Schroeder Samuel R, White Carl W, Jones Tara N, Hendry-Hofer Tara B, Day Brian J, Eaton Sandra S
Department of Chemistry and Biochemistry, University of Denver, 2101 E. Wesley Ave, Denver, CO 80208, USA.
Appl Magn Reson. 2011 Feb;40(1):125-134. doi: 10.1007/s00723-010-0188-y.
The superoxide dismutase (SOD)-mimetic effectiveness of [meso-tetrakis (R)porphyrinato]manganese with R = 1,3-di--ethylimidazolium-2-yl (Mn-TDEIP), 1,3-di--methylimidazolium-2-yl (Mn-TDMIP), 1,3-di--propylimidazolium-2-yl (Mn-TDPIP), -ethyl-2-pyridyl (Mn-T2EPyP), 4-sulphonatophenyl (Mn-TSP), 1-methyl-4-pyridyl (Mn-T4PyP), 4-carboxyphenyl (Mn-TBAP), and β-octabromomeso-tetrakis(4-carboxyphenyl porphyrinato)manganese (MnBrTBAP) was compared with Cu, Zn SOD. Superoxide generated by reaction of xanthine oxidase with hypoxanthine was trapped with 5-tert-butoxycarbonyl-5-methyl-1-pyrroline -oxide (BMPO), forming BMPO-OOH, which was monitored by electron paramagnetic resonance. Manganoporphyrins with redox potentials ranging from -0.190 to 0.346 V relative to the standard hydrogen electrode were selected for this study. With 0.1 µM manganoporphyrins and 20 mM BMPO, the effectiveness of the manganoporphyrins in inhibiting formation of BMPO-OOH increases in the order Mn-TSP < Mn-TBAP < MnBrTBAP < Mn-T4PyP < Mn-T2EPyP < Mn-TDEIP ~ Mn-TDMIP ~ Mn-TDPIP ~ Cu, Zn SOD. However, at higher concentrations of manganoporphyrin and BMPO, a BMPO-OH signal was observed. The formation of BMPO-OH was not inhibited by catalase or dimethylsulfoxide, which demonstrated that it was not produced from hydroxyl radical. The artifactual formation of BMPO-OH is attributed to oxidation of the water adduct of BMPO by the manganoporphyrins or decomposition of BMPO-OOH. Although spin trapping is an effective method for evaluating SOD-mimetic efficacy, caution must be exercised to ensure that artifact signals are not interpreted improperly.
将[中位-四（R）卟啉基]锰（R = 1,3 - 二 - 乙基咪唑 - 2 - 基（Mn - TDEIP）、1,3 - 二 - 甲基咪唑 - 2 - 基（Mn - TDMIP）、1,3 - 二 - 丙基咪唑 - 2 - 基（Mn - TDPIP）、 - 乙基 - 2 - 吡啶基（Mn - T2EPyP）、4 - 磺酸苯基（Mn - TSP）、1 - 甲基 - 4 - 吡啶基（Mn - T4PyP）、4 - 羧基苯基（Mn - TBAP）和β - 八溴中位 - 四（4 - 羧基苯基卟啉基）锰（MnBrTBAP）的超氧化物歧化酶（SOD）模拟效果与铜锌超氧化物歧化酶进行了比较。黄嘌呤氧化酶与次黄嘌呤反应产生的超氧化物用5 - 叔丁氧羰基 - 5 - 甲基 - 1 - 吡咯啉 - N - 氧化物（BMPO）捕获，形成BMPO - OOH，通过电子顺磁共振对其进行监测。本研究选择了相对于标准氢电极氧化还原电位范围为 - 0.190至0.346 V的锰卟啉。在0.1 μM锰卟啉和20 mM BMPO的条件下，锰卟啉抑制BMPO - OOH形成的效果按以下顺序增加：Mn - TSP < Mn - TBAP < MnBrTBAP < Mn - T4PyP < Mn - T2EPyP < Mn - TDEIP ~ Mn - TDMIP ~ Mn - TDPIP ~ 铜锌超氧化物歧化酶。然而，在较高浓度的锰卟啉和BMPO下，观察到了BMPO - OH信号。过氧化氢酶或二甲基亚砜不能抑制BMPO - OH的形成，这表明它不是由羟基自由基产生的。BMPO - OH的人为形成归因于锰卟啉对BMPO水加合物的氧化或BMPO - OOH的分解。尽管自旋捕获是评估SOD模拟效果的有效方法，但必须谨慎操作以确保不会错误解读人为信号。
