Hülya Karaca

Antimicrobial activity and a SAR study of some novel benzimidazole derivatives bearing hydrazone moiety

In this study 12 novel benzimidazole compounds bearing hydrazone moiety were synthesized in order to investigate their possible antibacterial and antifungal activity. Structures of the synthesized compounds were elucidated by spectral data. Six different gram-negative and four different gram-positive bacterial strains were used in antibacterial activity tests. Antifungal activity tests were also performed against three different fungal strains. Most of the test compounds found to be significantly effective against Proteus vulgaris, Staphylococcus typhimurium, Klebsiella pneumoniae and Pseudomonas aeruginosa gram-negative bacterial strains. A structure-activity relationship (SAR) study including some electronic parameters was carried out and a connection between antibacterial activity and electronic properties of the target compounds was determined. Toxicity of the most effective compounds was established by performing Brine-Shrimp lethality assay.

Antimicrobial Activity of a New Combination System of Benzimidazole and Various Azoles

In the present study a new series of benzimidazole derivatives bearing various (benz)azolylthio moieties were synthesized so as to investigate their antimicrobial activity. Structures of the target compounds (5a–5i) were confirmed by their IR, 1H‐NMR, ES‐MS spectral data, and elemental analyses. The synthesized compounds (5a–5i) exhibited poor activity against bacterial strains. On the other hand, antifungal activity of the compounds against Candida species was very significant. Brine‐Shrimp lethality assay was performed for determination of toxicity of the compounds. Compounds 5a, 5c, and 5d were evaluated as non‐toxic in addition to their attractive antifungal activity. However, the other compounds (5b, e–i) in the series showed toxicity to different extents.

Antimicrobial activity of a new series of benzimidazole derivatives

Due to antimicrobial importance of benzimidazoles and hydrazones, some benzimidazolehydrazone compounds were synthesized to screen their antimicrobial activity. Structures of the synthesized compounds were elucidated by 1H-NMR, IR and ES-MS spectral data and elemental analysis. The synthesized benzimidazole-hydrazones exhibited very weak antibacterial activity. However, antifungal activity of some of the synthesized compounds was very notable against Candida species. The compounds displaying important antifungal activity were screened for their toxicity. Artemia salina 96-well assay was used to determine cytotoxicity of the compounds. Tested compounds exhibited toxicity to different extents (LD50 = 126.33−368.72 μg/mL). Nevertheless, determination of 3–14 folds higher LD50 than minimum inhibitory concentration is a significant finding, which demonstrates that the compounds display antifungal activity at non-toxic concentration.

Synthesis and antimicrobial activity of some new hydrazone-bridged thiazole-pyrrole derivatives

In this work, we synthesized fourteen different compounds which contain hydrazone bridged thiazole and pyrrole rings. For this purpose, pyrrole-2-carboxaldehydes were reacted directly with thiosemicarbazide in ethanol and then obtained thiosemicarbazones were condensed with α-bromoacetophenone derivatives (Hantzsch reaction) to give 1-substituted pyrrole-2-carboxaldehyde [4-(4-substituted phenyl)-1,3-thiazol-2-yl] hydrazones. The structures of the obtained compounds were elucidated by using IR, 1H-NMR and FAB+-MS spectral data and elemental analyses results. All of the compounds were screened for their antibacterial and antifungal activities against twelve different microorganisms by using microbroth dilution method. Ketoconazole and chloramphenicol were used as standard drugs. All of the compounds showed good activity against Staphylococcus aureus and Enterococcus faecalis.

Antimicrobial and anticancer effects of some 2-(substitutedsulfanyl)-N-(5-methyl-isoxazol-3-yl)acetamide derivatives

In the present study, some isoxazole-(benz)azole derivatives (3a–3j) were synthesized by considering antimicrobial and anticancer potencies of azole compounds. Chemical structures of obtained compounds (3a–3j) were confirmed by the data of spectral and elemental analyses. Anticancer activity evaluation was performed at two steps. Initially, cytotoxic effects of the compounds (3a–3j) on HT-29 (colon carcinoma) and C-6 (melanoma) cell lines were determined by MTT assay. Secondly, the compounds 3g–3i, which indicated significant cytotoxicity were selected and analysed for their inhibitory activity on DNA synthesis of carcinogenic cells. The compounds 3g and 3h showed notable DNA synthesis inhibition on both cancer cell lines. Antibacterial and antifungal activities of the synthesized compounds (3a–3j) were also examined. All of the compounds exhibited very poor antibacterial activity against gram negative and gram positive bacterial strains, whereas antifungal activity of the compounds 3a–3f was equal to that of Ketoconazole.

Synthesis and biological evaluation of pyrazoline derivatives bearing an indole moiety as new antimicrobial agents.

1‐(p‐Methylphenyl)‐3,5‐diaryl‐2‐pyrazoline derivatives (2a–f) were synthesized via the treatment of 1‐(1H‐indol‐3‐yl)‐3‐aryl‐2‐propen‐1‐ones (1a–f) with p‐methylphenylhydrazine hydrochloride in hot acetic acid. The structures of these compounds were elucidated by IR, 1H NMR, and mass spectral data and elemental analysis. These compounds were investigated for their antimicrobial activity. Brine‐Shrimp lethality assay was carried out to determine the toxicity of the compounds. Compound 2e, which is the pyrazoline derivative bearing the 2,5‐dichlorophenyl moiety, can be identified as the most promising agent against Klebsiella pneumoniae (ATCC 13883) and Candida glabrata (ATCC 36583) due to its inhibitory effects on K. pneumoniae and C. glabrata with a MIC value of 100 µg/mL as a non‐toxic agent (LC50 > 1000 µg/mL).