Yazar "Toydemir, Gamze" seçeneğine göre listele

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    Coffee induces AHR- and Nrf2-mediated transcription in intestinal epithelial cells
    (Elsevier Sci Ltd, 2021) Toydemir, Gamze; Loonen, Linda M. P.; Venkatasubramanian, Prashanna Balaji; Mes, Jurriaan J.; Wells, Jerry M.; De Wit, Nicole
    Coffee induces a health-promoting adaptive response of cells in the body. Here, we investigated enterocyte responses to AHR agonists in coffee and measured their transport across a polarized intestinal epithelium. AHR-activating potencies of Turkish, filter, and instant coffee were determined using DR CALUX (R) bioassay, before and after intestinal metabolization by Caco-2 cells. Furthermore, effects of coffee on induction of AHRand Nrf2-pathway genes in Caco-2 cells were evaluated by real-time qPCR. Coffee samples showed considerable AHRactivating potencies in DR CALUX (R) bioassay (up to 79% of positive control activity). After incubation with Caco2 cells, AHR activity of different coffees was between 35 and 64% of their initial value, suggesting rapid uptake and metabolization by epithelial cells. Expression of AHR-regulated gene CYP1A1 increased up to 41-fold and most Nrf2-pathway genes were up-regulated by coffee. This in vitro study may support the notion that coffee bioactives contribute to antioxidant defense and detoxification processes in vivo.
  • Küçük Resim
    Öğe
    Effect of food processing on antioxidants, their bioavailability and potential relevance to human health
    (2022) Toydemir, Gamze; Şubaşı, Büşra Gültekin; Hall, Robert D.; Beekwilder, Jules; Boyacıoğlu, Dilek; Çapanoğlu, Esra
    It has long been recognized that the antioxidants present in fresh plant materials may be very different to those we ingest via our foods. This is often due to the use of food processing strategies involving thermal/non-thermal treatments. Current research mostly focuses on determining what is present in vegetative starting materials; how this is altered during processing; how this influences activity in the gut and following uptake into bloodstream; and which in vivo physiological effects this may have on human body. Having a better understanding of these different steps and their importance in a health-and-nutrition-context will place us in a better position to breed for improved crop varieties and to advise the food industry on how to optimize processing strategies to enhance biochemical composition of processed foods. This review provides an overview of what is currently known about the influence which food processing treatments can have on antioxidants and gives some pointers as to their potential relevance.
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    Investigating the antioxidant and antimicrobial activities of different vinegars
    (Springer, 2017) Bakır, Sena; Devecioğlu, Dilara; Kayacan, Selma; Toydemir, Gamze; Karbancıoğlu Güler, Funda; Çapanoğlu, Esra
    In this study, the antioxidant contents and the antimicrobial activities of 18 vinegar samples were investigated. For this purpose, total flavonoid contents (TFC) and total phenolic contents (TPC) of different vinegar samples were determined. In addition, total antioxidant capacities (TAC) of vinegars were analyzed using four different in vitro tests: ABTS, CUPRAC, DPPH, and FRAP, in parallel. Results obtained from antioxidant analyses showed that balsamic vinegar had the highest TFC (96 +/- 18 mg CE/100 mL) and TPC values (255 +/- 24 mg GAE/100 mL), as well as the highest TAC determined using CUPRAC (709 +/- 108 mg Trolox/100 mL) and FRAP (421 +/- 28 mg Trolox/100 mL) methods. The phenolic profiles of vinegar samples were identified by performing HPLC analysis. Among all vinegar samples studied, the most abundant phenolic compounds were determined to be gallic acid, protocatechuic acid, and p-hydroxybenzoic acid. Furthermore, antimicrobial activities of different vinegars, against Staphylococcus aureus, Salmonella Typhimurium, and Escherichia coli, were evaluated using disc diffusion method; the results of which were related to the acetic acid contents and the pH values of the vinegar samples. Balsamic vinegar was again determined to be the sample that had the highest antimicrobial activity, which showed a strong antibacterial activity against S. Typhimurium. Antibacterial activities of vinegars could partly be related to both their acetic acid contents and the pH values, and also to their phenolic contents.
