Bilim-Teknoloji Uygulama ve Araştırma Merkezi
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Öğe Antimicrobial and antioxidant potential of novel s-alkylated and reduced schiff base 1,2,4-triazole derivatives(Bilal Gümüş, 2025) Gültekin, ErgünIn this study, four new 1,2,4-triazole derivatives (5–8) were designed, synthesized, and structurally characterized through FT-IR, ¹H-NMR, and ¹³C-NMR spectroscopic techniques. Antimicrobial properties were evaluated against standard Gram-positive (S. aureus ATCC 25923, S. pyogenes ATCC 19615) and Gram-negative bacteria (E. coli ATCC 25922, P. aeruginosa ATCC 27853), as well as the fungal strain C. albicans ATCC 10231, using the disk diffusion method. Antioxidant activities were assessed via ferric reducing antioxidant power (FRAP) and DPPH radical-scavenging assays. The results demonstrated that the synthesized compounds exhibited selective antimicrobial efficacy. Schiff base derivatives (5, 6) showed notable inhibitory activity against Gram-positive bacteria, particularly S. aureus and S. Pyogenes, while Gram-negative strains displayed intrinsic resistance. Furthermore, compounds 5 and 6 also presented moderate antifungal activity against C. albicans. Antioxidant analyses revealed that compound 6 possessed remarkable reducing capacity (14.166 mg TE/g) and radical-scavenging activity (IC50 = 0.227 mg/mL), outperforming the other derivatives. These findings suggest that structural modifications, particularly the introduction of heptylthio and Schiff base functionalities, play a decisive role in shaping biological activity. Among the tested molecules, compound 6 emerged as the most promising candidate, exhibiting a dual profile of antimicrobial and antioxidant activities. Collectively, this study highlights the potential of 1,2,4-triazole derivatives as versatile scaffolds for the development of new therapeutic agents aimed at addressing infectious diseases and oxidative stress-related pathologies.Öğe Pyridine hybrid 1,2,4-triazole-5-thione-Schiff base derivatives: synthesis, characterization, antimicrobial, and antioxidant activity evaluations(TAYLOR & FRANCIS LTD, 2025) Gültekin, ErgünAntimicrobials are fundamental agents in the control and treatment of infections; however, increasing antimicrobial resistance severely reduces therapeutic efficacy and exacerbates the global burden of disease and mortality. In this context, a novel series of pyridine-containing 1,2,4-triazole-5-thione Schiff base derivatives (6a-g) were synthesized in good to excellent yields and evaluated for their antimicrobial and antioxidant potential. The structural elucidation of the synthesized compounds was accomplished through FT-IR, 1H-NMR, and 13C-NMR spectroscopy. Antimicrobial activity was assessed using both disc diffusion and minimum inhibitory concentration (MIC) methods against a panel of Gram-positive, Gram-negative bacteria, and the yeast Candida albicans. Compounds 6b, 6d, and 6 g showed potent antibacterial activity against Streptococcus pyogenes ATCC 19615 with low MIC values (19.531 mu g/mL), while compound 6 g demonstrated broad-spectrum activity, also inhibiting Staphylococcus aureus and C. albicans. In antioxidant assays, compound 6f exhibited the highest radical scavenging activity in the DPPH assay, whereas compound 6d showed superior reducing power in the FRAP assay (290.16 mg TE/g). The results indicated that electron-donating (e.g. methoxy) and electron-withdrawing (e.g. nitro) groups on the aromatic ring significantly influenced biological activity. These findings highlight compounds 6d and 6 g as promising candidates for further pharmacological development owing to their multifunctional bioactivity profiles.Öğe Synthesis and characterization of triazole-based schiff bases as novel highly efficient organocatalysts for rapid H2 generation via NaBH4 methanolysis(ELSEVIER SCI LTD, 2025) Işık, Uğur; Gültekin, Ergün; Elma Karakaş, Duygu; Kaya, MustafaThe triazole skeleton is a fundamental building block in heterocyclic chemistry and has been widely investigated for its applications in various fields such as materials science, medicinal chemistry and organic synthesis. Despite this broad utility, the use of this building group as an organocatalyst for hydrogen production is a largely neglected and under-researched topic in literature. While Schiff base-metal complexes (M = Cu, Zn, Ni, etc.) have