Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Conference Object Antioxidant, Antimicrobial and Cytotoxic Activities of Some Turkish Plant Extracts(John Wiley and Sons Inc., 2006) Altıok, Evren; Asbagh, L. Abbasi; Bulut, Çisem; Ülkü, Semra; Bayraktar, OğuzPlant extracts have been known to possess notable biological activity, including antioxidant, antimicrobial and cytotoxic properties. There is a growing interest in the use of natural products in the human food industries as consumer resistance to synthetic additives increases. These products can be used to improve human health. In vitro antioxidant, antimicrobial and cytotoxic activities of ethanol extracts of some plants from Urla region in Turkey were investigated. Plant materials were collected from Pistacia lentiscus, Vitex agnus-castus, Cistus creticus and Nerium oleander in October, November and December.Conference Object Citation - WoS: 2Incorporation of Equisetum Arvense Extract Into Silk Fibroin-Hyaluronic Acid Sponge Matrices for Wound Dressing Applications(Elsevier, 2012) Uslu, Mehmet Emin; Erdoğan, İpek; Bayraktar, OğuzEquisetum arvense extract has frequently been investigated for its antioxidant capacity, antimicrobial and antitumor properties. However, one of the challenges in natural compound investi-gations is to maintain the stability of polyphenolic compounds during their storage and applications. For this purpose extracts can be incorporated into different forms of biomaterial. In this research silk fibroin (SF) and hyaluronic acid (HA) was used as sponge matri-ces for wound dressing application.Conference Object In Vitro Antitumor Activity of Sarcopoterium Spinosum Leaf Extract With Bioactive Natural Compounds(Elsevier, 2013) Süngüç, Ceren; Erdoğan, İpek; Uslu, Mehmet Emin; Bayraktar, OğuzCancer cell lines cause generation of reactive oxygen species and free radicals at high levels (Wang and Yi, 2008). Then generated free radicals lead to breakdown of the structure of DNA, lipid or protein (Gul et al., 2011). When plant extracts including antioxidant phytochemicals are exposed to the redox reactions, the harmful effects of free radicals are effectively prevented. The aim of present research was to evaluate the antitumor potential of the extract derived from Sarcopoterium spinosum leaves. The leaves of S. spinosum were collected in Izmir, Turkey. Total phenol content of ethanolic.Conference Object Investigation of Anti-Tumoral Activity of Cistus Creticus Extract Against Pc-3 Cell Line(Elsevier, 2013) Erdoğan, İpek; Süngüç, Ceren; Uslu, Mehmet Emin; Bayraktar, OğuzRecent studies have revealed that plant extracts show cytotoxic activities against cancer cell lines by ceasing cell division in particular phases (Xu et al., 2012, Yıldırım et al., 2013). Expression of specific genes was found to be activated according to pathway in which cell death occurs. Objective of this study was to identify antitumoural effect of Cistus creticus, which is a perennial shrub, found in Mediterranean region, against prostate cancer cell line by measuring the cytotoxic activities and apoptotic gene expression levels.Article Citation - WoS: 16Citation - Scopus: 21Ph- and Electro-Responsive Characteristics of Silk Fibroin-Hyaluronic Acid Polyelectrolyte Complex Membranes(Elsevier Ltd., 2009) Malay, Özge; Batıgün, Ayşegül; Bayraktar, OğuzpH-responsiveness of recently developed silk fibroin (SF) and hyaluronic acid (HA) polyelectrolyte complex (PEC) membranes and their potential use in electro-responsive drug release systems were investigated. PEC membranes were prepared within a narrow pH window (3.0-3.5) for a SF-HA weight ratio of 20 and they were characterized by Atomic Force Microscopy in addition to characterization studies previously reported by our group. Swelling kinetics of the membranes was studied for a pH window of 2.5-7.4 and cyclic swelling test was performed to determine the pH-responsiveness of the membranes. It was shown that membranes swelled more in alkaline conditions and responded to variations in pH of the medium. Electric-stimuli assisted drug permeation and release studies were performed with a custom-made diffusion cell under both passive condition and electric field applied in pulsatile fashion. The instantaneous flux raised as the current was applied and then declined when the current application was terminated, and this process was repeated on subsequent applications. SF-HA complex membranes were found promising for the electric-stimuli-sensitive release of a high molecular weight and charged model drug for a membrane-permeation controlled formulation.Article Citation - WoS: 10Citation - Scopus: 10Clinoptilolite-Rich Mineral as a Novel Carrier for the Active Constituents Present in Ginkgo Biloba