Melike Ekizoğlu

Synthesis and antimicrobial activity of some 1,3,4-oxadiazole derivatives

Six new 5-(1-/2-naphthyloxymethyl)-1,3,4-oxadiazole-2(3H)-thione, 2-amino-5-(1-/2-naphthyloxymethyl)-1,3,4-oxadiazole, 5-(1-/2-naphthyloxymethyl)-1,3,4-oxadiazole-2(3H)-one derivatives have been synthesized from 1-and/or 2-naphthol. The structures of the compounds were confirmed by IR and 1H NMR spectral data and microanalysis. The antimicrobial properties of the compounds were investigated against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, Candida albicans, C. krusei and C. parapsilosis using microbroth dilution method. 2-Amino-5-(2-naphthyloxymethyl)-1,3,4-oxadiazole and 5-(2-naphthyloxymethyl)-1,3,4-oxadiazole-2(3H)-one show significantly (32 microg/ml), compounds 5-(1-/2-naphthyloxymethyl)-1,3,4-oxadiazole-2(3H)-thione, 2-amino-5-(1-naphthyloxymethyl)-1,3,4-oxadiazole and 5-(1-naphthyloxymethyl)-1,3,4-oxadiazole-2(3H)-one moderately (64 microg/ml) active against C. krusei. All the compounds were active against S. aureus, E. coli, P. aeruginosa, C. albicans, and C. parapsilosis at 64-256 microg/ml concentration.

Monitoring the perturbation of soil and groundwater microbial communities due to pig production activities

ABSTRACT This study aimed to determine if biotic contaminants originating from pig production farms are disseminated into soil and groundwater microbial communities. A spatial and temporal sampling of soil and groundwater in proximity to pig production farms was conducted, and quantitative PCR (Q-PCR) was utilized to determine the abundances of tetracycline resistance genes (i.e., tetQ and tetZ) and integrase genes (i.e., intI1 and intI2). We observed that the abundances of tetZ, tetQ, intI1, and intI2 in the soils increased at least 6-fold after manure application, and their abundances remained elevated above the background for up to 16 months. Q-PCR further determined total abundances of up to 5.88 × 109 copies/ng DNA for tetZ, tetQ, intI1, and intI2 in some of the groundwater wells that were situated next to the manure lagoon and in the facility well used to supply water for one of the farms. We further utilized 16S rRNA-based pyrosequencing to assess the microbial communities, and our comparative analyses suggest that most of the soil samples collected before and after manure application did not change significantly, sharing a high Bray-Curtis similarity of 78.5%. In contrast, an increase in Bacteroidetes and sulfur-oxidizing bacterial populations was observed in the groundwaters collected from lagoon-associated groundwater wells. Genera associated with opportunistic human and animal pathogens, such as Acinetobacter, Arcobacter, Yersinia, and Coxiella, were detected in some of the manure-treated soils and affected groundwater wells. Feces-associated bacteria such as Streptococcus, Erysipelothrix, and Bacteroides were detected in the manure, soil, and groundwater ecosystems, suggesting a perturbation of the soil and groundwater environments by invader species from pig production activities.

An investigation of the bactericidal effect of certain antiseptics and disinfectants on some hospital isolates of gram-negative bacteria.

The effect of widely used antiseptics and disinfectants on some hospital isolates of gram-negative bacteria was assessed by the quantitative suspension test Chlorhexidine gluconate (4%), savlon (1:100), and 5.25% sodium hypochlorite were tested. Savlon and chlorhexidine gluconate were effective at in-use concentrations and sodium hypochlorite was effective at 1:50 dilution.

Synthesis of 3-(4-substituted benzoylmethyl)-2-benzoxazolinones and screening antimicrobial activities.

A number of 3-(4-substituted benzoylmethyl)-2-benzoxazolinones have been synthesized by reacting with 2-benzoxazolinone and 4-substituted phenacyl bromide in ethanol. Their chemical structures were confirmed by IR, 1H NMR and elemental analysis. For screening antimicrobial activity, minimum inhibitory concentration (MIC) values were determined against two Gram positive, one Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus) and three yeast-like the fungi (Candida albicans, Candida krusei, Candida parapsilosis).

