Browsing by Author "Cittan, M"

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    Effects of Galium aparine extract on the cell viability, cell cycle and cell death in breast cancer cell lines
    Atmaca, H; Bozkurt, E; Cittan, M; Tepe, HD
    Ethnopharmacological relevance: Galium species have been traditionally used for its anti-cancer, antioxidant, anti-inflammatory, antimicrobial and cardioprotective effects in the folk medicine. Galium aparine (GA) is a typical climbing plant growing widespread in Anatolia. Aim of the study: To investigate the potential anti-proliferative and apoptotic effect of GA methanol (MeOH) extract on MCF-7 and MDA-MB-231 human breast cancer cells and MCF-10A untransformed breast epithelial cells. Materials and methods: First, the extract was characterized by both liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF/MS) and gas chromatography-mass spectrometry (GC-MS) analyses. Then, cell viability and cell cycle distribution were investigated by XTT assay and PI staining by flow cytometry, respectively. Cell death was determined by Annexin V FITC/7-AAD staining. Results: A total of 14 major phytochemicals were identified by LC/Q-TOF/MS and 34 volatile compounds were determined by GC-MS. The extract was cytotoxic in both breast cancer cell lines in a concentration and time dependent manner and showed G1 block after 72 h extract treatment. However, it was not cytotoxic to MCF-10A breast epithelial cells. Flow cytometry analyses revealed that apoptosis was induced in MDA-MB-231 cells; however, necrosis was induced in MCF-7 cells. Conclusion: Our study suggests that GA MeOH extract may have potential anti-cancer effects against breast cancer cells without impairing normal breast epithelial cells. Ability to induction of non-apoptotic cell death besides apoptotic cell death by this complex plant-derived mixture may enable the killing of apoptosis resistant breast cancer cells but further studies should be conducted to investigate the bioavailability and metabolism of it in vivo. (C) 2016 Elsevier Ireland Ltd. All rights reserved.
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    Liquidambar orientalisMill. gum extract induces autophagy via PI3K/Akt/mTOR signaling pathway in prostate cancer cells
    Atmaca, H; Pulat, CC; Cittan, M
    Liquidambar orientalisMill . (LOM), is an endemic species having a local distribution in the southwestern coastal district of Turkey. Styrax liquidus gum (SLG), is a gum-like resinous which exudates in response to injury of the trunk of LOM. The aim of the study was to investigate the cytotoxic effects and the molecular mechanisms of the ethanolic SLG extract in human prostate cancer cells. GC-MS analysis was performed to identify the volatile compound composition. Cytotoxicity was determined by XTT analysis. Apoptosis and necrosis were evaluated via ELISA assay. Autophagic cell death was detected via monodansylcadaverine (MDC) staining and by measuring the levels of LC3I and LC3II. The protein levels of p-PI3K, p-Akt and p-mTOR were evaluated by western blot analysis. In the present study, it is shown that the SLG extract containing a considerable amount of ravidomycin derivate induced autophagic cell death in prostate cancer cells via inhibiting the PI3K/Akt/mTOR pathway.
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    Evaluation of antioxidant capacities and phenolic profiles in Tilia cordata fruit extracts: A comparative study to determine the efficiency of traditional hot water infusion method
    Cittan, M; Altuntas, E; Çelik, A
    Herbal infusions are a common practice among people. Making a hot water infusion is the simplest way to extract the medicinal properties of a plant. One of the most frequently used plants for this purpose is linden. Antioxidants (especially phenolic compounds) may also enhance the immune system and reduce the risk of cancer and infections such as colds, a frequent medicinal use for this species. In this work, ultrasound-assisted extraction (UAE) method and infusion extraction (IE) technique using only water as the extractant were carried out comparatively for the extraction of phenolic compounds from Tilia cordata fruits to evaluate the efficiency of the hot water infusion technique. Both extracts obtained with IE and UAE techniques were initially screened for their total phenolic contents (TPCs) and total antioxidant capacities (TACs) via Folin-Ciocalteu and CUPRAC methods, respectively. TPCs of the extracts obtained with IE and UAE were found as 58.86 +/- 21.51 and 111.84 +/- 13.99 mg gallic acid equivalent (GAE)/g dry sample, respectively. Furthermore, TACs of the extracts obtained with IE and UAE were calculated as 82.99 +/- 13.13 and 197.52 +/- 12.69 mg trolox equivalent (TE)/g dry sample, respectively. Subsequently, 31 phenolic compounds in the same extracts were scanned by liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) method. Among phenolics, 24 compounds were quantitatively determined with protocatechuic acid as the dominant one (1723.1-2183.5 mu g/g dry sample). Consequently, the traditional hot water infusion which can be easily applied at home was considered to be a comparatively effective method for the extraction of phenolic compounds from Tilia cordata fruits.