Leaf Extract(Elsevier Ltd., 2008) Göktaş, Selda; Ülkü, Semra; Bayraktar, OğuzThe possible use of clinoptilolite-rich mineral as a novel carrier for the active constituents present in Ginkgo biloba leaf extract solutions was investigated. The flavonoid aglycone constituents were found to be selectively adsorbed on the clinoptilolite surface. The antioxidant activity determinations of the extract solutions were performed by the Trolox Equivalent Antioxidant Capacity (TEAC) assay. The antioxidant activity measurements performed for the Ginkgo leaf extract solutions showed decreasing antioxidant activities due to adsorption. The decrease in antioxidant activity was attributed to the adsorption of phenolic constituents on the clinoptilolite surface.Article Citation - WoS: 32Citation - Scopus: 33Characterization of Silk Fibroin/Hyaluronic Acid Polyelectrolyte Complex (pec) Films(Springer Verlag, 2008) Malay, Özge; Yalçın, Dilek; Batıgün, Ayşegül; Bayraktar, OğuzThis study aimed the characterization of the films casted from the aqueous mixtures of the pH induced complexes between silk fibroin (SF) and hyaluronic acid (HA). The insoluble and transparent films were subjected to scanning electron microscopy (SEM) analyses to show the morphological changes. Thermal analysis of complex films was determined by a differential scanning calorimeter (DSC). The changes in the crystalline state were monitored by X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). It was shown that the complexation between HA and SF was dominantly induced by pH. It was shown that the complex films comprised mixtures of crystalline and non-crystalline regions.Article Citation - WoS: 42Citation - Scopus: 46Characterization and Recovery of Tartaric Acid From Wastes of Wine and Grape Juice Industries(Springer Verlag, 2008) Yalçın, Dilek; Özçalık, Onur; Altıok, Evren; Bayraktar, OğuzTartaric acid is mainly used in food, pharmaceuticals and cosmetics industries. In this study, the waste samples, which contain tartaric acid, from the wastes of wine and grape juice industries were characterized by using TG, DSC, FTIR and XRD techniques. HPLC was used to determine tartaric acid content of samples. The decomposition temperatures of waste samples were found to be relatively higher compared with that of pure tartaric acid. This difference in decomposition temperatures was attributed to the presence of potassium tartrate since high potassium content was detected with ICP-AES.Article Citation - WoS: 72Citation - Scopus: 87Adsorption of Olive Leaf (olea Europaea L.) Antioxidants on Silk Fibroin(American Chemical Society, 2007) Bayçın, Deniz; Altıok, Evren; Ülkü, Semra; Bayraktar, OğuzThe adsorption isotherms of oleuropein and rutin were evaluated at different temperatures, pH values, and solid/liquid ratios. The experimental data of adsorption isotherms were well fitted to a Langmuir model. The maximum adsorption capacities were determined as 108 mg of oleuropein/g of silk fibroin and 21 mg of rutin/g of silk fibroin. After adsorption of oleuropein and rutin, the antioxidant capacity of silk fibroin increased from 1.93 to 3.61 mmol of TEAC/g. Silk fibroin also gained antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae after adsorption of olive leaf antioxidants. In a desorption process, 81% of rutin and 85% of oleuropein were removed from the adsorbent surface in 70% aqueous ethanol solution. Consequently, silk fibroin was found to be a promising biomaterial for the production of functional food or dietary supplements and for the purification of oleuropein and rutin from olive leaf extracts.Article Citation - WoS: 68Citation - Scopus: 70Complex Coacervation of Silk Fibroin and Hyaluronic Acid(Elsevier Ltd., 2007) Malay, Özge; Bayraktar, Oğuz; Batıgün, AyşegülThis study aimed to investigate the pH-induced complexation of silk fibroin (SF) and hyaluronic acid (HA). SF-HA complex coacervation was investigated by monitoring turbidity of the SF-HA system under slow acidification. Gravimetric analysis was performed to determine the yield of complex coacervation and viscosity of the system was measured to study the formation of the complexes at different pH values. The influences of total biopolymer concentration and biopolymer weight ratio on complex coacervation were examined during the analyses. Formation of the complexes was evidenced by the minimum viscosity and the maximum turbidity observed in the system. SF-HA complexes were formed within the pH-window of 2.5-3.5 regardless of the total biopolymer concentration or biopolymer ratio. Complex coacervation of SF-HA showed a reversible behavior and coacervation could be handled even in excess amounts of the biopolymers, which pointed out a non-stoichiometric complexation.