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Dive into the research topics where Tijen Önkol is active.

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Featured researches published by Tijen Önkol.


Journal of Enzyme Inhibition and Medicinal Chemistry | 2008

Synthesis and antimicrobial activity of new 1,2,4-triazole and 1,3,4-thiadiazole derivatives

Tijen Önkol; Deniz S. Dogruer; Leyla Uzun; Selcen Adak; Semiha Özkan; M. Fethi Şahin

In this study, new 3-[(1(2H)-phthalazinone-2-yl(methyl/ethyl]-4-aryl-1,2,4-triazole-5-thione and 2-[[1(2H)-phthalazinone-2-yl]methyl/ethyl]-5-arylamino-1,3,4-thiadiazole derivatives were synthesized. Antimicrobial properties of the title compounds were investigated against two Gram (+) bacteria (S. aureus, B. subtilis), two Gram ( − ) bacteria (P. aeruginosa, E. coli) and two yeast-like fungi (C. albicans and C. parapsilosis) using the broth microdilution method. Generally the compounds were found to be active against B. subtilis and the fungi. Derivatives carrying a 1,3,4-thiadiazole ring generally showed higher antimicrobial activity against B. subtilis and the fungi when compared to other synthesized compounds.


Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2009

Experimental and density functional theory and ab initio Hartree-Fock study on the vibrational spectra of 5-chloro-6-(4-chlorobenzoyl)-2-benzothiazolinone molecule.

Erol Taşal; İsa Sıdır; Yadigar Gülseven; Cemil Öğretir; Tijen Önkol

The vibrational frequencies and infrared intensities of 5-chloro-6-(4-chlorobenzoyl)-2-benzothiazolinone (abbreviated as CCB) molecule in the ground state were calculated by HF and DFT (B3LYP and BLYP) methods using different basis sets to elucidate the molecular structure. The solid-state FT-IR spectrum was measured and compared with calculated values. CCB was found to have two different stable conformations. The dihedral angles alpha and beta (i.e. C9-C8-C12-C18 and C8-C12-C18-C17, respectively) were computed as -59.6 degrees and -14.5 degrees for the most stable conformer. The comparison of the theoretical and experimental geometries of the title compound indicated that the X-ray parameters fairly well agree with the theoretically obtained values for the most stable conformer. The calculated vibrational frequencies are also in good agreement with the experimental results.


Archiv Der Pharmazie | 2000

Synthesis and antinociceptive activity of (5-chloro-2-benzothiazolinon-3-yl)acetamide derivatives.

Tijen Önkol; Deniz S. Dogruer; Shigeru Ito; Mustafa Fethi Sahin

The synthesis of (5‐chloro‐2‐benzothiazolinon‐3‐yl)acetamide derivatives is reported. The structure of these compounds is supported by their IR and 1H‐NMR spectra. The compounds were tested for antinociceptive activity.


Archives of Pharmacal Research | 2004

Synthesis and antinociceptive activity of (5-chloro-2(3H)-benzoxazolon-3-yl) propanamide derivatives

Tijen Önkol; M. Fethi Sahin; Engin Yildirim; Kevser Erol; Shigero Ito

In this study, (5-chloro-2(3H)-benzoxazolon-3-yl)propanamide derivatives were synthesized. The chemical structures of the compounds were elucidated by their IR and1H-NMR spectral data and microanalysis. The compounds were tested for antinociceptive activity by using the tail clip, tail flick, hot plate, and writhing methods. The varying levels of antinociceptive activity of the compounds were compared with those of dipyrone and aspirin. Among these compounds, compound5e, 5g, and5h have been found to be significantly more active than the others and the standards in all the tests.


