Person: DİNCEL, DEMET
10 results
Search Results
Now showing 1 - 10 of 10
Publication Metadata only ANALYTICAL METHODS FOR THE DETERMINATION OF POLYBROMINATED DIPHENYL ETHERS IN HUMAN MILK(2020-03-01T00:00:00Z) ASRAM SAĞIROĞLU, ALİ; Onal, Cem; DİNCEL, DEMET; Onal, Armagan; ASRAM SAĞIROĞLU, ALİ; TEKKELİ, ŞERİFE EVRİM; DİNCEL, DEMETPolybrominated diphenyl ethers (PBDEs), which are used as flame retardants, are widely used additives so many different kind of materials that are consumed by public. Current researches reveal a significant increase in the levels of PBDEs in human biological fluids all around the world. According to International Agency for Research on Cancer (IARC), PBDEs are declarated as carcinogenic agents and additionally a considerable risks have been shown in animal studies such as liver damage, alteration of thyroid hormone levels, neurotoxicity and hazardous effects on development of fetus. Due to the simplicity of human exposure routes such as ingestion, inhalation or dermal contact, it gains high importance to quantify PBDEs in biological fluids. The exposure to PBDEs is critic aspecially during pregnancy, fetus development and infancy. Excretion of PBDEs in human milk is the focus area for researchers in recent years.Publication Metadata only Ent-kaurane diterpenoids isolated from Sideritis congesta(2011-12-01) Topcu, GÜLAÇTI; Ertas, Abdulselam; Ozturk, Mehmet; Dincel, Demet; Kilic, Turgut; Halfon, Belkis; TOPÇU, GÜLAÇTI; DİNCEL, DEMETA new ent-kaurane diterpenoid, together with eight known ent-kauranes, were isolated from the petroleum ether and acetone extracts of the whole plant of Sideritis congesta P. H. Davis & Hub.-Mor. and their structures were elucidated as the new compound ent-7 alpha-acetoxy-16 beta, 18-dihydroxy-kaurane (7-acetyldistanol) (1) and the known compounds ent-3 beta,7 alpha-dihydroxy, 18-acetoxy-15 beta,16 beta-epoxykaurane (epoxyisolinearol) (2), sideroxol (3), sideridiol (4), siderol (5), 7-epicandicandiol (6), foliol (7), linearol (8) and sidol (9). Characterization of compounds 1-9 was based on spectral analyses and comparison with reported data, particularly the new compound 1 was identified by 1D- and 2D-NMR and mass spectroscopic analyses. The antioxidant potential of the extracts, and also of the ent-kauranes except for 7, was investigated by three methods including beta-carotene bleaching method, free radical scavenging activity and superoxide anion scavenging activity. The anticholinesterase activity was also evaluated for the ent-kauranes except for 7, and most of the diterpenes exhibited weak acetylcholinesterase inhibitory activity. However, almost all diterpenes exhibited some inhibitory activity against butyrylcholinesterase; particularly, compounds 3 and 6 exhibited better BChE inhibitory activity than the standard compound galanthamine. (C) 2011 Phytochemical Society of Europe. Published by Elsevier B. V. All rights reserved.Publication Metadata only An HPLC Method for the Determination of Saxagliptin in Human Plasma with Fluorescence Detection(2013-12-01) Tekkeli, Şerife Evrim; Kızıltas, M. V.; Dincel, Demet; TEKKELİ, ŞERİFE EVRİM; DİNCEL, DEMETPublication Open Access Spectrophotometric Determination of Erdosteine at Capsule Dosage Forms(2021-03-01T00:00:00Z) Onal, Cem; DİNCEL, DEMET; DİNCEL, DEMETAbstract Objective: Two simple, rapid and sensitive methods were developed for determination of Erdosteine (ERD) in pure form as well as in their pharmaceutical formulations. Methods: The methods were based on formation of colored charge transfer complexes with ERD with chloranil (CA) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The obtained charge-transfer complexes were measured at 454 and 843 nm for CA and TCNQ methods, respectively. Optimization of different experimental conditions were investigated. Results: Beer's plots were obeyed in a general concentration range of 10-500 mu g mL(-1) and 20-600 mu g mL(-1) for CA and TCNQ methods, respectively. The validity of methods in terms of specificity, linearity, accuracy, precision, limit of detection and limit of quantitation were evaluated. Conclusion: The methods were applied successfully in the determination of ERD in capsule dosage forms. Developed new spectrophotometric methods have been found to be very practical and practical. The lack of complex sample preparation increases the applicability of the method.Publication Metadata only Simultaneous Determination of Phenol and p-Cresol in Human Urine by an HPLC Method(2016-06-01) Tekkeli, S. E. Kepekci; Kiziltas, M. V.; Dincel, DEMET; ERKOC, R.; Topcu, GÜLAÇTI; TEKKELİ, ŞERİFE EVRİM; DİNCEL, DEMET; TOPÇU, GÜLAÇTIIntroduction: In patients with chronic kidney disease (CKD), uremic toxins accumulate in blood and cannot be excreted with urine. Accumulation of these toxins has negative effects on many body functions. Because of the importance of these toxins, we developed and validated a simple, sensitive, accurate, and precise method for the determination of two main uremic toxins:phenol and p-cresol in human urine. Materials and methods:Separation of these analytes in urine samples was achieved by reverse-phase high-performance liquid chromatography (RP-HPLC) with a C18 column at 35 degrees C using the mobile phase of methanol-water (65:35) at a flow rate of 1.4 mL min(-1). Fluorimetric detection was used at 284 nm for excitation and 310 nm for emission. Results:The method is linear over the range of 1.5-35 ng mL(-1) and 1-45 ng mL(-1) for phenol and p-cresol, respectively. The