The effect of gamma radiation sterilization on dental biomaterials

Biomaterials are used in the field of bone and tissue engineering, orthopaedics and dentistry. Dental biomaterials including commercially available biodegradable materials act as physical barriers to help quicker healing while stimulating the regeneration of periodontal tissues, which is defined as Guided Tissue Regeneration (GTR). Amongst natural and synthetic biomaterials, collagen and aliphatic polyesters, such as polylactic acid (PLA) and poly (lactic-co-glycolic) acid (PLGA) are the most frequently used biomaterials for regenerative therapies due to their excellent biocompatibility and biodegradability. Due to their resorption in the body and interaction with biological systems, the GTR membranes must be sterile and pyrogen free. The sterility and apyrogenicity of the GTR membranes before human use is a regulatory requirement, however the sterilization of biomaterials is challenging due to the physicochemical changes and toxic residues with the commonly used sterilization techniques. The purpose of the present study was to evaluate the effect of gamma radiation and ethylene oxide sterilization on dental biomaterials with analytical, microbiological and histological examinations. PLGA-based GTR dental biomaterial is selected as the most gamma stable membrane according to the FTIR, DSC, TGA, and SEM results. This dental membrane was sterilized with ethylene oxide (EtO) and the effect of sterilization method on PLGA-based membrane was also investigated. Animal experiments were carried out to evaluate the regenerative properties and inflammatory responses of gamma and EtO sterilized PLGA-based GTR membrane after implantation. Histological examinations showed that resorption and bone formation of gamma sterilized PLGA-based GTR membrane was completed in 12 weeks without any inflammatory response; while only 60.095 ± 2.019% of new bone formation was observed with EtO sterilized one. Gamma sterilized PLGA membrane had significantly faster (P < 0.05) resorption and bone formation in comparison with EtO sterilization. In conclusion, the PLGA-based biomaterials could be sterilized safely and time- and cost-effectively with validated radiation doses for the tissue engineering applications.

Nano drug delivery systems and gamma radiation sterilization

Abstract In recent years, drug delivery systems such as liposomes and microparticles have been used in clinic for the treatment of different diseases and from a regulatory point of view, a parenterally applied drug and drug delivery systems must be sterile and pyrogen free. Radiation sterilization is a method recognized by pharmacopoeias to achieve sterility criteria of parenterals. It has the ability to kill microorganisms in therapeutic products. The ability of, however, irradiation might also affect the performance of drug delivery systems. One of the most critical points is irradiation dose, because certain undesirable chemical and physical changes may accompany with the irradiation, especially with the traditionally applied dose of 25 kGy. Its ionizing property may cause fragmentation of covalent bond. The care must be paid to the applied dose. In this research, the effects of gamma irradiation on different drug delivery systems such as chitosan microparticles, liposomes, niosomes and sphingosomes were investigated. According to the experimental data, it can be concluded that gamma irradiation can be a suitable sterilization technique for liposome, niosome and sphingosome dispersions. When all irradiated drug carrier systems were taken into consideration, chitosan glutamate microparticles were found as the most radioresistant drug delivery system among the others.

Design and evaluation of gamma-sterilized vancomycin hydrochloride-loaded poly(ɛ-caprolactone) microspheres for the treatment of biofilm-based medical device-related osteomyelitis.

Abstract Context: There is a great necessity to find and use accomplished terminal sterilization technique for industrial manufacturing, research and development studies. Gamma (γ)-sterilization has been commonly employed for wide range of products as indicated by the pharmacopoeias. However, carefully examination should be performed prior to administration since γ-radiation can cause changes in drug and polymer excipients. No information is available in literature about γ-sterilization effects on vancomycin HCl-loaded poly (ɛ-caprolactone) (PCL) microspheres. Objective: Formulations were developed using a different preparation approach for the treatment of medical device-related osteomyelitis, and γ-sterilization effects on the physicochemical characterization of the formulations were examined. Methods: Water-in-oil-in-water (w/o/w) emulsion technique using polyvinyl alcohol (PVA) in inner and outer phase was applied to prepare formulations. Physicochemical properties of the formulations were investigated before and after γ-sterilization and the antibacterial activity against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) were measured. Results: The particle size of the nonsterilized formulations were between 58 and 134 μm. 60% or 20% of vancomycin HCl were released from 42.500 Mn or 70.000–90.000 Mn PCL microspheres, respectively, in 24 h. No difference was observed in the particle size, drug-loading efficiency, morphology, in vitro release and antimicrobial activity of the formulations after γ-sterilization (p > 0.05).

Infectious Diseases of the Brain

Abstract Brain or central nervous system infections are likely to be caused by bacterial, viral, fungal, or parasitic infections. Nowadays, although there are advanced antimicrobial treatments, these infections still cause a high level of mortality and morbidity. The main problems that are encountered during treatments are the inability of antibiotics to surpass the blood–brain barrier and the blood–cerobrospinal fluid barrier, as well as the resistance developed against antibiotics. To this end, nanotechnological drug targeting methods are being used to overcome the problems in the treatment of infectious diseases of the brain. This chapter summarizes brain infections and their treatments, the main obstacles during treatments, and recently developed antimicrobial agents that can be targeted to the infection site.

CCDC 852350: Experimental Crystal Structure Determination

Related Article: Umut Salgin Goksen, Yelda Bingol Alpaslan, Nesrin Gokhan Kelekci, Şamil Isik, Melike Ekizoglu|2013|J.Mol.Struct.|1039|71|doi:10.1016/j.molstruc.2013.01.066