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    Nanosensors for foods
    (Springer, 2020) Toydemir, Gamze; Çekiç, Sema Demirci; Özkan, Gülay; Uzunboy, Seda; Avan, Aslı Neslihan; Çapanoğlu, Esra; Apak, Reşat
    Nanotechnology, as being a branch of science taking the advantage of the unique chemical and physical properties of matter on the nanoscale, has a great potential of application in food systems, including the development of effective and innovative analytical techniques for monitoring food safety and quality. At this point, nanosensors and nanobiosensors take the first place as promising alternatives to the classical quantification methods used for ensuring safety and quality of foodstuffs. The electrochemical nanosensors, optical nanosensors, nanoparticle-based nanosensors, nano-tube based nanosensors, quantum dots, nanofibers, electronic nose and electronic tongue, and nanobarcode technology have greatly added to the food detection practices in food systems with their superior sensing capabilities. Current research report many applications of these important tools to improve the quality and safety of food products, including nanosensors to detect chemical (i.e. pesticides, antibiotics, heavy metals) and biological (toxins and pathogens) contaminants, as well as adulterants (i.e. melamine); to improve in-package protection of foods through enhanced thermal and mechanical properties; to monitor freshness and traceability in raw and processed products; and to control the use of food additives (i.e. aroma and coloring agents). The present chapter is focused on the recent progress in nanotechnology-enabled biosensing through the introduction of current research on various types of nanosensors followed by their applications in food safety. © Springer Nature Switzerland AG 2020.
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    Polyphenol-protein interactions and changes in functional properties and digestibility
    (Elsevier, 2018) Özdal, Tuğba; Yalçınkaya, İpek Ekin; Toydemir, Gamze; Çapanoglu, Esra
    Polyphenols provide extensive health benefits including prevention of certain chronic diseases. Polyphenols form complexes with proteins resulting with functional, nutritional and structural changes in both proteins and polyphenols. There exist a variety of factors that influence protein-phenolic interactions, including type of protein, structure of phenolic compounds, and environmental factors such as temperature, pH, salt concentration and presence of certain reagents. Processing may change the interactions, as well as stability and bioaccesibility of phenolic compounds. Even though the exact mechanism of protein-phenolic interactions is still unknown, their effects on the structural, functional and nutritional properties of proteins and phenolic compounds have been investigated. Although there exist controversial results (due to different analytical techniques used), in general, the published studies reveal that secondary and tertiary structures and solubility of proteins are altered with enhanced thermal stability while antioxidant capacity and bioavailability of phenolic compounds would likely decrease. In this chapter, the chemistry behind protein-phenolic interactions, factors affecting these interactions, and the structural, functional and nutritional changes in proteins and phenolic compounds resulting from the interactions and the characterization methods used are described. © 2019 Elsevier Inc.
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    Prunus fruit juices
    (John Wiley & Sons Ltd, 2017) Toydemir, Gamze; Boyacıoğlu, Dilek; Hall, Robert D.; Beekwilder, Jules; Çapanoğlu, Esra
    [No abstract available]
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    Use of microarray datasets to generate Caco-2-dedicated networks and to identify reporter genes of specific pathway activity
    (Nature Publishing Group, 2017) Venkatasubramanian, Prashanna Balaji; Toydemir, Gamze; de Wit, Nicole; Saccenti, Edoardo; dos Santos, Vitor A. P. Martins; van Baarlen, Peter; Mes, Jurriaan J.
    Intestinal epithelial cells, like Caco-2, are commonly used to study the interaction between food, other luminal factors and the host, often supported by microarray analysis to study the changes in gene expression as a result of the exposure. However, no compiled dataset for Caco-2 has ever been initiated and Caco-2-dedicated gene expression networks are barely available. Here, 341 Caco-2-specific microarray samples were collected from public databases and from in-house experiments pertaining to Caco-2 cells exposed to pathogens, probiotics and several food compounds. Using these datasets, a gene functional association network specific for Caco-2 was generated containing 8937 nodes 129711 edges. Two in silico methods, a modified version of biclustering and the new Differential Expression Correlation Analysis, were developed to identify Caco-2-specific gene targets within a pathway of interest. These methods were subsequently applied to the AhR and Nrf2 signalling pathways and altered expression of the predicted target genes was validated by qPCR in Caco-2 cells exposed to coffee extracts, known to activate both AhR and Nrf2 pathways. The datasets and in silico method(s) to identify and predict responsive target genes can be used to more efficiently design experiments to study Caco-2/intestinal epithelial-relevant biological processes.