Elif Loğoğlu

Synthesis and biological activity studies of furan derivatives

The organic compounds, 4-Ethyl-2,5,5-triphenyl-4,5-dihydrofuran-3-carbonitrile; 2,4,5-Triphenyl-5-propyl-4,5-dihydrofuran-3-carbonitrile; 4-Ethyl-5,5-diphenyl-2-thien-2-yl-4,5-dihydrofuran-3-carbonitrile; 2-(1-Benzofuran-2-yl-)-5-propyl-4,5-diphenyl-4,5-dihydrofuran-3-carbonitrile; 4-Ethyl-5,5-diphenyl-4,5-dihydro-2,2’-bifuran-3-carbonitrile, were synthesized and purified through column chromatography and preparative TLC. All compounds were characterized by IR, 1H, 13C NMR, MS, and microanalysis. The in vitro antibacterial and antifungal activities of these compounds were investigated against some bacteria and fungi. The antibacterial and antifungal activities were measured by using the disc-diffusion method against gram-positive bacteria, i.e., Staphylococcus aureus ATCC 25923, Staphylococcus enteritidis ATCC1376, Psydomamonas aeruginosa ATCC 29212, Bacillus subtilis RSKK 244, Bacillus megaterium gram-negative bacteria Escherichia coli ATCC 27853, Listeria monocytogenes ATCC 7644, and as fungus Micrococcus Luteus NRRLB was used. All compounds in this study showed activity against test bacteria. Their antibiogram tests showed better results than some known antibiotics.

Structure and characterization of N-(2-hydroxy-1-naphthylidene)threonine

Abstract Threonine Schiff base derived 2-hydroxy-1-naphthaldehyde and threonine has been isolated and investigated. The stoichiometry of this compound was derived from the results of elemental analyses, IR, 1 H-NMR and UV spectroscopic techniques. X-ray diffraction method was also used to obtain the single-crystal structure. The compound crystallizes in the space group P 2 1 with cell dimensions a =5.109(2), b =11.334(2), c=11.155(3) A and β =91(3)° with Z =2. The molecule has phenol-imine tautomeric form in the crystal structure. Some of bond lengths and angles found in the molecular structure are distorted due to π-electron delocalization and steric effect of naphthylidene and threonine groups.

Synthesis and evaluation of a series of aminocyanopyridines as antimicrobial agents

With the aim of developing potential antimicrobials, a series of 2-amino-3-cyanopyridines incorporating both sulfur and oxygen as part of the heteroaromatic ring (methyl thiophene, methyl furan) and fused cycloalkane groups were synthesized and characterized by FTIR, 1H-NMR, 13C-NMR, and bases of elemental analysis. All synthesized compounds were evaluated for their in vitro antibacterial and antifungal activity. Antibacterial and antifungal activities of aminocyanopyridines against Pseudomonas aeruginosa ATCC 29212, Bacillus subtilis RSKK 244, Bacillus megaterium (clinical isolate), the gram-positive bacterium Micrococcus luteus NRRLB 4375, and the fungus Candida albicans ATCC 90028 were studied. The relationship between the functional-group variation and the biological activity of the evaluated compounds is discussed.

Development of Lactose Biosensor Based on β‐Galactosidase and Glucose Oxidase Immobilized into Gelatin

In this article, we describe the preparation of a new lactose biosensor based on electrode coating with β‐galactosidase and glucose oxidase immobilized gelatin. For this purpose, β‐galactosidase and glucose oxidase enzymes were immobilized onto gelatin by crosslinking with glutaraldehyde. Properties of the immobilized β‐galactosidase and glucose oxidase enzymes electrode have been studied. The effects of glutaraldehyde concentration, temperature and pH variations and reusability were among the subjects analyzed. Lactose biosensors were subjected to continuous repeated use in order to observe reusability and shelf life; where standard lactose and milk samples were used as substrate solutions. Continuous reuse experiments showed that most of the lactose biosensors activities were retained even after the 10th use in a period of 30 days.

Antimicrobial activity studies on some piperidine and pyrrolidine substituted halogenobenzene derivatives

The in vitro antibacterial and antifungal activities of the compounds synthesised from some 1,2,3,5-tetrahalogeno benzenes in presence of sodium piperidide and sodium pyrrolidide (2,6-dipiperidino-1,4-dihalogenobenzenes; 2,6-dipyrrolidino-1,4-dibromobenzene; 2,4,6-tripyrrolidino chlorobenzene; and 1,3-dipyrrolidino benzene) were investigated. The in vitro antimicrobial activities were screened against the standard strains: Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633 as Gram positive, Yersinia enterocolitica ATCC 1501, Escherichia coli ATCC 11230 and Klebsiella pneumoniae as Gram negative, and Candida albicans as yeast-like fungus. Compounds (3, 5, 6, 7) inhibited the growth of all the test strains at MIC values of 32–512 μg/ml. None of the four compounds (1, 2, 4, 8) studied showed antimicrobial activity against any of the test strains within the MIC range 0.25–512 μg/ml.

