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    C-H Bond activation of 2-isobutylthiazole at C5 position catalysed by Pd-N-heterocyclic carbene complexes
    (Elsevier Science Sa, 2021) Bugday, Nesrin; Khan, Siraj; Yasar, Sedat; Ozdemir, Ismail
    A highly efficient and effective protocol has been developed for the synthesis of C5-(hetero)arylated 2-isobutylthiazole derivatives. Four different palladium N-heterocyclic carbene (Pd-NHCs) complexes [Pd(mu-Cl)Cl(SIMes)](2) (2), (LCl2 Pd-SIMes) (3: L = PPh3; 4: L = Py; 5: L = 3-CHO-Py) were synthesized and used for the first time as a catalysts in direct C-H arylation reaction of 2-isobutylthiazole at C5 position. Utilizations of these catalytic systems, the arylation of 2-isobutylthiazole with substituted (hetero)aryl bromides efficiently proceeded at low catalyst loading (1 mol%) and without any additives such as PivOH under argon or aerobic conditions at 120 degrees C in a short time. Different substituted (hetero)aryl bromides, even some deactivated or highly sterically hindered (hetero)arylbromides, with a wide range of functional groups were successfully utilized under the optimum reaction conditions. In all cases, the C5 arylated 2-isobutylthiazoles were obtained in moderate to excellent yields. (C) 2021 Elsevier B.V. All rights reserved.
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    Molecular docking and in vitro anticancer studies of silver(I)-N-heterocyclic carbene complexes
    (Elsevier Sci Ltd, 2022) Akkoc, Mitat; Khan, Siraj; Yuce, Hande; Turkmen, Nese Basak; Yasar, Seyma; Yasar, Sedat; Ozdemir, Ismail
    A series of symmetric and unsymmetrical benzimidazolium-based N-heterocyclic carbene (NHC) precursors (1a-i) and their silver complexes (2a-i) have been synthesized. The Ag(I)-NHC complexes were characterized by H-1, C-13 {H-1} NMR, FTIR, LC/MS-QTOF, and elemental analysis. Anticancer and cytotoxic activity of all Ag(I)-NHC complexes were tested against healthy fibroblast cell line (L929), breast cancer cell line (MCF-7), and neuro-blastoma cell line (SH-SY5Y) by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4sulfo-phenyl)-2H-tetrazolium] assay. The 2b, 2c, 2e, 2g, 2h, and 2i complexes showed higher cytotoxicity than cisplatin against SH-SY5Y and MCF-7 and lower cytotoxic activity against L929 cell lines. Because of their high cytotoxic activity against cancer cells and low cytotoxicity against healthy fibroblast cell lines, the 2b, 2c, 2e, 2g, 2h, and 2i are expected to be new lead compounds. In addition, molecular docking studies were performed to explore the binding interactions of silver complexes with the enzyme to explore new anticancer compounds. Furthermore, ADME properties of all complexes were predicted to explore lead-like characteristics and may be a potential drug candidate for cancer treatment.
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    Pd-N-heterocyclic carbene complex catalysed C-H bond activation of 2-isobutylthiazole at the C5 position with aryl bromides
    (Royal Soc Chemistry, 2021) Khan, Siraj; Bugday, Nesrin; Yasar, Sedat; Ullah, Naseem; Ozdemir, Ismail
    An effective and efficient catalytic system has been reported for the synthesis of C5-arylated 2-isobutylthiazoles. Pd-N-heterocyclic carbene complexes like [Pd(mu-Cl)Cl(SIPr)](2) (2) and (LCl2Pd-SIPr) (3: L = PPh3, 4: L = Py; 5: L = 3-CHO-Py) were synthesized and characterized by H-1, C-13, P-31 NMR, LC-MS/MS, elemental analysis, and FTIR spectroscopy. These Pd-N-heterocyclic carbene complexes were assessed for the first time as catalysts for the C-H arylation reaction of 2-isobutylthiazole at the C5 position with different (hetero)aryl bromides. The catalytic system showed a low catalyst loading (1 mol%) and did not require the use of additional additives such as pivalic acid. The catalytic system developed with these catalysts enables the synthesis of fine chemicals in high yields under aerobic or anaerobic conditions. All complexes showed moderate to good yields in the C5 direct arylation of 2-isobutylthiazole, while complex 2 exhibited higher catalytic activity than the other complexes.
