Person: BİLĞİÇ ALKAYA, DİLEK
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BİLĞİÇ ALKAYA
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DİLEK
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Publication Open Access Determination of Natamycin in Turkish Yoghurt(HINDAWI LTD, 2016) BİLĞİÇ ALKAYA, DİLEK; Alkaya, Dilek Bilgic; Karalomlu, OzlemThis study was aimed at developing RP-HPLC method for determination of natamycin in Turkish yoghurt. Chromatographic separation was achieved on a C8 column (150mm x 4.6mm x 5 mu m) with a mobile phase of methanol : water : acetic acid (12 : 8 : 1 v/v/v), at 1 mL/min flow rate with a detection of 303 nm. Natamycin was spiked into handmade yoghurt samples and used for validation. The method has been fully validated according to ISO 9233-2, 2007 (IDF 140-2, 2007). It was successfully applied to determination of 28 different Turkish yoghurt products. Findings dealing with the presence of natamycin in cheese samples are presented.Publication Open Access Preparation and characterization of pure natural hydroxyapatite derived from seashells for controlled drug delivery(2022-09-01) OKTAR, FAİK NÜZHET; GÜNDÜZ, OĞUZHAN; BİLĞİÇ ALKAYA, DİLEK; AYAZ SEYHAN, SERAP; CESUR, SÜMEYYE; AYAZ SEYHAN S., Alkaya D., Cesur S., OKTAR F. N., GÜNDÜZ O.The marine species are specially used for the fabrication of bioceramic nano-powders with natural methods for their use in controlled drug delivery. However, there are only very limited studies regarding the production and synthesis of hydroxyapatite (HA)-based drug delivery systems from marine structures. In this study, poly (vinyl alcohol) (PVA) containing Rifampicin (RIF)-loaded Orange Spiny Oyster Seashell (Spondylus barbatus) hydroxyapatite (HA) composite is synthesized by an in situ ultrasound-assisted method. All samples were analyzed by X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, and Scanning electron microscope (SEM), respectively. The in vitro drug release tests of the obtained samples were performed in a phosphate-buffered medium (PBS) at 37 degrees C. Drug release was evaluated according to five varying kinetic models. In vitro RIF release from HA/PVA composite in phosphate buffer (pH 7.4) showed prolonged sustained drug release. From the drug release kinetic models, Higuchi and Korsmeyer-Peppas were found to be the best model for the three ratios based on the correlation coefficient. The diffusion component is less than 0.5, which indicates quasi-fickian diffusion. From the kinetic study results, the RIF-loaded marine phase composite has potential use in drug delivery applications as it shows positive sustained drug release behavior.Publication Open Access Influence of extraction method on antioxidant properties of Rheum ribes root extract(OVIDIUS UNIV PRESS, 2019-01-01) BİLĞİÇ ALKAYA, DİLEK; Bilgic Alkaya, Dilek; Ayaz Seyhan, Serap; Ozturk, Busra NagihanRheum species are important medicinal herbs, often used in pharmacological research, due to the presence of anthracene derivatives in the subterranean parts of the plant. In this study, we intended to assess its antioxidant capacity, in correlation with the method of extraction. For this purpose, Rheum ribes extraction was realized with four solvents of different polarities (50% methanol, 70% ethanol, 80% acetonitrile, and petroleum ether). We used different extraction techniques, such as orbital shaker, ultrasonic stirrer, microwave, and Soxhlet extraction, and the total phenolic content of the Rheum ribes extracts was determined by modified Folin-Ciocalteu method. The reducing power and radical scavenging activity of the extracts were also evaluated. The results shown that the antioxidant activity of the extracts depends on the extraction methods especially through the used solvent and decreases in the order: ethanol > methanol > acetonitrile > petroleum ether.Publication Open Access Temperature dependence studies and microscopic protonation constants of L-alanine and β-alanine in acetonitrile – water mixtures(2022-07-01) BİLĞİÇ ALKAYA, DİLEK; AYAZ SEYHAN, SERAP; ERENSOY H., BİLĞİÇ ALKAYA D., AYAZ SEYHAN S.L-alanine and