Medicinal Chemistry Research | 2010

Amide derivatives of [6-acyl-2-benzothiazolinon-3-yl] acetic acids as potential analgesic and anti-inflammatory compounds

Tijen Önkol; Erden Banoglu; Yasemin Dündar; Esra Küpeli; M. Fethi Şahin

In this study, we investigated the analgesic and anti-inflammatory activities of [6-acyl-2-benzothiazolinon-3-yl]acetic acids by the derivatization of the carboxylate moiety into amides. We have tested the analgesic and anti-inflammatory activities of the synthesized compounds in vivo by using p-benzoquinone-induced writhing test and carrageenan-induced hind paw edema model, respectively. Compounds 4h, 4i, 4n, and 4o showed comparable analgesic and anti-inflammatory activities to the references without gastric lesions in the tested animals. In addition, all compounds also tested for their inhibitory activity against cyclooxygenase (COX)-1, COX-2 and 5-lipoxygenase (LOX), but no significant inhibition was observed under assayed conditions.


Drug Research | 2012

Microwave-Assisted Synthesis of 1,3-Benzothiazol-2(3H)-one Derivatives and Analysis of Their Antinociceptive Activity

Tijen Önkol; Yasemin Dündar; E. Yıldırım; Kevser Erol; Mustafa Fethi Şahin

A rapid and efficient method was developed for synthesis of 6-acyl-1,3-benzothiazol-2(3H)-one derivatives under microwave irradiation (MWI) conditions. The reaction times were shortened compared to conventional heating. Additionally, we synthesized acetic acid and acetamide derivatives of 1,3-benzothiazol-2(3H)-one, 6-acyl-1,3-benzothiazol-2(3H)-one, 5-chloro-1,3-benzothiazol-2(3H)-one and 6-acyl-5-chloro-1,3-benzothiazol-2(3H)-one with the microwave-assisted method and analyzed their antinociceptive activity with the tail flick, tail clip, hot plate and writhing tests. Among the synthesized compounds, 3-[2-(4-ethylpiperazin-1-yl)-2-oxoethyl]-1,3-benzothiazol-2(3H)-one (6a), 5-chloro-3-{2-oxo-2-[4-(propan-2-yl) piperazin-1-yl]ethyl}-1,3-benzothiazol-2(3H)-one (7e) and 3-[2-(4-butylpiperazin-1-yl)-2-oxoethyl]-5-chloro-1,3-benzothiazol-2(3H)-one (8e) showed significant antinociceptive activity in the tail clip, tail flick, hot plate and writhing tests. Supporting Information available online at http://www.thieme-connect.de/ejournals/toc/amf.


Drug Research | 2014

The Effects of p-nonylphenol on the Myometrial Contractile Activity.

F. Yasemin Özatik; Bilgin Kaygisiz; Kevser Erol; Yasemin Dündar; Tijen Önkol; M. F. Şahin

We aimed to investigate the effects and mechanisms of action of p-nonylphenol(p-NP) on uterine contractility in rats. The uterine tissues of female Sprague Dawley rats in diestrus were bathed in isolated organ bath. The effects of vehicle alone (0.1% ethanol), the positive control 17-β-E2 (10(-5) M) and p-NP (10(-9) M, 10(-8) M, 10(-7) M, 10(-6) M) on spontaneous and KCl-induced uterine contractility of rats were studied. Also, the effects of p-NP in combination with actinomycin D (10(-5) M) (gene transcription inhibitor), cycloheximide (10(-4) M) (protein synthesis inhibitor), fulvestrant (10(-6) M) (pure estrogen receptor antagonist), 2-hydroxy-5-nonanoylbenzamide (10(-3) M) (compound 1b, anti-uterotrophic compound) on spontaneous uterine contractions, and with propranolol (20 µM) (β-adrenoceptor antagonist) and noradrenaline (5 µM) on KCl (40 mM) induced contractions were investigated. p-NP exhibited a concentration-dependent inhibition on spontaneous uterine contractions. There was no significant difference between the highest p-NP concentration (10(-6) M) and the positive control 17-β-E2 in terms of % inhibition (p>0.05). The inhibitory effect of p-NP (10(-6) M) on spontaneous contractions was blocked by actinomycin D (p<0.001), cycloheximide (p<0.001), fulvestrant (p<0.001) and compound 1b (p<0.001). 17-β-E2 (10(-5) M) exerted a higher inhibition % on KCl induced contractions than p-NP (10(-6) M). The relaxant effect of p-NP on KCl-induced uterine contractions was inhibited by noradrenaline (p<0.05) but not by propranolol (p>0.05). We suggest that p-NP inhibited uterine contractions similar as 17-β-E2 and genomic pathways are involved and β-adrenoceptors might modulate the activity of p-NP. In addition, compound 1b showed an uterotonic activity and reversed the effect of p-NP.


