Synthesis,structure–activity relationship and antinociceptive activities of some 2-(2′-pyridyl) benzimidazole derivatives

In the present study, a new series of 2-(2′-pyridyl) benzimidazole derivatives 1–11 were resynthesized and evaluated for analgesic activity. The 2-(2′-pyridyl) benzimidazole was quaternized at its nitrogen atom in the ring with various substituted and unsubstituted phenacyl halides. As a result, eleven novel derivatives were synthesized. The structures of these new synthetic derivatives of 2-(2′-pyridyl) benzimidazole were confirmed by using different spectroscopic techniques i.e., UV/Visible, IR, ¹HNMR and Mass spectroscopy. Percentage of carbon, hydrogen and nitrogen was also determined by elemental analysis. All the synthetic compounds showed significant analgesic activity with dose-dependent manner.     

Synthesis and pharmacological activity of derivatives of 3-aminomethylene-1-(2′,6′-dichlorophenyl)oxindole and 2-aminomethyleneindoxyl

Derivatives of 3-aminomethylene-1-(2,6-dichloro)phenyloxindole and 2-aminomethyleneindoxyl were synthesized. The¹H and¹³C NMR spectra and pharmacology of the compounds were studied.     

Synthesis and antiproliferative activity evaluation of new thiazole–benzimidazole derivatives using real-time cell analysis (RTCA DP)

A series of new 2-[(5-substituted-1H-benzimidazol-2-yl)thio]-N-[4-[2-phenylthiazol-4-yl]phenyl]acetamide derivatives (4a–p) were synthesized according to the reported literature, and anticancer activity of the compounds was evaluated. Cytotoxic activity was confirmed by real-time cytotoxicity analysis system determining half maximal inhibitory concentrations (IC₅₀) of the title compounds based on the dose–response curves derived by xCELLigence measurements against NIH/3T3, A549 and Caco2 cell lines for 24, 48 and 72 h exposure. Compound 4c was found to be as the most efficient molecule that exhibited selective antiproliferative activity against both of the cancer cells.     

Synthesis and antibacterial activity of 4,4′-(aryl or alkyl methylene)-bis(1H-pyrazol-5-ol) derivatives

A rapid, improved, and environmentally benign synthesis of 4,4′-aryl or alkyl methylene-bis(1H-pyrazol-5-ols) has been accomplished by tandem Knoevenagel–Michael reaction of 1-aryl-3-alkyl-1H-pyrazol-5-ol with various aldehydes catalyzed by ammonium acetate. All the synthesized compounds 3a–v were evaluated in vitro for their antibacterial activity against Pseudomonas aeruginosa, Xanthomonas protophormiae, Bacillus licheniformis, and Staphylococcus aureus. Among the tested compounds, compounds with trifluromethyl group show excellent antibacterial activity.     

Metabolism and presynaptic inhibitory activity of 2′,3′ and 5′-adenine nucleotides in rat vas deferens

