The Distribution And Bioavailability Of Selenium And Its Effect On The Metabolism Of Phospholipid And Cholesterol Ester

This paper studied on selenium, and analyzed the distribution in protein and polysaccharide from Penaeus vannamei Boone and evaluated selenium bioavailability and its effect on the metabolism of phospholipid (PL) and cholesterol ester (CE) using a mouse model. There are two parts in this paper. The first part was establishing microwave digestion-inductively coupled with plasma-mass spectrometry (MD-ICP-MS) for analysis of Se and determining the distribution of Se in protein and polysaccharide from Penaeus vannamei Boone. The second part of this research was investigating selenium bioavailability and the effect on metabolism of phospholipid (PL) and cholesterol ester (CE) using a mouse model.In first part, microwave digestion-inductively coupled with plasma-mass spectrometry (MD-ICP-MS) for analysis of Se was established and the optimization of pre-treatment, instrument parameters was carried out. The results showed this method has an advantage in sample preparation, good linearity in the range of0.2-20μg/L (r=0.9999), low detection limit and high sensitivity. The precision (RSD<1.84%) and recovery ration (87.16%～90.18%) all met the requirements of analysis. The content of selenium in Penaeus vannamei Boone was0.225±0.015mg/kg (n=3). Then, different extraction methods were used to extract the water-soluble protein, salt-soluble protein, alcohol-soluble protein, and alkali-soluble protein in turn. The content of alkali-soluble protein, water-soluble protein and salt-soluble protein in Penaeus vannamei Boone were63.17%,23.79%,13.04%, respectively. The content of selenium in alkali-soluble protein, water-soluble protein and salt-soluble protein was1.320mg/kg,1.283mg/kg and1.052mg/kg, respectively. The percentage of selenoprotein in total Se was66.67%, which demonstrated selenoprotein was the main fonn of Se. At the meantime, we analyzed the Se content in polysaccharide of Penaeus vaimamei Boone using MD-ICP-MS. The optimal extraction parameters were established as follows:ratio of material to solvent was1:25, extraction temperature was70℃, extraction time was5h and extraction1time. The optimal extraction yield of polysaccharide from Penaeus vannamei Boone was75.67%. During the deprotein study, sevag method, papain emzymolysis combined with sevag method and trypsin emzymolysis combined with sevag method have been compared. The optimum method of deprotein was a combination of trypsin and sevag method according to the rate of deproteinzation and the rate of polysaccharide losing. Meanwhile, the content of Se in polysaccharide was0.911±0.014mg/kg (n=3) determined by ICP-MS. The Se-polysaccharide made5.89%of total Se in Penaeus varmamei Boone.In second part, selenium bioavailability from Penaeus vannamei Boone was evaluatd using a mouse model by analyzing Se content in organs and feces samples and Se-dependent enzyme (GPX) activities in liver and blood samples. Comparing with control group which received normal diet, group Ⅰ,Ⅱ and Ⅲ which received2,8and16μg/kg body weights of mice had an increasing in Se content. Se content in liver and kidney samples in group Ⅰchanged non-significantly, group II (P<0.05) and group Ⅲ(P<0.01) changed more significantly; in blood samples, group I and Ⅱ showed no significant increasing and group III changed significantly (P<0.05); and there was a significant increasing in spleen in all three groups (P<0.01). The absorption of Se was in87.6%,87.9%,85.7%and85.6%in four groups by determination of Se content in organs and feces samples. The utilization of Se in body was determined by GPX activities. The results showed that GPX activity of liver in group II and group III showed significant increase (P<0.05) and whereas as for blood in the corresponding groups, the differences appeared more obvious (P<0.01). Finally, we investigated Se’s effect on metabolism of phospholipid (PL) and cholesterol ester (CE) based on established mouse model. The content of PL and CE were analyzed by ESI combine with tandem triple quadrupole mass spectrometry (ESI-MS/MS), the method of precursor ion scan and neutral loss scan were performed to monitor and quantity different classes of phospholipid (phosphatidyl choline, PC; phosphatidyl ethanolamine, PE; phosphatidyl serine, PS) and CE. The result showed that at least22species of PC,22species of PE,24species of PS and18species of CE were identified from intestine samples. Even though the species of PLs and CE in4groups showed no difference, the total content and the relative percentage were somewhat differentiated for species of PLs and CE. The trend of changing was proportional to Se concentration in mice diet. The results suggest that there might be some correlation between the Se intake and the metabolism of phospholipid and cholesterol ester.