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    Pd-NHC complex catalyzed C-H bond activation reactions of caffeine and 2-isobuthylthiazole
    (Elsevier, 2022) Bugday, Nesrin; Khan, Siraj; Yasar, Sedat; Bulut, Fatih; Boulebd, Houssem; Karabiyik, Hande; Karabiyik, Hasan
    A series of new Pd-NHC complexes were synthesized, characterized, and utilized as catalysts on 8-(hetero)ary-lation of xanthines and C-5 (hetero)arylation of 2-isobuthylthiazole. All the synthesized derivatives were characterized by NMR, Q-TOF-LC/MS, FTIR, and X-ray (for 4a, 5a, and 5b) analysis. In addition, DFT calculations and computational NBO studies for Pd-NHC complexes were examined, and HOMO and LUMO energy levels and electron density of each Pd-NHC complex were defined. 4a-c and 5a-b complexes showed good catalytic activity in C-H bond activation reactions. DFT studies have also been conducted to examine the reaction mechanism following the CMD pathway. Complex 5a was chosen as a representative catalyst for the reaction of unsubstituted phenyl with caffeine and 2-isobuthylthiazole. Although the delta E values of the complexes are so close, slight difference in the catalytic activity were observed for 4a-c and 5a-b. Since this low delta E value facilitates the oxidative addition reaction of (hetero)aryl bromides, thanks to this catalytic system, new 8-(hetero)aryl xan-thines and 5-(hetero)aryl thiazole derivatives could be synthesized with high yields and low catalyst loading.
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    Synthesis and biological evaluation of Au-NHC complexes
    (Wiley, 2022) Ekinci, Orhan; Akkoc, Mitat; Khan, Siraj; Yasar, Sedat; Gurses, Canbolat; Noma, Samir; Balcioglu, Sevgi
    New seven Au-N-heterocyclic carbene (NHC) complexes have been synthesized via transmetalation from Ag-NHC complexes. NHC salts, Ag-NHC, and Au-NHC complexes were fully characterized by widely used spectroscopic techniques. The molecular and crystal structures of 3b and 3f Au-NHC complexes were clarified through the single-crystal X-ray diffraction method. According to X-ray diffraction analysis results, the coordination geometry around Au(I) atoms in the complexes are revealed to be almost linear with C-Au-Cl angle. Anticancer activity, DNA binding, xanthine oxidase (XO) inhibitory activity studies, and molecular docking studies were evaluated for all Au-NHC complexes to explore the binding mechanism at the active site. The IC50 value of Au-NHC complexes against human colorectal cancer (Caco-2) and breast cancer (MCF-7) cell lines was defined by MTT assay. The IC50 values for MCF-7 in the range of 5.2 +/- 2 to 152.4 +/- 1 mu M and Caco-2 5.2 +/- 1 to 152.7 +/- 2 mu M showed that 3a, 3b, 3c, 3d, and 3g have better anticancer activity than Cisplatin incredibly complex 3a against both cancer cell line. All Au-NHC complexes showed excellent antimicrobial activity against different bacteria and fungi. 3a was the complex that exhibited the best antimicrobial activity here as well. The XO inhibitory activity experimental results indicated that all gold complexes showed remarkable inhibition activity against XO compared to the generally used standard, allopurinol. The range of IC50 value was determined from 0.407 to 2.681 mu M. 3d complex showed the lowest IC50 value at 0.407 mu M. DNA binding experiments were performed using agarose gel electrophoresis to observe the ability of synthesized Au-NHC complexes to interact with the supercoiled pUC19 plasmid DNA. Molecular docking studies were performed to determine the binding mode of all active compounds against the XO enzyme, antibacterial, antifungal, and MCF-7 cell lines.