Summary In the isolated rat vas deferens stimulated at 0.2 Hz, [¹⁴C]labelled 5-AMP, 5-ADP and 5-ATP (10 M) inhibited twitch responses, were broken down to [¹⁴C]adenosine in the medium and incorporated into [¹⁴C]adenine ribonucleotides in the tissue. Pretreatment of tissues with 6-(2-hydroxy-5-nitrobenzyl)-thioguanosine (NBTGR), a potent inhibitor of adenosine transport, potentiated the presynaptic inhibitory action of these 5 nucleotides and reduced their incorporation in [¹⁴C]adenine nucleotides, but did not alter the appearance of [¹⁴C]adenosine in the medium.A series of 2, 3 and 5-substituted adenine nucleotides (10 M) inhibited the twitch responses of the vas deferens stimulated at 0.2 Hz. This effect was potentiated by NBTGR. Addition of exogenous adenosine deaminase very significantly reduced the inhibitory actions of adenosine, 5-AMP, 5-ADP and 5-ATP and also reduced those of 2, 5-ADP, NAD⁺ and dePCoA. The inhibitory actions of the other 2, 3 and 5 adenine nucleotides studied were not altered by exogenous adenosine deaminase.These results indicated that the presynaptic inhibitory actions of 5-AMP, 5-ADP and 5-ATP in rat vas deferens predominantly result from their prior hydrolysis to adenosine whereas the 2, 3 and 5-substituted adenine nucleotides appear to act mainly directly to inhibit transmitter release.Abbreviations. The following abbreviations are used 5-ADP 5-adenosine diphosphate - 2,5-ADP 2,5-adenosine diphosphate - 3,5-ADP 3,5-adenosine diphosphate - 2,3 or 5-AMP 2,3 or 5-adenosine monophosphate - 5-ATP 5-adenosine triphosphate - CoA coenzyme A - 2,3-cAMP 2,3-cyclic adenosine monophosphate - cNADP⁺ -nicotinamide dinucleotide 2,3-cyclic monophosphate - dePCoA dephosphocoenzyme A - NAD⁺ -nicotinamide adenine dinucleotide - NADP⁺ -nicotinamide adenine dinucleotide phosphate - NBTGR 6-(2-hydroxy-5-nitrobenzyl)-thioguanosine - oxid CoA oxidized-coenzyme A     

Design, synthesis and antidepressant activity evaluation 2′-hydroxy-4′,6′-diisoprenyloxychalcone derivatives

In this study, 14 2′-hydroxy-4′,6′-diisoprenyloxychalcone compounds were synthesized and their antidepressant activities were evaluated using the forced swimming test. The pharmacological results showed that six compounds significantly reduced immobility times during the forced swimming test at a dose of 10 mg/kg, indicative of antidepressant activity. Among these, three compounds (4d, 4e, and 4g) exhibited better antidepressant activity, with reduced immobility time by 38.3, 34.0, and 27.4 %, respectively. For explanation of the putative mechanism of action, compounds 4e, 4g were tested in chemical induced models.     

New steroids from Anemarrhena asphodeloides rhizome and their α-glucosidase inhibitory activity

Two new steroids were isolated from acid hydrolysis residue of the rhizomes of Anemarrhena asphodeloides. Their structures were identified on the basis of several spectroscopic analysis approaches including 1D, 2D-NMR techniques, and MS data, and by the comparison of spectral data of the known compounds. The biological activities of these two isolated compounds were explored on α-glucosidase. Compound 1 displayed 4.7 folds inhibitory activity against α-glucosidase compared with the positive control acarbose.     

A facile synthesis of emodin derivatives,emodin carbaldehyde,citreorosein, and their 10-deoxygenated derivatives and their inhibitory activities on μ-calpain

A new procedure for the preparation of emodin carbaldehyde and citreorosein was described, in which, ω,ω′-dibromomethylemodin triacetate was prepared as a key intermediate by NBSmediated bromination of 1,3,8-triacetylemodin. Reduction of emodin and citreorosein with SnCl₂ in a 1:1 mixture of HOAc and HCl afforded the corresponding anthrones in 90% and 92% yield, respectively, while the corresponding 10-desoxyemodin carbaldehyde was prepared by MnO₂ oxidation of 10-desoxycitreorosein. 10-Desoxycitreorosein and emodin carbaldehyde showed feasible μ-calpain inhibitory activities with IC₅₀ values of 20.15 and 25.77 M, respectively.     

Synthesis and studies on antidepressant activity of 2′,4′,6′-trihydroxychalcone derivatives

In this study, we synthesized a series of 2′,4′,6′-trihydroxychalcone derivatives and evaluated their antidepressant activities. The results of the nine compounds showed significantly reduced times during the forced swimming test at a dose of 10?mg/kg, indicative of antidepressant activity. Among the compounds, 2-bromo-2′,4′,6′-trihydroxychalcone (3h) was found to be the most potent, and it was observed that compound 3h at dose of 10, 20, and 40?mg/kg significantly reduced the duration of immobility times in the FST and TST in mice 30?min after treatment.     

