Gülgün Ayhan-Kılcıgil

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 Antioxidant Properties of Novel Benzimidazole Derivatives

Some novel benzimidazole derivatives carrying thiosemicarbazide and triazole moieties at the N1 position were synthesized and their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels determined by measuring the formation of 2-thiobarbituric acid reactive substance. The free radical scavenging properties of the compounds were also examined in vitro by determining the capacity to scavenge superoxide anion formation and the interaction with the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The compounds showed a significant effect in the above tests except to scavenge superoxide anion formation.

Synthesis, antifungal and antioxidant screening of some novel benzimidazole derivatives

Some novel benzimidazole derivatives were synthesized and their in vitro effects on rat liver microsomal NADPH-dependent lipid peroxidation (LP) level, ethoxyresorufin O-deethylase (EROD) and antifungal activities were determined. A significant decrease in male rat liver microsomal LP level was noted by compounds 4c (52%), 4e (58%) and 4h (43%) at 10− 3 M concentration. Compounds 4c (100.0%), 4h (100.0%), 5c (98.0%) and 5h (100.0%) inhibited the microsomal ethoxyresorufin O-deethylase (EROD) enzyme activity better than that of the specific inhibitor caffeine (85%). Among these compounds, only compounds 4b and 4h exhibited moderate activity against C.albicans whereas the others had weak effects.

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 activity of some new benzimidazole carboxylates and carboxamides

Some benzimidazole carboxylates and carboxamides were synthesized and evaluated for their antimicrobial activities against Staphylococcus aureus, Escherichia coli and Candida albicans. Among the investigated compounds 2d exhibited best activity against C. albicans.

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.

Synthesis and Evaluation of Antioxidant Properties of Novel 2‐[2‐(4‐chlorophenyl) benzimidazole‐1‐yl]‐N‐(2‐arylmethylene amino) acetamides and 2‐[2‐(4‐chlorophenyl) benzimidazole‐1‐yl]‐N‐(4‐oxo‐2‐aryl‐thiazolidine‐3‐yl) acetamides‐I

Our approach was to synthesize and examine the antioxidant properties of some new 2‐[2‐(4‐chlorophenyl)benzimidazole‐1‐yl]‐N‐(2‐arylmethyleneamino) acetamide (1–18) and 2‐[2‐(4‐chlorophenyl)benzimidazole‐1‐yl]‐N‐(4‐oxo‐2‐aryl‐thiazolidine‐3‐yl)acetamide (1t–18t) derivatives. Their in vitro effects on rat liver microsomal NADPH‐dependent lipid peroxidation levels (LP assay) and microsomal ethoxyresorufin O‐deethylase activities (EROD assay) were determined. The free radical scavenging properties of the compounds were also examined in vitro determining the interaction of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical. The compounds showed significant effects in the above tests.

Chromatographic Separation and Identification of Sildenafil and Yohimbine Analogues Illegally Added in Herbal Supplements

Herbal medicines are major source of aphrodisiacs and have been used worldwide for thousands of years by different cultures and civilizations. Recently, consumption of dietary supplements has been becoming more popular around the world. Unfortunately, the adulteration of dietary supplements with undeclared synthetic chemical compounds is steadily increasing according to the literature. Some herbal products advertised as “all natural” have in contrast been found to contain synthetic PDE-5 inhibitors. There are currently three PDE5 inhibitors Sildenafil (Langtry & Markham, 1999) (Viagra; Pfizer, New York, US), Tadalafil (Meuleman, 2003) (Cialis; Eli Lilly, Indianapolis, US), and Vardenafil (Keating & Scott, 2003) (Levitra; Bayer Pharmaceuticals Co, Wuppertal, Germany), approved worldwide for the treatment of male erectile dysfunction, further two agents Udenafil (Salem et al., 2006) (Zydena; Dong-A PharmTech Co, Korean), Mirodenafil (Jung, 2008) (Mvix, Life Science R&D Center of SK chemical, Beijing, Tianjin, Shanghai) were licensed only in Korea. They produce vascular smooth muscle relaxation, promote penile blood flow, and hence, induce erection. These kinds of commercially available herbal aphrodisiac products have been spiked with the above-mentioned legal drugs, but also with their analogues, which have not been subjected to formal pharmacokinetic or other pharmacological testing in either humans or animals.

Crystal structures and intermolecular interactions of two novel antioxidant triazolyl-benzimidazole compounds

The crystal structures of 5-(2-(p-chlorophenylbenzimidazol-1-yl-methyl)-4-(3-fluorophenyl)-2,4-dihydro-[1,2,4]-triazole-3-thione (G6C) and 5-(2-(p-chlorophenylbenzimidazol-1-yl-methyl)-4-(2-methylphenyl)-2,4-dihydro-[1,2,4]-triazole-3-thione (G4C) have been determined by single-crystal X-ray diffraction. Benzimidazole ring systems in both molecules are planar. The triazole part is almost perpendicular to the phenyl and the benzimidazole parts of the molecules in order to avoid steric interactions between the rings. The crystal structures are stabilized by intermolecular hydrogen bonds between the amino group of the triazole and the nitrogen atom of benzimidazole of a neighboring molecule.

Identification of a Novel Series of N-Phenyl-5-[(2-phenylbenzimidazol-1-yl)methyl]-1,3,4-oxadiazol-2-amines as Potent Antioxidants and Radical Scavengers

In this study, some novel 5‐[[2‐(phenyl/p‐chlorophenyl)‐benzimidazol‐1‐yl]‐methyl]‐N‐substituted phenyl‐1,3,4‐oxadiazol‐2‐amine derivatives (28–45) with an oxadiazole ring were synthesized. The antioxidant properties and radical scavenging activities of the compounds were investigated employing various in vitro systems: hepatic microsomal NADPH‐dependent inhibition of lipid peroxidation levels, scavenging of DPPH free radicals, and inhibition of microsomal ethoxyresorufin O‐deethylase activity (EROD). Compounds 34 and 41 were found to be good scavengers of DPPH radicals (76% and 84%) when compared to BHT (90%). Almost all of the compounds examined were found to possess a good inhibitor effect on the microsomal EROD activity. Moreover, 32 and 41 were more active analogs (97% and 98%) on the microsomal EROD activity than caffeine (85%).