previously been employed in sodium borohydride (NaBH4) hydrolysis reactions, it is particularly noteworthy that, for the first time, only triazole-based organocatalysts have been utilized as catalysts for hydrogen generation via the NaBH4 methanolysis. In this work, we synthesized, characterized, and optimized triazolebased organocatalysts (MF-MB-PF) and focused on as an efficient catalyst for hydrogen evolution via the alcoholysis of NaBH4. The hydrogen production performance of the MF catalyst was systematically evaluated on the basis of parameters such as catalyst type and amount used, NaBH4 concentration, different solvent systems, various methanol-water ratios, temperature conditions and catalyst reusability. The MF-catalyzed NaBH4 methanolysis reaction was completed in just 0.8 min. Moreover, the hydrogen generation rate (HGR) for the MFcatalyzed reaction was calculated to be 20,540 mL min-1gcat-1 at 30 degrees C, which is comparable to, or better than, that of most metal-free catalysts used for similar purposes. In addition, we determined the activation energy for the MF-catalyzed reaction to be 16.98 kJ/mol. The MF catalyst exhibited remarkable reusability with no significant loss in the first three cycles in the catalytic activity used for the five-cycle reaction. Additionally, the possible mechanism of the MF catalyst in the NaBH4 methanolysis reaction is discussed. Overall, this study introduces MF as a novel metal-free catalyst for hydrogen generation and highlights its potential as an efficient material.Öğe Investigation of antioxidant and antidiabetic activities of different extracts of Vitis labrusca fruit peels(WILEY, 2025) Canbolat Gültekin, Deniz; Akmeşe, Osman; Gültekin, Ergün; Erşen Bak, Funda; Özkan, Ahmet İsmail; Turan, İbrahim; Demir, Selim; Aliyazıcıoğlu, YükselÖğe Investigation of antioxidant and antidiabetic activities of propolis obtained from different locations of Artvin(WILEY, 2025) Turan, İbrahim; Canbolat Gültekin, Deniz; Akmeşe, Osman; Gültekin, Ergün; Demir, Selim; Aliyazıcıoğlu, YükselÖğe Investigation of the properties of 1,2,4-triazole-3-thione schiff base derivatives by urease inhibition as therapeutic or agrochemical candidate molecules(John Wiley and Sons Inc, 2024) Zehir Kırkbir, Gamze; Gültekin, Ergün; Kolcuoğlu, Yakup; Bekircan, Olcay; Çolak, AhmetWith the production of bacterial urease, bacteria can provide the best conditions for colonization and survival of the stomach in acidic environment. Due to this reproductive ability, H. pylori can cause various diseases such as cancer, urinary tract infections, and peptic ulcer in human metabolism. Consequently, the discovery of substances that can inhibit urease activity holds great promise for treating certain diseases. In this study, Schiff base derivatives of 1,2,4-triazole-3-thione were synthesized in good to excellent yields. The structures of the obtained compounds were elucidated using spectroscopic techniques, such as FT-IR, ¹H-NMR and ¹³C-NMR. The urease inhibitory activities of the obtained products were evaluated against the reference inhibitor thiourea. Out of these compounds, compound 6 c exhibited the highest inhibitory effectiveness, with an IC?? value of 0.0109 ?M against refenrence inhibitor (IC??=11 ?M). Kinetic studies revealed that compound 6 c acts as a non-competitive inhibitor. According to the results of the docking studies, compound 6 c exhibited the highest binding affinity (with the lowest ?G value as ?8.4 kcal/mol) and efficiently interacted with the enzyme as a potent inhibitor among all the molecules examined in the study.Öğe Development of biobased, sustainable and environmentally friendly glycerol ester rosins for the production of thermoplastic road marking paint(John Wiley and Sons Inc, 2024) Yılmaz, Bilge; Deniz, İlhan; Fazlı, Hilal; Bekircan, Olcay; Gültekin, Ergün; Pranovich, AndreyIn recent years, natural rosin derivatives have gained significant importance in the production of sustainable bio-based materials, including thermoplastic road marking paint (TRMP). This study evaluates the use of sustainable natural glycerol ester rosins as bio-based binders in TRMP formulations, specifically focusing on pine, wood, and tall oil rosins. Various analytical techniques, such as FT-IR, TGA, MALDI-TOF-MS and GPC-HPLC, were utilized to analyze both unmodified and glycerol ester rosins. Standard tests, including acid