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Öğe Microwave-assisted and conventional synthesis of novel antimicrobial 1,2,4-triazole derivatives containing nalidixic acid skeleton(Walter De Gruyter Gmbh, 2016) Ceylan, Şule; Bayrak, Hacer; Özdemir, Serap Başoğlu; Uygun, Yıldız; Mermer, Arif; Demirbaş, Neslihan; Ülker, SerdarCarbothioamides 4a,b, obtained from nalidixic acid, were converted to the corresponding 1,3-thiazolidine derivatives 5a,b by cyclocondensation with 2-bromo-1-(4-chlorophenyl)ethanone. Treatment of 4a,b with base afforded 1,2,4-triazoles 6a,b. The synthesis of 1,3-oxazolidine 7 was performed by the reaction of compound 4a with ethyl bromoacetate. Treatment of 4a with acid produced 1,3,4-thiadiazole 8. The reaction of compounds 6a and 6b with several heterocyclic amines in the presence of formaldehyde gave the corresponding Mannich bases 9–15 containing various pharmacophore groups. Conventional and microwave-assisted methods were used for the synthesis. The effect of an acid catalyst on Mannich reactions was investigated. The structures of the newly synthesized compounds were elucidated on the basis of 1H NMR, 13C NMR, FTIR, EIMS techniques, and elemental analysis. All compounds were screened for their antimicrobial activity.Öğe Novel microwave assisted synthesis and antimicrobial activity of new quinolone-hybrids(Bentham Science Publ Ltd, 2016) Ceylan, Şule; Bayrak, Hacer; Özdemir, Serap Başoğlu; Uygun, Yıldız; Mermer, Arif; Demirbaş, Neslihan; Ülker, SerdarBackground: Carbo(thio)amid derivatives 4a, 4b were obtained starting from nalidixic acid in three steps. The acidic treatment of compound 4a generated the corresponding 1,3,4-oxadiazole (5), while the compound 4a gave 1,2,4-triazole derivatives 8a, 8b in basic media. The condensation of 4a with ethyl bromoacetate and 4-chlorophenacyl bromide afforded 1,3-oxazolidine, 6 and 1,3-thiazolidine, 7 derivatives. The synthesis of Mannich bases of 9-15 and 17-19 were achieved from the reaction of 1,2,4-triazoles, 8a, 8b and 1,3,4-oxadiazole, 16, with several heterocyclic amines that has biological activity. Methods: In this article, a series of triazole or 1,3,4-oxadiazole rings containing some novel biologically active quinolone derivatives. Conventional and microwave assisted methods were used for all syntheses. Moreover, the effect of acid catalyst on Mannich reactions was investigated. The structures of newly synthesized compounds were elucidated on the basis of H-1 NMR, C-13 NMR, FT IR, EI MS techniques and elemental analysis. All these compounds were screened in vitro for their antimicrobial activity against various gram-positive and gram-negative bacterial and fungal strains. Results: This study reports the successful synthesis of some new hybrid compounds starting from nalidixic acid. Two methods containing conventional and microwave assistance with/without catalyst were used to obtain the target compounds. Microwave assistance supplied more efficient way leading the formation of target compounds. Moreover, the effect of acid catalyst on Mannich reactions was investigated. The antimicrobial activity screening studies were also performed in the study. Conclusion: The antimicrobial screening suggests that the compounds containing norfloxacin (9a,b and 17), ciprofloxacin (10a,b and 18) or 7-aminocephalosporanic (12) acid nucleus displayed excellent antimicrobial activity. Moreover, some of them (5-7, 8-13, 15-18) displayed inhibition properties on Escherichia coli (Ec) and Mycobacterium smegmatis (Ms) better from ampicillin or streptomycin with the mic value 0.24 mu g/mL.Öğe Synthesis and antimicrobial activities of hybrid heterocyclic molecules based on 1-(4-fluorophenyl) piperazine skeleton(Bentham Science Publishers, 2017) Özdemir, Serap Başoğlu; Demirbaş, Neslihan; Cebeci, Yıldız Uygun; Bayrak, Hacer; Mermer, Arif; Demirbaş, Ahmet; Ceylan, ŞuleBackground: The amine (2) was prepared starting from 1-(4-fluorophenyl) piperazine via two steps, and then converted to the corresponding hydrazide (4). The reaction of hydrazide (4) with carbon disulfide generated the corresponding 1,3,4-oxadiazole (5), while the treatment of hydrazide with ethyl bromoacetate produced 4-oxo-2-thioxo-1,3-thiazolidine compound (6). The four-component condensation of 4 with several aldehydes gave the corresponding 4-oxo-2-thioxo-1,3-thiazolidinglycinamides (7a-f). Methods: The synthesis of 4-oxo-1,3-oxazolidines (9a, b), 1,3-oxazoles (10a, b) and 1,3,4-triazoles (11a, b) was carried out starting from compounds 8a, b. Mannich bases (12a-d and 13a-f) were prepared using three component condensation of compounds 5 and 12a, b and corresponding amines. The synthesis of 16a-c, which were considered as the new analogues of azole class antifungals, was performed starting from the compound 14a via three steps. Results and Conclusion: All the reactions were examined under traditional and microwave irradiation conditions, and optimum conditions were defined. The antimicrobial activities of the newly synthesized compounds were screened and some of the tested compounds were displayed good-moderate antibacterial activity.Öğe Synthesis and antimicrobial activity of new piperazine-based heterocyclic compounds(Walter De Gruyter Gmbh, 2017) Özdemir, Serap Başoğlu; Cebeci, Yıldız Uygun; Bayrak, Hacer; Mermer, Arif; Demirbaş, Ahmet; Karaoğlu, Sengül Alpay; Demirbaş, Neslihan; Ceylan, ŞuleThe hydrazide 5, that was obtained from -1-(4-fluorophenyl) piperazine (1), was converted to the cor-responding carbothioamides 6a-c by the reaction with alkyl(aryl) isothiocyanates. The synthesis of conazole analogs 10a-f was performed via the intermediary of triazoles 7a-c. The condensation of triazoles 7a-c with -several -heterocyclic amines in the presence of formalde-hyde afforded the corresponding N-aminoalkylated tria-zoles 11-14. The effect of different catalysts and solvents on conventional and microwave (MW)-prompted reac-tions was examined. The synthesized compounds were screened for their antimicrobial activities.Öğe Synthesis of novel Schiff bases using green chemistry techniques; antimicrobial, antioxidant, antiurease activity screening and molecular docking studies(Elsevier Science BV, 2019) Mermer, Arif; Demirbaş, Neslihan; Uslu, Harun; Demirbaş, Ahmet; Ceylan, Şule; Şirin, YakupSchiff base derivatives were synthesized in this study via conventional, microwave irradiation and ultrasound sonication methods. Optimization conditions were examined for several parameter such as solvent, reaction time and yield. After determining the optimization conditions, the compounds were synthesized by using ultrasound sonication. The structures of the synthesized compounds were examined by spectral data, and the antiurease, antioxidant and antimicrobial activities of the Schiff bases derivatives were investigated due to the imine group (-C=N-) and promising results were obtained. The enzyme inhibitory potentials of these compounds were further validated through molecular docking studies. Also, In Silico ADME prediction studies were calculated for compounds.