IN VITRO ANTIMICROBIAL ACTIVITY STUDIES OF THIOETHOXY-AND THIOPHYENOXYHALOBENZENE DERIVATIVES

The in vitro antibacterial and antifungal activities of thioethoxyand thiophyenoxyhalobenzene derivatives were investigated. Thioethoxyand thiophyenoxyhalobenzenedervatives synthesized and identified by spectroscopic means IR and NMR and elemental analysis. The antibacterial and antifungal activities were measured by Minumum inhibition concentration (MIC) method against gram-positive bacteria i.e. Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633; Gram-negative bacteria as Yersinia enterocolitica ATCC 1501, Escherichia coli ATCC 11230, Klebsiella pneumoniae and fungus as Candida albicans from our strain collection. Antimicrobial activies of these compounds tended to increase with size and numerous and kinds of halogene and thiogroups substitutents.

Purification and characterization of organic solvent stable serine alkaline protease from newly isolated Bacillus circulans M34

A protease from newly isolated Bacillus circulans M34 was purified by Q-Sepharose anion exchange chromatography and Sepharose-bacitracin affinity chromatography followed by (NH4)2SO4 precipitation. The molecular mass of the purified enzyme was determined using SDS-PAGE. The optimum pH and temperature for protease activity were 11 and 50°C, respectively. The effect of various metal ions on protease activity was investigated. Alkaline protease from Bacillus circulans M34 wase activated by Zn(2+), Cu(2+) and Co(2+) up to 31%. The purified protease was found to be stable in the organic solvents, surfactants and oxidizing agent. The substrate specificity of purified protease was investigated towards different substrates. The protease was almost completely inhibited by the serine protease inhibitor phenylmethanesulfonyl fluoride. The kinetic parameters of the purified protease, maximum rate (Vmax) and Michaelis constant (Km), were determined using a Lineweaver-Burk plot.

Immobilization of Saccharomyces cerevisiae in Gelatin Cross-Linked with Chromium Ions for Conversion of Sucrose by Intracellular Invertase

A novel immobilized biocatalyst with invertase (β-D-fructofuranosidase, E.C.3.2.1.26) activity was prepared by immobilizing Saccharomyces cerevisiae cells into gelatin by using chromium salts. The effect of chromium salts on cell growth of free and immobilized cells was investigated, and optimum concentrations for chromium acetate and chromium sulfate were found to be 0.016 M and 0.008 M, respectively. Since a medium feeding strategy was applied, higher enzymatic activities were obtained with developed biocatalyst compared to free S. cerevisiae cells. Immobilized samples could be used 10 times in a 30-day period with negligible activity loss. After storing it at 25°C for 28 days, our biocatalyst was used 15 times with 2-day intervals with only a slight amount of activity decrease. As a result we managed to produce a very stable biocatalyst with high invertase activity using an inexpensive methodology.

In vivo toxicity of a new antifungal agent 2,4-dithiophenoxy-1-iodo-4-bromo benzene: a follow up on our in vitro study