number (mg KOH/g) ASTM D 465-05 and softening point (°C) ASTM E 28-99, were also conducted on the samples. The optimum synthesis conditions for glycerol ester rosins (GER) were determined as follows: a rosin/glycerol molar ratio of 2.54, catalyst/rosin weight ratio of 0.5%, and antioxidant/rosin weight ratio of 1.0%. GPC-HPLC analysis revealed average esterification reaction yields of over 90.85%. Furthermore, TRMPs underwent various tests, including gloss factor (?), chromaticity coordinates (x, y), UVB aging, and softening point (°C). The results demonstrated that GERs exhibited superior performance, especially in the UVB aging test, with all TRMPs classified as UV1 type. These findings highlight the promising potential of GERs derived from different types of rosins in producing sustainable, environmentally friendly, and bio-based next-generation TRMPs.Öğe Environmental effects of acid mine drainage and rehabilitation options at closed mine site: a case study(Springer, 2024) Konanç, Mustafa Umut; Değermenci, Gökçe DidarIrregular waste storage at closed mine sites poses severe environmental problems. This study evaluates the concentrations and effects of trace elements released into the environment by mining activity by analyzing soil, water, and sediment samples taken from a copper mining site. According to the data, acidic mine drainage was the main cause of the high concentrations of trace elements in the soil and sediments, including arsenic (As), cadmium (Cd), lead (Pb), and copper (Cu). The concentrations of As, Cd, Pb, and Cu in soil and sediments were 2734-times, 1189-times, 157-times and 32 times higher, respectively, in comparison to the background values of averaged concentrations of these elements in the upper crust. Geological and statistical studies indicate that the primary constituents of these pollutants are chalcopyrite and pyrite derivatives present in the primary rock structure. Using water analysis data from 2011 to 2020, the release of essential trace element into water was investigated to monitor the environmental effects of acidic mine drainage (AMD) from the closed Kuvarshan copper mine in the Artvin region of Turkey. This study demonstrates that trace elements concentrations may change according to local and seasonal factors and highlights the importance of conducting routine environmental monitoring studies.Öğe 1,3,4-thiadiazole and 1,2,4-triazole-5-thione derivatives bearing 2-pentyl-5-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-one ring: Synthesis, molecular docking, urease inhibition, and crystal structure(Wiley, 2022) Gültekin, Ergün; Bekircan, Olcay; Kara,Yakup; Güler, Halil İbrahim; Soylu, Mustafa SerkanTwo series of 1,3,4-thiadiazole (40a–o) and 1,2,4-triazole-5-thione (41a–l) derivatives bearing a 2-pentyl-5-phenyl-1,2,4-triazole-3-one ring were synthesized and then studied for their urease inhibitory activities using thiourea as a standard drug. Among the two groups, the first group (40a–o) did not show good activity while the second group (41a–l) showed excellent activity. Compound 41j (1091.24?±?14.02?µM) of the second series of compounds showed lower activity than thiourea, while the remaining 11 compounds (41a–i, k, and l) showed better activity than thiourea (183.92?±?13.14?µM). Among the 11 compounds, 41b (15.96?±?2.28?µM) having the 3-F group on the phenyl ring showed the highest inhibitory activity. Urease kinetic studies of 41b, which is the most active compound, determined it to have an un-competitive inhibition potential. Moreover, in silico analysis against urease from jack bean with 27 new heterocyclic compounds and the reference molecule was carried out to see the necessary interactions responsible for urease activity. The docking calculations of all compounds supported stronger binding to the receptor than the reference molecule, with high inhibition constants. In addition, compound 40m was characterized by single-crystal X-ray diffraction analysis. X-ray analysis reveals that the structures of the compound 40m crystallize in the monoclinic P21/c space group with the cell parameters: a?=?10.2155(9)?Å, b?=?22.1709(18)?Å, c?=?21.4858(17)?Å, ??=?99.677(8)°, V?=?4797.0(7)?Å3. X-ray diffraction analyses were also performed to gain insights into the role of weak intermolecular interactions and C-H…X (halogen) interactions in compound 40m that influence the crystal packing.
