Mantar örneklerinde toplam antioksidan kapasite tayini
Determination of total antioxidant capacity of mushrooms
- Tez No: 558789
- Danışmanlar: PROF. DR. BİRSEN ÖZTÜRK
- Tez Türü: Yüksek Lisans
- Konular: Kimya, Chemistry
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2019
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Kimya Ana Bilim Dalı
- Bilim Dalı: Kimya Bilim Dalı
- Sayfa Sayısı: 78
Özet
Canlıların metabolik faaliyetleri esnasında oluşan kimyasal reaksiyonlar, özellikle oksidasyon reaksiyonları, serbest radikallerin oluşmasına sebep olur. Fazlasıylareaktif olma özelliğine sahip olan serbest radikaller birçok molekül ile rahatça reaksiyona verebilir, hücreler bu reaksiyonlar yüzünden tahrip olabilir, enzimlerin ve DNA'nın yapısı bozulabilir. Ayrıca gıdalar, kozmetik ürünler, ilaçlar, sigara dumanı gibi faktörler serbest radikallerin oluşmasına sebebiyet verirler ve bu serbest radikaller zincir reaksiyonunun başlangıcını oluştururlar. Antioksidanlar serbest radikalleri inhibe ederek zincir reaksiyonunu engellerler. Gıdalar ile organizmaya alınan antioksidanların en önemli etkisi“oksidatif stresi”engellemesidir. Serbest radikallerin miktarının giderek yükselmesi ve hücre yapısına zarar vermesi ile kendini gösteren oksidatif stresin kendisi direkt bir hastalık özelliği taşımaz fakat çeşitli hastalıklara sebep olur. Antioksidanların kimyasal çeşitliliği, sebze, meyve ve bitki matrikslerinden ayrılmalarını ve miktarlarının tayinini zorlaştırmaktadır. Toplam antioksidan kapasite (TAC), karmaşık bir örnekteki tüm antioksidanların antioksidan kapasitelerinin toplamsallığını içeren bir parametredir. TAC (reaksiyon termodinamiğine veya dönüşüm verimliliğine dayalı) veya aktivitenin (reaksiyon kinetiğine dayalı) ölçülebilmesi için çeşitli analitik yöntemler geliştirilmiştir. Mantarlar, bitki grubunda yer almakla birlikte yaprak gibi organlara sahip değildirler ve besinlerini ortamda bulunan organik maddelerden sağlarlar (fotosentezle değil). Bu nedenle mantarlar önemli bir gıda kaynağı olmalarının yanında, tıbbi amaçlarla da yetiştirilmektedir. Bu çalışma da Türkiye'nin Antalya şehrinde yetişen doğal kestane mantarının (Agaricus Spp.) saf su ve % 80 metanol-su kullanılarak dört farklı ektraksiyon yöntemi (ultrasonik ekstraksiyon, mikrodalga ekstraksiyon, ultrasonik-mikrodalga ekstraksiyon ve maserasyon) ile elde edilen ekstraktların antioksidan özellikleri incelenmiştir.
Özet (Çeviri)
In living beings, chemical reactions formed during metabolic activities, particulary oxidation reactions, results in formation of free radicals, which are very reactive and can easily react with different molecules, cells can be damaged due to that reactions and structure of enzymes can be destroyed, moreover even chemical composition of DNA can be changed. On the other hand, foods, drugs, cosmetics, smoke give rise to occuring of free radicals. Chain reactions are initiated by means of free radicals which are formed through oxidation reactions. These chain reactions are inhibited in presence of antioxidants compounds, which have the ability of binding free radicals. Antioxidants are beneficial compounds to health that fight reactive oxygen and nitrogen species and free radicals that may eventually give rise to various diseases. Plant foods, fruit and vegetable are rich in antioxidant vitamins, phenolic and hydroxycinnamic acids, flavonoids, carotenoids, and anthocyanins. Consumption of vegetables and fruits in the diet is one of the most efficient ways of preventing DNA and protein damage, lipid peroxidation, cancer, atherosclerosis, ageing, and inflammatory diseases.The most significant property of antioxidants, that are ingested through nutrians, is equilibration of ''oxidative stress''. The oxidative stress arises with escalating quantity of free radicals, which devastate structure of cells and that oxidative stres is not a disease only it‟s self it also paves the way to other healt disorders. Total antioxidant capacity is a parameter including the cumulative action of all antioxidants in a complex sample. Several analytical methods have been developed to measure total antioxidant capacity (based on reaction thermodynamics or conversion efficiency) and total antioxidant activity (based on reaction kinetics). There are twenty analitical methods developed to determine antioxidant capacity. Litrature investigations reveal that the antioxidant capacity of an antioxidant compound determined with a certain method, may be different compared to another method. Therefore it is necessary to use more than one antioxidant determination method and compare them to analyze of antioxidant capacity of a nutrient. A classification of total antioxidant capacity methods according to mechanism is the type of reaction: Electron transfer (ET)- and hydrogen atom transfer (HAT)- based assays. ET-based assays include ABTS/TEAC (trolox-equivalent antioxidant capacity), DPPH (2,2- diphenyl-1-picrylhydrazeyl) assay, FCR (Folin-Ciocalteu reagent) assay, FRAP (ferric ion reducing antioxidant power), CERAC (cerium (IV) ions reducing antioxidant capacity) and CUPRAC (Cupric Reducing Antioxidant Capacity) methods. Generally, ET-based methods are commonly used than HATbased ones, because they are cheaper and require less