为了发现新的31 P NMR 标记物用于探测生物环境中的细微 pH 变化(<0.2 pH 单位),合成了 15 种新的构象受限或空间位阻的 α-氨基膦酸盐,它们源自二乙基(2-甲基吡咯烷-2-基)膦酸盐,并测试了它们的 pH 值报告和体外细胞毒性。所有化合物均显示出接近中性的 p K a s(范围为 6.28–6.97)、与磷代谢物不重叠的化学位移和光谱灵敏度(即化学位移变化 Δ δ ab介于酸性和碱性形式之间)范围为 9.2-10.7 ppm,比传统的内源性标记物(如无机磷酸盐)大四倍。X 射线晶体学研究与预测性经验关系和从头计算相结合,解决了与质子化胺功能相关的取代基的诱导和立体化学效应。在 p K a s 与二维结构和磷的金字塔化之间建立了令人满意的相关性,表明磷周围的空间拥挤对于调节 Δ δ ab至关重要。最后,命中31 P NMR pH 探针1b带有未取代的 1,3,2-二氧杂磷环烷环,它具有中等亲脂性,对
CyDEPMPOs: A class of stable cyclic DEPMPO derivatives with improved properties as mechanistic markers of stereoselective hydroxyl radical adduct formation in biological systems
The cis/trans diastereoisomeric composition of hydroxyl radical adducts to chiral cyclic nitrones can be used to approach mechanisms of free radical formation in biological systems. Such determination is greatly simplified when both diastereoisomers have ESR spectra with at least two non-overlapping lines. To achieve this prerequisite, a series of DEPMPO-derived spin traps bearing one unsubstituted or alkyl-substituted 2-oxo-1,3,2-dioxaphosphorinane ring were synthesized and their structures were confirmed by X-ray diffraction, H-1, C-13 and P-31 NMR. These CyDEPMPOs nitrones showed variable lipophilicities and LD50 values on murine fibroblasts compatible with a safe use in biological spin trapping. All CyDEPMPOs formed persistent spin adducts with a series of free radicals, including superoxide and hydroxyl (i.e., CyDEPMPOs-OH) and the in vitro half-life times of these two latter were at least as extended as those of parent DEPMPO. Using four methods of CyDEPMPOs-OH formation, the cis-CyDEPMPOs-OH percentage was found significantly varied with substitution on the P-containing ring and, more interestingly, with the generating system. (C) 2011 Elsevier Ltd. All rights reserved.