Oxidized phospholipids, isolevuglandins, and atherosclerosis

Autoxidation of polyunsaturated phosphatidylcholines (PCs) generates isolevuglandins (isoLGs) through rearrangements of isoprostanoid endoperoxides. Within seconds, isoLGs are sequestered by covalent adduction with proteins. Murine plasma isoLG-protein levels increased at least 2.5-fold in response to inflammation. IsoLG-protein adducts accumulate in vivo providing a convenient dosimeter of oxidative stress. Elevated blood isoLG-protein levels present in atherosclerosis (AS) patients point to an independent defect that is not associated with total cholesterol levels, which results in an abnormally high level of oxidative injury in AS. Protein adduction and cross-linking caused by isoLGs can obstruct protein function. For example, it interferes with proteosomal degradation of proteins and, consequently, may result in apoptotic death of smooth muscle cells and destabilization of atherosclerotic plaques. Phospholipid autoxidation also generates biologically active oxidatively truncated PCs through fragmentation of dihydroperoxydienes that can be promoted by alpha-tocopherol. The oxidatively truncated PCs in oxidized low-density lipoprotein (oxLDL) contribute to the etiology of AS by inhibiting enzymatic activities required for normal processing of oxLDL by macrophages. They promote interactions of monocytes with endothelial cells that may foster migration of monocytes into the subendothelial space. They are also ligands for unregulated receptor-mediated uptake of oxLDL by monocyte macrophages leading to foam cell formation.     

高效液相色谱法测定大豆磷脂类保健食品中磷脂酰胆碱含量

目的建立高效液相色谱法(highperformance liquid chromatography,HPLC)测定大豆磷脂类保健食品中磷脂酰胆碱含量的分析方法。方法采用高效液相色谱仪、Kromasil 100-5-SIL硅胶柱,以流动相正己烷:异丙醇:水=0.25:4:1(V:V:V),流速为0.5 mL/min,检测波长为207 nm,柱温为30℃,进样量10μL,进行检测。结果磷脂酰胆碱浓度为0.1～2.0mg/mL时,线性关系良好,回归方程的相关系数r2=0.9998,相对标准偏差(relative,standarddeviation,RSD)为0.50%,平均回收率为98.01%～98.73%。结论该方法高效,准确,简便,适合于检测大豆磷脂类保健食品中磷脂酰胆碱的含量。     

磷脂改性方法的研究进展(Ⅰ)——物理与化学改性

磷脂通过物理或化学方法改性,可以改变磷脂的HLB值范围,扩大磷脂在工业上的应用范围。综述了国内外磷脂物理和化学改性方法研究的进展。物理改性方法主要包括溶剂分提法、超临界CO2萃取法、膜分离法、有机溶剂沉淀法、金属离子沉淀法、色谱柱分离法、微胶囊法等。化学改性方法主要包括酸碱水解法、乙酰化法、羟基化法、羟酰化法、氢化法、磺化法、乙氧基改性法等。     

乙醇萃取菜籽油卵磷脂的工艺研究

为充分利用菜籽油磷脂资源,研究了乙醇萃取菜籽油粉末磷脂中的卵磷脂的工艺。考虑了萃取体系中酒精浓度、固液比、萃取时间、萃取温度及体系pH对萃取效果的影响。并应用曲面响应法优化了萃取条件。在最优萃取条件:料液比1∶6.8,温度41.87℃,乙醇浓度93.77%,萃取时间41.96min下卵磷脂纯度达到46.48%,比原料中卵磷脂提高了4.89倍,提取率为93.29%。     

传统金华火腿加工过程中皮下脂肪的变化

分别提取0、32d、60d、160d、240d的金华火腿中的皮下脂肪,分析其甘油酯、磷脂、游离脂肪酸的含量和脂肪酸组成。结果表明:甘油酯的含量从95.7%减少到85.4%,游离脂肪酸的含量从2.1%增加到14.3%,磷脂的含量没有发生显著性变化;甘油酯中的SFA有显著性变化,MUFA和PUFA无显著性变化;磷脂中的SFA、MUFA和PUFA都没有显著性变化;游离脂肪酸中,PUFA的含量显著减少,MUFA的含量减少,但其变化不显著,SFA的含量显著增加。     

