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Catechol-bearing imidazolium and benzimidazolium chlorides as promising antimicrobial agents
(Wiley-V C H Verlag Gmbh, 2020) Karatas, Mert O.; Gunal, Selami; Mansur, Ahmet; Alici, Bulent; Ozdemir, Ismail
Catechol-containing imidazolium (four) and benzimidazolium chlorides (eight) were synthesized to evaluate their antimicrobial properties. All the compounds were fully characterized using H-1 and C-13 nuclear magnetic resonance, liquid chromatography-mass spectrometry, infrared spectroscopic methods, and elemental analyses. Antimicrobial activities of the compounds were tested against the bacteria Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Enterococcus faecalis, and the fungal strains Candida albicans and Candida glabrata, and promising results were achieved. The two most important benzyl-substituted benzimidazolium chlorides, 3l and 3k, showed comparable activity to vancomycin against MRSA.
Comparison of the catalytic performances of bridged bi-metallic and non-bridged mono-metallic PEPPSI type palladium N-heterocyclic carbene complexes
(Elsevier, 2020) Karatas, Mert Olgun; Alici, Bulent
Palladium-N-heterocyclic carbene complexes are widely investigated catalysts in cross-coupling reactions. However, studies about the catalytic activities of bridged bi-metallic complexes are quite rare. Therefore, in this study, anthracene-substituted one mono-metallic and one bridged bi-metallic PEPPSI-type Pd-NHC complexes were synthesized in order to compare their catalytic activities in Suzuki-Miyaura and Mizoroki-Heck reactions. Both complexes were fully characterized by H-1 and C-13 NMR, LC-MS, IR spectra and elemental analyses. The results of catalytic reactions clearly revealed that mono-metallic complex performs better catalytic activity than bi-metallic analogue in the use of same amount of palladium.
Coumarin or benzoxazinone based novel carbonic anhydrase inhibitors: synthesis, molecular docking and anticonvulsant studies
(Taylor & Francis Ltd, 2016) Karatas, Mert Olgun; Uslu, Harun; Sari, Suat; Alagoz, Mehmet Abdullah; Karakurt, Arzu; Alici, Bulent; Bilen, Cigdem
Among many others, coumarin derivatives are known to show human carbonic anhydrase (hCA) inhibitory activity. Since hCA inhibition is one of the underlying mechanisms that account for the activities of some antiepileptic drugs (AEDs), hCA inhibitors are expected to have anti-seizure properties. There are also several studies reporting compounds with an imidazole and/or benzimidazole moiety which exert these pharmacological properties. In this study, we prepared fifteen novel coumarin-bearing imidazolium and benzimidazolium chloride, nine novel benzoxazinone-bearing imidazolium and benzimidazolium chloride derivatives and evaluated their hCA inhibitory activities and along with fourteen previously synthesized derivatives we scanned their anticonvulsant effects. As all compounds inhibited purified hCA isoforms I and II, some of them also proved protective against Maximal electroshock seizure (MES) and ScMet induced seizures in mice. Molecular docking studies with selected coumarin derivatives have revealed that these compounds bind to the active pocket of the enzyme in a similar fashion to that previously described for coumarin derivatives.
Cytotoxic effects of coumarin substituted benzimidazolium salts against human prostate and ovarian cancer cells
(Indian Acad Sciences, 2019) Karatas, Mert Olgun; Tekin, Suat; Alici, Bulent; Sandal, Suleyman
Coumarin and benzimidazole derivatives have individual biological activities including anticancer. In this study, we aimed to synthesize coumarin-benzimidazole hybrids in order to investigate their anticancer properties. For this purpose, six 6-substituted-4-chloromethylene coumarin derivatives were synthesized. Sixteen coumarin substituted benzimidazolium chlorides were synthesized by the reaction of 4-chloromethylene coumarin and N-benzylbenzimidazole derivatives. All of the synthesized compounds were characterized by 1H and 13C NMR, IR spectroscopic techniques and elemental analyses. Cytotoxicities of all compounds were tested by [ 3-(4,5-dimethylthiazole)-2-yl]-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay against human prostate (PC-3) and ovarian (A2780) cancer cells. All compounds performed significant cytotoxicities at 100 mu Magainst both cancer cell lines. Moreover, some compounds performed significant activities at 1 mu M against both cancer cell lines and the obtained results suggest that this type of compounds are promising candidates for the treatment of human prostate and ovarian cancers.
