Progress in the proxifan class: heterocyclic congeners as novel potent and selective histamine H(3)-receptor antagonists

Synthesis and anti-inflammatory activity of benzimidazole derivatives; an in vitro, in vivo and in silico approach

Many non-steroidal anti-inflammatory drugs (NSAIDs) concurrently inhibit both COX-1 and COX-2, with a preference for specifically targeting COX-2 due to its significant involvement in various pathologies. In addition to COX enzymes, several other targets, including Aldose reductase, Aldo-ketoreductase family 1-member C2, and Phospholipase A2, have been identified as contributors to inflammation and a myriad of other diseases. In this context, a series of 2-substituted benzimidazole derivatives was synthesized and assessed for their anti-inflammatory potential through both in vitro and in vivo assays. Molecular docking studies were conducted to elucidate the mechanism of action of these compounds against COX enzymes and other therapeutic targets associated with NSAIDs, such as Aldose reductase, AIKRC, and Phospholipase A2. Among the synthesized compounds, B2, B4, B7, and B8 demonstrated IC50 values lower than the standard ibuprofen, as determined by the Luminol-enhanced chemiluminescence assay. Validation of these findings was achieved through an in vivo carrageenan-induced mice paw edema model, confirming a comparable anti-inflammatory effect to diclofenac sodium observed in vitro. Notably, these compounds exhibited significant binding affinity with all therapeutic targets investigated in this study. These results suggest that the newly synthesized derivatives possess noteworthy anti-inflammatory potential, warranting further exploration for the development of novel multi-targeting inhibitors.

Synthesis, characterization, molecular dynamic simulation, and biological assessment of cinnamates linked to imidazole/benzimidazole as a CYP51 inhibitor

A class of 2-(1H-imidazol-1-yl)-1-phenylethyl cinnamates 6a-6j and 2-(1H-benzo[d]imidazol-1-yl)-1-phenylethyl cinnamates 7a-7j were synthesized, and their synthesis was validated using various spectroscopic techniques like IR, NMR, and Mass spectrometry. In addition, the compounds were assessed for in-vitro antibacterial against gram-positive and gram-negative strains and in-vitro antifungal against six different fungal strains. Compounds 6 g, 7 b, 7f, and 7 g exhibited significant activity against all bacterial strains ranging from MIC = 12.5-50 µg/mL, and compounds 6 g, 7 b, and 7 g exhibited considerable activity against all fungal strains ranging from MFC = 125-200 µg/mL. A molecular docking study indicated that compounds 6 g, 7 b, 7 g, and 7j could be lodged in the active pocket and inhibit C. albicans Sterol 14α-demethylase (CYP51) protein via various interactions, and these studies validate the antifungal results. Different parameters from the 100 ns MD simulation study are investigated to evaluate the dynamic stability of protein-ligand complexes. According to the MD simulation study, the proposed compounds effectively kept their molecular interaction and structural integrity within the C. albicans Sterol 14-demethylase. Compounds 6 g, 7 b, and 7 g are promising lead compounds in searching for novel antifungal drug-like molecules. Furthermore, in silico ADME indicates that these compounds possess drug-like physicochemical properties to be orally bioavailable.Communicated by Ramaswamy H. Sarma.

Novel Mixed Complexes Derived from Benzoimidazolphenylethanamine and 4-(Benzoimidazol-2-yl)aniline: Synthesis, Characterization, Antibacterial Evaluation and Theoretical Prediction of Toxicity

Benzoimidazolphenylethanamine (BPE) has been synthesized using condensation reaction from o-phenyldiamine and L-phenylalanine. Some metal complexes have been synthesized from 4-(benzoimidazol-2-yl)aniline, benzoimidazolylphenylethanamine and cadmium(II), tin(II), copper(II) and nickel(II) metal in a molar ratio (1:1:1). All new metal complexes were characterized by spectroscopic data of FTIR, UV-visible electronic absorption, X-ray powder diffraction and thermal analysis. Spectra analysis of the mixed metal complexes showed the coordination of ligands to the metal ions via nitrogen atoms. The XRD powder showed that metal complexes have a monoclinic system. The preliminary tested in vitro antibacterial activities of Sn(II) complex was assayed against four bacterial isolates namely Micrococcus luteus, Staphylococcus aureus as Gram-positive, Pseudomonas aerugmosa and Escherichia coli.

