GCRIS

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Antimicrobial, Antioxidant Properties and Chemical Composition of Some Spices/Herbs
(Izmir Institute of Technology, 2013) Yavuzdurmaz, Hatice; Baysal, Ayşe Handan
The present study aims to investigate the chemical composition, antimicrobial activity, and mechanism of antimicrobial activity, antioxidant properties of essential oils and extracts and the effects of them when applied to minced beef samples. For this purposes; four essential oils (bay leaf, thyme, clove and cumin), two extracts (grape seed and olive leaf) and constituents of essential oils (eucalyptol, linalool, α-terpineol and α-pinene) were subjected to related tests. Chemical characterization was complemented for all essential oils and extracts. Antimicrobial activity was examined against Staphylococcus aureus, Escherichia coli O157:H7, Salmonella Typhimurium, Listeria innocua, Shewanella putrefaciens, Carnobacterium divergens and Serratia liquefaciens. All tested compounds were effective on the bacteria with different concentrations. Antioxidant activity was proved by FRAP and DPPH methods. Physical disturbance and changes in the structures of bacteria was demonstrated by various techniques. The activity of two most potent essential oils (thyme and clove) was investigated in the minced meat application study. The findings represented that clove essential oil restricted the growth of S. Typhimurium and coliform bacteria. They did not have a significant inhibition effect on the aerobic mesophilic bacteria, total yeasts and molds and also psychrotrophic organisms. The results indicated that L* and a* values were maintained during the storage period. The featured effect of essential oils was antioxidant characteristic in meat application study. All treatment showed significant reduction in oxidation comparing with control. The obtained results may suggest that tested essential oils possess compounds with antimicrobial characteristic as well as antioxidant activity and therefore they can be used as natural preservatives in food especially in meat products.
Preparation and Characterization of Hemodialysis Membranes With Improved Biocompatibility Through Anticoagulant, Antioxidant and Enzyme Immobilization
(Izmir Institute of Technology, 2013) Yaşar Mahlıçlı, Filiz; Alsoy Altınkaya, Sacide
The objective of this thesis is to improve blood compatibility of polysulfone (PSF) based hemodialysis membranes through generating thromboresistant and/or antioxidative surfaces with biomolecule immobilization. To create a nonthrombogenic surface, support membrane was modified with layer by layer (LBL) deposition of polyethyleneimine (PEI) and alginate (ALG) and heparin (HEP) was immobilized on the outermost surface of the assembly by blending with ALG. α-lipoic acid (ALA) and superoxide dismutase (SOD)/catalase (CAT) enzyme couple were choosen to provide antioxidative properties. ALA was immobilized site-specifically to PEI deposited support membrane while SOD/CAT enzyme couple were attached both covalently and ionically on the plasma treated and PEI deposited membranes, respectively. Blending a small amount of HEP with alginate remarkably prolonged the coagulation time (APTT) of HEP free membranes. The stability of ALA under typical hemodialysis conditions was improved by immobilization, and the greatest enhancement was achieved when it was sandwiched between two PEI layers. In vitro studies showed that all ALA or SOD/CAT coated PSF membranes are capable of reducing reactive oxygen species levels in blood, furthermore, they can significantly prolong APTT. The hemocompatibility results also demonstrated that the adsorption of human plasma proteins, platelet and cell activation on all modified membranes decreased significantly compared with the unmodified PSF membranes due to the change in surface properties such as hydrophilicity, surface charge and roughness upon immobilization of the biomolecules. The modification methods proposed in this study did not change high permeability, mechanical strength and nontoxic property of the PSF membranes.
Recovery of Phytochemicals (having Antimicrobial and Antioxidant Characteristics) From Local Plants
(Izmir Institute of Technology, 2010) Altıok, Evren; Ülkü, Semra
The objective of the present work was to assess the selective isolation of polyphenols from olive leaf and grape skin, which are supplied from the main local plants. The effects of extraction conditions on the types and amounts of polyphenolic compounds and selective separation of them by adsorption were investigated. The batch adsorption and dynamic column studies were performed by silk fibroin and clinoptilolite. Kinetic models were used to determine the mechanism of adsorption. Dynamic column models were applied to optimize the operating parameters. The biological activities of isolated fractions from the crude extracts were determined by analyzing their antioxidant, antimicrobial and cytotoxic activities. Recovered trans-resveratrol significantly inhibited all pathogenic microorganisms. However, higher concentration of grape skin crude extract is required to achieve same inhibition. Although grape skin extract did not have any effect on prostate and breast cancer cells, trans-resveratrol has very significant inhibition effect.

Phd Degree / Doktora

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