【作者】 刘凌云；

【导师】 霍军生； 崔同；

【作者基本信息】 河北农业大学 ， 农产品加工及贮藏工程， 2006， 硕士

【摘要】 乙二胺四乙酸铁钠（NaFeEDTA）是一种新型的螯合型铁营养强化剂,近年来由于其在预防缺铁性贫血方面具有显著效果而备受关注。1993年,隶属国际食品法典委员会的国际权威机构JECFA经过全面评价后推荐NaFeEDTA作为铁营养强化剂使用。作为食品营养强化剂,NaFeEDTA具有口感好,铁锈味较小,未见胃肠刺激,不易受铁吸收抑制剂的干扰,对载体食物的感官和理化品质影响小,在人体中的吸收利用率高等特点,是目前公认的综合性能较好的铁营养强化剂。NaFeEDTA作为铁强化剂,其生物利用率比其他强化剂如FeSO₄高2-3倍,在预防和控制缺铁性贫血方面取得了很大的成效,但是NaFeEDTA在生物体胃肠道吸收的机理还没有得到较明确的阐述。本实验采用体外模型法、透析袋模型法和外翻肠囊法三种方法探讨了NaFeEDTA可能的吸收机理。 通过体外模型法研究发现:NaFeEDTA在pH为2～7.5的条件下化学稳定性较好;在模拟生物体胃肠液环境的人工胃肠液中NaFeEDTA没有发生任何变化,生物体消化道分泌的消化酶（胃蛋白酶和胰蛋白酶）对NaFeEDTA的稳定性没有影响;在人工胃肠液中加入草酸和植酸后,当Fe∶草酸（植酸）的摩尔比为1∶1,1∶3,1∶5和1∶8时,NaFeEDTA均可以稳定存在,表明草酸和植酸不能够从络合强度足够大的FeEDTA螯合物中“抢夺”其中的三价铁离子。由此推测NaFeEDTA在生物体的胃肠道溶液中的化学稳定性较高。 透析袋模型实验发现,NaFeEDTA在透析袋内透过量的大小与渗透时间有关。2h时透析袋内NaFeEDTA浓度为透析袋外的61%,4h时为84%,6h时达到94%,8h后透析袋内、外NaFeEDTA浓度几乎达到平衡。再次表明NaFeEDTA可以整体形式存在于模拟胃肠液环境中,并以整体形式通过透析袋,NaFeEDTA的肠粘膜通透性良好。由此推测生物体对NaFeEDTA的吸收可能是通过小肠粘膜细胞的整体吸收。 外翻肠囊法通过采用体外培养大鼠十二指肠、空肠和回肠的外翻肠囊来考察不同肠段粘膜吸收细胞对NaFeEDTA的摄取情况。实验发现:十二指肠、空肠和回肠肠囊在含有NaFeEDTA的粘膜测培养液中培养一段时间后,浆膜测肠囊内的溶液中均能检测到NaFeEDTA的存在,且随着培养时间的延长,肠囊内溶液中NaFeEDTA的含量呈逐渐增加的趋势,表明NaFeEDTA可以整体的形式被肠粘膜上皮吸收细胞所摄取。进一步比较肠囊内溶液中总铁和NaFeEDTA的浓度,发现两者之间没有显著差异,表明总铁中的铁全部来自于NaFeEDTA,即NaFeEDTA全部是以整体形式摄取的。三段肠段之间的比较发现,在相同的培养时间条件下,空肠肠囊内透过的NaFeEDTA的量大于十二指肠的,而回肠的又大于空肠的,说明回肠更有利于摄取NaFeEDTA。在培养液中加入草酸和植酸后,NaFeEDTA透过肠囊的量与不加入的差异不显著,表明在小肠上皮吸收细胞摄取NaFeEDTA的过程中,草酸和植酸可能没有影响。更多还原

【Abstract】 Sodium iron (III) ethylenediaminetetraacetate(NaFeEDTA)is a new type of chelating iron fortificant. It attracts great attention in recent years because of it’s remarkable impact on iron deficiency anemia (IDA). NaFeEDTA has been applied in IDA intervention projects in several countries in past decades, thus it was recommended by the approval of Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1993. As a food fortificant, NaFeEDTA has many advantages compared with other iron fortificants such as less ferruginous taste, no detectable side effects on intestines and stomach, less influence to iron absorption inhibitors, less adverse effects on sensory, physical and chemical properties of food vehicles and high bioavailability etc. NaFeEDTA is believed a better iron source for control and prevention of ID and IDA in terms of food fortificant.As an iron fortificant, the bioavailability of NaFeEDTA is two or three times higer than other iron fortificants such as ferrous sulfate. Although it has shown remarkable achievements on the IDA control and prevention, the mechamism of NaFeEDTA absorption in the organism gastrointestinal tract has not been illuminated clearly. In this study, three methods such as in vitro stomach and intestine model, dialysis bag model and everted intestinal sac model were used to observe the possible mechanism of NaFeEDTA absorption systematically.The results of the in vitro model indicate that NaFeEDTA was stable under different pH conditions from 2 to 7.5. That NaFeEDTA did not show any changes in the artificial gastrointestinal juice suggests that enzymes such as pepsin and pancreatin have no effects on NaFeEDTA. When oxalic acid and phytate was added to the artificial gastrointestinal juice at molar ratios of iron/ oxalic acid and iron/phytate as 1:1, 1:3, 1:5 and 1:8, NaFeEDTA was also stable and remained its chelate form. It indicates that oxalic acid and phytate could loot ferric iron ion from NaFeEDTA. It can be speculated from these results that NaFeEDTA had high stability in the organism gastrointestinal tract.Dialysis bag model test showed that the contents of NaFeEDTA in the dialysis bag were correlated with infiltration time. The concentration of NaFeEDTA in the dialysis bag was 61 percent that of outside the dialysis bag after 2 hours infiltration, 84 percent for 4 hours, 94 percent for 6 hours and almost reached equilibrium after 8 hours. It shows that NaFeEDTA existed as an intact complex in the artificial gastrointestinal juice and it might penetrate through the dialysis bag in an intact form. These results supposed thatNaFeEDTA could be absorbed intact by the small intestine mucous membrane.The everted intestine sac model was used to investigate how the mucosal absorptive cells of different intestinal segments intake NaFeEDTA by using in vitro incubation of duodenum, jejunum and ileum everted intestine sac of rats. The results showed that after incubation of everted intestine sac of duodenum, jejunum and ileum in the mucous membrane side solution for some time, NaFeEDTA was detected in the serous membrane side solution and the contents was increased with the incubation time. It indicates that NaFeEDTA could be uptaked intact by the epithelium absorptive cells. The comparision of the concentration of total iron and NaFeEDTA showed that there was little difference between the two quantums. The total iron content was equal to iron content of NaFeEDTA so that it should be considered that NaFeEDTA was fully uptaked in an intact form. Comparation among the three different intestinal segments showed that the content of NaFeEDTA in the jejunum sac was higer than that of duodenum and ileum was higer than that of jejunum. Ileum is more effective to uptake NaFeEDTA. When adding oxalic acid and phytate to the incubation solution, there is little difference in the NaFeEDTA contents. It suggests that oxalic acid and phytate may have no influence on the uptake of NaFeEDTA by small intestine epithelium absorptive cells.更多还原