Yavuz Ergun

Fluorescence study on the interaction of bovine serum albumin with two coumarin derivatives

The interactions between bovine serum albumin (BSA) and two substituted hydroxychromone derivatives of coumarin, 3-hydroxy-7,8,9,10-tetrahydro-6H-benzo[c]chromen-6-on (C3) and 1,3-dihydroxy-7,8,9,10-tetrahy-dro-6H-benzo[c]chromen-6-on (C1.3), were investigated by fluorescence quenching spectra and UV-vis absorption spectra. It was proved that the fluorescence quenching of BSA by C3 and C1, 3 was mainly a result of the formation of C3 and C1.3-BSA complexes. The Stern-Volmer quenching constants, binding constants, binding sites and the corresponding thermodynamic parameters ΔHo, ΔSo and ΔGo at different temperatures were calculated. The results indicated that van der Waals interactions and hydrogen bonds were the predominant intermolecular forces in stabilizing each complex. The detection limits of C3 and C1.3 were 5.08 × 10−7 and 1.11 × 10−7 M in the presence of BSA, respectively.

A Novel Synthesis Towards Ellipticine and Its Derivatives. Synthesis of a New Precursor Compound

Abstract The synthesis of a new precursor compound 3, which may be important for the synthesis of ellipticine and its derivatives, was described. Many new intermediates 5–10 have also been synthesized.

Synthesis of new ibuprofen derivatives with their in silico and in vitro cyclooxygenase-2 inhibitions.

Cyclooxygenase-2 (COX-2) is one of the important targets for treatment of inflammation related diseases. In the literature, most of drug candidates are first synthesized and then their COX-2 inhibitory activities are tested by in vitro and in vivo experiments. However, synthesis of dozens of drug analogues without any interpretations on their inhibitory activity can result in loss of time and chemicals. Therefore, synthetic drug designs with molecular modeling are of importance to synthesize selective drug candidates against inflammatory diseases. The synthesis of the novel ibuprofen derivatives through their in silico and in vitro COX-2 inhibitory activities were investigated in the present study. Starting from ibuprofen, ibuprofen amide and ibuprofen acyl hydrazone derivatives were synthesized. According to the results of the in silico molecular docking and in vitro enzyme inhibition studies, the synthesized novel ibuprofen derivatives have selective COX-2 inhibition, and molecule 3a and 3c were showed higher inhibition compared to ibuprofen. In conclusion, the newly synthesized ibuprofen derivatives can be used in model in vivo studies.

Inhibition of human DNA topoisomerase IIα by two novel ellipticine derivatives.

Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is an antineoplastic agent that intercalates into DNA and alters topoisomerase II activity. Unfortunately, this compound displays a number of adverse properties. Therefore, to investigate new ellipticine-based compounds for their potential as topoisomerase II-targeted drugs, we synthesized two novel derivatives, N-methyl-5-demethyl ellipticine (ET-1) and 2-methyl-N-methyl-5-demethyl ellipticinium iodide (ET-2). As determined by DNA decatenation and cleavage assays, ET-1 and ET-2 act as catalytic inhibitors of human topoisomerase IIα and are both more potent than the parent compound. Neither compound impairs the ability of the type II enzyme to bind its DNA substrate. Finally, the potency of ET-1 and ET-2 as catalytic inhibitors of topoisomerase IIα appears to be related to their ability to intercalate into the double helix.

Synthesis and spectroscopic studies of 3,6-diphenyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dion's N,N'-dialkyl derivatives.

Abstract3,6-diaryl-2,5-dihydro-1,4-diketopyrrolo[3,4-c]pyrrole-1,4-dione (DPPD) derivatives are used commercially as red pigments, because of their color strength, brightness, and very low solubility in most common solvents. These products, although highly colored, appear to be of limited value as dyes, since they show a tendency to form an aggregate when incorporated into a solvent. Monoalkyl and dialkyl derivatives of DPPD were synthesized and then characterized with IR, 1HNMR, UV-Vis absorption and emission spectroscopy. Molar absorption coefficient, singlet energy level and Stokes’ shift values of DPPD derivatives were declared. Monoalkyl and dialkyl derivatives of DPPD’s solubilities were measured from saturated solutions of dimethylformamide (DMF), tetrahydrofuran (THF), dichloromethane (DCM), acetonitrile (ACN) and toluene and they are compared with each other.