Abstract Triazole fungicide fluconazole has become the most widely used antifungal agent in the world, mainly because of its ability to penetrate well into body fluids and tissues. However, it has been reported to interact with many drugs and because of its common use, the risk of resistance to fluconazole increases. This calls for new anti-fungal drugs that would be able to replace it. In 2006, a new thialo benzene derivative - 2,4-dithiophenoxy-1-iodo-4-bromo benzene (C18H12S2IBr) - was synthesised with a carbon backbone similar to fluconazole, and, according to the early in vitro tests, much greater efficiency. Followed an in vitro test of its cytotoxicity, in which the new drug showed promising results as an alternative to fluconazole. The aim of this study was take the next step and test C18H12S2IBr toxicity in vivo. We opted for a four-week test on Wistar rats, in which the new antifungal agent was orally applied at doses two and a half and five times lower than those of fluconazole. There were no changes in daily food and water consumption, but weight gain in female rats and relative organ weights changed in the treated groups, pointing to sex-related differences in drug metabolism and effects. Fluconazole significantly increased leukocytes and lowered neutrophils whereas C18H12S2IBr did not, while other haematological changes in respect to the vehicle control were similar between the treated groups. Differences in cytochrome c in the liver and kidney suggested greater apoptotic effect of the new drug, but interpretation remains inconclusive, considering that other key indicators (biochemistry and histopathology) do not support greater toxicity. Considering that C18H12S2IBr is more active at lower concentrations and has comparable toxic effects to fluconazole in rats, this new compound shows some promise in the treatment of fungal infections. Future, more detailed animal studies are needed, that will include drug interactions and molecular toxicity pathways. If the results are promising, clinical studies should follow. Triazolni antifungalni lijek flukonazol danas je najrašireniji antimikotik u svijetu, mahom zato što dobro prodire u tjelesne tekućine i tkiva. Primijećeno je međutim da ulazi u interakciju s drugim lijekovima, a zbog česte uporabe sve je veći i rizik od stvaranja rezistencije na njega. Stoga se traži njegova dostojna zamjena. Godine 2006. sintetiziran je novi derivat tialobenzena - 2,4-ditiofenoksi-1-jodo-4-bromobenzen (C18H12S2IBr). Iako je ugljikova osnovica tog derivata slična onoj flukonazolu, u prvim in vitro istraživanjima pokazao se puno djelotvorniji. Uslijedilo je in vitro istraživanje njegove citotoksičnosti, u kojem se novi spoj pokazao obećavajućom zamjenom za flukonazol. Cilj je ovog istraživanja bio otići korak dalje i istražiti toksičnost C18H12S2IBr in vivo. Odlučili smo se za četverotjedno istraživanje na štakorima Wistar, kojima se je novi antimikotik davao na usta u dozama dva i pol i pet puta nižima od uobičajene doze flukonazola. U životinja nisu primijećene promjene u konzumiranju hrane i vode, ali je relativna težina organa u ženki bila drugačija u odnosu na kontrolnu skupinu, što upućuje na razlike između spolova u metabolizmu lijeka. Za razliku od C18H12S2IBr, flukonazol je prouzročio značajno povišenje razine leukocita i smanjenje neutrofila. Ostale hematološke promjene u odnosu na kontrolnu skupinu bile su slične u skupina koje su primale bilo flukonazol bilo novi lijek. Razlike u imunolokalizaciji citokroma c u jetrima i bubrezima pokazatelj su snažnijeg apoptotičkog učinka novoga lijeka, ali se zbog drugih ključnih pokazatelja (biokemijskih i histopatoloških) ne može ništa zaključiti jer oni ne odgovaraju nalazima citokroma c. S obzirom na to da C18H12S2IBr snažnije djeluje od flukonazola pri nižim koncentracijama, uz podjednake toksične učinke u štakora, ovaj je novi spoj nesumnjivo obećavajuća alternativa liječenju gljivičnih infekcija. Potrebna su daljnja, podrobnija istraživanja u životinja, koja će obuhvatiti interakcije spojeva i molekularne putove toksičnosti. Bude li se lijek i u tim istraživanjima pokazao boljom alternativom, trebalo bi provesti klinička ispitivanja u ljudi.

Cytotoxic Effects of a Novel Thialo Benzene Derivative 2,4-Dithiophenoxy-1-iodo-4-bromobenzene (C18H12S2IBr) in L929 Cells

The aim of this study was to compare the cytotoxic effects of a newly synthesized thialo benzene derivative 2,4-dithiophenoxy-1-iodo-4-bromobenzene (C18H12S2IBr) and a well-known antifungal agent, fluconazole, in L929 cells. L929 cells were treated with 250, 500, or 1000 µg/mL of C18H12S2IBr and with the same doses of fluconazole. Cytotoxicity tests including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), lactate dehydrogenase (LDH) leakage, and protein content were compared. Glucose and lactate concentrations were measured to determine alterations in metabolic activity. Apoptosis was investigated by TUNEL test and results were supported with survivin enzyme-linked immunosorbent assay. Treatment with C18H12S2IBr resulted in a concentration-dependent cytotoxicity as indicated by MTT, LDH leakage assay, and decreased protein concentration. The loss of cell viability and the increased LDH leakage in 500 µg/mL and 1000 µg/mL C18H12S2IBr and fluconazole groups indicated cell membrane damage and necrotic cell death. In all groups, metabolic activities were altered but apoptosis was not induced. We have previously investigated lower doses of C18H12S2IBr; there was no cytotoxicity in L929 cells. In this study, higher doses caused cytotoxicity and alterations in metabolic activity . When we consider the similar results obtained from fluconazole and especially the lowest dose of C18H12S2IBr, this newly synthesized compound may be a good alternative antifungal agent.