method was applied to urine samples from 10 healthy subjects and 10 chronic kidney disease patients. Conclusions:This assay appears to be useful in routine analysis of clinical samples for simultaneous determination of phenol and p-cresol levels in urine.Publication Metadata only LIQUID CHROMATOGRAPHIC ANALYSIS OF CAROTENOIDS IN FOODS(2019-06-01) Tekkeli, Serife Evrim Kepekci; DİNCEL, DEMET; Onal, Cem; Onal, Armagan; Sagirli, Olcay; DİNCEL, DEMET; TEKKELİ, ŞERİFE EVRİMCurrent scientific studies indicate that carotenoids (CRTDs) are beneficial for maintaining health and lowering the risk of different pathologies. Considering the increasing role of carotenoids in healthcare, determination of carotenoid content of foods become important. Mostly, the analytical procedures that are used for this aim, are based on extraction techniques followed by different analytical procedures, especially high performance liquid chromatography. In this publication, a review of various analytical techniques developed for the determination of carotenoids in different food commodities starting from 2006 up to now, has been presented.Publication Open Access Anticholinesterase furocoumarins from Heracleum platytaenium, a species endemic species to Ida Mountains(2013-01-01) Dincel, DEMET; Hatipoglu, Seda Damla; GOREN, AHMET CEYHAN; Topcu, Gulacti; DİNCEL, DEMET; GÖREN, AHMET CEYHAN; TOPÇU, GÜLAÇTIThe petroleum ether extract of Heracleum platytaenium afforded 8 furocoumarins (psoralen, bergapten, xanthotoxin, pimpinellin, isopimpinellin, sphondin, byakangelicin, and heraclenol) and the methanol extract of H. platytaenium gave only 1 glycosylated dihydrofurocoumarin, apterin. In addition, stigmasterol was also obtained from petroleum ether extract. Structure identification of the isolated compounds has been achieved by using spectroscopic methods, namely 1D and 2D NMR experiments and mass spectral analyses. The antioxidant activity of the extracts and pure compounds was investigated by 2 methods, including DPPH free radical scavenging activity and lipid peroxidation inhibitory activity by beta-carotene-linoleic acid assays. The anticholinesterase activity of petroleum ether and methanol extracts of the plant and the isolated furocoumarins was investigated against acetylcholinesterase and butyrylcholinesterase enzymes by the Ellman method in vitro.Publication Metadata only A High-Performance Liquid Chromatographic Method for the Determination of Meropenem in Serum(2020-02-01T00:00:00Z) Dincel, Demet; Topçu, Gülaçtı; DİNCEL, DEMET; TOPÇU, GÜLAÇTIPublication Metadata only Determination of dihydrocapsaicin adulteration in dietary supplements using LC-MS/MS(2020-01-01T00:00:00Z) DİNCEL, DEMET; Olgan, Hatice; Canbaloglu, Zeynep; Yalcin, Sule; Erkucuk, Aysen; TIRIS, GİZEM; GÖREN, AHMET CEYHAN; DİNCEL, DEMET; TIRIS, GİZEM; GÖREN, AHMET CEYHANAdulterations of dietary supplements are serious threats to public health in all around of world. Nowadays, in order to obtain the intended effect from natural remedies, the adulteration of natural products via artificial or harmful chemicals are increasing. A rapid LC-MS/MS method for determination of capsaicin and dihydrocapsaicin in dietary supplements via Fortis C18 (150 x 3 mm; 3 mu m) column at 25 degrees C was developed and validated in a mixture of mobile phase A (1 % formic acid solution and 0.1 % ammonium formate in water) and B (1 % formic acid solution and 0.1 % ammonium formate in methanol) with gradient program at a flow rate of 0.35 mL/min. The recoveries of developed methods weytre obtained in the range of % 95.4-106.3 for capsaicin and % 96.3-108.9 for dihydrocapsaicin. This study shows that synthetic compound dihydrocapsaicin is widely use in dietary supplements products for adulteration to increase the effects of product without any declaration.Publication Metadata only Determination of fingerprints contents of different extracts and parts of six endemic Salvia taxa by GC-MS: Source species for valuable compounds with drug or drug potential(2021-11-01T00:00:00Z) Akdeniz, Mehmet; Yener, Ismail; DİNCEL, DEMET; Fırat, Mehmet; Degirmenci, Dilek Karatas; ERTAŞ, ABDULSELAM; DİNCEL, DEMETPublic use of Salvia species and their importance in the scientific world is continually increasing. It is known that this use and the importance of Salvia species are mostly due to the terpenoid compounds that they contain. In this context, the terpenoid-steroid-flavonoid contents of extracts of six endemic Salvia (S. kurdica, S. pseudeuphratica, S. rosifolia, S. siirtica, S. cerino-pruinosa var. cerino-pruinosa and S. cerino-pruinosa var. elazigensis) species prepared with different solvents were determined by gas chromatography-mass spectrometry. Within the framework of the ingredient analysis, content analysis of the ethanol extracts of the root, branch, leaf and flower parts of the species collected in the same period between 2015 and 2017 years was performed. In general, extracts prepared with chloroform and ethanol were found to contain a wide variety of compounds while petroleum ether extracts were found to contain much less varied compounds. In addition, in general, root extracts are richer in terpenoid compounds than aerial part extracts. Some species can be used as source species in terms of ferruginol, cryptanol, 6,7-dehydroroyleanone, lup-(20)29-ene-2 alpha-hydroxy-3 beta-acetate, salvigenin and beta-sitosterol contents (52,114.28, 75,979.08, 101,247.41, 40,071.29, 33,952.13 and 34,010.90 mu g analyte/g extract, respectively).