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    Development of a spiramycin sensor based on adsorptive stripping linear sweep voltammetry and its application for the determination of spiramycin in chicken egg samples
    Cittan, M
    Herein, an adsorptive stripping linear sweep voltammetric technique was described to determine spiramycin, a macrolide antibiotic, using a carboxylic multiwalled glassy carbon electrode modified with carbon nanotubes. The main principle of the analytical methodology proposed was based on the preconcentration of spiramycin by open-circuit accumulation of the macrolide onto the modified electrode surface. As a result of the adsorption affinity of spiramycin to the modified surface, the sensitivity of the glassy carbon electrode was significantly increased for the determination of spiramycin. The electrochemical behavior of spiramycin was evaluated by cyclic voltammetry and the irreversible anodic peak observed was measured as an analytical signal in the methodology. The proposed electrochemical sensing platform was quite linear in the range of 0.100-40.0 mu M of spiramycin concentration with a correlation coefficient of 0.9993. The limit of detection and the limit of quantification were 0.028 and 0.094 mu M, respectively. The intra- and interday repeatability of the proposed sensor was within acceptable limits. Finally, the applicability of the electrochemical methodology was examined by determining the drug content of chicken egg samples spiked with spiramycin standard. A rapid and easy extraction technique was performed to extract spiked spiramycin from the egg samples. The extraction technique followed had good recovery values between 85.3 +/- 4.0% and 93.4 +/- 1.9%.
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    An electrochemical sensing platform for trace analysis of Eriochrome Black T using multi-walled carbon nanotube modified glassy carbon electrode by adsorptive stripping linear sweep voltammetry
    Cittan, M; Çelik, A
    A highly sensitive electrochemical sensing platform was proposed for trace analysis of Eriochrome Black T in aqueous solutions by adsorptive stripping linear sweep voltammetry based on the open-circuit accumulation of Eriochrome Black T onto the fabricated multi-walled carbon nanotubes modified glassy carbon electrode surface. The proposed methodology was quite linear between 0.1 and 10 mu M of Eriochrome Black T concentration with a correlation coefficient of 0.9981. The precision of the technique was acceptable with the relative standard deviations of lower than 13.4% for inter-day assays. In addition, the sensitivity properties of the proposed method were compared with those of the spectrophotometric method, which is frequently used in the literature for Eriochrome Black T analysis. The results showed that the proposed electrochemical sensing platform would be a more sensitive alternative to the existing spectrophotometric techniques. Finally, the methodology was successfully applied to the determination of Eriochrome Black T in a well water spiked at different concentration levels.