laboratory equipment, more flexible, and thus more suitable to routine testing of natural products. However, ET based assays may be less reproducible due to strong dependency on the protocol, such as reagent concentrations, pH, solvent, and time of incubation. The problem can be likely solved by standardization of protocols. In this study, total antioxidant capacity is tried to be determined with five different methods. These methods are CERAC method, CUPRAC method, DPPH method, ABTS/TEAC method and lastly Modifiye Folin- Ciocalteu method, These methods are cheap, more flexible, less laborious and widely used for routine testing of natural products. The chemical variety of antioxidants makes it hard to separate and quantify antioxidants from the vegetable, fruit and plant matrix . Extraction is the first part of separation of natural antioxidant compound from the plant materials. Most common extraction methods are percolation and reflux extraction, solvent extraction, distillation method, pressing and sublimation, usually organic solvents and large volume of solvents are used for these methods, moreover a long extraction time is consumed. Solvent extraction is the most widely used method. Furthermore there are some contemporary and environment sensitive extraction methods such as super critical fluid extraction, pressurized liquid extraction, ultrasound wave assisted extraction and microwave assisted extraction, they are applied in natural products extraction, and they have some advantages such as less organic solvent consumption, shorter extraction time and higher selectivity. The extraction process of vegetable, fruit and plant have got four steps, firstly the solvent penetrates into the solid matrix, secondly the solute dissolves in the solvent, after that the solute is diffused out of the solid matrix and lastly the extracted solutes are collected. Factors affecting the extraction efficiency are the properties of the extraction solvent, the particle size of the raw materials, the solvent-to-solid ratio, the extraction temperature and the extraction time. The selection of the solvent is crucial for solvent extraction. Selectivity, solubility, cost and safety should be considered in selection of solvents. Based on the law of similarity which states that polar compounds are likely to dissolve in polar solvents and apolar compounds are likely to dissolve in apolar solvents as well. Alcohols such as ethanol and methanol are universal solvents in solvent extraction for phytochemical investigation. Generally, the smaller the particle size is, the more efficiency the extraction is. The extraction efficiency will be enhanced by the small particle size due to the enhanced penetration of solvents and diffusion of solutes. High temperatures increase the solubility and diffusion, but too much high temperature levels lead to solvents to be lost and lead to extraction of undesirable impurities, additionally the decomposition of thermo sensitive components. The extraction efficiency increases with the increase in extraction duration in a certain time range. Increasing time will not affect the extraction after the equilibrium of the solute is reached inside and outside the solid material. While mushrooms are included in plant group they don‟t have organs such as leaf and they obtain their foods by organic materials from the environment (not by photosynthesis). For this reason muchrooms are significant nutrient source and also grown for medical aims as well. Ultrasonic extraction, also called ultrasonic extraction or sonication, uses ultrasonic wave energy in the extraction. Ultrasound in the solvent producing cavitation accelerates the dissolution and diffusion of the solute as well as the heat transfer, which improves the extraction efficiency. The other advantage of ultrasonic extraction is less solvent and energy consumption, and the reduction of extraction temperature and time. It is applicable for the extraction of thermolabile and unstable compounds and commonly used in the extraction of many types of natural products. Microwave extraction generate heat by interacting with polar compounds such as water and some organic components in the plant matrix according to the ionic conduction and dipole rotation mechanisms. The transfers of heat and mass are in the same direction in microwave extraction, which accelerates and improve extraction yield. The application of microwave extraction provides many advantages, such as increasing the extract yield, decreasing the thermal degradation and selective heating of vegetal material. It is also regraded as a green chemistry because it lowers the usage of organic solvent. This is a very simple extraction method with the disadvantage of long extraction time and low extraction efficiency. It could be used for the extraction of thermolabile components. In this study antioxidant features of extractions, which are obtained by four different extraction methods (ultrasonic extraction, microwave extraction, ultrasonicmicrowave extraction and maceration) of natural chestnut mushrooms(Agaricus Spp.), which is grown in Antalya city of Turkey, are studied by using distilled water and % 80 methanol-water.
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