Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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2016 - 20174

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Access Right: Open AccessAuthor: search.filters.author.Güleç, Şükrü

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  • Master Thesis
    Extraction of Phytochemicals From Scolymus Hispanicus and Determination of Potential Health Effects
    (Izmir Institute of Technology, 2017) Ahmad, Bilal; Büyükkileci, Ali Oğuz; Güleç, Şükrü
    Golden thistle (Scolymus hispanicus) is an edible medicinal plant growing in Turkey. It has been in use since decades for the treatment of various disorders by local folks. In the past the extracts from the root barks of S. hispanicus were in use in the form of a medicine for the removal of kidney stones. Its root barks are the only eaten part and the root internal and aerial parts are considered as residues. The effect of harvesting time and plant maturity on phytochemicals composition of this plant have not been studied before. Besides that, in previous studies only the edible part was analyzed for bioactive constituents and the residues (aerial parts and root internal parts) have not been analyzed before. In this study, various phytochemicals and total antioxidant activities in the ethanol extracts of aerial parts, root barks and root internal tissues of S. hispanicus harvested from November 2016 to July 2017 were measured. The dominant phytochemicals were different in the roots and the aerial parts, whereas phytochemicals were influenced differently by the harvesting time. Total phenol contents and total antioxidant activities were higher in the aerial parts than the root parts, while total triterpenoid contents were higher in root barks and root internal tissues. Thin Layer Chromatography (TLC) analysis showed that there were not any free triterpenoids in the extracts, however there were glycosides, which may have contained triterpenoids. The crude extracts of S. hispanicus showed cytotoxic effects on Caco-2 cells growth. The results suggested that these extracts might have potential preventative effects on colon cancer.
  • Master Thesis
    Testing of Antidiabetic Features of Formulated Food Products in Enterocyte Cell Culture Model
    (Izmir Institute of Technology, 2017) Pilatin, Gözde; Güleç, Şükrü
    In recent years, there has been an increasing interest in designing low calorie functional foods that might have health benefit against development of obesity and T2D. However, researches on developing low calorie foods in Turkey are quite insufficient. Even if the products are developed, in vitro and in vivo approaches to design low calorie foods are not carried out properly. Thus, we aimed to test diabetic features of newly formulated low calorie and no-added sugar containing cake, almond paste and pudding in intestinal cell culture system. Cake, almond paste and pudding were developed by “Egepak Gıda ve Ambalaj San.” and same type foods were chosen from market to use as reference. We modeled human carbohydrates digestive systems in test tube and relative glucose efflux were measured from rat enterocyte cells that were grown on bicameral cell culture system. Bioaccessibility of glucose was found at least 61%, 89% and 64% lower in cake, almond paste and pudding respectively relative to references. The levels of cellular glucose efflux were significantly lower from 30min (for cake 1.9 fold; for almond paste 4.3; for pudding 3.3 fold) to 120 min (for cake 2.2 fold; for almond paste 3.7 fold) to 180 min (for pudding 2.0 fold) in products than their references. To the best of our knowledge, this is the first exemplary study in Turkey to develop newly formulated foods by analyzing their diabetic features in in vitro model of human intestine system.
  • Master Thesis
    Xylan Degradation Mechanism of Human Intestinal Bacteria
    (Izmir Institute of Technology, 2017) Polat, Nüket; Büyükkileci, Ali Oğuz; Güleç, Şükrü
    Xylan is the second most abundant plant cell wall polysaccharide after cellulose. The xylan rich lignocellulosic material obtained from agriculture, forestry and industrial wastes provides cost effective raw materials. The degradation of xylan in the human body is an important process contributing to the continuation of the microbial communities living in the human colonic ecosystem. Due to its complex, long chain structure and the various chemical bonds it contains, xylan hydrolysis requires different enzymatic activities. Bacteria that live in the colon and are useful for human health, such as Bifidobacterium and Lactobacillus species can not perform xylan utilization. However, several types of xylan are utilized by the Bacteroides species, which have the second largest density in the colon. In this study, different Bifidabacterium and Bacteriodes species were investigated for their ability to degrade beechwood xylan and corncob xylan. Bifidabacterium and Bacteriodes were cultured together in tubes containing xylan as the sole carbon source. It was observed that; the B. animalis subsp. lactis, which does not have the ability to use the xylan, could grow when cultured on xylan-containing medium with Bacteroides species. These showed that, the xylan in the media was degraded into xylooligosaccharides by the Bacteroides species and the XOS formed was used as a carbon source by both species. The short chain fatty acid and lactic and succinic acid production profiles of co-cultures were different than the mono cultures, indicating a positive effect of co-culturing. This study showed that xylan is a potential prebiotic carbohydrate, which can selectively stimulate the growth of beneficial bacteria in the colon, as a result of possible cross feeding of different bacteria residing in the colon.
  • Master Thesis
    Investigation of the Molecular and Genetic Response in Enterocytes of Duodenum During Elevated Intracellular Glucose Level
    (Izmir Institute of Technology, 2016) Boztepe, Tuğçe; Güleç, Şükrü; Seyrantepe, Volkan
    Glucose is one of the nutritional factor that involves in developing of obesity and type 2 diabetes in human. The studies indicated that enterocyte cells on intestine might play a role in dietary glucose sensing during obesity. Obese people are consumed high amount of dietary glucose and enterocyte cells consequently are exposed to high glucose. Thus, we aimed to find relevant physiological pathways and genome-wide mRNA expression profiles that can be regulated by glucose in fully differentiated human intestinal epithelial (CaCo-2). The cells were maintained two different glucose levels (5.5mM for control, 25mM for high glucose) at least three passages. The cells were grown on transwell system for 21 days to mimic human intestine system. Transepithelial electrical resistances (TEER) were measured to control monolayer formation and polarization. RNA isolation was performed and whole genome mRNA expression profile were determined following gene ontology analysis to find affected molecular pathways. Compared to control relative glucose level was found high in basolateral side of CaCo-2 cells that were under high glucose condition without effecting TEER. GLUT2, SGLT1, GLUT5 mRNA levels were significantly reduced during elevated glucose levels which is consistent with literature. Significant fold change analysis showed that 351 genes upregulated and 468 genes under high glucose condition. We found high glucose significantly leads changes of molecular pathways (downregulated; glycolysis and gluconeogenesis, adherens junction, fructose/mannose metabolism, pentose phosphate pathway and upregulated; protein export). These results provide us better understanding and open new window for glucose metabolism of enterocytes during obesity.