Browsing by Author "Yilmaz E.S."

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    Production of rhamnolipid (a biosurfactant) using free and immobilized cells of Pseudomonas sp; [Serbest ve tutuklanmış Pseudomonas sp. hücrelerinden ramnolipid (biyosürfektan) eldesi]
    (Veteriner Fakultesi Dergisi, 2012) Sidal U.; Yilmaz E.S.
    This study presents a method for the production of rhamnolipid, a biosurfactant, by Pseudomonas sp. Pseudomonas sp. cells that were grown in nutrient agar were inoculated into sterile liquid medium. Following an incubation period of 24 h, 2 ml of cells were inoculated into a different liquid medium and the results were obtained at the end of 26 hours incubation time. In our study, the effects of temperature, pH, and glucose concentration on rhamnolipid production were also investigated. Later, the same procedure was applied to immobilized cells that were kept away from the free microorganisms. The production of rhamnolipid by free cells was found to be much higher than that of immobilized cells. Free cells could be used for rhamnolipid production effectively.
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    4-Propargyl-substituted 1H-pyrroles induce apoptosis and autophagy via extracellular signal-regulated signaling pathway in breast cancer
    (John Wiley and Sons Inc, 2021) Atmaca H.; Ilhan S.; Yilmaz E.S.; Zora M.
    Novel pyrrole derivatives (PDs) with propargyl units (1–7) were investigated for their anticancer activity on breast cancer cells. The MTT assay was used to assess the cell viability. Morphological changes in human breast cancer cells were visualized under a phase-contrast microscope. Apoptosis and autophagy were detected using the DNA fragmentation assay and staining by autophagic vacuoles, respectively. The levels of apoptosis- and autophagy-related proteins such as cytochrome c, Bcl-2, LC3-I/II were investigated by Western blot analysis. The effect of PDs on the ERK1/2 signaling pathway was investigated using specific inhibitors. All the tested PDs were found to be active in the range of 36.7 ± 0.2 to 459.7 ± 4.2 µM. Compounds 3 and 4 showed cytotoxic activity in breast cancer cells, but were found to be safer with lower cytotoxicity on human nontumorigenic epithelial breast cells. Compound 4 induced apoptosis, whereas compound 3 induced autophagy. Both compounds inhibited the ERK signaling pathway in breast cancer cells. The present study revealed that both synthesized PDs induced different programmed cell death types by inhibiting the ERK signaling pathway in two genotypically different breast cancer cells. Therefore, novel PDs might be promising anticancer agents for breast cancer therapy and further structural modifications of PDs may yield promising anticancer agents. © 2021 Deutsche Pharmazeutische Gesellschaft
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    COVID-19: vaccination vs. hospitalization
    (Springer Science and Business Media Deutschland GmbH, 2022) Uzun O.; Akpolat T.; Varol A.; Turan S.; Bektas S.G.; Cetinkaya P.D.; Dursun M.; Bakan N.; Ketencioglu B.B.; Bayrak M.; Baris S.A.; Guner R.; Gunal O.; Nural S.; Deniz P.P.; Toprak O.B.; Ozkan G.; Gumus A.; Kerget F.; Ercelik M.; Ataoglu O.; Yuksel A.; Ates G.; Kutsoylu O.E.; Kose N.; Kizilirmak D.; Keskin S.; Gultekin O.; Coskun N.; Yilmaz E.S.; Uslu S.; Basyigit İ.; Ergan B.; Deveci F.; Yakar M.N.; Zuhur C.; Sagcan G.; Yuce Z.T.; Kuluozturk M.; Sezgin M.E.; Sezgin E.N.A.; Havlucu Y.; Cuhadaroglu C.; Kilinc O.; Boyaci H.; Altunay H.; Akti M.; Dursun Z.B.; Kalem A.K.; Isik S.A.; Akyildiz L.; Aykac N.; Almaz M.S.; Kokturk N.; Itil O.
