Browsing by Author "Gumus, Aysegul"

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Characterization, in Vitro Bioaccessibility and Antidiabetic Activities of Maltodextrin and Lecithin Nanomaterials Loaded With Ellagic Acid
(Springer, 2024) Okumus, Emine; Bakkalbasi, Emre; Gumus, Aysegul
Pomegranate peel is one of the wastes generated in large quantities in the food industry and ellagic acid is a natural bioactive phenolic compound in pomegranate peel. In this study, high-purity and low-cost ellagic acid was produced by acid hydrolyze process from pomegranate peel and characterization, in vitro bioaccessibility, antioxidant, and antidiabetic activity of the ellagic acid nanoencapsulated with maltodextrin and soy lecithin were studied. The extract yield and purity of ellagic acid was 6.47 and 88.74%, respectively. Results showed that lecithin coated samples were more stable with - 43.16 mV zeta potential and had higher encapsulation efficiency (99.29%) compared to maltodextrin. However, coated samples with maltodextrin had higher production efficiency (91.40%) and loading capacity (54.70%). The thermal resistance of ellagic acid after the nanoencapsulation process was significantly raised. The ellagic acid nanoencapsulated with maltodextrin had higher bioaccessibility (80.22%) and solubility in biological buffers (64.00-98.20%). The alpha-amylase and alpha-glucosidase inhibitiory activities of the ellagic acid decreased after the encapsulation process. However, the alpha-amylase inhibitory activities of the nanoencapsulated materials were higher than acarbose as a positive control. As a result, thermal resistance, solubility in a biological medium, and bioaccessibility of ellagic acid after nanoencapsulation with maltodextrin can be increased. Thus, the use of ellagic acid nanoencapsulated with maltodextrin in the food, cosmetic, and pharmacological industries can be diversified.
Chemoenzymatic Synthesis of a 1,2,3-Triazolo Derivative
(Walter de Gruyter Gmbh, 2015) Gumus, Aysegul; Mert, Kudret
The stereoselective synthesis of a 1,2,3-triazolod-lactone (+)-6 derived from a homoallyl alcohol (S)-(-)-1 backbone was accomplished. 2-Thienyl-substituted allyl alcohol rac-1 was efficiently resolved through enzymatic method with high ee (95%) and known stereochemistry. An enantiomerically enriched azidoalcohol (+)-4 derived from a homoallyl alcohol was subjected to the Huisgen 1,3-dipolar cycloaddition reaction with diethyl acetylenedicarboxylate, followed by intramolecular cyclization of the corresponding cycloadduct (+)-5, to yield the 1,2,3-triazolo-delta-lactone derivative.
A Computational Study on A Series of Phenanthrene and Phenanthroline Based Potential Organic Photovoltaics
(Soc Chemists Technologists Madeconia, 2017) Gumus, Aysegul; Gumus, Selcuk
A series of phenanthrene and phenanthroline derivatives were considered computationally by the application of Density Functional Theory at the B3LYP/6-31++G(d,p) level to investigate their potential usage as organic solar cell components, thermally activated delayed fluorescence and nonlinear optic compounds. The structures were constructed as a D-pi-A motif in order to increase the ability to achieve intramolecular charge transfer enabling them to act as organic semiconductors. The inter-frontier energy gap of all compounds was found to be in the range of semiconductors. The thermally activated delayed fluorescence (TADF) properties of the compounds were also discussed in relation to the results obtained by TD-DFT calculations. Some of them possessed very narrow triplet-singlet transition energy leading to future TADF applications. Moreover, the nonlinear optic characteristics of all compounds were investigated through calculations of the total molecular dipole moment (mu(tot)), linear polarizability (alpha(tot)) and hyperpolarizability (beta(tot)). The results indicate the potential nonlinear optic property of all of the systems.