Efficiency enhancement with chloride to iodide ion exchange of benzimidazolium salt as a redox mediator
(Tubitak Scientific & Technological Research Council Turkey, 2021) Dayan, Serkan; Karatas, Mert Olgun; Alici, Bulent; Kalaycioglu Ozpozan, Nilgun
The new benzimidazolium derivative (SM-1) salt with ion exchange from the (SM-0) was fabricated and characterized by proton-nuclear magnetic resonance (H-1-NMR), carbon-nuclear magnetic resonance (C-13-NMR), Fourier-transform infrared spectroscopy (FTIR), electrospray ionization (EIS-MS), thermal analysis (TG), cyclic voltammetry (CV), and ultraviolet-visible spectroscopy (UV-vis), for electrolytes (liquid or dried) in the DSSC charge transportation mechanism. Also, the influence of ion exchange from chloride to iodine in the synthesized electrolytes, compared to other electrolytes (conventional or commercial), was investigated about DSSC performance efficiency. When using as a liquid electrolyte (SM-1), the power conversion efficiency (eta) of the working DSSC device was recorded as 1.980% and it was observed that the performances of DSSCs increased up to 56% when comparing dried electrolyte for SM-1 without conventional redox material (I-/I3-). In the future, different molecular modifications of this type of benzimidazole derivatives or mixtures with conventional redox couples may further improve the performance of DSSC devices.
Functionalized imidazolium and benzimidazolium salts as paraoxonase 1 inhibitors: Synthesis, characterization and molecular docking studies
(Pergamon-Elsevier Science Ltd, 2016) Karatas, Mert Olgun; Uslu, Harun; Alici, Bulent; Gokce, Basak; Gencer, Nahit; Arslan, Oktay; Arslan, N. Burcu
Paraoxonase (PON) is a key enzyme in metabolism of living organisms and decreased activity of PON1 was acknowledged as a risk for atherosclerosis and organophosphate toxicity. The present study describes the synthesis, characterization, PON1 inhibitory properties and molecular docking studies of functionalized imidazolium and benzimidazolium salts (1a-5g). The structures of all compounds were elucidated by IR, NMR, elemental analysis and structures of compounds 2b and 2c were characterized by single-crystal X-ray diffraction. Compound 1c, a coumarin substituted imidazolium salt showed the best inhibitory effect on the activity of PON1 with good IC50 value (6.37 mu M). Kinetic investigation was evaluated for this compound and results showed that this compound is competitive inhibitor of PON1 with K-1, value of 2.39 mu M. Molecular docking studies were also performed for most active compound 1c and one of least active compound 2c in order to determine the probable binding model into active site of PON1 and validation of the experimental results. (C) 2016 Elsevier Ltd. All rights reserved.
In vitro inhibition effect of some coumarin compounds on purified human serum paraoxonase 1 (PON1)
(Taylor & Francis Ltd, 2016) Gokce, Basak; Gencer, Nahit; Arslan, Oktay; Karatas, Mert Olgun; Alici, Bulent
Human serum paraoxonase 1 (PON1; EC 3.1.8.1) is a high-density lipoprotein associated, calcium-dependent enzyme that hydrolyses aromatic esters, organophosphates and lactones and can protect the low-density lipoprotein against oxidation. In this study, in vitro effect of some hydroxy and dihydroxy ionic coumarin derivatives (1-20) on purified PON1 activity was investigated. Among these compounds, derivatives 11-20 are water soluble. In investigated compounds, compounds 6 and 13 were found the most active (IC50 = 35 and 34 mu M) for PON1, respectively. The present study has demonstrated that PON1 activity is very highly sensitive to studied coumarin derivatives.