    Objective: Vaccination is the most efficient way to control the coronavirus disease 2019 (COVID-19) pandemic, but vaccination rates remain below the target level in most countries. This multicenter study aimed to evaluate the vaccination status of hospitalized patients and compare two different booster vaccine protocols. Setting: Inoculation in Turkey began in mid-January 2021. Sinovac was the only available vaccine until April 2021, when BioNTech was added. At the beginning of July 2021, the government offered a third booster dose to healthcare workers and people aged > 50 years who had received the two doses of Sinovac. Of the participants who received a booster, most chose BioNTech as the third dose. Methods: We collected data from 25 hospitals in 16 cities. Patients hospitalized between August 1 and 10, 2021, were included and categorized into eight groups according to their vaccination status. Results: We identified 1401 patients, of which 529 (37.7%) were admitted to intensive care units. Nearly half (47.8%) of the patients were not vaccinated, and those with two doses of Sinovac formed the second largest group (32.9%). Hospitalizations were lower in the group which received 2 doses of Sinovac and a booster dose of BioNTech than in the group which received 3 doses of Sinovac. Conclusion: Effective vaccinations decreased COVID-19-related hospitalizations. The efficacy after two doses of Sinovac may decrease over time; however, it may be enhanced by adding a booster dose. Moreover, unvaccinated patients may be persuaded to undergo vaccination. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.
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    N-Propargylic β-enaminones in breast cancer cells: Cytotoxicity, apoptosis, and cell cycle analyses
    (John Wiley and Sons Inc, 2023) Ilhan S.; Atmaca H.; Yilmaz E.S.; Korkmaz E.; Zora M.
    Breast cancer is one of the most common cancers worldwide and the discovery of new cytotoxic agents is needed. Enaminones are regarded to be a significant structural motif that is found in a variety of pharmacologically active compounds however the number of studies investigating the anticancer activities of N-propargylic β-enaminones (NPEs) is limited. Herein we investigated the potential cytotoxic and apoptotic effects of 23 different NPEs (1-23) on human breast cancer cells. Cytotoxicity was evaluated via MTT assay. Apoptotic cell death and cell cycle distributions were investigated by flow cytometry. CM-H2DCFDA dye was used to evaluate cellular ROS levels. Expression levels of Bcl-2, Bax, p21, and Cyclin D1 were measured by quantitative real-time PCR. ADME properties were calculated using the ADMET 2.0 tool. NPEs 4, 9, 16, and 21 showed selective cytotoxic activity against breast cancer cells with SI values >2. NPEs induced apoptosis and caused significant changes in Bcl-2 and Bax mRNA levels. The cell cycle was arrested at the G0/G1 phase and levels of p21 and Cyclin D1 were upregulated in both breast cancer cells. ROS levels were significantly increased by NPEs, suggesting that the cytotoxic and apoptotic effects of NPEs were mediated by ROS. ADME analysis revealed that NPEs showed favorable distributions in both breast cancer cell lines, meaning good lipophilicity values, low unfractionated values, and high bioavailability. Therefore, these potential anticancer compounds should be further validated by in vivo studies for their appropriate function in human health with a safety profile, and a comprehensive drug interaction study should be performed. © 2023 Wiley Periodicals LLC.
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    Novel Enyne-Modified 1,4-Thiazepines as Epidermal Growth Factor Receptor Inhibitors: Anticancer and Computational Studies
    (American Chemical Society, 2025) Atmaca H.; Camlı Pulat C.; Ilhan S.; Yilmaz E.S.; Zora M.
    1,4-Thiazepines (TZEPs) featuring enyne modifications represent promising candidates in cancer therapy. We synthesized novel TZEP derivatives and assessed their cytotoxicity, apoptosis induction, EGFR inhibition, and molecular interactions. TZEPs exhibited cytotoxic effects against cancer cell lines, with compounds TZEP6 and TZEP7 showing significant activity. Flow cytometry analysis revealed TZEP7-induced apoptosis across various cancer types. RT-qPCR analysis demonstrated downregulation of antiapoptotic Bcl-2, upregulation of pro-apoptotic Bax, and increased caspase levels following TZEP7 treatment. Additionally, TZEP7 inhibited EGFR kinase activity in cancer cells, with molecular docking confirming strong binding affinities to EGFRWT and mutant EGFRT790M. AdmetSAR analysis indicated favorable pharmacokinetic properties for TZEP7. These findings underscore the potential of enyne-modified TZEPs as selective cytotoxic agents with apoptotic and EGFR inhibitory activities, highlighting their significance in cancer therapy. © 2024 The Authors. Published by American Chemical Society.