Süheyla Özbey

Synthesis and antioxidant properties of novel N-methyl-1,3,4-thiadiazol-2-amine and 4-methyl-2H-1,2,4-triazole-3(4H)-thione derivatives of benzimidazole class

Some novel 1-methyl-4-(2-(2-substitutedphenyl-1H-benzimidazol-1-yl)acetyl)thiosemicarbazides (16a-20a), 5-[(2-(substitutedphenyl)-1H-benzimidazol-1-yl)methyl]-N-methyl-1,3,4-thiadiazol-2-amines (17b-20b), and 5-[(2-(substitutedphenyl)-1H-benzimidazol-1-yl)methyl-4-methyl-2H-1,2,4-triazole-3(4H)-thiones (16c-20c) were synthesized and tested for antioxidant properties by using various in vitro systems. Compounds 16a-20a were found to be a good scavenger of DPPH radical (IC(50), 26 microM; IC(50), 30 microM; IC(50), 43 microM; IC(50), 55 microM; IC(50), 74 microM, respectively) when compared to BHT (IC(50), 54 microM). Noteworthy results could not be found on superoxide radical. Compound 19b, which is the most active derivative inhibited slightly lipid peroxidation (28%) at 10(-3)M concentration. Compound 17c inhibited the microsomal ethoxyresorufin O-deethylase (EROD) activity with an IC(50)=4.5 x 10(-4)M which is similarly better than the specific inhibitor caffeine IC(50)=5.2 x 10(-4)M.

Synthesis and hypnotic activity of new 4-thiazolidinone and 2-thioxo-4,5-imidazolidinedione derivatives.

Conveniently accessible 4‐[(2‐(3,4‐dimethoxyphenyl)ethyl]‐3‐thiosemicarbazide (2) was converted to new 1‐substituted benzylidene/furfurylidene‐4‐[2‐(3,4‐dimethoxyphenyl)ethyl]‐3‐thiosemicarbazides (3) which furnished 2‐(substituted benzylidene/furfurylidene)hydrazono‐3‐[2‐(3,4‐dimethoxyphenyl)ethyl]thiaz‐olidin‐4‐ones (4) and 1‐(substituted benzylidene/furfurylidene)‐amino‐3‐[2‐(3,4‐dimethoxyphenyl)ethyl]‐2‐thioxo‐4,5‐imidazol‐idinediones (5) on reaction with chloroacetic acid and oxalyl chloride, respectively. The structure of 5 was confirmed by X‐ray diffraction studies performed on 5a. 4 and 5 were evaluated for their potentiating effects on pentobarbital induced hypnosis. Most of the compounds caused remarkable increases in pentobarbital sleeping time.

Synthesis of some 1-(2-naphthyl)-2-(imidazole-1-yl)ethanone oxime and oxime ether derivatives and their anticonvulsant and antimicrobial activities.

In this study, oxime and oxime ether derivatives of anticonvulsant nafimidone [1-(2-naphthyl)-2-(imidozole-1-yl)ethanone] were prepared as potential anticonvulsant compounds. Nafimidone oxime was synthesized by the reaction of nafimidone and hydroxylamine hydrochloride. O-Alkylation of the oxime by various alkyl halides gave the oxime ether derivatives. Anticonvulsant activity of the compounds was determined by maximal electroshock (MES) and subcutaneous metrazole (scMet) tests in mice and rats according to procedures of the Antiepileptic Drug Development (ADD) program of the National Institutes of Health (NIH). In addition to anticonvulsant evaluation, compounds were also screened for possible antibacterial and antifungal activities because of the structural resemblance to the azole antifungals, especially to oxiconazole. All compounds were evaluated against three human pathogenic fungi and four bacteria using the microdilution method. Most of the compounds exhibited both anticonvulsant and antimicrobial activities; the O-alkyl substituted compounds (2, 3, 4 and 5) were found to be more active than the O-arylalkyl substituted compounds in both screening paradigms.

Intramolecular hydrogen bonding and tautomerism in N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine

N-(3-pyridil)-2-oxo-1-naphthylidenemethylamine (C16H12N2O) was studied by elemental analysis, IR, 1H NMR, and UV–visible techniques and X-ray diffraction methods. The UV–visible spectrum of the compound was investigated in solutions effect polarity. The polarity of the some solvents was modifierly the additional (CF3COOH) and [(C2H5)3N]. The compound is in tautomeric equilibrium (phenol-imine O–H···N and keto-amine O···H–N forms) in polar and nonpolar solvents. The keto-amine form is observed in basic solutions of DMSO, ethanol, chloroform, benzene, cyclohexane, and in acidic solutions of chloroform and benzene, but not in acidic solutions of DMSO and ethanol. The compound crystallizes in the monoclinic, space group P21/a with a = 7.010(5) Å, b = 13.669(4) Å, c = 12.764(4) Å, β = 101.23(4)°, V = 1199.6(10) Å3, Z = 4, Dc = 1.375 g/cm3, μ(Mo Kα) = 0.088 mm−1, R = 0.045 for 1658 reflections [I > 2σ(I)]. The title compound is not planar two Schiff base moieties A [C1–C11, O1] and B [N1, C12, C13, N2, C14, C15, C16] are inclined at an angle of 27.4(1)° reflecting mainly the twist about C12–N1 [C11–C12–N1–C13, 29.7(2)°]. There is a strong intramolecular hydrogen bond (O–H···N) of 2.529(2) Å.