Inhibition of paraoxonase 1 by coumarin-substituted N-heterocyclic carbene silver(I), ruthenium(II) and palladium(II) complexes
(Wiley, 2019) Karatas, Mert Olgun; Calgin, Gamze; Alici, Bulent; Gokce, Basak; Gencer, Nahit; Tok, Tugba Taskin; Arslan, Oktay
We synthesized three coumarin-substituted benzimidazolium chlorides and their silver(I), ruthenium(II) and palladium(II) N-heterocyclic carbene (NHC) complexes. All compounds were characterized using appropriate spectroscopic techniques and elemental analyses. Single-crystal X-ray structure of a Pd(II)-NHC complex (6b) was also determined. The inhibitory properties of all compounds were tested on the activity of human paraoxonase 1 (PON1). All complexes exhibited weaker inhibitory properties than their corresponding benzimidazolium salts except for complex 6b which is the most active inhibitor with an IC50 value of 3.01 mu M among the compounds reported in this study. A kinetic evaluation showed that this complex inhibits PON1 activity in a non-competitive manner. Molecular docking studies were also performed for 6b in order to obtain more insight into the binding mode.
Iridium(i) complexes bearing hemilabile coumarin-functionalised N-heterocyclic carbene ligands with application as alkyne hydrositytation catalysts
(Royal Soc Chemistry, 2021) Karata, Mert Olgun; Alici, Bulent; Passarelli, Vincenzo; Ozdemir, Ismail; Perez-Torrente, Jesus J.; Castarlenas, Ricardo
A set of iridium(I) complexes of formula IrCl(kappa C,eta(2)-I(R)Cou(R))(cod) or IrCl(kappa C, eta(2)-Bz(lR)Cou(R))(cod) (cod = 1,5-cyclooctadiene; Cou = coumarin; I = imidazolin-2-carbene; Bzl = benzimidazolin-2-carbene) have beeen prepared from the corresponding azolium salt and [ir(mu-OMe)(cod)](2) in THE at room temperature. The crystalline structures of 4b and 5b show a distorted trigonal bipyramidal configuration in the solid state with a coordinated coumarin moiety. In contrast, an equilibrium between this pentacoordinated structure and the related square planar isomer is observed in solution as a consequence of the hemilability of the pyrone ring. Characterization of both species by NMR was achieved at the low and high temperature limits, respectively. In addition, the thermodynamic parameters of the equilibrium, Delta H-R and Delta S-R were obtained by VT H-1 NMR spectroscopy and fall in the range 22-33 kJ mol(-1) and 72-113 J mol(-1) k(-1), respectively. Carbonylation of IrCl(kappa C,eta(2)-BzI(Tol)Cou(7.8-Me2))(cod) resulted in the formation of a bis-CO derivative showing no hemilabile behaviour. The newly synthesised complexes efficiently catalyze the hydrosilylation of alkynes at room temperature with a preference for the beta-(Z) vinylsilane isomer.
Microwave-assisted synthesis of 1-substituted-1H-benzimidazolium salts: Non-competitive inhibition of human carbonic anhydrase I and II
(Wiley-V C H Verlag Gmbh, 2019) Karlik, Ozgul; Gencer, Nahit; Karatas, Mert O.; Ergun, Adem; Cikrikci, Kubra; Arslan, Oktay; Alici, Bulent
A series of 1-substituted-1H-benzimidazolium p-toluenesulfonate salts were synthesized in good yields by the reaction of 1-substituted benzimidazole derivatives and p-toluenesulfonic acid under microwave irradiation. Two iodide salts were synthesized by the anion exchange reaction of the corresponding p-toluenesulfonate salt and NaI. All compounds were characterized by H-1 NMR, C-13 NMR, IR, LC-MS spectroscopic methods, and elemental analyses. The crystal structure of 1-methoxyethyl-1H-benzimidazolium p-toluenesulfonate 2d showed that cation and anion are interconnected by N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds. All compounds were examined as inhibitor of human carbonic anhydrase (hCA) I and II, and all of them inhibited hCA I and hCA II. Kinetic investigation results revealed that these compounds inhibit hCA I and hCA II in a non-competitive manner. The iodide salts had higher inhibitory activity than their corresponding p-toluenesulfonate salts.
