Speciation Of Selenium In Agaricus Blazei

Selenium is trace element of human body, which is also a significant ingredient of glutathione peroxidase. Short of selenium may cause lower GPX activity and various diseases. Therefore, safe and effective research and development of supplementing selenium is one of the important issues currently. Selenium exists in two forms of inorganic selenium and organic selenium. The inorganic selenium’s toxicity is greater than the organic selenium’s and the absorption, bioavailability of organic selenium is superior to inorganic selenium. Agaricus blazei is a rare food, medicine used along with fungi. Agaricus blazei is not only delicious, but also contains large amounts of active ingredients such as polysaccharide、protein、lectin、sterols、lipids、vitamins and trace elements selenium. Agaricus blazei has become a functional food "new favorite" in the 21st century. At present the research of polysaccharides, sterols, polyphenols and peptides in Agaricus blazei more, whereas study trace elements selenium less. Therefore, study the occurrence and distribution of selenium in Agaricus blazei provides the scientific basis for the development of drugs, health foods or the synthesis of organic selenium. The subject owns important academic significance and practical value.The main contents of this paper and the results are as follows:1. To establish the method of hydride generation atomic fluorescence spectrometry for the determination of selenium in the fruiting body of Agaricus blazei. The best determination conditions:the concentration of lamp current was 80 mA, minus high voltage was 270V, carrier hydrochloride was 10%, sodium borohydride was 0.9%, medium acid were 2.4mol/l. The linear range was 1-10ng/mL, the detection limit was 0.002ng/mL, the precision was 1.32-4.11%(r=10), the recovery rate was 92.89-106.49%(n=5). Agaricus blazei was digested with wet digestion and microwave high pressure dissolution method and determined the contents of selenium by hydride generation atomic fluorescence spectrometry. The content of selenium in Agaricus blazei was 1.243±0.0344μg/gand 1.304±0.0387μg/g, respectively; the RSD was 2.76% and 2.97, respectively. The method was simple and accuracy to determine selenium in Agaricus blazei. The two method of digest were accurate, sensitive, simple rapid and suitable to determine selenium in Agaricus blazei.2. To study the occurrence and distribution of selenium in Agaricus blazei. To remove inorganic selenium by dialysis, obtained selenium nucleonic acid, selenium polysaccharide, total-soluble selenium protein, water-soluble selenium protein, salt-soluble selenium protein, alcohol-soluble selenium protein and alkali-soluble selenium protein by different extraction methods, determined the selenium content by hydride generation atomic fluorescence. The results show that the selenium in Agaricus blazei was mainly in the organic selenium and the percentage of total selenium was 81.57%. Distribution of organic selenium is selenium protein>selenium polysaccharide>selenium nucleic acids, including protein selenium most and the protein selenium shared 73.53% in the organic selenium,60.15% in the total selenium; Followed by the polysaccharide selenium, sharing 12.23% in the organic selenium, 9.98% in the total selenium. Therefore, selenium protein is the main form of protein in Agaricus blazei. The distribution of selenium in the protein was alkali-soluble selenium protein> water-soluble selenium piotein> salt-soluble selenium protein>alcohol-soluble selenium protein. In the selenium protein alkali-soluble seleniumprotein and water-soluble selenium protein were the principal protein. Alkali-soluble selenium protein shared 74.99% in the protein selenium,55.15% in the organic selenium,45.11% in the total selenium; Water-soluble selenium protein shared 10.28% in the protein selenium,7.56% in the organic selenium,6.17% in the total selenium;3. To Purify and characterize selenium polysaccharide in Agaricus blazei. Studied the purification of Agaricus blazei selenium polysaccharide, determined the molecular weight, composition and selenium content of the selenium polysaccharide. Polysaccharide was deproteinized by trichloroacetic acid after water extraction and alcohol precipitation, then purified for 3 polysaccharide compositions, they are AB-SeP-1, AB-SeP-2 and AB-SeP-3, respectively. The results showed that the yield of Agaricus blazei crude polysaccharide was 12.06%, polysaccharide content was 32.51%; AB-SeP-1 and AB-SeP-3 showed single symmetrical peak on the HPLC icon, the molecular weight of AB-SeP-1 and AB-SeP-3 was 3075 and 111074, respectively; The selenium content of them was 1.911μg/g and 0.671μg/g, respectively. AB-SeP-2 was mainly composed by two kinds of polysaccharide whose molecular weight were 21254 and 34778, the selenium content was 0.613μg/g.Themonosaccharides fraction of AB-SeP-1 were galactose and glucose,the molar ratio was gal:glu=1:7.49; The monosaccharides fraction of AB-SeP-2 were mannose,galactose and glucose,the molar ratio was man:gal:glu=1:1.55:27.01; The monosaccharides fraction of AB-SeP-3 were galactose, mannose and glucose,the molar ratio was gal:man:glu=1:1.22:9.81.4.To purify the selenium protein of Agaricus blazei and characterize them.Studied the purification of Agaricus blazei selenium protein, determined the selenium content and subunits components. Four kinds of Agaricus blazei selenium protein were obtained by different solvents and then water-soluble selenium protein and alkali-soluble selenium protein were purified with DEAE-52 cellulose and sephadex G-100 column chromatography. The purity of the purified composition was characterized by Native-PAGE and the subunits components molecular weight was determined by SDS-PAGE. The results showed that the yield of Agaricus blazei water-soluble selenium protein was 5.01%, protein content was 15.90%; Salt-soluble selenium protein was 0.33%, protein content was 13.34%; Alcohol-soluble selenium was 0.41%, protein content was 21.31%;Alkali-soluble selenium protein was 27.51%, protein content was 28.63%; A single electrophoretic band indicated that AB-SePA-22 was a single protein fraction. The molecular weight of AB-SePA-22 was composed by four subunits whose molecular weight were 16.7kDa,21.7kDa, 26.3kDa and 33.6kDa, while the alkali-soluble selenium protein AB-SePG-22 electrophoretic bands were not clear,appearing serious tailing phenomenon.The selenium contents of AB-SePA-22 and AB-SePG-22 was 4.935μg/g and 6.083μg/g, respectively.