Molecular Modelling Studies of 1,4-Diaryl-2-Mercaptoimidazole Derivatives for Antimicrobial Potency

Background: :

Imidazoles are considered as potent antimicrobial agents. In view of this 2-mercaptoimidazoles were synthesized and evaluated for antimicrobial study.

Methods::

Some new 2-mercaptoimidazoles 4a-r were synthesized using substituted aniline and substituted phenacyl bromides in the presence of anhydrous sodium carbonate or potassium carbonate and potassium thiocyanate under solvent-free conditions catalyzed by eco-friendly ptoluene sulfonic acid.

Results: :

The structure of compounds was evaluated on the basis of Infrared spectroscopy (IR), 1HNMR (proton nuclear magnetic resonance) and mass spectral studies. These novel compounds were screened for in-vitro antibacterial and antifungal potency against Staphyllococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Further, the study was rationalized by molecular modeling studies. All the compounds were subjected to molecular modeling studies for inhibition of enzyme 14α-demethylase.

Conclusions::

The compounds were found to be effective in inhibiting the growth of pathogens. The in-silico results depicted that, all the synthesized compounds have minimum binding energy and good affinity towards the active site and thus can be considered as good inhibitors of 14α- demethylase enzyme.

Biological Activity and Molecular Structures of Bis(benzimidazole) and Trithiocyanurate Complexes

1-(1H-Benzimidazol-2-yl)-N-(1H-benzimidazol-2-ylmethyl)methanamine (abb) and 2-(1H-benzimidazol-2-ylmethylsulfanylmethyl)-1H-benzimidazole (tbb) have been prepared and characterized by elemental analysis. These bis(benzimidazoles) have been further used in combination with trithiocyanuric acid for the preparation of complexes. The crystal and molecular structures of two of them have been solved. Each nickel atom in the structure of trinuclear complex [Ni₃(abb)₃(H₂O)₃(μ-ttc)](ClO₄)₃·3H₂O·EtOH (1), where ttcH₃ = trithiocyanuric acid, is coordinated with three N atoms of abb, the N,S donor set of ttc anion and an oxygen of a water molecule. The crystal of [(tbbH₂)(ttcH₂)₂(ttcH₃)(H₂O)] (2) is composed of a protonated bis(benzimidazole), two ttcH₂ anions, ttcH₃ and water. The structure is stabilized by a network of hydrogen bonds. These compounds were primarily synthesized for their potential antimicrobial activity and hence their possible use in the treatment of infections caused by bacteria or yeasts (fungi). The antimicrobial and antifungal activity of the prepared compounds have been evaluated on a wide spectrum of bacterial and yeast strains and clinical specimens isolated from patients with infectious wounds and the best antimicrobial properties were observed in strains after the use of ligand abb and complex 1, when at least 80% growth inhibition was achieved.

1-[(2E)-3-Phenylprop-2-enoyl]-1H-benzimidazoles as anticancer agents: synthesis, crystal structure analysis and binding studies of the most potent anticancer molecule with serum albumin

The anticancer activity of 1H-benzimidazoles was studied against NCI 60 cell panel. Compound 3f showed antitumor activity with good to moderate selectivity ratio. Mechanism of interaction of 3f with protein was studied by spectral methods.

A novel role of transient receptor potential mucolipin1 (TRPML1) in protecting against imidazole-induced cytotoxicity

Lysosomotropic amines cause serious side effects such as cytoplasmic vacuolation and cell death. TRPML1 (also known as mucolipin1), a member of the transient receptor potential (TRP) protein family, may regulate fusion/fission of vesicles along the endocytic pathway and some aspects of lysosomal ion homeostasis. Nevertheless, it is still unknown whether TRPML1 is involved in death of mammalian cells induced by lysosomotropic agents. In this study, imidazole was used as a model to investigate the role of TRPML1 in the cytotoxicity of lysosomotropic agents. Overexpression of wild-type TRPML1 inhibited imidazole-induced vacuole formation and cell death in human endometrial adenocarcinoma (HEC-1B) cells. In contrast, siRNA-mediated TRPML1 knockdown increased the cell death induced by imidazole. Bafilomycin A1 raises the pH of acidic organelles and therefore suppresses accumulation of weak bases in them. Similarly, lysosomal pH was raised in TRPML1-overexpressing cells; therefore, we inferred that TRPML1 protected against imidazole toxicity by regulating the pH of acidic organelles. We concluded that TRPML1 had a novel role in protecting against lysosomotropic amine toxicity.