Microwave-Assisted Synthesis of Novel Perimidinium Salts as N-Heterocyclic Carbene Precursors: Involvement in Palladium-Catalyzed Cross-Coupling Reactions
(Springer, 2015) Onar, Gulnihan; Karatas, Mert Olgun; Alici, Bulent; Cetinkaya, Engin
In the current study, five novel perimidinium chlorides were synthesized in good yields by reaction of 1-(3-methylbenzyl)perimidine with five different alkyl chlorides under microwave irradiation in 30 minutes. Synthesized compounds were characterized by IR, H-1, C-13 NMR spectroscopic methods and elemental analyses. Performance of in situ formed catalytic system which consist of the perimidinium salts and Pd(OAc)(2) was investigated for Heck and Suzuki reactions in aqueous media, and desired products were obtained in good yields.
N-heterocyclic carbene palladium complexes with different N-coordinated ligands: Comparison of their catalytic activities in Suzuki-Miyaura and Mizoroki-Heck reactions
(Pergamon-Elsevier Science Ltd, 2020) Karatas, Mert Olgun; Ozdemir, Namik; Alici, Bulent; Ozdemir, Ismail
In this paper, we have reported the synthesis and catalytic activities of four new anthracene substituted imidazole-based palladium N-heterocyclic carbene complexes. The synthesized complexes, 2a-d, were stabilized with different N-heterocycles, namely pyridine, N-methylimidazole, N-vinylimidazole and 4,5-dimethylthiazole, respectively. The complexes were completely characterized using H-1 NMR, C-13 NMR, IR, LC-MS spectroscopic methods and elemental analyses. The crystal structures of 2a, 2c and 2d were also reported. The catalytic activities of all the complexes were tested for Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions in aqueous medium. According to the results, for the Suzuki-Miyaura reaction, the pyridine bearing complex 2a, and for the Mizoroki-Heck reaction, the 4,5-dimethylthiazole bearing complex 2d were found to be the most active catalysts. (C) 2019 Elsevier Ltd. All rights reserved.
New coumarin derivatives as carbonic anhydrase inhibitors
(Taylor & Francis Ltd, 2014) Karatas, Mert Olgun; Alici, Bulent; Cakir, Umit; Cetinkaya, Engin; Demir, Dudu; Ergun, Adem; Gencer, Nahit
In the current study, a series of 4-chloromethyl-7-hydroxy-coumarin derivatives containing imidazolium, benzimidazolium, bisbenzimidazolium and quaternary ammonium salts were synthesized, characterized and the inhibition effects of the derivatives on human carbonic anhydrases (hCA I and hCA II) were investigated as in vitro. Structures of these coumarins were confirmed by FT-IR, (1)H NMR, (13)C NMR and LC-MS analyses. Structure activity relationship study showed that 3d (IC50: 79 mu m M for hCA I and 88 m M for hCA II) performed higher inhibitory activity than others.
Pentacoordinated Rhodium(I) Complexes Supported by Coumarin-Functionalized N-Heterocyclic Carbene Ligands
(Amer Chemical Soc, 2018) Karatas, Mert Olgun; Di Giuseppe, Andrea; Passarelli, Vincenzo; Alici, Bulent; Perez-Torrente, Jesus J.; Oro, Luis A.; Ozdemir, Ismail
New coumarin-tethered benzimidazolium (BzICou(R)HCl) and imidazolium (ICou(R)HCl) salts have been prepared as precursors for coumarin-NHC rhodium(I) complexes RhCl(NHC)(cod). Trigonal bypiramidal pentacoordinated bis-coumarin-NHC rhodium(I) species, RhCl(NHC)(2), can be obtained by heating rhodium-cod derivatives in the presence of coumarin-azolium salts and a base. These unusual species are stabilized by coordination of the unsaturated bond of both coumarin moieties by the same enantioface. The allyl substituent on doubly functionalized NHC competes for coordination with coumarin wingtips. DFT calculations upon coordination of the olefin moieties support the experimental results.