Two new phragmalin-type limonoids from Chukrasia tabularis and their α-glucosidase inhibitory activity

Phytochemical investigation on the stems of C. tabularis (Meliaceae) led to the isolation of two new phragmalin-type limonoids, named tabularisins S and T (1–2), along with five known ones (3–7). The structures of the new limonoids were established by spectroscopic methods including UV, IR, HRESIMS, and 1D and 2D NMR. All the compounds were evaluated for α-glucosidase inhibitory activity in vitro. Compounds 2 and 3 exhibited significant inhibitory activity against α-glucosidase with IC₅₀ values of 0.15 and 0.03 mM, respectively (acarbose as positive control, IC₅₀ 0.95 mM).     

Antitumor activity of 2(S)-5,2′,5′-trihydroxy-7,8-dimethoxyflavanone and its analogues

In an effort to increase of the antitumor activity of 2(S)-5,2',5'-trihydroxy-7,8-dimethoxyflavanone isolated fromScutellaria indica, we synthesized its analogues,II, III, andIV. They showed potent cytotoxicityin vitro against cancer cell lines, L1210, K562 and A549. On the basis of ED(50) values against the cancer cell lines,III exhibited about 2-7 times stronger activity thanI against various cell lines. We tested the antitumor activity of the analogues against Sarcoma 180 cellsin vivo and evaluated the structure-activity relationship. The antitumor activity appeared to be related to the hydrogen bond between carbonyl group at C-4 and hydroxyl group at C-5, in contrast to cytotoxic action.     

N-adamantyl derivatives of arylamides of α-azacycloalkanecarboxylic acids and their topical anesthetic activity

A series of arylamides of -[N-adamantylpyrrolidyl-(or piperidyl)]carboxylic acids was obtained by reacting 1-(or 2-)aminoadamantanes with arylamides of ,-dihalovaleric (or caproic) acid. The compounds exhibited a pronounced anesthetic activity in experiments.     

Microwave-assisted synthesis of pyrido[1,2-a]benzimidazole derivatives of β-aryloxyquinoline and their antimicrobial and antituberculosis activities

A new series containing pyrido[1,2-a]benzimidazole derivatives of β-aryloxyquinoline has been synthesized via base catalyzed microwave-assisted multi-component cyclocondensation reaction. This methodology allowed us to achieve the desired products in good yields in very short time with the use of 10 mol% NaOH as a non-hazardous organic base. The chemical structures of compounds 6a–x were elucidated by ¹H NMR, ¹³C NMR, FT-IR, elemental analysis, and mass spectral data. The titled derivatives were tested against a panel of pathogenic strains of bacteria and fungi for antimicrobial activity and against Mycobacterium tuberculosis H37Rv for their antitubercular activity. The structural activity relationship study revealed that antimicrobial and antitubercular potency of the title compounds depends not only on the bicyclic heteroaromatic pharmacophore appended through ether linked aryl ring but also on the nature of the peripheral substituents and may also upon their spatial relationship and positional changes.     

Synthesis of 6-[2-(Benzoxazol-2-ylmethylamino)ethoxy]-1-Alkyl-1H-lndole-2-Carboxylic acid and inhibitory activity on β-Amyloid aggregation

6-[2-(benzoxazol-2-ylmethylamino)ethoxy]-1-alkyl-1H-indole-2-carboxylic acids were designed and synthesized as beta-amyloid (Abeta) fibril assembly inhibitors. Their inhibitory activity on Abeta, aggregation was evaluated by thioflavin T assay although their activities were insignificant.     

Synthesis and anticonvulsant activity of indolin(5′-bromoindolin)-3′-spiro-1-(1,2,3,4-tetrahydro)-β-carboline and 3-methyl-β-carboline dihydrochlorides

A series of new spiro-condensed indoles have been synthesized and the relationship between their chemical structure and biological activity has been established. Reduction of the oxo group in previously synthesized hydrochlorides of 2′-oxyindolin(5′-bromoindolin)-3?-spiro-1-(1,2,3,4-tetrahydro-β-carboline and 3-methyl-β-carboline followed by treatment with an ether solution of HCl leads to the dihydrochlorides of indolin-(5′-bromoindolin)-3′-spiro-1-(1,2,3,4-tetrahydro-β-carboline and 3-methyl-β-carboline.     

