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Öğe The anticancer activity of visnagin, isolated from Ammi visnaga L., against the human malignant melanoma cell lines, HT 144(Springer, 2019) Aydogmus-Ozturk, Fatma; Jahan, Humera; Beyazit, Neslihan; Gunaydin, Keriman; Choudhary, Muhammad IqbalMelanoma is a cancer of melanocyte cells and has the highest global incidence. There is a need to develop new drugs for the treatment of this deadly cancer, which is resistant to currently used treatment modalities. We investigated the anticancer activity of visnagin, a natural furanochromone derivative, isolated from Ammi visnaga L., against malignant melanoma (HT 144)cell lines. The singlet oxygen production capacity of visnagin was determined by the RNO bleaching method while cytotoxic activity by theMTT assay. Further, HT 144 cells treated with visnagin were alsoexposed to visible light (400 nm) for 25min to examine the illuminationcytotoxicactivity.The apoptosis was measured by flow cytometry with annexin V/PI dual staining technique. The effect of TNF-secretion on apoptosis was also investigated. In standard MTT assay, visnagin (100 mu g/mL) exhibited 80.93% inhibitory activity against HT 144 cancer celllines, while in illuminated MTT assayat same concentration it showed lesser inhibitory activity (63.19%). Visnagin was induced apoptosis due to the intracellular generation of reactive oxygen species (ROS) andshowed an apoptotic effect against HT 144 cell lines by 25.88%. However, it has no effect on TNF- secretion. Our study indicates that visnagin can inhibit the proliferation of malignant melanoma, apparently by inducing the intracellular oxidative stress.Öğe CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF MENTHA PIPERITA VAR. CITRATA EXTRACTS OBTAINED BY DIFFERENT EXTRACTION SOLVENTS(2022) Kürekci, Cemil; Beyazit, NeslihanThe main aim of this study was to evaluate the phytochemical composition of extracts of Mentha piperita var. citrata obtained by using three different solvents as well as their antimicrobial activity against a panel of Gram positive and Gram negative bacteria. The antibacterial activities of the extracts (hexane, chloroform, and 70% aqueous methanol) were tested against a panel of bacteria using broth microdilution method. Rosmarinic acid (10.505 mg/g extract), cynaroside (8.545 mg/g extract) and cosmosiin (8.489 mg/g extract) appeared to be the major components of methanolic extract, whereas acacetin was the most abundant (8.438 mg/g extract) component of chloroform extract. M. citrata extracts showed significant antimicrobial activity against Gram positive bacteria at different concentrations. Chloroform extract from M. citrata showed antimicrobial activity at concentration of 512-4096 µg/mL, whereas hexane and methanolic extracts had activity at 1024-4096 µg/mL and 2048-4096 µg/mL, respectively. This study shows the different chemical composition and antimicrobial activities of M. citrata extracts obtained by using different extraction solvents.Öğe Chromone-based Schiff base metal complexes as catalysts for catechol oxidation: Synthesis, kinetics and electrochemical studies(Pergamon-Elsevier Science Ltd, 2017) Beyazit, Neslihan; Cakmak, Didem; Demetgul, CahitTwo new Schiff base ligands with chromone moiety and their transition metal complexes were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conductance and TGA analyses, FT IR, UV-Vis, NMR and mass spectroscopy. All the complexes synthesized have been investigated as functional models for catechol oxidase (catecholase) activity by employing 3,5-di-tert-butylcatechol as a model substrate. The two mononuclear copper(II) and two mononuclear iron(II) complexes show catecholase activity with turnover (k(cat)) numbers lying in the range 27.2-1328.4 h(-1). According to the kinetic measurement results, the rate of catechol oxidation follows first order kinetics and iron(II) complexes were found to have higher catalytic activity than those of copper(II) complexes. Electron donating substituent on Schiff base ligand enhanced the catalytic activity of metal complexes while the electron-withdrawing substituent led to a decrease in activity. The electrochemical properties of two Schiff bases and their metal complexes were also investigated by Cyclic Voltammetry (CV) using glassy carbon electrode (GCE) at various scan rates. Electrochemical processes of all the compounds were observed as irreversible. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Crystal structure and DNA binding properties of khellin oxime(Elsevier, 2019) Beyazit, Neslihan; Kaya, Kerem; Senel, Pelin; Ozdemir, Ayse Daut; Golcu, AysegulThe dried fruits of Ammi visnaga were subjected to Soxhlet extraction with water, followed by hexane and purified by column chromatography to yield Khellin (1). Oximation of 1 yielded khellin oxime (2), crystallized by slow evaporation from CH2Cl2:EtOAc (6:3), characterized by single-crystal X-ray diffraction method for the first time. The DNA binding affinities of the 1 and 2 have been appraised by examining their ability to bind to dsFSDNA with ultraviolet-visible and fluorescence spectroscopies, thermal denaturation and square wave voltammetry techniques. The binding constants of the both compounds with dsFSDNA are calculated by UV-vis measurements. The square wave voltammograms proved that both compounds bind to dsFSDNA by intercalative binding mode. Competitive studies with ethidium bromide (EB) have shown that 1 and 2 exhibit the ability to displace the DNA-bound EB indicating 1 and 2 bind to DNA with intercalation with EB for the intercalative binding site as a challenging displacement. (C) 2019 Elsevier B.V. All rights reserved.Öğe Khellin and visnagin in different organs of Ammi visnaga and Ammi majus(Taylor & Francis Ltd, 2023) Adimcilar, Veselina; Beyazit, Neslihan; Erim, F. BediaAmmi visnaga and Ammi majus are plants that have long been used in traditional medicine. Nowadays, both herbs are commercially marketed as alternative medicines in different formulations. The main active ingredients of A. visnaga are known as khellin and visnagin. Information on the quantitative amounts of both bioactive substances in the different organs of the plant is lacking. This study aims to determine the amounts of these two active substances in the five organs of both plants from Turkey and provide information to the pharmaceutical industry. For this purpose, a fast and reliable micellar electrokinetic chromatography method was applied. It was found that Ammi visnaga, flowers, seeds, and leaves are good sources of both khellin and visnagin. Ammi majus only contains khellin in its seeds and flowers.Öğe The protective effect of Boswellic acid and Ellagic acid loaded, colon targeted, and pH-sensitive N-succinyl chitosan in ulcerative colitis rat model(Elsevier, 2022) Yipel, Mustafa; Tekeli, Ibrahim Ozan; Altinok-Yipel, Fulya; Coskun, Pinar; Aslan, Abdullah; Guvenc, Mehmet; Beyazit, NeslihanTargeted drug delivery systems that provide therapeutic activity with lower concentrations of both herbal and other substances, while reducing access to non-target sites and undesirable effects; have an important potential for future projections in terms of pharmacological and toxicological studies. The present study aimed to investigate the protective effects of Acetyl 11-keto-beta-boswellic acid (AKBA) and Ellagic acid (EA) loaded, colon targeted, and pH-Sensitive N-succinyl chitosans (NsCh) in ulcerative colitis (UC) model induced by acetic acid (AA) in rats. The physicochemical characterization (elemental analysis, FT-IR, DSC, XRD, SEM, NMR) analyses, swelling, and releasing tests of NsCh's suggested that AKBA and EA were successfully loaded to pH-sensitive polymer and targeted to the colon. The targeted AKBA and EA were administered to Wistar rats (n:30, 5 groups) and damage, inflammatory cytokine, protein expression, oxidative stress, and antioxidant parameter levels in colon tissues of the groups were determined. Increase in the levels of CAT, GPx activities, and decrease in necrosis, inflammation, and levels of MDA, TNF-alpha, COX-2, NF-kB were observed in the targeted EA and AKBA groups compared to the UC group. The potential protective effect of EA and AKBA loaded, colon-targeted, pH sensitive controlled releasing system against UC and the potential to be licensed preparations by completing the next stages of in vitro and in vivo studies were demonstrated.