Some coumarins and benzoxazinones as potent paraoxonase 1 inhibitors
(Taylor & Francis Ltd, 2016) Karatas, Mert Olgun; Uslu, Harun; Alici, Bulent; Gokce, Basak; Gencer, Nahit; Arslan, Oktay
In this study, we aimed to investigate the effect of some coumarin and benzoxazinone derivatives on the activity of human PON1. Human serum paraoxonase 1 was purified from fresh human serum blood by two-step procedures that are ammonium sulfate precipitation (60-80%) and then hydrophobic interaction chromatography (Sepharose 4B, L-tyrosine and 1-napthylamine). The enzyme was purified 232-fold with a final specific activity of 27.1 U/mg. In vitro effects of some previously synthesized ionic coumarin or benzoxazinone derivatives (1-21) on purified PON1 activity were investigated. Compound 14 (1-(2,3,4,5,6)-pentamethyl-benzyl-3-(6,8-dimethyl-2H-chromen-2-one-4-yl)) benzimidazolium chloride was found out as the strongest inhibitor (IC50 = 7.84 mu M) for PON1 among the compounds. Kinetic investigation and molecular docking study were evaluated for one of the most active compounds (compound 12) and obtained data showed that this compound is competitive inhibitor of PON1 and interact with Leu262 and Ser263 in the active site of PON1. Moreover, coumarin derivatives were found out as the more potent inhibitors for PON1 than benzoxazinone derivatives.
Synthesis and antimicrobial properties of cycloheptyl substituted benzimidazolium salts and their silver(I) carbene complexes
(Walter De Gruyter Gmbh, 2016) Karatas, Mert Olgun; Gunal, Selami; Mansur, Ahmet; Alici, Bulent; Cetinkaya, Engin
Due to increasing infections caused by microbes, there is an urgent need for the development of new effective antimicrobial agents. Silver-N-heterocyclic carbene (silver-NHC) complexes are a new class of antimicrobial agents. In this study, we aimed to synthesize highly lipophilic silver-NHC complexes. Four new complexes were synthesized by the reaction of the corresponding benzimidazolium salts and Ag2O in dichloromethane at room temperature. The synthesized compounds were characterized by H-1 NMR, C-13 NMR, IR and elemental analysis. The antimicrobial performances of benzimidazolium salts and silver complexes were tested against the standard bacterial strains Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and the fungi Candida albicans and Candida tropicalis. Minimum inhibitory concentrations (MICs) of all compounds were determined. The obtained data demonstrate that all benzimidazolium salts and silver complexes inhibit the growth of bacteria and fungi. Silver complexes are more active than the corresponding benzimidazolium salts (MIC: 6.25 mu g/mL for Gram-positive bacteria and fungi).
Synthesis and carbonic anhydrase inhibitory properties of novel coumarin derivatives
(Informa Healthcare, 2013) Karatas, Mert Olgun; Alici, Bulent; Cakir, Umit; Cetinkaya, Engin; Demir, Dudu; Ergun, Adem; Gencer, Nahit
A newly series of water-soluble 1-alkyl-3-(4-methyl-7, 8-dihydroxy-2H-chromen-2-one) benzimidazolium chloride salts (3a-j) were synthesized and their inhibitory effects on the activity of purified human carbonic anhydrase (hCA) I and II were evaluated. hCA I and II from human erythrocytes were purified by a simple one step procedure by using Sepharose 4B-L-tyrosine-sulphanilamide affinity column. The result showed that all the synthesized compounds were inhibited the CA isoenzymes activity. Among them, 3g and 3j were found to be most active (IC50 = 22.09 mu M and 20.33 mu M) for hCA I and hCA II, respectively.