Design, Stereoselective Synthesis and Computational Calculations of Novel Hybrid Compounds Via Pauson-Khand Reactions
(Pergamon-elsevier Science Ltd, 2017) Gumus, Selcuk; Aslan, Nezir; Buyukadali, Nalan Nuriye; Gumus, Aysegul
A series of novel chiral hybrid compounds between benzofuran and bicyclic cyclopentenone and also benzothiophene and bicyclic cyclopentenone have been designed and synthesized. Chiral enynes derived from enantiomerically enriched homoallyl and homopropargyl alcohols were converted into bicyclic cyclopentenone structures by intramolecular Pauson-Khand reactions. This strategy provides a facile access to various bicyclic cyclopentenones substituted with benzofuran or benzothiophene ring systems in good yields. In addition to the experimental work, the ground state geometries of the hybrid compounds were optimized using Density Functional Theory applications at the B3LYP/6-31G(d,p) level in order to obtain information about the 3D geometries and electronic structure. (C) 2017 Elsevier Ltd. All rights reserved.
Investigation of Tadf Properties of Novel Donor-Acceptor Type Pyrazine Derivatives
(Soc Chilena Quimica, 2019) Irak, Zeynep Turhan; Gumus, Aysegul; Gumus, Selcuk
In this study 2,3-dicyanopyrazine based acceptor was combined with donors to obtain Donor-Acceptor type potential thermally activated delayed fluorescence (TADF) emitters (1-10). All molecules' structural and electronic properties were computed theoretically at the level of Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) with the application of three different hybrid functionals. Most of the designed structures have been found to possess the potential to be TADF compounds because they have very narrow energy gap between their first excited singlet and triplet states. As a result, 6-10 molecular pyrazine derivative has been calculated as the best candidate for the purpose. Moreover, having 0.90 eV interfrontier molecular orbital energy band gap, compound 6 has a very strong potential to serve as an efficient OLED material.
Investigation of the Aromaticity of Mono, Di, Tri and Tetraazaphenanthrene Derivatives
(Walter de Gruyter Gmbh, 2020) Ozturk, Erhan; Irak, Zeynep Turhan; Karakoyun, Necdet; Gumus, Aysegul; Gumus, Selcuk
In this chapter mono, di, tri and tetraaza substituted phenanthrene derivatives have been investigated computationally with B3LYP/6-31 + G(d,p) level of theory. Substitution of carbon atom of the main structure with nitrogen obviously disturbs the aromaticity, indeed it decreases it. Thus, the idea of regaining of the aromaticity back by using electron withdrawing groups came across. As a result of the computational calculations, energetically most unfavored structures have been found to be those where aza substitutiona are vicinal. Secondly, the aromaticities of the present species depend on the position of the centric substituent. In addition, the effect position of the side substituent has been considered. The system becomes more aromatic (possess greater negative NICS values or smaller HOMA value) when the electron withdrawing atoms or groups are adjacent to the centrically substituted heteroatoms.
Isoquinoline-Substituted Hybrid Compounds: Synthesis and Computational Studies
(Mdpi, 2016) Gumus, Aysegul; Gumus, Selcuk; Yenidede, Duygu
The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazoles from isoquinoline-substituted homopropargyl alcohol backbone is described (42-88% yields). A ring closing metathesis (RCM) reaction and an intramolecular Pauson-Khand reaction (PKR) of enyne system derived from a homopropargyl alcohol backbone to afford the corresponding isoquinoline-substituted dihydropyran and cyclopentenone-pyran, respectively, are also described (54% and 78% yields). Information about the structural, electronic and physico-chemical properties of the novel compounds, obtained by density functional theory application, is also reported.
Isoquinoline-Substituted Triazole and Pyran Derivatives: Synthesis and Computational Studies
(Tubitak Scientific & Technological Research Council Turkey, 2016) Yenidede, Duygu; Gumus, Selcuk; Gumus, Aysegul
The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazoles from isoquinoline-substituted homopropargyl alcohol backbone is described (42%-88% yields). A ring closing metathesis reaction and an intramolecular Pauson-Khand reaction of enyne system derived from a homopropargyl alcohol backbone to afford the corresponding isoquinoline-substituted dihydropyran and cyclopentenone-pyran, respectively, are also described (54% and 78% yields). Information about the structural, electronic, and physico-chemical properties of the novel compounds, obtained by density functional theory application, is also reported.