Ethyl 1-phenyl-2-[4-(trifluoro-meth-yl)phen-yl]-1H-benzimidazole-5-carboxyl-ate

The asymmetric unit of the title compound, C(23)H(17)F(3)N(2)O(2), contains two mol-ecules. In one of the mol-ecules, the phenyl and triflouromethyl-substituted benzene rings form dihedral angles of 52.05 (8) and 33.70 (8)°, respectively, with the benzimidazole ring system, while the dihedral angle between them is 58.24 (10)°. The corresponding values in the other mol-ecule are 58.40 (8), 25.90 (8) and 60.83 (10)°, respectively. In the crystal, mol-ecules are linked into chains along [100] by C-H⋯O and C-H⋯N hydrogen bonds. Aromatic π-π stacking inter-actions [centroid-centroid distance = 3.6700 (12) Å] also occur.

Ethyl 2-(1,3-benzodioxol-5-yl)-1-[3-(2-oxopyrrolidin-1-yl)prop-yl]-1H-benz-imidazole-5-carboxyl-ate

In the title compound, C₂₄H₂₅N₃O₅, the benzimidazole and benzodioxole ring systems are each approximately planar [maximum deviations = 0.043 (1) and 0.036 (1) Å, respectively]. Their mean planes form a dihedral angle of 42.85 (4)°. The pyrrolidine ring has an envelope conformation with one of the methyl­ene C atoms forming the flap. In the crystal, weak C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. The crystal packing is further stabillized by weak π–π inter­actions between the benzene rings within the benzimidazole ring system [centroid–centroid distance = 3.7955 (7) Å]. A weak C—H⋯π inter­action involving the benzodioxole ring is also present.

Ethyl 2-(1,3-benzodioxol-5-yl)-1-[3-(1H-imidazol-1-yl)prop-yl]-1H-benzimidazole-5-carboxyl-ate

In the title compound, C₂₃H₂₂N₄O₄, the essentially planar [maximum deviation = 0.022 (1) Å] benzimidazole ring system forms dihedral angles of 86.16 (7) and 37.38 (6)°, respectively, with the imidazole and benzene rings. The dioxolane ring adopts an envelope conformation with the methyl­ene C atom at the flap. In the crystal, C—H⋯O and C—H⋯N inter­actions link the mol­ecules into a ribbon along the a axis. The crystal packing is further stabilized by weak π–π stacking inter­actions [centroid–centroid distances = 3.5954 (8) and 3.7134 (8) Å] and C—H⋯π inter­actions.

5-[(E)-(2-Hy-droxy-benzyl-idene)amino]-1H-1,3-benzimidazole-2(3H)-thione

There are two mol­ecules in the asymmetric unit of the title compound, C₁₄H₁₁N₃OS. In each, the benzimidazole ring system is essentially planar, with maximum deviations of 0.010 (2) and 0.006 (2) Å, and makes dihedral angles of 8.70 (9) and 13.75 (8)°, respectively, with the hy­droxy-substituted benzene rings. Each mol­ecule adopts an E configuration about the central C=N double bond. In the crystal, the two independent mol­ecules are connected via inter­molecular N—H⋯S hydrogen bonds, forming dimers. Furthermore, the dimers are connected by N—H⋯O hydrogen bonds into mol­ecular ribbons along the c axis. There is an intra­molecular O—H⋯N hydrogen bond in each mol­ecule, which generates an S(6) ring motif.

Ethyl 1-(2-hydroxyethyl)-2-p-tolyl-1H-benzimidazole-5-carboxylate

The asymmetric unit of the title compound, C₁₉H₂₀N₂O₃, contains two mol­ecules (A and B) with slightly different orientations of the ethyl groups with respect to the attached carboxyl­ate groups. Intra­molecular C—H⋯O hydrogen bonds generate S(8) ring motifs in both mol­ecules A and B. In each mol­ecule, the benzimidazole ring system is essentially planar, with maximum deviations of 0.023 (1) and 0.020 (1) Å, respectively, for mol­ecules A and B. The dihedral angle between the benzimidazole ring system and the phenyl ring is 37.34 (5)° for mol­ecule A and 42.42 (5)° for mol­ecule B. In the crystal, O—H⋯N and C—H⋯O hydrogen bonds link the mol­ecules into [100] columns with a cross-section of two-mol­ecule by two-mol­ecule wide, and further stabilization is provided by weak C—H⋯π and π–π inter­actions [centroid separations = 3.5207 (7) and 3.6314 (8) Å].

