Steger P J, Mühlebach S F
Department of Pharmacy, Kantonsspital Aarau, Switzerland.
Nutrition. 1998 Feb;14(2):179-85. doi: 10.1016/s0899-9007(97)00438-3.
Four commercial i.v. lipid emulsions containing soybean oil were investigated to determine the tocopherol content. A sensitive high-performance liquid chromatography (HPLC) on a diol column was established to quantitate the tocopherol isomers in lipid emulsions. A previously described iodometric titration was used to assess the peroxide value (mmol peroxides/L). The pH was measured also. The initial tocopherol concentration ranges in three of the four commercial soybean oil-based 20% lipid emulsions studied were compared ([mg/L]: alpha: 17-23, beta: 4, gamma: 88-129, delta: 40-44). One product showed an increased alpha-tocopherol content (172 mg/L) due to supplementation during manufacture. During storage in an ethylvinyl acetate (EVA) bag at 40 degrees C under light-protection (LP) for 34 d, a lipid emulsion 20% with a natural alpha-tocopherol content showed a peroxide value (PV) of 9.18 (about 450 times the value of controls in glass bottles) with a concomittant reduction of the tocopherol isomers to 61.6% (alpha), 86.5% (gamma), and 88.9% (delta) compared to the initial values. Comparison of two lipid emulsions with different amounts of alpha-tocopherol (Lipidem 20%, B. Braun, Switzerland: 156.29 mg/L vs. Intralipid 20%, Pharmacia Upjohn, Switzerland: 8.75 mg/L) for their antioxidative capacity using the same stress conditions revealed for the emulsion with the high alpha-tocopherol content a significantly higher PV over the whole test period (after 5 wk: 33.63 vs. 6.23; P < 0.001) and an increased alpha-tocopherol decomposition (51.6% vs. 8.7%). The drop in pH was higher, also (1.9 vs. 1.0 pH units). In contrast to ordinary concentrations of about 20 mg/L, alpha-tocopherol in 20% lipid emulsions showing antioxidative properties, a supplementation with about 160 mg/L showed a prooxidative effect when exposed to ambient atmosphere in an EVA bag.
对四种含大豆油的市售静脉注射用脂质乳剂进行了研究，以测定生育酚含量。建立了一种在二醇柱上的灵敏高效液相色谱法（HPLC），用于定量脂质乳剂中的生育酚异构体。采用先前描述的碘量滴定法评估过氧化值（毫摩尔过氧化物/升）。还测量了pH值。比较了所研究的四种市售大豆油基20%脂质乳剂中三种的初始生育酚浓度范围（[毫克/升]：α：17 - 23，β：4，γ：88 - 129，δ：40 - 44）。一种产品由于在生产过程中添加了生育酚，其α - 生育酚含量增加（172毫克/升）。在40℃下于乙烯 - 醋酸乙烯酯（EVA）袋中避光保存34天后，一种天然α - 生育酚含量的20%脂质乳剂的过氧化值（PV）为9.18（约为玻璃瓶中对照品值的450倍），同时生育酚异构体与初始值相比分别降至61.6%（α）、86.5%（γ）和88.9%（δ）。在相同应激条件下，比较两种α - 生育酚含量不同的脂质乳剂（Lipidem 20%，B. Braun，瑞士：156.29毫克/升与Intralipid 20%，Pharmacia Upjohn，瑞士：8.75毫克/升）的抗氧化能力，结果显示α - 生育酚含量高的乳剂在整个测试期间的过氧化值显著更高（5周后：33.63对6.23；P < 0.001），且α - 生育酚分解增加（51.6%对8.7%）。pH值下降也更高（1.9对1.0个pH单位）。与普通浓度约为二十毫克/升相比，在20%脂质乳剂中显示抗氧化特性的α - 生育酚，当在EVA袋中暴露于环境大气时，添加约160毫克/升会显示出促氧化作用。