Modular Logic Gates: Cascading Independent Logic Gates Via Metal Ion Signals
(Royal Soc Chemistry, 2014) Ecik, Esra Tanriverdi; Atilgan, Ahmet; Guliyev, Ruslan; Uyar, T. Bilal; Gumus, Aysegul; Akkaya, Engin U.
Systematic cascading of molecular logic gates is an important issue to be addressed for advancing research in this field. We have demonstrated that photochemically triggered metal ion signals can be utilized towards that goal. Thus, independent logic gates were shown to work together while keeping their identity in more complex logic designs. Communication through the intermediacy of ion signals is clearly inspired from biological processes modulated by such signals, and implemented here with ion responsive molecules.
Potential Thermally Activated Delayed Fluorescence Properties of a Series of 2,3-Dicyanopyrazine Based Compounds
(Walter de Gruyter Gmbh, 2018) Gumus, Aysegul; Gumus, Selcuk
2,3-Dicyanopyrazine based acceptor was combined with a series of well studied donors to obtain donor-acceptor type potential thermally activated delayed fluorescence emitters. Their structural and electronic properties were computed theoretically at the level of density functional theory and time dependent density functional theory with the application of two different hybrid functionals and various basis sets. Almost all of the designed structures were computed to have the potential of being TADF compounds since they possess very narrow singlet-triplet gaps. Indeed, acridine-pyrazine (9) derivative was calculated to be the best candidate for the purpose among them.
Potential Thermally Activated Delayed Fluorescence Properties of a Series of 2,3-Dicyanopyrazine Based Compounds
(Walter de Gruyter Gmbh, 2019) Gumus, Aysegul; Gumus, Selcuk
2,3-Dicyanopyrazine based acceptor was combined with a series of well studied donors to obtain donor-acceptor type potential thermally activated delayed fluorescence emitters. Their structural and electronic properties were computed theoretically at the level of density functional theory and time dependent density functional theory with the application of two different hybrid functionals and various basis sets. Almost all of the designed structures were computed to have the potential of being TADF compounds since they possess very narrow singlet-triplet gaps. Indeed, acridine-pyrazine (9) derivative was calculated to be the best candidate for the purpose among them.
Regioselective One-Pot Synthesis of 1,4-Disubstituted 1,2,3-Triazole Derivatives
(Walter de Gruyter Gmbh, 2014) Gumus, Aysegul; Ucur, Sibel
The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazole derivatives derived from homopropargyl alcohol backbones has been accomplished. Triazoles are obtained in good yields from a variety of readily available aromatic and aliphatic halides without isolation of potentially unstable organic azide intermediates.
The Solvatochromism and Electronic Structure of (e)-2
(Tubitak Scientific & Technological Research Council Turkey, 2019) Gumus, Aysegul; Gulseven Sidir, Yadigar; Sidir, Isa; Gumus, Selcuk
The (E)-2-(2-hydroxystyryl)quinolin-8-ol (abbreviated as HSQ) molecule was synthesized and characterized. The ESIPT, solvatochromism properties, electronic structure, and ground and excited electric dipole moments of this molecule were measured using absorption and fluorescence spectra recorded in 13 different solvents. Its electronic structure via electronic transitions was investigated to find the quantitative values of solvatochromism properties by LSER calculations. The ESIPT mechanism was clarified; ground and excited dipole moments were determined using solvatochromic shift methods. The DFT (B3LYP)/6-311 ++ G(d,p) method and basis set with potential energy surface (PES) calculations of proton transfer were used to explain the ESIPT mechanism. NBO analysis, NLO properties, and behavior under an electric field were also determined.
