WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14627/6
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Article Modulation of Brain Antioxidant Defense, Inflammation, and SIRT1 Activity by a Sunflower Oil-Based High-Fat Diet: Protective Role of L-Arginine in Rats(Springer, 2026) Şekerler, Turgut; Şener, Azize; Çavuşoğlu, Nuray; Doğan, ÖzgeBackgroundChronic consumption of omega-6-enriched dietary fat may disturb brain redox balance and neuroinflammatory homeostasis. Among the sirtuins, sirtuin 1 (SIRT1) exerts critical neuroprotective functions by suppressing oxidative stress and inflammatory signaling; however, the impact of sunflower oil-based high-fat diets (SO-HFD) on brain SIRT1 activity has not been investigated.ObjectiveThis study aimed to investigate the effects of SO-HFD on oxidative stress parameters, inflammatory markers, and SIRT1 activity in rat brain tissue, and to evaluate the potential modulatory role of L-arginine supplementation.MethodsFour-week-old female Sprague-Dawley rats were allocated into three groups: control, SO-HFD, and SO-HFD + L-arginine. Both SO-HFD groups were fed a diet containing sunflower oil for 16 weeks; from week 10 onward, 1.5% L-arginine was supplemented in the drinking water of the SO-HFD + L-arginine group. Following the 16-week protocol, serum and brain specimens were collected. Serum biochemical parameters and adiponectin were quantified; brain homogenates were assayed for lipid peroxidation (MDA), reduced glutathione (GSH), protein thiols (protein-SH), nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha) levels, and SIRT1 activity.ResultsAlthough brain MDA levels were not significantly elevated, SO-HFD animals exhibited reduced GSH and protein-SH content together with diminished SIRT1 activity. The SO-HFD increased TNF-alpha and NO levels. L-arginine supplementation decreased MDA and increased GSH, protein-SH, and SIRT1 activity. L-arginine also suppressed TNF-alpha levels in brain tissue compared to the SO-HFD group. NO levels in the SO-HFD + L-arginine group were lower than in the SO-HFD group, though not significantly.ConclusionThese findings suggest that chronic exposure to an omega-6-dominant dietary environment disturbs redox regulation and inflammatory balance in brain tissue, accompanied by reduced SIRT1 activity. L-arginine may attenuate cerebral oxidative stress and neuroinflammation by reinforcing endogenous antioxidant mechanisms, highlighting its potential as a nutritional strategy against SO-HFD-induced brain oxidative stress.Article Citation - WoS: 1Citation - Scopus: 1A Comparative Study of Biochemical, Antimicrobial Effects and Phytochemical Composition Analysis of Glycyrrhiza Glabra L. Varieties Root Extracts(Marmara University, 2025) Sen, Ali; Servı, Hüseyın; Barak, Timur Hakan; Tekin, Fethullah; Şener, Azize; Marzi, Mahdi; Gülmez, GizemPlants are the significant global interest as alternative treatment sources with their biologically activecompounds. This study compares the chemical composition and the antioxidant, antidiabetic, and antimicrobialproperties of ethanol extracts of G. glabra L. two different varieties from different regions. The phytochemicalcompositions was determined using GC-MS. Additionaly, total phenolic (TPC), flavonoid (TFC) and triterpene (TTC)contents were determined. Glycyrrhizic acid contents were analysed by HPLC. G. glabra var. glandulifera (GF1) showedthe highest antioxidant activity. All extracts had strong antidiabetic effects, besides GF1 showing the highest effect. TheMIC values was determined against 8 bacterial and 1 yeast strain and values ranged from 2.500 to 0.500; 2.500 to 0.714;2.500 to 0.714 for G. glabra var. glabra (GB), GF1, G. glabra var. glandulifera (GF2) respectively. Phytochemical studies haveshown that TPC was 100.60±5.06, 127.90±0.30, 69.01±0.30 mg GAE /g extract; TFC was 80.07±0.15, 25.35±0.0, 16.58±0.31mg KE/g and TTC was 217.30±6.05,172.40±2.17, 126.30±4.50 mg OE/g extract for GB, GF1, GF2, respectively. GF1 inparticular has the highest glycyrrhizic acid content. This study will contribute to the creation of new treatment strategiesand potential therapeutic agents in addition to the use of G. glabra L. in traditional treatments. Our study is also apreliminary study for future studies.Article The Effect of Vitamin D and Paricalcitol on Protein Disulfide Isomerase(Marmara University, 2025) Koksal, Murat; Şekerler, Turgut; Şener, Azize; Koksal, Muhammed MuratProtein disulfide isomerase (PDI), a multifunctional protein plays an important role as oxidoreductase, isomerase and chaperone in the cell. Prior studies have identified PDI is highly expressed in many different cancer types and presented as a new potential target for cancer treatment. Here, we investigated vitamin D and its analogue paricalcitol in silico interaction of the human PDI and inhibition of PDI reductase activity in vitro. We observed a non-covalent mechanism where the main skeleton of the vitamin D3 ans paricalcitol sturcture is located at the hydrophobic site in the b' domain of PDI and forms a hydrogen bond with a residue (His138) in tihs domain. They also form multiple weak hydrophobic interactions with various chemical groups of the b' subunit. For the first time, we demonstrate that 1,25-dihydroxyvitamin D3 (1a,25(OH)2 vitamin D3) and paricalcitol inhibit the PDI reductase activity in vitro and their IC50 values are 20.79±1.43 nmol/L and 32.83±3.15 nmol/L respectively. The two compounds can also block the denistrosation activity of PDI.