National Jewish Center for Immunology and Respiratory Medicine, Denver, CO, USA.
J Am Soc Mass Spectrom. 1996 May;7(5):490-9. doi: 10.1016/1044-0305(95)00709-1.
F2-isoprostanes are complex metabolites of arachidonic acid generated via nonenzymatic free radical oxidation and are isomeric to prostaglandin F2α, enzymatically produced by prostaglandin H2 synthase. In theory, four distinct regioisomeric families are possible. These regioisomeric families have a common 1,3-diol cyclopentane structural feature, but differ by the comparative length of two attached alkyl chains and the position of a third hydroxyl group. Eight synthetic PGF2α isomers were found separable by capillary gas chromatography (GC) and reversed-phase high-performance liquid chromatography (HPLC). Electrospray ionization tandem mass spectrometry was used to detect the elution of these isomers from the HPLC column by monitoring the characteristic loss of 44 u (C2H4O) from the 1,3-diol cyclopentane ring. Catalytic reduction, derivatization, and electron ionization mass spectrometric techniques were used to obtain definitive information as to the location of the side chain hydroxyl position in these isomers through abundant α-cleavage ions. Free radical oxidation of arachidonic acid was used to generate a complex mixture of F2-isoprostanes, which were separated by HPLC and capillary GC. Members of each of the four specific regioisomeric isoprostane families could be identified in this mixture from the predicted α-cleavage ions. Although many epimers within a single family type could be separated, the four regioisomeric families were substantially superimposed in their HPLC and GC elution. The Type I and Type IV regioisomers were the major F2-isoprostane products, but the complexity of the isomers required more than a simple GC-mass spectrometry assay to precisely identify a particular stereoisomer within a regioisomeric family (e. g., 8-epi-PGF2α). Type I F2-isoprostanes are unique noncyclooxygenase products and may be more specific targets to measure lipid peroxidation in vivo.
F2-异前列腺素是花生四烯酸通过非酶自由基氧化生成的复杂代谢物，与前列腺素 H2 合酶酶促生成的前列腺素 F2α 是同系物。理论上，可能存在四种不同的区域异构体家族。这些区域异构体家族具有共同的 1,3-二醇环戊烷结构特征，但通过两个附着的烷基链的比较长度和第三个羟基的位置而有所不同。通过毛细管气相色谱 (GC) 和反相高效液相色谱 (HPLC) 发现 8 种合成的 PGF2α 异构体可分离。电喷雾串联质谱法用于通过监测 1,3-二醇环戊烷环从特征性损失 44 u（C2H4O）来检测这些异构体从 HPLC 柱洗脱。通过丰富的α-裂解离子，催化还原、衍生化和电子电离质谱技术用于获得这些异构体中亚烷基羟基位置的明确信息。花生四烯酸的自由基氧化用于生成 F2-异前列腺素的复杂混合物，该混合物通过 HPLC 和毛细管 GC 分离。可以从预测的α-裂解离子中从该混合物中鉴定出每种特定区域异构体家族的成员。尽管在单个家族类型内可以分离许多差向异构体，但四个区域异构体家族在 HPLC 和 GC 洗脱中基本上重叠。I 型和 IV 型区域异构体是主要的 F2-异前列腺素产物，但异构体的复杂性需要超过简单的 GC-质谱分析来准确鉴定区域异构体家族内的特定立体异构体（例如，8-epi-PGF2α）。I 型 F2-异前列腺素是独特的非环加氧酶产物，可能是测量体内脂质过氧化的更特异靶标。