Dissolved Carbon Dioxide Sensing with Phenyl-Linked Carbazole Oxazolones in Ionic Liquid and Ethyl Cellulose Moieties

ABSTRACT A new optical dissolved carbon dioxide (dCO2) sensor based on the spectrofluorimetric signal changes of the fluorescent carbazole derivative in room temperature ionic liquid was proposed. Response of the offered sensor composition to gaseous and dissolved carbon dioxide was tested in ethyl-cellulose- and imidazolium-based ionic liquid moieties. The detection limit was found to be 5 × 10−7 M [ ] for dCO2. When embedded in ionic liquid, the employed molecule exhibits excitation wavelength beyond 465 nm, extinction coefficients around 185,000 cm−1 M−1, and Stokes shifts extending to 56 nm. The ionic liquid—1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4)—provided longer storage time and highly stable microenvironment for the indicator molecule due to the buffering effect. The dissolved carbon dioxide sensor based on dye-doped RTIL does not need extra protection from the ambient air of the lab.

Photophysical and Complexation Properties of Benzenesulfonamide Derivatives with Different Donor and Acceptor Moieties

Pyrrolobenzosulfonamide, indolobenzosulfonamide and carbazolobenzosulfonamide derivatives with different acceptor groups were synthesized and their photophysical properties were compared. The electron donor linking sites are found to influence the emission characteristics of these compounds while acceptor linking sites have no noticeable effects on the spectral properties. P2-A5 which is a C–C linked pyrrole derivative exhibited different spectral properties from the C–N linked pyrrole derivatives. The complexation properties of the molecules were also investigated employing Na (I), Ca (II), Li (I), Mg (II), Zn (II) and Cu (II) ions.

Ethyl 1-oxo-1,2,3,4-tetra-hydro-9H-carbazole-3-carboxyl-ate.

The title compound, C15H15NO3, contains a carbazole skeleton with an ethoxycarbonyl group at the 3 position. In the indole ring system, the benzene and pyrrole rings are nearly coplanar, forming a dihedral angle of 1.95 (8)°. The cyclohexenone ring has an envelope conformation. In the crystal structure, pairs of strong N—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers with R 2 2(10) ring motifs. π–π contacts between parallel pyrrole rings [centroid–centroid distance = 3.776 (2) Å] may further stabilize the structure. A weak C—H⋯π interaction is also observed.

2-(Naphthalen-1-yl)-4-(thio-phen-2-yl-methyl-idene)-1,3-oxazol-5(4H)-one.

The asymmetric unit of the title compound, C18H11NO2S, contains two crystallographically independent molecules. In one molecule, the oxazole and thiophene rings are oriented at dihedral angles of 17.40 (9) and 18.18 (7)° with respect to the naphthalene ring system, while the oxazole and thiophene rings are oriented to each other at a dihedral angle of 0.86 (9)°. In the other molecule, the corresponding angles are 3.05 (8), 9.62 (6) and 7.02 (8)°, respectively. In each molecule, a weak intramolecular C—H⋯N hydrogen bond links the oxazole N atom to the naphthalene group. Weak intermolecular C—H⋯O hydrogen bonding is present in the crystal structure. π–π stacking between the oxazole and thiophene rings, between the thiophene and naphthalene rings, and between the oxaozole and naphthalene rings, [centroid–centroid distances = 3.811 (2), 3.889 (2), 3.697 (2) and 3.525 (2) Å] may further stabilize the crystal structure.

2-(Naphthalen-1-yl)-4-(naphthalen-1-yl­methyl­idene)-1,3-oxazol-5(4H)-one

In the title compound, C24H15NO2, the oxazole ring is oriented at dihedral angles of 10.09 (4) and 6.04 (4)° with respect to the mean planes of the naphthalene ring systems, while the two naphthalene ring systems make a dihedral angle of 4.32 (3)°. Intramolecular C—H⋯N hydrogen bonds link the oxazole N atom to the naphthalene ring systems. In the crystal, intermolecular weak C—H⋯O hydrogen bonds link the molecules into centrosymmetric dimers. π–π contacts between the oxazole and naphthalene rings and between the naphthalene ring systems [centroid–centroid distances = 3.5947 (9) and 3.7981 (9) Å] may further stabilize the crystal structure. Three weak C—H⋯π interactions also occur.