Önder İdil

Synthesis of some novel purine derivatives incorporating tetrazole ring and investigation of their antimicrobial activity and DNA interactions

Abstract This work describes a novel purine derivatives incorporating tetrazole ring for biological applications. Initially, (6-aminopurin-9-yl)alkanenitrile compounds were synthesized. Then, 9-((1H-tetrazol-5-yl)alkyl)-9H-purin-6-amine compounds were synthesized via the addition of sodium azide to nitrile group. These novel purine analogues incorporating tetrazole ring were characterized by Fourier transform infrared, nuclear magnetic resonance and mass spectroscopic techniques. All the synthesized compounds were screened for their antibacterial activities against Gram-positive and Gram-negative bacteria and for their antifungal activities against yeast strains. The effect of the compounds on pBR322 plasmid DNA was studied by gel electrophoretic mobility measurements. The antibacterial activities and plasmid DNA interaction studies suggest that purine derivatives incorporating tetrazole ring cause DNA damages, and higher antibacterial activities than other derivatives.

The role of oxidative stress genes and effect of pH on methylene blue sensitized photooxidation of Escherichia coli.

In this study, the survival time of wild type E. coli W3110 and 11 mutants was analysed with a plate count method in methylene blue added or control groups under daylight fluoroscence illumination (4950 lux) at different pH values (5.0, 6.0, 7.0, and 8.0) in phosphate buffer. As a result, while the number of bacteria did not decrease under photooxidative stress at pH 5.0 and 6.0 during a 6-hour incubation, the wild type and all mutants decreased more than 2 log. at pH 8.0, and approximately one log. at pH 7.0. It was determined that a 2 log decrease in wild type E. coli takes 3.7 h according to t99 value at pH 8, these values were 2.39 h in the katE mutant, 2.64 h in the soxR mutant, 2.67 h in the oxyR mutant, 2.71 h in the sodB mutant, 3 h in the btuE mutant, 3.38 h in the zwf mutant and 3.40 h in the soxS mutant, respectively (p < 0.05). The roles of these genes were proved with complement tests. Finally, it is found that the effectiveness of photooxidative stress is in direct relation with pH, and the katE, soxR, oxyR, sodB, btuE, zwf, and soxS genes are important for the protection against this stress.

Evaluation of phytochemical content, antioxidant, antimicrobial activity and DNA cleavage effect of endemic Linaria corifolia Desf. (Plantaginaceae)

Abstract The aim of this study is to isolate Linaria corifolia Desf. (Plantaginaceae) and identify new apigenine derivatives 6,3′-dimethoxyapigenin-7-O-[(rhamnosyl)-(1–2)-6″-acetyl glucoside]. Moreover, we analyzed biological activity and flavonoids by using HPLC methods from extracts. The L. corifolia Desf. samples were collected in Black Sea Region of Turkey. Ethanol (EtOH), ethyl acetate (EtOAc) and dichloromethane (DCM) extracts in aerial and under solid parts of plant were evaluated for antioxidant, antimicrobial activity and effect of DNA cleavage. Quercetin, gallic acid and catechin as flavonoids were identified in EtOH, EtOAc, DCM extracts.