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    Dichloro-Bis(1-Alkyl/Styryl-Benzimidazole)-Cobalt(II) Pre-Catalyst for Ethylene Dimerization
    (Mdpi, 2025) Hkiri, Shaima; Sahin, Neslihan; Sabourin, Romain; Brandt, Remi; Ozdemir, Ismail; Semeril, David
    A series of five cobalt(II) complexes, dichloro-bis(1-benzyl-benzimidazole)-cobalt(II) (1a), dichloro-bis[1-(4-fluorobenzyl)-benzimidazole]-cobalt(II) (1b), dichloro-bis((Z)-1-styryl-benzimidazole)-cobalt(II) (1c), dichloro-bis[(Z)-1-(2-fluorostyryl)-benzimidazole]-cobalt(II) (1d) and dichloro-bis(1-cinnamyl-benzimidazole)-cobalt(II) (1e), were evaluated in ethylene dimerization. Four of these complexes were described for the first time and fully characterized by IR, elemental analysis, mass and NMR spectroscopy. In the solid state, the cobalt atom exhibited a typical tetrahedral geometry and was found to be coordinated to two chlorine atoms and two benzimidazole rings. In the presence of 20 bar of ethylene and diethylaluminium chloride as a co-catalyst, the complex with styryl substituents on the benzimidazole rings, complex 1c, exhibited the highest activity with a turnover frequency of 3430 mol(ethylene)mol(Co)-1h-1.
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    In Vitro Evaluation of Silver-NHC Complexes Against a Clinical Isolate of Acanthamoeba castellanii: Time- and Dose-Dependent Effects
    (Mdpi, 2025) Akin-Polat, Zuebeyda; Sahin, Neslihan; Hkiri, Shaima; Ly, Bui Minh Thu; Oezdemir, Ismail; Semeril, David
    The synthesis of a series of six chloro[N-alkyl-N-cinnamyl-benzimidazol-2-yliden]silver(I) complexes was successfully achieved, wherein allyl (3a), methoxymethyl (3b), benzyl (3c), 3-fluorobenzyl (3d), 4-fluorobenzyl (3e) and 4-methyl-benzyl (3f) substituents were grafted on the benzimidazole ring. The isolated silver N-heterocyclic carbene (NHC) complexes were identified by microanalyses and mass spectrometry and characterized by FT-IR and NMR spectroscopic techniques. Conclusive evidence for the structures of complexes 3c and 3d was provided by single-crystal X-ray crystallography. The in vitro inhibitory activity of the six Ag-NHC complexes was tested against trophozoites and cysts of the pathogenic Acanthamoeba castellanii strain and the efficacy sequence is as follows: 3d > 3c > 3f > 3a > 3b > 3e. At a concentration of 100 mu M in complexes 3c, 3d and 3f and after 72 h of incubation, 5.3, 3.2 and 6.3% A. castellanii trophozoite viabilities were observed, respectively. The utilization of elevated silver(I) drug concentrations, 1000 mu M, resulted in the near-total eradication of pathogenic protozoa.
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    Silver(I)-NHC Complexes as Dual-Action Agents Against Pathogenic Acanthamoeba Trophozoites: Anti-Amoebic and Anti-Adhesion Activities
    (Mdpi, 2025) Hkiri, Shaima; Sahin, Neslihan; Akin-Polat, Zubeyda; Ustun, Elvan; Ly, Bui Minh Thu; Ozdemir, Ismail; Semeril, David
    A series of six silver(I) complexes, namely bromo(1-benzyl-3-cinnamyl-benzimidazol-2-ylidene)silver (I) (1a), bromo[1-(4-methylbenzyl)-3-cinnamyl-benzimidazol-2-yliden]silver(I) (1b), bromo[1-(3-methoxylbenzyl)-3-cinnamyl-benzimidazol-2-yliden]silver(I) (1c), bromo[1-(3,5-dimethoxy-benzyl)-3-cinnamyl-benzimidazol-2-ylidene]silver(I) (1d), bromo[1-(naphthalen-1-ylmethyl)-3-cinnamyl-benzimidazol-2-ylidene]silver(I) (1e) and bromo[1-(pyren-1-ylmethyl)-3-cinnamyl-benzimidazol-2-yliden]silver(I) (1f), were synthetized and characterized by microanalyses and mass spectrometry and characterized by FT-IR and NMR spectroscopic techniques. The in vitro effects of silver(I) complexes on trophozoites of two Acanthamoeba isolates obtained from patients with keratitis were investigated. The parasites were exposed to concentrations of 10, 100 and 1000 mu M for 24, 48 and 72 h. The complexes exhibited potent, dose- and time-dependent activity. Complete inhibition was observed within 24 h at a concentration of 1000 mu M. At a concentration of 100 mu M, complexes 1c-e exhibited reduced viability to less than 10% within 48 to 72 h. At a concentration of 10 mu M, partial inhibition was observed. Preliminary morphological changes included the loss of acanthopodia, rounding, and detachment. These effects were not observed in the presence of the pre-ligands or commercially available silver compounds. Furthermore, molecular docking was utilized to analyze the molecules against Acanthamoeba castellanii CYP51, A. castellanii profilin IA, IB, and II. The highest recorded interactions were identified as -9.85 and -11.26 kcal/mol for 1e and 1f, respectively, when evaluated against the A. castellanii CYP51 structure.