Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Article Citation - WoS: 9Citation - Scopus: 8Quantitative Determination of Phenolic Compounds in Propolis Samples From the Black Sea Region (türkiye) Based on Hptlc Images Using Partial Least Squares and Genetic Inverse Least Squares Methods(Elsevier, 2023) Güzelmeriç, Etil; Özdemir, Durmuş; Şen, Nisa Beril; Çelik, Cansel; Yeşilada, ErdemThe complex chemical composition of propolis is related to the plant source to be used by honeybees. Propolis type is defined based on the plant source with the highest proportion in its composition, which is determined by chromatographic techniques as high-performance thin-layer chromatography (HPTLC). In addition to marker component identification to specify the propolis type, quantification of its proportion is also significant for prediction and reproducible pharmacological activity. One drawback for propolis marker component quantita-tion is that during the chromatographical analysis, not the main but the other plant sources with less proportion may cause interferences during the chemical analysis. In this study, the amounts of marker components were compared with the reference analysis data obtained by high-performance liquid chromatography (HPLC) and from HPTLC images using Partial Least Squares (PLS) and Genetic Inverse Least Squares (GILS) regression methods. Firstly, HPTLC images of propolis samples were processed by an image algorithm (developed in MATLAB) where the bands of each standard and the samples were cut same dimensional pieces as 351 x 26 pixels in height and width, respectively. Simultaneously, reference analysis of the marker components in propolis samples was performed with a validated HPLC method. Consequently, the reference values obtained from HPLC versus PLS, and GILS predicted values of the eight compounds based on the digitized HPTLC images of the chromatograms were found to be matched successfully. The results of the multivariate calibration models demonstrated that HPTLC images could be used quantitatively for quality control of propolis used as a food supplement.Article Citation - WoS: 3Citation - Scopus: 3Synthesis and Antifungal and Antibacterial Bioactivities of Diborolanes Containing Arylamines(Elsevier, 2023) Aygün, Muhittin; Sevinçek, Resul; Özgener, Hüseyin; Bıyık, Hacı Halil; Metin, Kubilay; Şahin, Yüksel; Poyrazoğlu Çoban, Esra; Gürbüz, BurçinA good yield of 1,2-diarylamino-1,2-diborolanes 2 was obtained from the reaction of 1,2-dichloro-1,2-diborolane 1 and ArNHLi (an anilide). The structures of these new derivatives were characterized by nuclear magnetic resonance spectroscopy. The molecular structures of 2a and 2b were also determined using single-crystal X-ray diffraction. Antimicrobial activities of synthesized compounds against some Gram-positive and -negative bacteria and yeasts were determined. Some compounds were found to have strong antibacterial and antifungal properties, especially against the bacterium, S. pneumonia, which is the causative agent of pneumonia, and the fungus, C. albicans, which is the causative agent of candidiasis. The compounds 2a and 3 had a powerful effect (compound 2a and 3 = 1 μgmL−1) against S. pneumoniae ATCC 27336 bacteria. In addition, compounds 2a, 3 and 2f were observed to have strong effects (compound 2a, 3, 2f = 2 μgmL−1) against C. albicans ATCC 10231 and C. utilis ATCC 9950. The results obtained were found to be more effective than the MIC values (128–64 μgmL−1) of Streptomycin and Flukanozol drugs used for bacteria and yeasts. The results of our study show that the synthesized substances can be used for new drug applications that are being developed against infectious diseases in the pharmaceutical industry. © 2023 Elsevier B.V.Article Citation - WoS: 7Citation - Scopus: 7Regio- and Stereo-Chemical Ring-Opening Reactions of the 2,3-Epoxy Alcohol Derivative With Nucleophiles: Explanation of the Structures and C-2 Selectivity Supported by Theoretical Computations(Elsevier, 2022) Gündoğdu, Özlem; Atalay, Abdurrahman; Çelebioğlu, Neslihan; Anıl, Barış; Şahin, Ertan; Şanlı Mohamed, Gülşah; Bozkaya, Uğur; Kara, YunusThe ring-opening reactions of (1aS,2S,6bR)-5-ethyl-2-hydroxyhexahydro-4H-oxireno[2,3-e]isoindole-4,6(5H)-dione were investigated under very mild and nonchelated conditions. C-2 selective ring-opening products were obtained with nucleophilic additions such as Cl−, Br− and N3−. The exact configuration of (3aS,4R,5R,6S,7aS)-5-chloro-2-ethyl-4,6-dihydroxyhexahydro-1H-isoindole-1,3(2H)-dione was determined by X-Ray diffraction analysis which was obtained from the reaction of epoxy alcohol with HCl. On the other hand, theoretical computations were carried out to explain the regioselectivity in the ring opening reaction of epoxy alcohols. The results showed that the ring-opening reaction of both epoxy alcohols proceeds in a kinetically controlled manner and regioselectivity occurs depending on the transition state.Article Citation - WoS: 3Citation - Scopus: 6Hybrid Photonic-Plasmonic Mode-Coupling Induced Enhancement of the Spontaneous Emission Rate of Cds/Cdse Quantum Emitters(Elsevier, 2022) Gökbulut, Belkıs; İnanç, Arda; Topçu, Gökhan; Özçelik, Serdar; Demir, Mustafa Muammern this paper, a hybrid photonic-plasmonic resonator, which comprises an electrospun polymer fiber with a micrometer diameter and a core/shell nanostructure with a gold nanoparticle core, is constructed to investigate the dynamics of the coupled spontaneous emission of CdS/CdSe quantum dots (QDs). The gold nanoparticle core; covered with a silica shell, anchored with individual CdS/CdSe QDs, is placed