Synthesis of the Coumarin-Containing Porous Silica as Column Packing Material
(Springer, 2016) Kazmaz, Emine Sura; Karatas, Mert Olgun; Koytepe, Suleyman; Ates, Burhan; Erdogan, Ali; Alici, Bulent; Seckin, Turgay
For the synthesis of the coumarin based column packing materials, amino functionalized porous silica was prepared from the modification of silica with 3-aminopropyl triethoxysilane. This amino functional silica was reacted with 4-chloromethyl-7,8-dihydroxycoumarin. The produced silica based column packing material was characterized by spectral techniques, scanning electron microscope, X-ray diffraction analysis (X-ray), N-2 adsorption isotherms and thermal analysis techniques. The effect of coumarin group on the silica structure and separation properties as well as the thermal stability of materials was investigated. Average particle diameters, pore size and surface areas of the coumarin based silica particles were 2680 +/- A 750 mu m, similar to 33 nm and 118 +/- A 6 m(2)/g, respectively. 240 mm x 4.6 mm high performance liquid chromatography column was packed with coumarin functionalized porous silica. Then, this column was applied to the separation of similar structure aromatic compounds such as benzene, toluene and xylene. Column performance was investigated by measuring time of continuous use peak asymmetry, resolution, and selectivity. Chromatographic resolutions of coumarin-modified packing material were in the range of 2.28-2.35. According to these data, for the separation of aromatic compounds, while pure silica does not provide effective separation, coumarin based column packing material has showed good separation and selectivity.
Synthesis, characterization and antimicrobial activities of novel silver(I) complexes with coumarin substituted N-heterocyclic carbene ligands
(Pergamon-Elsevier Science Ltd, 2016) Karatas, Mert Olgun; Olgundeniz, Begum; Gunal, Selami; Ozdemir, Ilknur; Alici, Bulent; Cetinkaya, Engin
Eight new coumarin substituted silver(I) N-heterocyclic carbene (NHC) complexes were synthesized by the interaction of the corresponding imidazolium or benzimidazolium chlorides and Ag2O in dichloromethane at room temperature. Structures of these complexes were established on the basis of elemental analysis, H-1 NMR, C-13 NMR, IR and mass spectroscopic techniques. The antimicrobial activities of carbene precursors and silver NHC complexes were tested against standard strains: Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and the fungi Candida albicans and Candida tropicalis. Results showed that all the compounds inhibited the growth of the all bacteria and fungi strains and some complexes performed good activities against different microorganisms. Among all the compounds, the most lipophilic complex bis[1-(4-methylene-6,8-dimethyl-2H-chromen-2-one)-3-(naphthalene-2-ylmethyl)benzimidazol-2-ylidene]silver(I) dichloro argentate (5e) was found out as the most active one. (c) 2015 Elsevier Ltd. All rights reserved.
Synthesis, characterization and tyrosinase inhibitory properties of benzimidazole derivatives
(Maik Nauka/Interperiodica/Springer, 2014) Karatas, Mert Olgun; Alici, Bulent; Cetinkaya, Engin; Bilen, Cigdem; Gencer, Nahit; Arslan, Oktay
1-Alkylbenzimidazole and 1,3-dialkyl benzimidazolium salts were synthesized and characterized by the data of IR, H-1 NMR, C-13 NMR spectra and elemental analyses. These compounds were investigated as tyrosinase inhibitors. Tyrosinase has been purified from banana by affinity chromatography on a Sepharose 4B gel conjugated with L-tyrosine-p-aminobenzoic acid. All the synthesized compounds inhibited the tyrosinase activity. Among the compounds studied, 1,4-di(1H-benzo[d]imidazol-1-yl)butane was found to be the most active tyrosinase inhibitor (IC50 0.31 mM).

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