Molecular Crystals and Liquid Crystals | 2013

Synthesis and Crystal Structure of 3-Amino-1-(5-Chloro-2-Hydroxyphenyl)Imidazolidine-2,4-Dione

Abdullah Aydın; Tijen Önkol; Mehmet Akkurt; Orhan Büyükgüngör; M. Fethi Şahin

The present study describes the synthesis, spectral data, and single crystal X-ray structural analysis of 3-amino-1-(5-chloro-2-hydroxyphenyl)imidazolidine-2,4-dione. X-Ray analysis revealed that the title compound did not have the anticipated structure, but had that of a different substance. This unexpected conformation generated the interest in studying the synthesis of this compound. The inspected compound, 3-amino-1-(5-chloro-2-hydroxyphenyl)imidazolidine-2,4-dione, is a pharmaceutical intermediate and is nonplanar. Its benzene and five-membered rings have a dihedral angle of 53.95(7)°. The conformation is stabilized by intermolecular O‒H … O, O‒H … N, and N‒H … O interactions and a weak C‒H … π interaction.


Acta Crystallographica Section E-structure Reports Online | 2013

3-({4-[(2-Methyl-benzyl-idene)amino]-5-sulfanyl-idene-1H-1,2,4-triazol-3-yl}meth-yl)-1,3-benzoxazol-2(3H)-one.

Abdullah Aydın; Nuray Hekimoğlu; Mehmet Akkurt; Tijen Önkol; Şölen Urlu Çiçekli; Orhan Büyükgüngör

In the title compound, C18H15N5O2S, a weak intramolecular C—H⋯S hydrogen bond results in a small dihedral angle of 3.71 (9)° between the methylphenyl and triazole rings, which, in turn, form dihedral angles of 80.09 (8) and 77.32 (8)°, respectively, with the benzoxazolone mean plane. In the crystal, N—H⋯O hydrogen bonds link molecules into chains along [001], and weak C—H⋯N hydrogen bonds and π–π interactions between the five- and six-membered rings [centroid–centroid distances = 3.5074 (11) and 3.616 (1) Å] consolidate the crystal packing.


Zeitschrift für Naturforschung C | 2012

Synthesis and in vitro biological activity of new 4,6-disubstituted 3(2H)-pyridazinone-acetohydrazide derivatives.

Murat Sukuroglu; Tijen Önkol; Fatma Kaynak Onurdağ; Gulsen Akalın; M. Fethi Şahin

New 3(2H)-pyridazinone derivatives containing a N’-benzyliden-acetohydrazide moiety at position 2 were synthesized. The structures of these newly synthesized compounds were confi rmed by IR, 1H NMR, and MS data. These compounds were tested for their antibacterial, antifungal, antimycobacterial, and cytotoxic activities. The compounds 2-[4-(4-chlorophenyl)- 6-(morpholin-4-yl)-3-oxo-(2H)-pyridazin-2-yl]-N’-(4-tert-butylbenzyliden)acetohydrazide and 2-[4-(4-chlorophenyl)-6-(morpholin-4-yl)-3-oxo-(2H)-pyridazin-2-yl]-N’-(4-chlorobenzyliden) acetohydrazide exhibited activity against both Gram-positive and Gram-negative bacteria. Most of the compounds were active against E. coli ATCC 35218. The preliminary results of this study revealed that some target compounds exhibited promising antimicrobial activities

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Kevser Erol

Eskişehir Osmangazi University

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