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TOPÇU, GÜLAÇTI

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Author: Topcu, GÜLAÇTI × Rights: info:eu-repo/semantics/openAccess ×

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    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, GÜLAÇTI
    Introduction: 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.
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    Synthesis of Oleanolic Acid Analogues and Their Cytotoxic Effects on 3T3 Cell Line
    (2018-01-01) Tuncay, Salih; Kocyigit, ABDÜRRAHİM; SEÇEN, Hasan; Ocal, Nuket; Topcu, GÜLAÇTI; Guler, ERAY METİN; ŞENOL, HALIL; GÜLER, ERAY METİN; KOÇYİĞİT, ABDÜRRAHİM; TOPÇU, GÜLAÇTI
    Background: Oleanolic acid (OA) is a known natural compound with many important biological activities. Thirteen oleanolic acid derivatives linked at C-3 and C-28 were synthesized and their structures were confirmed by H-1- and C-13 NMR and mass spectral analyses. Among them, compounds 4, 6, 8-10, 12, 13 were synthesized for the first time. They were evaluated for their cytotoxic activity. They showed proliferative effect at low concentrations while cytotoxic effect was observed at high concentrations in a dose dependent manner.
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    Chemical Characterization of 64 Propolis Samples from Hakkari, Turkey
    (2018-11-01) Bayram, Nesrin Ecem; SORKUN, KADRİYE; Oz, Gul Cevahir; SALİH, BEKİR; Topcu, GÜLAÇTI; TOPÇU, GÜLAÇTI
    Propolis is a resinous substance produced by honey bees from various plants they visit. Sixty-four propolis samples were collected from different localities of four districts (Merkez, Yiiksekova, Semdinli, and Qukurca) in Hakkari territory. Ethanol extracts of the propolis samples were prepared, and their chemical contents were determined by gas chromatography-mass spectroscopy (GC-MS). Flavonoids were generally found in a high concentration in Semdinli samples of Turkey. Twenty-seven coumarins were identified in the 28 propolis samples among studied 64 ones. Except suberosin, the coumarins were never reported before in any propolis sample with Turkish origin. The propolis samples belonging to Yuksekova were found to be richer in coumarins than the others, and the most richest one among the Yfiksekova apiaries, was found to be Akocak sample (Y2) with 41.99% total yield, followed by Akcall sample (Y5) (30.86%). This is a first comprehensive and original report about the chemical profile of propolis samples from Hakkari. The propolis samples from Hakkari exhibited a chemical content rich in flavonoids including coumarins and furocoumarins.
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    Bioassay-guided isolation, identification of compounds from Origanum rotundifolium and investigation of their antiproliferative and antioxidant activities.
    (2017-12-01) ERENLER, R; MERAL, B; SEN, O; ELMASTAS, M; AYDIN, A; EMINAGAOGLU, O; Topcu, GÜLAÇTI; TOPÇU, GÜLAÇTI
    Context: Origanum (Lamiaceae) has been used in food and pharmaceutical industries. Objective: Isolation and identification of bioactive compounds from Origanum rotundifolium Boiss. and investigation of their antiproliferative and antioxidant activities. Materials and methods: The aerial part of O. rotundifolium was dried and powdered (1.0 kg ±2.0 g) then extracted with hexane, ethyl acetate, methanol and water. Solvent (3 × 1 L) was used for each extraction for a week at room temperature. The aqueous extract was partitioned with ethyl acetate (3 × 1 L) to yield the water/EtOAc extract subjected to chromatography to isolate the active compounds. The structures of isolated compounds were elucidated by 1 D, 2 D NMR and LC-TOF/MS. Results: Apigenin (1), ferulic acid (2), vitexin (3), caprolactam (4), rosmarinic acid (5), and globoidnan A (6) were isolated and identified. Globoidnan A (6), vitexin (3), and rosmarinic acid (5) revealed the excellent DPPH• scavenging effect with IC50 values of 22.4, 31.4, 47.2 μM, respectively. Vitexin (3) (IC50 3.6), globoidnan A (6) (IC50 4.6), apigenin (1) (IC50 8.9) and ferulic acid (2) exhibited more ABTS•+ activity than standard Trolox (IC50 13.8 μg/mL). Vitexin (3) revealed the most antiproliferative activity against HeLa, HT29, C6 and Vero cells lines with IC50 values of 35.6, 32.5, 41.6, 46.7 (μM), respectively. Discussion and conclusion: Globoidnan A (6) has the most antioxidant effects on all assays. This has to do with the chemical structure of the compound bearing the acidic protons. Vitexin (3) could be a promising anticancer agent.