Synthesis of 2-alkynyl substituted 4′-thioadenosine derivatives and their binding affinities at the adenosine receptors

On the basis of high binding affinity of 2-hexynyl-N(6)-methyladenosine and N(6)-substituted-4'-thioadenosine derivatives at the A3 adenosine receptor (AR), novel 2-alkynyl-substituted-N(6)-methyl-4'-thioadenosine derivatives, combining the characteristics of two classes of nucleosides were designed and synthesized from D-gulonic gamma-lactone via palladium-catalyzed cross coupling reaction as a key step. Among compounds tested, only compound 3b showed moderate binding affinity at the human A3 adenosine receptor without binding affinities at other subtypes.     

New substituted benzimidazole derivatives: a patent review (2013 – 2014)

Introduction: The benzimidazole nucleus is found in a variety of naturally occurring compounds and is of significant importance in medicinal chemistry. Owing to its conspicuous pharmacological properties, benzimidazoles have become an important pharmacophore and sub-structure in drug design and have been screened for a wide range of biological activities.

Areas covered: Areas covered in this paper include a review of the biological effects, mechanisms and synthesis of benzimidazole derivatives in the past 2 years based on patents. The patent databases Scifinder and esp@cenet were used to locate patent applications that were published between 2013 to present. Information from articles published is also included.

Expert opinion: Benzimidazole derivatives are remarkably effective compounds to many diseases and may have the potential to be the first effective therapy against Ebola virus. Therefore, it is of great importance to develop specific design software and sustainable industrial synthetic routes for the development of effective and clinically relevant benzimidazole compounds.     

Synthesis of β-amino carbonyl derivatives of coumarin and benzofuran and evaluation of their biological activity

A series of β-amino carbonyl compounds containing coumarin (4a–h) and benzofuran (6a–i) moieties was synthesized by a three component Mannich reaction of 3-acetyl-2H-chromen-2-one (1) or 1-(1-benzofuran-2-yl) ethanone (5) with p-substituted aromatic aldehydes (2a–g) and aromatic amines (3a–b) in the presence of cerric ammonium nitrate as a catalyst. The newly synthesized compounds were screened for antimicrobial and antioxidant activities. Compounds 4b, 4e, 4f, 6f, 6g, and 6i showed microbial inhibition with minimal inhibition concentration ranging between 0.040 and 0.500 mg/mL, compounds 4b, 4c, 6c, 6e, and 6i showed promising free radical scavenging activity and compounds 4b, 4f, 6c, 6d, and 6h showed good chelating ability with Fe²⁺ ions. The synthesized compounds were studied for docking on the enzyme, glucosamine-6-phosphate synthase to predict the binding affinity and orientation at the active site of the receptor.     

Synthesis of bioactive spiro-2-[3′-(2′-phenyl)-3H-indolyl]-1-aryl-3-phenylaziridines and SAR studies on their antimicrobial behavior

The present communication deals with synthesis of a new series of spiro-2-[3′-(2′-phenyl)-3H-indolyl]-1-aryl-3-phenylaziridines. Infrared (IR), ¹H nuclear magnetic resonance (NMR), mass spectral, and elemental analysis data corroborated the structure of all synthesized compounds. Synthesized compounds were screened for antimicrobial activity against a representative panel of Gram-positive and Gram-negative bacteria. All newly synthesized compounds showed remarkable antimicrobial behavior. Structure–activity relationship (SAR) investigations were applied to investigate the correlation between the molecular refractive index (M_R) parameter of the compounds and their biological activity profile. All compounds were subjected to acute toxicity studies to determine 50% lethal dose (LD₅₀) values.