Öğe Synthesis, characterization and antioxidant activity of chitosan Schiff base derivatives bearing (-)-gossypol(Elsevier Sci Ltd, 2020) Beyazit, Neslihan; Cakran, Halide Sinem; Cabir, Ali; Akiscan, Yasar; Demetgul, CahitIn this work, two new chitosan-Schiff base derivatives (HCS-GSP and LCS-GSP) were synthesized by the condensation reaction of high molecular weight chitosan (HCS) and low molecular weight chitosan (LCS) with (-)-gossypol (GSP), respectively. For this purpose, racemic gossypol was isolated from cotton seeds and it was further enantiomerically purified by diastereomeric resolution technique using L-tryptophan methyl ester hydrochloride. Then, chitosan polymers were derivatized with (-)-gossypol by the condensation reaction. The isolated and synthesized coumpounds were characterized by physical measurements and spectroscopic methods (elemental analysis C,H,N, Uv-vis, FT-IR, 1H&13C NMR and TG/DTG/DTA). The antioxidant activity of high molecular weight chitosan (HCS), low molecular weight chitosan (LCS) and their gossypol derivatives was evaluated as radical scavengers against 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH). The results showed that both of the chitosan-gossypol derivatives (HCS-GSP and LCS-GSP) had a better ability to scavenging DPPH radical (IC50, 12 mu g/mL and 16 mu g/mL, respectively) than its unmodified chitosan.Öğe Synthesis, characterization and antioxidant activity of chitosan-chromone derivatives(Elsevier Sci Ltd, 2018) Demetgul, Cahit; Beyazit, NeslihanIn this study, a new chromone-functionalized chitosan Schiff base and its cross-linked derivative were synthesized and characterized by FT-IR, UV-vis, C-13 CP/MAS solid-state NMR, TGA, XRD-powder and SEM measurements and elemental analysis data. Degrees of substitution (DS) were determined from the elemental analysis by using the C/N ratios. The in vitro antioxidant activity of high molecular chitosan and its chromone derivatives was evaluated as radical scavengers against 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH%). The results showed that both of the chitosan-chromone derivatives have good antioxidant potential which might be due to the phenolic group introduced after chemical modification of chitosan with a chromone derivative. Chromone-chitosan Schiff base (CSCH) had a better ability to scavenging DPPH radical (IC50, 0.88 mg/mL) than that of its cross-linked derivative (CSCH-TP) obtained by using terephthalaldehyde (IC50, 1.32 mg/mL).Öğe Synthesis, characterization and catecholase-like activity of new Schiff base metal complexes derived from visnagin: Theoretical and experimental study(Elsevier, 2016) Beyazit, Neslihan; Catikkas, Berna; Bayraktar, Sahin; Demetgul, CahitA new tetradentate, unsymmetrical Schiff base ligand (H2L) containing a donor set of N2O2 and its mononuclear Cu(II) and Fe(II) complexes ([CuL] and [FeL]), were synthesized and characterized on the basis of their elemental analysis, FT-IR, Raman, H-1 and C-13 NMR spectra, electronic and mass spectra, molar conductivity and magnetic susceptibility measurements. Density functional theory (DFT) calculations were performed in order to clarify molecular structures, 1H NMR and 13C NMR chemical shift values, frontier molecular orbitals (FMOs), nonlinear optical properties and map of molecular electrostatic potential (MEP) of the title molecules. In agreement with trials, the results provide a full explanation of the highest efficiency observed for the compounds in relation to the electronic and the structural characteristics. The catecholase-like activity of the complexes toward the oxidation of 3,5-ditert-butylcatechol (3,5-DTBC) to the corresponding quinone showed that both complexes have moderate catalytic activity. [FeL] shows higher activity (k(cat) = 26.4 h(-1)) than that of [CuL] (k(cat) = 23.4 h(-1)). (c) 2016 Elsevier B.V. All rights reserved.