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    Determination of oleuropein using multiwalled carbon nanotube modified glassy carbon electrode by adsorptive stripping square wave voltammetry
    Cittan, M; Koçak, S; Çelik, A; Dost, K
    A multi-walled carbon nanotube modified glassy carbon electrode was used to prepare an electrochemical sensing platform for the determination of oleuropein. Results showed that, the accumulation of oleuropein on the prepared electrode takes place with the adsorption process. Electrochemical behavior of oleuropein was studied by using cyclic voltammetry. Compared to the bare GCE, the oxidation peak current of oleuropein increased about 340 times at MWCNT/GCE. Voltammetric determination of oleuropein on the surface of prepared electrode was studied using square wave voltammetry where the oxidation peak current of oleuropein was measured as an analytical signal. A calibration curve of oleuropein was performed between 0.01 and 0.70 mu M and a good linearity was obtained with a correlation coefficient of 0.9984. Detection and quantification limits of the method were obtained as 2.73 and 9.09 nM, respectively. In addition, intra-day and inter-day precision studies indicated that the voltammetric method was sufficiently repeatable. Finally, the proposed electrochemical sensor was successfully applied to the determination of oleuropein in an olive leaf extract. Microwave-assisted extraction of oleuropein had good recovery values between 92% and 98%. The results obtained with the proposed electrochemical sensor were compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. (C) 2016 Elsevier B.V. All rights reserved.
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    Development and Validation of an Analytical Methodology Based on Liquid Chromatography-Electrospray Tandem Mass Spectrometry for the Simultaneous Determination of Phenolic Compounds in Olive Leaf Extract
    Cittan, M; Çelik, A
    A simple method was validated for the analysis of 31 phenolic compounds using liquid chromatography-electrospray tandem mass spectrometry. Proposed method was successfully applied to the determination of phenolic compounds in an olive leaf extract and 24 compounds were analyzed quantitatively. Olive biophenols were extracted from olive leaves by using microwave-assisted extraction with acceptable recovery values between 78.1 and 108.7%. Good linearities were obtained with correlation coefficients over 0.9916 from calibration curves of the phenolic compounds. The limits of quantifications were from 0.14 to 3.2 mu g g(-1). Intra-day and inter-day precision studies indicated that the proposed method was repeatable. As a result, it was confirmed that the proposed method was highly reliable for determination of the phenolic species in olive leaf extracts.
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    Simultaneous Electrochemical Determination of Sildenafil Citrate and Tadalafil Using a Multi Walled Carbon Nanotubes Modified Glassy Carbon Electrode by Adsorptive Stripping Linear Sweep Voltammetry
    Öksüz, M; Cittan, M; Dost, K
    An adsorptive stripping linear sweep voltammetric method was developed for the simultaneous determination of sildenafil citrate and tadalafil. The voltammetric working electrode was a glassy carbon electrode modified with carboxylic multi-walled carbon nanotubes. The sensitivity of the developed voltammetric method was significantly increased by this modification. Both analytes spontaneously adsorbed on the modified electrode surface due to their adsorption affinities. The irreversible oxidation signals of both analytes were used as the analytical signals. The electrochemical behaviour of sildenafil citrate and tadalafil was assessed using cyclic voltammetry. The developed voltammetric method was linear in the range of 0.01-0.50 mu M with a correlation coefficient of 0.9997 and 0.9985 for sildenafil citrate and tadalafil, respectively. The LOQs of the method for both analytes were 0.010 mu M. The intra- and inter-day reproducibility of the method was less than 10% RSD in all cases. The extraction recoveries for both analytes ranged between 83 and 94%. The applicability of the developed voltammetric method were investigated by determining the analyte in two different spiked samples (an energy drink and a traditional herbal product). Furthermore, the described method would represent the first electrochemical approach for the simultaneous detection of sildenafil citrate and tadalafil, providing an available alternative to current chromatographic techniques.
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    VIRGIN OLIVE OIL PHENOLS-SPECTROSCOPIC EVALUATION IN BASIC MEDIUM: ANALYSIS OF TOTAL CONTENT OF HYDROXYTYROSOL
    Cittan, M
    Here a spectrophotometric technique in the visible region combined with an environmental friendly ultra-pure water based liquid-liquid extraction procedure has been described for the determination of total hydroxytyrosol in virgin olive oils regardless of whether it is free or combined. Determination of total hydroxytyrosol was carried out where the absorption peak of the colored compounds formed with autopolymerization of quinones that occured following the oxidation of hydroxytyrosol and its secoiridoid derivatives in a basic medium was measured as an analytical signal. The method was linear in a concentration range of 0.2-15.0 mg L-1 with a correlation coefficient of 0.9990. Detection and quantification limits were 0.05 and 0.18 mg L-1, respectively. Intra-day and inter-day precision studies indicated that the proposed method was repeatable. In addition, the liquid-liquid extraction procedure was quite efficient with recovery values between 108 and 117%. Finally, the proposed method was successfully applied to the analysis of total hydroxytyrosol in a virgin olive oil and the results were compared with those obtained by a method existing in the literature for the determination of total hydroxytyrosol based on acid hydrolysis of secoiridoid aglycons followed by liquid chromatography-tandem mass spectrometry.