Stereoselective Synthesis of 1,2,3-Triazolooxazine and Fused 1,2,3-Triazolo Derivatives
(Wiley-v C H verlag Gmbh, 2014) Gumus, Aysegul; Mert, Kudret; Tanyeli, Cihangir
The stereoselective synthesis of 1,2,3-triazolooxazine and fused 1,2,3-triazolo--lactone by applying chemoenzymatic methods is described. trans-2-Azidocyclohexanol was successfully resolved by Novozyme 435 with an ee value of 99%. Installation of the alkyne moiety on the enantiomerically enriched azidoalcohol by O-alkylation, followed by intramolecular azidealkyne [3+2] cycloaddition resulted in the desired 1,2,3-triazolooxazine derivative. Enantiomerically pure azidocyclohexanol was also subjected to the Huisgen 1,3-dipolar cycloaddition reaction with dimethylacetylene dicarboxylate, followed by intramolecular cyclization of the corresponding cycloadduct, to furnish a fused 1,2,3-triazolo--lactone.
Stereoselective Synthesis of Benzofuran and Benzothiophene Substituted Dihydropyran Derivatives Via Ring Closing Metathesis
(Pergamon-elsevier Science Ltd, 2016) Buyukadali, Nalan Nuriye; Aslan, Nezir; Gumus, Selcuk; Gumus, Aysegul
Ring closing metathesis reactions have been applied to diene and enyne systems derived from homoallylic alcohol backbones are described. The key intermediates 2-benzofuranyl la and 2-benzothiophenyl lb substituted homoallylic alcohols were synthesized from their corresponding carboxaldehyde derivatives. Racemic 2-heteroaryl-substituted homoallylic alcohols are successfully resolved to give the corresponding enantiopure acetates and alcohols with 80-99% ee through enzymatic resolution by various lipases. Enantiomerically enriched diene and enyne skeletons derived from homoallylic alcohols were subjected to the ring closing metathesis via first and second generation Grubbs' catalysts and the corresponding chiral heteroaryl-substituted dihydropyran derivatives were obtained with good yields (41-96%). (C) 2016 Elsevier Ltd. All rights reserved.
Synthesis and Biological Evaluation of Quinoline-Triazole and Quinolone-Triazole Conjugates
(Tubitak Scientific & Technological Research Council Turkey, 2018) Gumus, Aysegul; Okumus, Veysi
One-pot synthesis of novel quinoline- and quinolone-substituted 1,2,3-triazoles has been performed from the key intermediates, quinoline- and quinolone-substituted propargyl derivatives 1-3 (48%-88% yields). The antioxidant properties of the newly synthesized compounds, 1a-1c, 2a-2c, and 3a-3c, were evaluated by monitoring DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging abilities, metal chelating effects, and reducing power. The scavenging effects of compounds on the free radical decreased in the order of 3b > 3a > 1b and were found to be 36.3%, 34.9%, and 27.6% at the concentration of 500 mu g/mL, respectively. All of the compounds showed low chelating capacity. Furthermore, the antibacterial activity was studied against gram-positive and gram-negative bacteria and the DNA binding ability of the compounds was evaluated with calf thymus DNA using agarose gel electrophoresis.
Synthesis of 2-Substituted 8-Propargyloxyquinoline Derivatives and Determination of Their Antioxidant, Antibacterial, and Dna Binding Activities
(Tubitak Scientific & Technological Research Council Turkey, 2018) Gumus, Aysegul; Okumus, Veysi; Gumus, Selcuk
2-Substituted 8-propargyloxyquinoline derivatives have been synthesized from 2-substituted-8-hydroxyquinolines by O-propargylation method (30%-98% yields). The newly synthesized compounds were tested for in vitro antioxidant activities such as DPPH radical scavenging, ferrous chelating, and reducing power activities. The maximum radical scavenging (46.5%) and reducing power activities were obtained from 1 and maximum ferrous chelating effect was obtained from 6 (72.1%) at the concentration of 500 mu g/mL. To indicate DNA binding activity of the complexes calf thymus DNA was used. The compounds were also evaluated for their antimicrobial activity against three gram-positive and three gram-negative bacteria. Compounds 3 and 5 exhibited antibacterial activity against all tested gram-positive bacteria.