inside a hollow cylindrical nanocavity formed on the surface of the microfiber to enable integration of the optical mode with the plasmonic effect, which is induced by the localized surface plasmons of the metal nanoparticle being present in the vicinity of the dipoles. The spontaneous emission rate of the QDs, coupled into the hybrid photonic-plasmonic mode, is measured to enhance by a factor of 23 via a time-resolved experimental technique. This result suggests that the regeneration of the optical mode-field inside the photonic-plasmonic resonator through the interaction of the dipoles with the localized surface plasmons of a metal nanoparticle strongly enhances the density of the electromagnetic states of the quantum emitters to facilitate an enhanced spontaneous emission within the host medium of the proposed polymer based-photonic structure.Article Citation - WoS: 8Citation - Scopus: 11The Effect of Protein Bsa on the Stability of Lipophilic Drug (docetaxel)-Loaded Polymeric Micelles(Elsevier, 2021) Polat, Hürriyet; Çevik Eren, Merve; Polat, MehmetPolymeric micelles are promising delivery vehicles for improving the efficacy of anticancer drugs and reducing their side effects. However, considering the binding ability of serum albumin, the possible interaction of micelles with the native plasma components in the bloodstream raises serious questions on micellar stability. The stability of barren or drug-loaded copolymeric micelles was investigated systematically in distilled water (DW) and simulated body fluid (SBF) solutions in the presence of a model protein. The copolymer was a Pluronic® series triblock copolymer (P-123), the drug was strongly lipophilic docetaxel (DOC) and the protein was Bovine Serum Albumin (BSA). The effect of such factors as BSA and DOC concentrations and the aging of the micellar solutions was studied. Both the barren and drug-loaded micelles were quite stable in blank DW and SBF solutions for long times up to 10 days. They lost integrity and showed no inclination to re-assemble when the BSA concentration reached a critical value, which was very close to the plasma Human Serum Albumin (HSA) concentration. The presence of DOC in the micellar cores could not prevent disintegration. The results illustrate clearly that ensuring the stability of polymeric micelles in blood plasma should be an important design factor in their use as drug carriers.Article Citation - WoS: 5Citation - Scopus: 5Synthesis and Structures of 1,3,2,4,5-Diazatriborolidines(Elsevier, 2019) Fırıncı, Erkan; Sevinçek, Resul; Bursalı, Banu; Özgener, Hüseyin; Burgaz, Osman; Şen, Ceren; Şahin, YükselThe derivatives of diazatriborolidine are a class of 5-membered heterocyclic compounds containing a ring with two nitrogen atoms and three boron atoms. The 1,3,2,4,5-diazatriborolidine derivatives were synthesized from 1,2-bis(N-lithium-arylamino) diborane(4) and dichloro-dimethylaminoborane with high yield. The structures of these new derivatives were determined using nuclear magnetic resonance (NMR) spectroscopy. The molecular structures of 3a, 3b, 3d, 4b and 4c were determined using single-crystal X-ray diffraction. Their structural features were discussed and compared with similar diazatriborolidines. In addition, the enthalpy of formation of B and N atoms containing five membered heterocycles were calculated theoretically for the first time. Also, an easy and efficient synthesis route has been reported for preparation of 1,3,2,4,5-diazatriborolidine derivatives.Article Citation - WoS: 13Citation - Scopus: 15Analysis of Dilution Induced Disintegration of Micellar Drug Carriers in the Presence of Inter and Intra Micellar Species(Elsevier, 2020) Polat, Hürriyet; Kutluay, Gülistan; Polat, MehmetMicelles of self-assembling polymeric surfactant molecules are promising nanoscopic carriers for lipophilic and toxic drugs, genes, and imaging molecules. Though it is a must for successful transport, ensuring micelle integrity is a challenge during intravenous injection where micelles must endure abrupt dilutional effects and encounters with native molecules. Therefore, direct observational evidence of how micelles behave during dilution is valuable in manipulating the designs of these carriers for a succesful drug delivery. Morphology and stability of the barren and a drug-loaded (lipophilic probucol) micelles of a polymeric surfactant (Pluronic® P123) were monitored during systematic re-dilution in distilled water and simulated body fluid in the presence of a model protein (bovine serum albumin). It was observed through surface tension, dynamic light scattering, laser velocimetry, transmission scanning and transmission electron microscopy, and atomic force microscopy analyses that the micelles disintegrated to various degrees in all cases upon dilution. The results indicate that dilution effects must be taken into account in designing micellar drug carriers. The assistance of some other means of protection such as encapsulation should be considered for ensuring micelle integrity within the bloodstream. © 2020 Elsevier B.V.Article Citation - WoS: 6Citation - Scopus: 6Palladium-Catalysed Reactions of Conjugated Enyne Oxiranes With Organoborons: a Diastereoselective Method of the Synthesis of 2,4,5-Trienol Derivatives(Elsevier, 2017) Ziyanak, Fırat; Kuş, Melih; Alkan Karadeniz, Leman; Artok, LeventA palladium-catalysed reaction of conjugated enyne oxiranes with organoboron reagents is described. This method allows aryl-substituted vinylallenes containing a hydroxyl group on the allylic position to be synthesized, with good diastereomeric ratios, under mild conditions.