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    Antioxidant effects of oleuropein on hydrogen peroxide-induced neuronal stress-an in vitro study
    (Bentham Science Publishers, 2020) Kucukgul, Altug; Isgor, Mehmet M.; Duzguner, Vesile; Atabay, Meryem N.; Kucukgul, Azime
    Background: Persistent oxidative stress can lead to chronic inflammation and mediate most chronic diseases including neurological disorders. Oleuropein has been shown to be a potent antioxidant molecule in olive oil leaf having antioxidative properties. Objective: The aim of this study was to investigate the protective effects of oleuropein against oxidative stress in human glioblastoma cells. Methods: Human glioblastoma cells (U87) were pretreated with oleuropein (OP) essential oil 10 µM. After 30 minutes, 100 µM H2 O2 was added to the cells for three hours. Cell survival was quantified by colorimetric MTT assay. Glutathione level, total oxidant capacity, total antioxidant capacity and nitric oxide levels were determined by using specific spectrophotometric methods. The relative gene expression level of iNOS was performed by qRT-PCR method. Results: According to viability results, the effective concentration of H2 O2 (100µM) significantly decreased cell viability and oleuropein pretreatment significantly prevented the cell losses. Oleuropein regenerated total antioxidant capacity and glutathione levels decreased by H2 O2 exposure. In addition, nitric oxide and total oxidant capacity levels were also decreased after administration of oleuropein in treated cells. Conclusion: Oleuropein was found to have potent antioxidative properties in human glioblastoma cells. However, further studies and validations are needed in order to understand the exact neuroprotective mechanism of oleuropein. © 2020 Bentham Science Publishers.
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    Some Anti-Inflammatory Agents Inhibit Esterase Activities of Human Carbonic Anhydrase Isoforms I and II: An In Vitro Study
    (Wiley, 2015) Alim, Zuhal; Kilinc, Namik; Isgor, Mehmet M.; Sengul, Bulent; Beydemir, Sukru
    Carbonic anhydrases (CAs) are known as a drug-target enzymes. The inhibitors of the enzyme are important compounds for discovering new therapeutic agents and understanding in detail protein-drug interactions at the molecular level. For this purpose, the invitro effects of some anti-inflammatory agents such as tenoxicam, fluorometholone acetate, and dexamethasone were investigated on esterase activity of human erythrocyte CA-I and CA-II in this study. hCA-I and hCA-II were purified by affinity chromatography with a yield of 47.25% and 87%, and a specific activity of 642.8EU/mg proteins and 5576.9EU/mg proteins, respectively. SDS-PAGE was performed to determine the purity of the enzymes. Inhibitory effects of the drugs on hCA-I and hCA-II were determined by spectrophotometric method. IC50 values for hCA-I and hCA-II were 0.198, 2.18, 11.7, 0.11, 17.5 and 14m using tenoxicam, fluorometholone acetate, and dexamethasone, respectively. For fluorometholone acetate and dexamethasone, K-i values from Lineweaver-Burk plots were obtained as 1.044 and 21.2m (noncompetitive) for hCA-I and 9.98 and 8.66m (non-competitive) for hCA-II. In conclusion, tenoxicam, fluorometholone acetate, and dexamethasone showed potent inhibitory effects on esterase activity of hCA-I and hCA-II isozymes under invitro conditions.