β-alanine are important biological molecules and have zwitterion structure. In this study, Lalanine and β-alanine’s microscopic protonation constants and thermodynamic parameters (enthalpy, entropy, and free energy changes) for the proton–ligand systems of L-alanine methyl ester, β-alanine and β-alanine methyl ester have been determined at 5; 20; 35 °C, in ACN-water (25% ACN and 50% ACN (v/v)) mixtures at constant ionic strength of 0.1000 mol L–1 NaClO4 by potentiometric method. The results shown that, L-alanine and β-alanine’s microscopic protonation constants generally tend to decrease with temperature rise and their protonation reactions in ACN-water mixtures generally favor enthalpy-driven.Publication Open Access Development and Validation of Liquid Chromatographic Method with DAD for the Quantification of Natamycin In Dairy Products(MARMARA UNIV, FAC PHARMACY, 2017-04-01) BİLĞİÇ ALKAYA, DİLEK; Karalomlu, Ozlem; Alkaya, Dilek BilgicIn this paper high performance liquid chromatography method was developed for the determination of natamycin in dairy product in Turkish market. Chromatographic separation was achieved on a C8 column (150 mm x 4.6 mm x 5 mu m 100 mm) with a mobile phase of methanol : water : acetic acid (12:8:1 v/v/v), at 1ml/min flow rate with DAD detection at 303 nm. Natamycin was analysed simultaneously using HPLC-UV method of ISO 9233+2, 2007(IDF 140-2, 2007). The method was found linear over the concentration ranges of 0.01-0.8 mg/L. Correlation coefficients (r) of the regression equations were greater than 0.999. The LOD and LOQ values for UV and DAD were found 0.321 mg/kg and 0.355 mg/kg; 0.321 mg/kg and 0.388 mg/kg for cheese samples respectively. The relative recoveries obtained for the spiked cheese samples were between 90 and 110 %. Also the interday precision of the method was found as 1.874% and 3.442 % RSD values for UV and DAD dedections. From the results of the present study using HPLC-DAD indicated that it is not reasonable to attribute the determination of natamycin in cheese. Therefore, the difference of the validation parameters were found insignificant for both detections. However, It was succesfully applied to determination of 46 different cheese products and finding dealing with the presence of natamycin in cheese samples were presented.Publication Open Access Production, characterization, and antioxidant activity evaluation of Rheum Ribes L. extract-loaded PLA/PEG nanofibers(2023-01-01) AYAZ SEYHAN, SERAP; BİLĞİÇ ALKAYA, DİLEK; AYAZ SEYHAN S., Demirel A. B., Cesur S., BİLĞİÇ ALKAYA D.© 2023 Marmara University Press.The use of natural compounds such as biocompatible and non-toxic plant extracts, without undesired side effects, in tissue engineering applications, is highly preferred compared to chemical drugs. In recent years, many studies have been carried out to produce nanofibrous materials produced by electrospinning of bioactive plant extracts. Electrospun nanofibers have very large surface area, controllable pore size, and tunable drug release profiles. Several biocompatible polymers with excellent biocompatibility and biodegradability including poly ethylene glycol (PEG) and poly-lactic acid (PLA) have been widely used for the synthesis of nanofibers using the electrospun technique. The ethanol-water extract of the root parts of the Rheum ribes L. plant has antioxidant, antimicrobial, and antiurease effects. In this study, the characterization and performance of electrospun Rheum ribes L.-loaded (20 mg, 40 mg, and 60 mg in 20mL) poly (lactic acid) (PLA) (8%, w/v) /Polyethylene glycol (PEG) (1%, w/v) /Tween 80 (3%, w/v) nanofibrous mats for skin tissue engineering were investigated. Morphological (SEM), molecular interaction (FT-IR), thermal analysis (DSC), antioxidant activity and physical analysis were carried out after the production process. According to the results obtained, Rheum ribes L.-loaded PLA/PEG nanofibers have smooth fiber morphology in fine structure without beads, proper tensile strength and antioxidant activity. Consequently, Rheum ribes L.-loaded nanofibrous mats are suitable for skin tissue engineering applications.