Analytical Methods for Quantification of Modified Fatty Acids and Sterols Formed as a Result of Processing

Fats and oils are often submitted to technological treatments before being consumed. Some treatments like refining, hydrogenation, and frying often lead to the formation of modified fatty acids such as cyclic fatty acid monomers (CFAM), geometrical fatty acid isomers, and/or oxidized fatty acids and sterols (cholesterol and phytosterols). Both cholesterol oxidation products (COP) and phytosterol oxidation products (POP), may be present in foods. As some of the newly formed components may present some adverse effects upon consumption, methods have been developed to analyze these compounds in food products and biological samples. Gas liquid chromatography (GC) on long polar columns (100m) is a good choice to quantify trans mono- and poly-unsaturated fatty acids. In some cases a pre-fractionation step using silver nitrate thin layer chromatography (AgNO₃-TLC) may be necessary to avoid GC overlapping of cis and trans isomers. Analysis of CFAM usually involves transformation of the sample in fatty acid methyl esters (FAME) which after addition of an internal standard (IS) are further hydrogenated. An enrichment step using reverse phase high performance liquid chromatography (RP-HPLC) permits to obtain a fraction which consists of a mixture of CFAM and the IS. This fraction is further analyzed by GC on a polar column. The analysis of oxidized triacylglycerol monomers (oxTG) as a group was feasible by a combination of adsorption and size-exclusion chromatography. Quantification in used frying fats and oils around the limit of rejection for human consumption (25% polar compounds) has shown that the amount of oxTG range 5.9–9.4% expressed on fat or oil weight. In foods and biological tissues, the level of oxidized sterols (SOP) is often a very small fraction of their unoxidized forms. Analysis of SOP involved extraction of lipids, saponification or transesterification, enrichment, and subsequent qualitative and quantitative determination by GC and GC-MS, or HPLC and HPLC-MS. In addition, enrichment of SOP requires complete separation from the unoxidized sterols in order to separate these compounds even by high resolution GC capillary columns.     

大豆磷脂软胶囊中铅、铬、镉、砷4种微量重金属的检测方法研究

为了方便、快速、准确地检测大豆磷脂软胶囊中铅、铬、镉、砷4种微量重金属元素的含量,建立了一种冷冻快速粉碎-微波消解的前处理方式,采用电感耦合等离子体质谱仪(ICP-MS)进行测定。试验结果表明:经冷冻快速粉碎后的软胶囊壳颗粒均一;微波消解耗时短、操作简便、耗费试剂少,ICP-MS测定结果显示铅、铬、镉、砷4种重金属的平均回收率在82. 6%～92. 9%之间。试验结果满意,可为日常工作中测定软胶囊类产品中重金属前处理作参考。     

正相色谱法测定大豆磷脂中的磷脂酰胆碱

目的建立正相色谱法测定大豆磷脂中磷脂酰胆碱含量,用于大豆磷脂类保健食品生产过程中该物质含量的测定和质量控制。方法采用硅胶柱(4.6 mm×250 mm,5.0μm)进行分离;色谱条件为流动相:异丙醇:正己烷:蒸馏水=70:16:14(V:V:V),等度洗脱,流速:1.0 m L/min;柱温:40℃;进样量:10μL;检测波长:205nm;并进行方法学验证,考察方法检测限、精密度、回收率等指标。结果磷脂酰胆碱峰面积与其浓度呈良好的线性关系,线性范围为0.1~0.8 mg/m L(r=0.9999),检出浓度0.04μg/m L,检出限为20μg/g,定量限为66.666μg/g,精密度(RSD)为0.6%,平均回收率99.37%(n=9)。结论本文建立的方法灵敏度高,重复性好,且具有很好的专属性,能够应用于大豆磷脂类保健食品中磷脂酰胆碱含量的检测。     

磷脂含量及组成的分析检测方法

综述了定量分析磷脂组成及含量的分析方法 ,重点介绍了TLC和HPLC方法 ,并列举了HPLC分析方法的不同类型检测器。另外还介绍了核磁共振、红外光谱等技术在磷脂的分析和检测中的应用。