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    Synthesis, biological evaluation and molecular docking studies of 8-(hetero)aryl caffeine derivatives
    (Elsevier Science Sa, 2023) Khan, Siraj; Bugday, Nesrin; Yasar, Seyma; Rehman, Asim Ur.; Ul Haq, Ihsan; Yasar, Sedat
    A series of 8-(hetero)aryl caffeine was synthesized by the C -H bond activation reaction using Pd-NHCs complexes as a catalyst. 8-(hetero)aryl caffeine derivatives were screened for their antioxidant, antimicro-bial, and enzyme inhibitory activities and in-silico studies. The 4a, 4b, 4e, 4f, 4 g, 4i, and 4n showed sig-nificant total antioxidant capacity (TAC) of 64.03, 50.87, 70.02, 98.14, 71.81, 45.48, and 44.28 & mu;g AAE/mg, respectively. The 4a, 4b, 4d, 4e, 6 h, 4i, 4j, 4k, and 4l were found active against Staphylococcus aureus at a minimum inhibitory concentration of 25, 12.5, 12.5, 12.5, 12.5, 6.25, 6.25, 6.25, and 6.25 & mu;g/ml, respec-tively. Some derivatives displayed activity against Escherichia coli, Bacillus subtilus, Klebsiella pneumonae, and Pseudomonas aeruginosa.A good activity was exhibited against Alternaria solani among five fungal strains. All the com-pounds (4a-4n) showed excellent protein kinase inhibitory activity except 4e, 4 g, and 4n. Addition-ally, 8-(hetero)aryl caffeine derivatives showed & alpha;-amylase inhibition potential (IC50 = 1.49 & PLUSMN; 0.317 to 7.44 & PLUSMN; 0.156 & mu;g/ml) compared to standard acarbose (IC50 = 4.34 & PLUSMN; 0.333 & mu;g/ml). The 4b, 4d, 4j, 4 m, and 4n compounds displayed good & alpha;-glucosidase inhibitory potential. Molecular modeling was done for protein kinase, & alpha;-amylase, and & alpha;-glucosidase. The results of these activities proved the caffeine deriva-tives to be bioactive.& COPY; 2023 Elsevier B.V. All rights reserved.
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    Synthesis, molecular docking, and biological evaluation of 5-alkyl(aryl)-2-isobutylthiazole derivatives: As ?-amylase, ?-glucosidase, and protein kinase inhibitors
    (Wiley, 2022) Khan, Siraj; Bugday, Nesrin; Rehman, Asim Ur; Ul Haq, Ihsan; Yasar, Sedat; Ozdemir, Ismail
    A series of 18 biologically active C5-arylated-2-isobutylthiazole derivatives that were synthesized by Pd-NHC complexes [Pd(mu-Cl)Cl (NHC)](2), NHC = SIXyl, 2), (LCl2Pd-NHC, L = PPh3, 3), (LCl2Pd-NHC, L = Py, 4), (LCl2Pd-NHC, L = 3-CHO-Py, 5) catalyzed C-H bond activation reactions. The catalytic activity of Pd-NHC complexes was examined on the C-H bond activation reaction of 2-isobutylthiazole. All Pd-NHC complexes were characterized by( 1)H nuclear magnetic resonance specroscopy (NMR), C-13 NMR, fouirer transform infrared spektroscopy (FTIR), quadrupole-time of flying-liquit cromotagraphy/mass spektroscopy (Q-TOF-LC/MS), gas chromatography-mass spectrometry (GCMS), and melting point detection technique. The physicochemical properties, pharmacokinetics, and drug-likeness were calculated by SwissADME. PkCSM database was used to calculate toxicities profile. All the products (6a-6s) were additionally assessed in vitro for their antidiabetic potential using alpha-amylase and alpha-glucosidase inhibitory activities. The protein kinase activity was performed to evaluate their anticancer activities. All the compounds possess drug-like characters as they followed Lipinski's rule of five (RO5). Almost all the compounds showed no to fewer toxicities. In addition, other than the compounds, that is, 6a, 6b, 6c, 6m, 6n, 6p, and 6s, the rest of the compounds showed good alpha-glucosidase inhibitory potential (IC50 7.17 +/- 0.201 to 74.08 +/- 0.244 mu g/ml) when compared with acarbose standard (IC50 16.59 +/- 0.135 mu g/ml). All compounds had moderate to good inhibitory potential against the alpha-amylase enzyme, with IC50 values ranging from 12.00 +/- 0.289 to 76.15 +/- 0.477 mu g/ml. Eleven analogs (6e, 6f, 6g, 6h, 6j, 6k, 6l, 6n, 6o, 6p, and 6r) showed good to moderate activity. Seven analogs (6a, 6b, 6c, 6d, 6i, 6m, and 6s) showed no alpha-amylase inhibitory activity. The protein kinase inhibition potential was determined for the first time, and the compounds 6d, 6e, 6f, 6h, 6k, 6p, and 6r depicted activity with the zone of inhibition in the range of 9 +/- 1.3 to 19 +/- 1.5 mm. The ligands and active site binding interactions of alpha-glucosidase, alpha-amylase, and protein kinase enzymes were also studied using molecular modeling.