs energy of adsorption was negative (-13.1 kJ mol^-1 at 25 °C), so adsorption was considered as a spontaneous process. Additionally, the power and mechanism of the interaction between studied adsorbent and adsorbate are explained through density functional theory computations. Computationally obtained data supported the experimental studies.

Synthesis and some enzyme inhibition effects of isoxazoline and pyrazoline derivatives including benzonorbornene unit

Four new and four known isoxazoline derivatives were synthesized from the reactions of benzonorbornadiene with nitrile oxides formed from the corresponding benzaldehydes. Three new and one known pyrazoline derivatives were also synthesized from the reactions of the benzonorbornadiene with nitrile imines formed from the corresponding compounds. The synthesized nitrogen-based novel heterocyclic compounds were evaluated against the human carbonic anhydrase isoenzymes I and II (hCA I and hCA II), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) enzymes. The synthesized nitrogen-based novel heterocyclic compounds showed IC₅₀ values in the range of 2.69-7.01 against hCA I, 2.40-4.59 against hCA II, 0.81-1.32 µM against AChE, and 20.83-1.70 µM against BChE enzymes. On the contrary, nitrogen-based novel heterocyclic compounds demonstrated K_i values between 2.93 ± 0.59-8.61 ± 1.39 against hCA I, 2.05 ± 0.62-4.97 ± 0.95 against hCA II, 0.34 ± 0.02-0.92 ± 0.17 nM against AChE, and 0.50 ± 0.04-1.20 ± 0.16 µM against BChE enzymes. The synthesized nitrogen-based novel heterocyclic compounds exhibited effective inhibition profiles against both indicated metabolic enzymes. These results may contribute to the development of new drugs particularly to treat some disorders, which are widespread in the world including glaucoma and Alzheimer's diseases.

Effect of fulvic acid on gastric mucosa damage caused by chronic water avoidance stress

We investigated the antioxidant and anti-ulcerogenic effects of fulvic acid (FA) on oxidative damage caused by water avoidance stress (WAS) in rat gastrointestinal mucosa. Three experimental groups were established: control (C), chronic stress (CS), and chronic stress + FA (CS + FA). After WAS, a single dose of FA was administered for 10 days to the CS + FA group. Samples of the pyloric region of the stomach were stained with hematoxylin and eosin (H & E) and periodic acid-Schiff (PAS). Immunohistochemical staining was performed for inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS). Total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) levels were measured biochemically. By light microscopy, we observed loss of gastric epithelial cells and greater polymorphonuclear cell migration into the mucosa in the CS group compared to the C group. We found intact epithelial cell structure and a thick superficial mucus layer in the CS + FA group compared to the CS group. These findings in the CS + FA group were similar to those for group C. iNOS staining was stronger in the CS group compared to the C group. TOS and OSI levels in the CS + FA group were decreased compared to the CS group, but TAS, SOD, GPx and CAT levels were increased. We found that WAS caused damage to epithelium and connective tissue of the stomach mucosa and that this damage was prevented by FA. Therefore, administration of FA appears to prevent stress induced damage to rat stomach.

Chemical Composition of Essential Oil and In Vitro Biological Activities of Dryopteris marginalis L

Introduction:

Dryopteris marginalis L. is a local plant in Bangladesh which is widely used as folk medicine.

Materials and Methods:

In this study, the chemical composition of essential oil of D. marginalis L. as well as the antioxidant activity, antibacterial activity and total phenolic content of various organic extracts were analyzed. The gas chromatography mass spectrometry analysis was used to identify the chemical compositions. The antibacterial activity of different extracts of Dryopteris marginalis was examined against three gram-negative bacteria and two gram-positive bacteria. The antibacterial activity of different extracts was investigated using the disc diffusion method and minimum inhibitory concentration showing important antibacterial activity and was measured by using the broth dilution method.

Results:

The antioxidant activity was determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and superoxide radical scavenging assay. The total phenolic portion of the extracts was ascertained by Folin-Ciocalteu in an alkaline medium. Twenty-two volatile compounds were identified from the essential oil. The methanol extract exhibited a significant inhibitory effect which was close to the value of standard antibiotic (Streptomycin). The zones of inhibition of different organic extracts against the tested bacteria were found in the range of (7-15) mm and the Minimum Inhibitory Concentrations (MIC) were recorded (15.62-1000) μg/ml. The antioxidant activity of D. marginalis was (82.13+1.2) % and (59.21+0.45) % highest activity with DPPH and superoxide radical scavenging assay, respectively.

Conclusion:

The methanol extract showed the highest (147.43+3.1) mg/g GAE of total phenolic content. The extracts and essential oil of D. marginalis showing strong antibacterial activity can be considered as a potential source of natural medicine and the ingredient of modern therapeutic agents.

Functionalisation of Indene

Dibromo- and tribromoindane were synthesised by bromination of indene. Treatment of dibromo- and tribromoindane with various silver salts (silver acetate, perchlorate, sulfate and nitrate) in different solvents opened up an entry to the synthesis of various di- and tri-substituted indane derivatives.

Highly brominated biphenylenes as precursors for the convenient synthesis of 5,6,8,10-tetrabromobenzocyclooctene

An efficient synthesis is described of hexabromides 5 and 6 by photobromination of biphenylene (1). Double dehydrobromination of hexabromides 5 and 6 with t-BuOK affords 5,6,8,10-tetrabromobenzocyclooctene (7) in nearly quantitative yield. The tetrabromide 7 is a valuable precursor for the preparation of functionalised substituted benzocyclooctenes (benzo[8]annulenes).

