Person: AYBASTIER, ÖNDER
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AYBASTIER
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ÖNDER
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Publication Slx5 deletion confers tolerance to oxidative stress in saccharomyces cerevisiae(Oxford Univ Press, 2022-09-01) Thomas, Pınar B.; Kaluç, Nur; Aybastıer, Önder; AYBASTIER, ÖNDER; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0002-0380-1992; X-4621-2018Slx5, a subunit of a SUMO-targeted ubiquitin ligase (STUbL) in yeast, has been implicated in maintenance of genomic stability. SUMOylation is an important post-translational modification involved in the regulation of several important cellular processes and cellular response to various environmental stressors. Oxidative stress occurs when production of reactive oxygen species (ROS) exceeds the antioxidant defense capacity of the cell. Elevated ROS levels cause oxidative damage to important cellular macromolecules such as DNA, lipids, and proteins, which is associated with several diseases. Herein, we investigated the role of Slx5 in oxidative stress tolerance in Saccharomyces cerevisiae. We show that deletion of SLX5 increases survival of yeast cells in response to H2O2-induced oxidative stress in a cell cycle independent manner. Accumulation of intracellular ROS as well as DNA and lipid damages were reduced; expressions of antioxidant defense mechanism-related genes were increased in slx5 Delta cells compared to wild type (WT) under oxidative stress. We also show that slx5 Delta cells have increased intracellular ROS levels and oxidative damage to DNA and lipids compared to WT in the absence of oxidative stress. Thus, our data together suggest that an adaptive stress induced by SLX5 deletion increases tolerance to oxidative stress in slx5 increment cells.An adaptive stress induced by SLX5 deletion increases tolerance to oxidative stress in Saccharomyces cerevisiae.Publication The anticancer effect of inula viscosa methanol extract by miRNSs' re-regulation: An in vitro study on human malignant melanoma cells(Taylor, 2021-02-04) Çolak, Dilara Kamer; Egeli, Ünal; Eryılmaz, Işıl Ezgi; Aybastıer, Önder; Malyer, Hulusi; Çeçener, Gülşah; Tunca, Berrin; Çolak, Dilara Kamer; EGELİ, ÜNAL; ERYILMAZ, IŞIL EZGİ; AYBASTIER, ÖNDER; MALYER, HULUSİ; ÇEÇENER, GÜLŞAH; TUNCA, BERRİN; Fen Edebiyat Fakültesi; Analitik Kimya Bölümü; 0000-0001-7904-883X; 0000-0002-0380-1992; 0000-0002-3820-424X; 0000-0002-1619-6680; 0000-0002-3316-316X; GWV-3548-2022; AAH-1420-2021; HXB-1173-2023; X-4621-2018; DDS-8738-2022; AAP-9988-2020; ABI-6078-2020Alternative and natural therapies are needed for malignant melanoma (MM), the most deadly skin cancer type due to chemotherapy's limited effect. In the present study, we evaluated the anticancer potentials of Inula viscosa methanol and water extracts (IVM and IVW) on MM cells, A2058 and MeWo, and normal fibroblasts. After the chromatographic and antioxidant activity analysis, their antiproliferative effects were determined with the increasing doses for 24-72 h. IVM induced more cell death in a dose and time-dependent manner in MM cells compared to IVW. This effect was probably due to the higher amount of phenolics in it. IVM significantly induced more apoptotic death in MM cells than fibroblasts (p < 0.01), which was also supported morphologically. IVM also caused cell cycle arrest at G0/G1 and G2/M phases in A2058 and MeWo, respectively, and suppressed the migration ability of MM cells (p < 0.01). Additionally, IVM was found to have significant potential in regulating MM-related miRNAs, upregulating miR-579 and miR-524, and downregulating miR-191 and miR-193, in MM cells (p < 0.05, p < 0.01). As a result, the anticancer effect of IVM via regulating miRNAs' expression has been demonstrated for the first time. Thus, IVM, with these potentials, may be a promising candidate for MM treatment.Publication Efficacy of methanol-water extract of inula helenium root against oxidative dna damage(Journal of Traditional Chinese Medical Sciences, 2021-04) Aybastıer, Önder; AYBASTIER, ÖNDER; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0002-0380-1992; X-4621-2018OBJECTIVE: To investigate the efficacy of methanol-water extract of Inula helenium root against oxidative DNA damage.METHODS: Antioxidant properties of methanol-water extract of Inula helenium root were revealed by 2,2'-azinobis (3-ethylbenzothiazoline-6-suphonic acid) di-ammonium salt (ABTS), Folin-Ciocalteu and high-performance liquid chromatography (HPLC) methods. The effect against oxidative DNA base damage was determined analyzing oxidative DNA base damage products by GC-MS/MS.RESULTS: The methanol-water extract of Inula helenium root showed good antioxidant capacity [32.20 mg trolox equivalents ( TE) /g dried weight (dw) by ABTS method, 54.53 mg TE/g dw by chromium reducing antioxidant capacity method] and total phenolic content [29.83 mg gallic acid equivalent (GAE) / g dw]. The chlorogenic acid, ferulic acid, rosmarinic acid and caffeic acid were determined in the extract by HPLC. The chlorogenic acid, ferulic acid and Inula helenium root extract were revealed to inhibit the oxidative DNA base damage by GC-MS/MS.CONCLUSION: The studies showed a crucial decrease in the amount of the DNA base damage products when antioxidants were used. The results showed that ferulic acid has better inhibition than chlorogenic acid for DNA oxidation. The methanol-water extract of Inula helenium root was determined to inhibit the oxidative DNA damage.Publication Investigation of antioxidant ability of grape seeds extract to prevent oxidatively induced dna damage by gas chromatography-tandem mass spectrometry(2018) Aybastier, Önder; Dawbaa, Sam; Demir, Cevdet; AYBASTIER, ÖNDER; Dawbaa, Sam; DEMİR, CEVDET; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0003-1508-0181; 0000-0002-9381-0410; 0000-0002-0380-1992; 0000-0001-7001-0739; AFR-1890-2022; ABA-2005-2020; KRQ-0516-2024; X-4621-2018Phenolic compounds have been studied elaborately for their efficacy to improve health and to protect against a wide variety of diseases. Herein this study, different analysis methods were implemented to evaluate the antioxidant properties of catechin and cyanidin using their standard substances and as they found in the grape seeds extracts. Total phenol contents were 107.39 +/- 8.94 mg GAE/g dw of grape seeds for grape seed extract (GSE) and 218.32 +/- 10.66 mg GAE/g dw of grape seeds for acid-hydrolyzed grape seed extract (AcGSE). The extracts were analyzed by HPLC-DAD system and the results showed the presence of catechin, gallic acid, chlorogenic acid and ellagic acid in the processed methanolic extract and cyanidin, gallic acid and ellagic acid in the processed acidified methanolic extract. The protective abilities of catechin and cyanidin were tested against the oxidation of DNA. The results showed that cyanidin has better protection of DNA against oxidation than catechin. GSE and AcGSE were revealed to inhibit the oxidatively induced DNA damage. GSE decreased about 57% of damage caused by the Fenton control sample. This study could show new aspects of the antioxidant profiles of cyanidin and catechin.Publication Optimization and validation of ultrasensitive GC-MS/MS method to measure oxidatively induced DNA damage products and role of antioxidants in oxidation mechanism(Elsevier, 2021-04-08) Aybastıer, Önder; Demir, Cevdet; AYBASTIER, ÖNDER; DEMİR, CEVDET; Fen Edebiyat Fakültesi; Kimya Bölümü; 0000-0002-0380-1992; 0000-0002-9381-0410; X-4621-2018; DTQ-5753-2022Oxidation of DNA due to exposure to reactive oxygen species (ROS) is a major source of DNA damage. ROS induced damage to DNA plays an important role in some diseases such as various cancers, aging and neurodegenerative diseases. The detection of DNA oxidation products plays a major role in assessing the mutagenicity potential of specific exposure. The GC-MS/MS method was developed for the ultrasensitive determination of individual DNA damage products. The validation results revealed that the proposed method was reliable and sensitive. Multiple response surface methodology (MRSM) was used to optimize derivatization conditions of oxidatively DNA base damage products before GC-MS/MS analysis. The optimum derivatization conditions were determined as 40 min for derivatization time, 120 degrees C for derivatization temperature and 1.4 for BSTFA/pyridine ratio under nitrogen atmosphere. The effects of thymol, carvacrol and thymoquinone as antioxidants were investigated on oxidative DNA damage. The determination of the oxidatively induced DNA damage products was performed after adding DNA and antioxidants with different concentrations under oxidative stress. Eighteen DNA base damage products were analyzed simultaneously using GC-MS/MS. This study showed a significant decrease in the amount of DNA base damage products when the antioxidants were present in the medium.