Synthesis of Quinoline-Pyrene Derivatives and Theoretical Investigation of Their Fluorescence and Electronic Properties
(Wiley-v C H verlag Gmbh, 2022) Gumus, Aysegul; Gumus, Selcuk
Synthesis of novel fluorescent quinoline-pyrene conjugates is described. The key intermediates 2-substituted 8-propynyloxy quinoline and azidomethyl pyrene were connected with triazole bridge by 1,3-dipolar alkyne-azide cycloaddition reaction. Density functional theory methodology with B3LYP/6-311++G(d,p) basis set was applied computationally to gather information about the structural and electronic properties of the quinoline-pyrene compounds. In addition, the metal coordination properties of the triazole bridged molecules were investigated through interactions with several cations. The effect of metal coordination on the stability of the complexes have also been discussed through computations on chelatoaromaticity.
Synthesis, Biological Evaluation of Antioxidant-Antibacterial Activities and Computational Studies of Novel Anthracene- and Pyrene-Based Schiff Base Derivatives
(Tubitak Scientific & Technological Research Council Turkey, 2020) Gumus, Aysegul; Okumus, Veysi; Gumus, Selcuk
Schiff base derivatives with anthracene- and pyrene-based units, Al-A6 and P1-P6 were synthesized (89%-99% yields). Schiff base derivatives were designed to possess an heterocyclic moiety on one side to enhance the coordination ability towards metals. To investigate the biological assay of the newly synthesized compounds, their DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, metal chelating, reducing power, antibacterial and DNA binding activities were tested. A6 (63.1%) showed the maximum free radical scavenging activity among all. However, compound P3 at concentration of 200 mu g/mL possessed the highest metal chelating (45.8%) activity and power of reduction. In addition, P3 and A6 showed antibacterial activity against all bacteria tested and both compounds were very well bound to CT-DNA. Density functional theory method with B3LYP/6-311++ G(d,p) basis set was performed to get information about the structural and electronic properties of the present compounds. In addition, the metal coordination properties of the dimers of the parent Schiff bases were investigated through interactions with Zn2+.
Synthesis, Solvatochromism, Electronic Structure and Nonlinear Optic Properties of Quinolin-8 2-Hydroxybenzoate
(Soc Chemists Technologists Madeconia, 2018) Gumus, Aysegul; Sidir, Yadigar Gulseven; Sidir, Isa; Gumus, Selcuk
Quinolin-8-yl 2-hydroxybenzoate (QHB) was synthesized and its physical and electronic properties were investigated both experimentally and theoretically. The electronic structure and spectral behavior were determined by using UV-vis absorption and fluorescence spectra in 11 different polarity solvent media. The absorption band observed at 306-308 nm is attributed to pi-pi* and n-pi* electronic transitions due to its geometric structure in the solution phase. Solvatochromism of QHB was investigated by using Kamlet-Taft and Catalan methods based on the linear solvation energy relationships (LSER). The Kamlet-Taft solvatochromic model indicates that spectral shifts of absorption and fluorescence spectra are effectively controlled by dispersion-polarization forces which describe the non-specific interactions. The solvatochromic model of Catalan states that solute-solvent interaction is governed by solvent polarity in the absorption spectra and by solvent acidity in the fluorescence spectra. Non-specific interactions have a greater effect on fluorescence spectra compared to absorption spectra. Computational calculations were performed by the application of the B3LYP/6-311+(d,p) level of theory. Conformational analysis performed for QHB showed five staggered conformers on torsional potential energy surfaces. Accordingly, the most stable conformer was found to be the one involving infra-molecular hydrogen bonding. The geometry of the other conformers indicated that the absence of hydrogen bonding gave rise to relatively higher energy. Frontier molecular orbitals (HOMO, LUMO) and non-linear optical (NLO) parameters were calculated by B3LYP/6-311+(d,p) level of theory. Theoretical UV spectra both in gas and solution phases were also investigated by TDDFT-CAM-B3LYP/6-311+(d,p) level of theory.