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    Epichlorohydrin crosslinked chitosan-clay composite beads for on-line preconcentration and determination of chromium(III) by flow injection flame atomic absorption spectrometry
    Cittan, M; Tirtom, VN; Dinçer, A; Çelik, A
    An on-line flow injection preconcentration-flame atomic absorption spectrometry (FI-AAS) method is developed for trace determination of chromium(III) by sorption on a mini-column packed with epichlorohydrin (ECH) crosslinked chitosan-clay composite beads. The factors affecting preconcentration of Cr(III) ions such as sample and eluent flow rate, loading time, sample and eluent pH, and eluent type and concentration were investigated. The Cr(III) ions were eluted from the mini-column with 0.1 M EDTA. Under the optimized parameters, the calibration graph using the preconcentration system for Cr(III) was linear with a correlation coefficient of 0.9982. Detection and quantification limits of the method were obtained to be 0.0162 and 0.0929 mu gmL(-1) respectively, with an enrichment factor of 13.4.
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    Multi-walled carbon nanotube modified glassy carbon electrode as curcumin sensor
    Cittan, M; Altuntas, E; Çelik, A
    A facile and efficient voltammetric sensing platform was described for curcumin analysis based on the adsorptive stripping voltammetry using multi-walled carbon nanotube modified glassy carbon electrode. As a result of the open-circuit accumulation of curcumin on the fabricated electrode surface, the described analytical procedure was shown to be a sensitive technique for curcumin analysis by increasing the sensitivity of the glassy carbon electrode. A good linear calibration curve in the range of 0.010-5.000 mu M (R-2 = 0.9967) was obtained. The repeatability of the methodology was quite satisfactory. The detection and quantification limits were found as 0.005 and 0.014 mu M, respectively. The methodology was successfully applied to determine the curcumin equivalent in a turmeric extract following the ultrasound-assisted extraction of a turmeric powder. The ultrasound-assisted extraction had a good recovery value between 103.5 and 106.0%. The described methodology would be a facile, sensitive, and cheap alternative to the current methods for curcumin analysis. [GRAPHICS] .
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    Determination of boscalid, pyraclostrobin and trifloxystrobin in dried grape and apricot by HPLC/UV method
    Dost, K; Öksüz, M; Cittan, M; Mutlu, B; Tural, B
    This paper describes the development of extraction and high-performance liquid chromatography with ultraviolet detection methods for the determination of boscalid, pyraclostrobin, and trifloxystrobin. The extraction method includes classical solid-liquid and liquid-liquid extraction methods. The fungicides and the internal standard were separated in less than 6.5 min on an ODS column with acetonitrile/water mobile phase at 1.5 mL min- 1 flow rate and detected at 265 nm. The limit of detection and quantification were 0.0084 and 0.0280 mg kg-1 for boscalid; 0.0032 and 0.0106 mg kg- 1 for pyraclostrobin; 0.0113 and 0.0377 mg kg- 1 for trifloxystrobin. The reproducibility of the method was lower than 0.6 % and 0.7 % relative standard deviation in terms of retention time for within day and between days, respectively, lower than 1.4 % in terms of the ratio of peak areas for both within day and between days. The accuracy of the analysis method in terms of relative error was lower than 11 % at low, 8 % at medium and 1 % at high concentrations. The recoveries were between 99-106 % for boscalid, 70-82 % for pyraclostrobin and 52-64 % for trifloxystrobin. These developed methods were then applied for the determination of selected fungicides in dried grape and apricot samples.