Ethyl 1-sec-butyl-2-phenyl-1H-benzimidazole-5-carboxylate

In the title mol­ecule, C₂₀H₂₂N₂O₂, the benzimidazole ring system is essentially planar, with a maximum deviation of 0.024 (1) Å. The dihedral angle between the phenyl and benzimidazole ring system is 43.71 (5)°. The atoms of the butyl group are disordered over two sets of sites with occupancies of 0.900 (4) and 0.100 (4). In the crystal structure, mol­ecules are connected by weak inter­molecular C—H⋯O hydrogen bonds, forming chains along the b axis. The crystal structure is further stabilized by C—H⋯π inter­actions.

Synthesis, characterization and evaluation of benzimidazole derivative and its precursors as inhibitors of MDA-MB-231 human breast cancer cell proliferation

A novel series of trisubstituted benzimidazole and its precursors (3-7) were synthesised and characterized by using 1H NMR, LC/MS, FTIR and elemental analysis techniques. The title compounds were evaluated for inhibition against MDA-MB-231 breast cancer cell proliferation. The results revealed that the compound N-(4-cyano-3-(trifluoromethyl) phenyl)-4-fluoro-3-nitrobenzamide (3) was the potent inhibitor.

Pro-apoptotic activity of imidazole derivatives mediated by up-regulation of Bax and activation of CAD in Ehrlich Ascites Tumor cells

In this study we report that, imidazole derivatives can induce apoptosis in Ehrlich ascites tumor (EAT) cells, which is clearly evident from annexin-V staining, flow cytometric analysis of cell cycle phase distribution and DNA fragmentation. Delineating further into molecular mechanisms leading to apoptosis of EAT cells, we observed that imidazole derivatives induce tumor cell death by the up-regulation of proto-oncoprotein Bax, release of cytochrome c from the mitochondria which activates caspase-3 and activated caspase-3 activates CAD (Caspase Activated DNase) causes DNA fragmentation. The status of Bcl-2 remains unaltered in EAT cells, and the under expression of Bcl-2 and up-regulation of Bax resulted in the increase of Bax: Bcl-2 ratio suggesting that Bcl-2 family involved in the control of apoptosis. These results suggest a further possible clinical application of imidazole derivatives as pro-apoptotic agent in association with conventional chemotherapeutic agents.

Search for Histamine H3Receptor Ligands with Combined Inhibitory Potency at HistamineN-Methyltransferase: ω-Piperidinoalkanamine Derivatives

In an effort to design new hybrid compounds with dual properties, i.e. binding affinity at histamine H(3) receptors and inhibitory potency at the catabolic enzyme histamine N(tau)-methyltransferase (HMT), a novel series of 1-substituted piperidine derivatives was synthesized. This alicyclic heterocycle is structurally linked via aminoalkyl spacers of variable lengths to additional aromatic carbo- or hetero-cycles. These new hybrid drugs were pharmacologically evaluated regarding their binding affinities at recombinant human H(3) receptors, stably expressed in CHO cells, and in a functional assay for their inhibitory potencies at rat kidney HMT. All compounds investigated proved to be H(3) receptor ligands with binding affinities in the micro- to nanomolar concentration range despite significant differences in the type of the aromatic moiety introduced. The most potent compound in this series was the quinoline derivative 20 (K(i) = 5.6 nM). Likewise, all new ligands studied showed impressive HMT inhibitory activities. Here, compounds 5, 10, 14 and 18-20 exhibited submicromolar potencies (IC(50) = 0.061-0.56 microM). The aminomethylated quinoline 19 showed almost the same, well balanced nanomolar activities on both targets. In this study, new hybrid compounds with a dual mode biological action were developed. These pharmacological agents are valuable leads for further development and candidates for treatment of histamine-dependent disorders.

Structure–activity relationships of non-imidazole H3 receptor ligands. Part 3: 5-Substituted 3-phenyl-1,2,4-oxadiazoles as potent antagonists

Further SAR studies on novel histamine H(3) receptor antagonists are presented. Compound 14bb is a potent antagonist of both the rat cortical and human clone receptors, and is demonstrated to act functionally as an antagonist in an in vivo mouse dipsogenia model.