THE CRYSTAL AND MOLECULAR STRUCTURE OF TWO BENZIMIDAZOLE DERIVATIVES : 1-(PHENYLMETHYL)-2-(4-METHOXYPHENYLMETHYL)-1H-BENZIMIDAZOLE-5-CARBOXYLIC ACID ( I) AND 1,2-DI-(PHENYLMETHYL)-1H-BENZIMIDAZOLE-5-CARBOXYLIC ACID (II)

Abstract The crystal structures of C23H20N2O3 (I) and C22H18N2O2 (II) have been determined by single-crystal X-ray diffraction. These two compounds crystallise in the monoclinic space groups, P 2 1 c and C 2 c . The structures have been determined by direct methods and refined to R, 0.041 (I) and 0.070 (II). The benzimidazole ring systems in (I) and (II) are planar. The phenyl rings attached to N1 and C2 in (I) are planar and make dihedral angles of 88.5(1) and 103.8(1)° with the benzimidazole ring systems. Corresponding angles in (II) are 95.0(2) and 105.1(2)°.

Synthesis, antioxidant and radical scavenging activities of novel benzimidazoles.

The synthesis and antioxidant evaluation of some novel benzimidazole derivatives (10–24) are described. Antioxidant properties of the compounds were investigated employing various in vitro systems viz., microsomal NADPH-dependent inhibition of lipid peroxidation (LP), interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and scavenging of superoxide anion radical. Compounds 12 and 13 showed very good antioxidant capacity and were 17–18 -fold more potent than BHT (IC50 2.3 × 10− 4M) with 1.3 × 10− 5M and 1.2 × 10− 5M IC50 values, respectively, by interaction of the stable DPPH free radical.

Synthesis and antimicrobial evaluation of some new substituted purine derivatives.

A series of 8,9-disubstituted adenines (4, 5, 8), 6-substituted aminopurines (10-13) and 9-(p-fluorobenzyl/cyclopentyl)-6-substituted aminopurines (16, 17, 19-30) have been prepared and the antimicrobial activities of these compounds against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA, standard and clinical isolate), Bacillus subtilis, Escherichia coli and Candida albicans were evaluated. 6-[(N-phenylaminoethyl)amino]-9H-purine (12) which has no substitution at N-9 position and 9-cyclopentyl-6-[(4-fluorobenzyl)amino]-9H-purine (24) exhibited excellent activity against C. albicans with MIC 3.12 microg/mL. These compounds displayed better antifungal activity than that of standard oxiconazole. Furthermore, compound 22 carrying 4-chlorobenzylamino group at the 6-position of the purine moiety exhibited comparable antibacterial activity with that of the standard ciprofloxacin against both of the drug-resistant bacteria (MRSA, standard and clinical isolate).

Crystal structure of hydrazone form of 1-butyl-3-cyano-6-hydroxy-4-methyl-5-(2-nitrothiazolylazo)-2(1H)-pyridone

Abstract The structural results clearly indicate that 1-butyl-3-cyano-6-hydroxy-4-methyl-5-(2-thiazolylazo)-2(1H)-pyridone, (C 14 H 15 N 5 O 2 S), exists primarily as the hydrazone tautomer in the solid state. The molecule is nearly planar not regarding the butyl group. Some of the bond lengths and angles are distorted due to π-electron delocalization and strain. A strong intramolecular N-H … O hydrogen bond was found [N…O =2.53(1)A]. The crystallographic parameters are as follows: triclinic P1, a=5.972(4)A, b=7.732(5)A, c=17.348(9)A, α=85.62(5) 0 , β=79.24(6) 0 , γ=78.41(7) 0 , V=770.4(9)A 3 , Z=2, D c =1.37 g cm −3 , μ(MoK α )=2.1 cm −1 , R=0.045, G.O.F.=1.78.

Synthesis of novel substituted purine derivatives and identification of the cell death mechanism.

Novel 9-(substituted amino/piperazinoethyl)adenines (4-12), 6-(substituted piperazino/amino)purines (15-27), 9-(p-toluenesulfonyl/cyclopentyl/ethoxycarbonylmethyl)-6-(substituted amino/piperazino)purines (28-34, 36, 37, 38-41) were synthesized and evaluated initially for their cytotoxic activities on liver Huh7, breast T47D and colon HCT116 carcinoma cells. N(6)-(4-Trifluoromethylphenyl)piperazine derivative (17) and its 9-(p-toluene-sulfonyl)/9-cyclopentyl analogues (28, 36) had promising cytotoxic activities. Compounds 17, 28 and 36 were further analysed for their cytotoxicity in a panel of a liver cancer cell lines. The compound 36 had better cytotoxic activities (IC50 ≤ 1 μM) than the nucleobase 5-FU and nucleosides fludarabine, cladribine, and pentostatine on Huh7 cells. Cytotoxicity induced by 36 was later identified as senescence associated cell death by SA-β-Gal assay.

Design and One-Pot and Microwave-Assisted Synthesis of 2-Amino/5-Aryl-1,3,4-oxadiazoles Bearing a Benzimidazole Moiety as Antioxidants

In this study, two new series of 2‐amino‐1,3,4‐oxadiazoles and 5‐aryl‐1,3,4‐oxadiazoles carrying a benzimidazole moiety were synthesized. The antioxidant properties of these compounds were investigated in vitro by the determination of the microsomal NADPH‐dependent inhibition of lipid peroxidation levels (LP), the microsomal ethoxyresorufin O‐deethylase activity (EROD), and DPPH radical scavenger effects. Among the tested compounds, 2‐[(2‐(4‐chlorophenyl)‐1H‐benzo[d]imidazole‐1‐yl)methyl]‐5‐(4‐fluorophenyl)‐1,3,4‐oxadiazole (9) was found to be the most active compound in all three in vitro systems.