9-Amino-5,7-dibromo-1,2,3,4-tetrahydroacridine hemihydrate

The asymmetric unit of the title compound, C13H12Br2N2·0.5H2O, includes two molecules of 5,7-dibromo-1,2,3,4-tetrahydroacridin-9-amine and one water molecule. In the crystal, C—H...O, N—H...N, N—H...O and O—H...N hydrogen bonds connect the molecules, forming a two-dimensional network parallel to (010). The two-dimensional sheets are further assembled into a three-dimensional structure through C—H...π and π–π stacking interactions [centroid–centroid distance = 3.719 (2) Å].

11-[Bis(trimethylsilyl)amino]-2,4-bis(trimethylsilyl)-7,8,9,10-tetrahydro-6H-cyclohepta[1,2-b]quinoline

In the title compound, C26H48N2Si4, the cycloheptane ring adopts a chair conformation, while the quinolinyl ring system is almost planar [maximum deviation = 0.040 (3) Å for one of the C atoms carrying a Me3Si group]. In the crystal, in the absence of classical hydrogen bonding, the packing is dominated by van der Waals forces. One of the N-bound trimethylsilyl groups is disordered by rotation about the C—SiMe3bond, and was modelled over two sets of sites in the ratio 0.873 (8):0.127 (8).

Synthesis of Bromoaminoindane and Bromoaminoindanone Derivatives

The bromination reactions of 5-aminoindane, 5-acetamidoindane, and 5-acetamidoindan-1-one were investigated using NBS, molecular bromine and photobromination, and the optimum reaction conditions were presented. The reaction of 5-aminoindane with glacial acetic acid at reflux temperature resulted in the formation of 5-acetamidoindane in high yield. 5-Acetamidoindan-1-one was generated by the reaction of 5-acetamidoindane with CrO3 in acetic acid. Selective bromination at C-6 position of 5-acetamidoindane was achieved by treatment of title compound with bromine in acetic acid and thus afforded 5-acetamido-6-bromoindane. Further bromination reactions of bromoindanones were achieved in various reaction conditions.

2,5-Dibromoindan-1-ol

In the title compound, C₉H₈Br₂O, the cyclo­pentene ring adopts an envelope conformation with the brominated C atom as the flap. In the crystal, mol­ecules are linked by strong O—H⋯O hydrogen bonds into zigzag C(4) chains along [010]. In addition, a C—H⋯π inter­action involving the benzene ring and the H atom attached to the hy­droxy­lated C atom is observed.

2,4-Dibromo-2,3-dihydro-1H-inden-1-yl acetate

In the title compound, C11H10Br2O2, the cyclopentene ring fused to the benzene ring adopts an envelope conformation, with the C atom attached to the Br atom as the flap. The crystal structure does not exhibit any classical hydrogen bonds. The molecular packing is stabilized by van der Waals forces and π–π stacking interactions with a centroid–centroid distance of 3.811 (4) Å.

2,3-Dihydro-1H-cyclo-penta-[b]naph-tha-len-1-ol

In the title compound, C(13)H(12)O, the cyclo-pentene ring fused with the naphthalene group adopts an envelope conformation. The cyclo-pentene torsion angle, with the fusion bond at the centre, has a magnitude of 1.16 (16)°. In the crystal, neigh-bouring mol-ecules are connected through O-H⋯O hydrogen bonds into an R(4) (4)(8) ring motif. The crystal packing also features weak π-π stacking inter-actions [centroid-centroid distance = 3.8981 (8) Å] and C-H⋯π inter-actions.

5-Amino-4-bromo-2,3-dihydro-1H-inden-1-one

In the title compound, C₉H₈BrNO, the non-H-atom framework is essentially planar, with a maximum deviation of 0.087 (3) Å. In the crystal, mol­ecules are inter­connected into a three-dimensional network by C—H⋯O and N—H⋯O hydrogen bonds. In addition, C—H⋯π inter­actions and a π–π stacking inter­action, with a centroid–centroid distance of 3.5535 (19) Å, are also observed.

Synthesis of New Anthracene Derivatives

An efficient synthesis is described for hexabromoanthracenes 3 and 4 by direct bromination of 9,10-dibromoanthrecene 2. Whereas base-induced elimination of hexabromide 3 with t-BuOK gave 2,3,9,10-tetrabromoanthracene 5, the reaction of hexabromide 4 with DBU afforded 1,3,9,10-tetrabromoanthracene 6 as the sole product. Tetrabromide 5 was also obtained by aromatization of 1,4-dinitroxy-2,3,9,10-tetrabromo-1,2,3,4-tetrahydroanthracene 17. Efficient and convenient synthetic routes are described for the preparation of dinotroxy 17, dimethoxy 23, and dihydroxides 18 and 19 with silver-induced substitution of hexabromides 3 and 4. The hydroxy compounds 19 and 18 were converted to diepoxide 20 and monoepoxide 21, respectively, with sodium methoxide. Base-promoted aromatization of dimethoxide 23 afforded dibromomonomethoxides 26 and 27. Bromoanthracenes and isomeric arene oxides constitute valuable precursors for the preparation of functionalized substituted anthracene derivatives that are difficult to prepare by other routes.