Mechanism of decomposition of cyclic peroxides, 4-alkoxy-1,4-dihydro-2,3-benzodioxin-1-ols, to afford hydroxyl radical.
作者:Seiichi MATSUGO、Nobuko KAYAMORI、Tatsuo OHTA、Tetsuya KONISHI
DOI:10.1248/cpb.39.545
日期:——
The decomposition of 4-alkoxy-1, 4-dihydro-2, 3-benzodioxin-1-ols (1, Bd) in aqueous media was examined. Increasing the water content of the medium accelerated the decomposition of 1 and increased the formation of the corresponding 2-formyl benzoic acid ester (2) as the decomposition product. Electron spin resonance (ESR) studies using dimethylpyrroline N-oxide (DMPO) as a spin trapping reagent had revealed that bydroxyl radicals are formed during the decomposition of 1 (Matsugo et al., FEBS Lett., 184, 25 (1985)). Thus, water-mediated decomposition of 1 was suggested to occur, affording the ester 2 and hydroxyl radical. Direct involvement of water was confirmed by an 18O isotopic tracer experiment which revealed that 18O was incorporated exclusively into the formyl position of the ester 2. It is plausible that a hydrated hydroperoxide (5) is formed by the addition of water at the formyl position of the ring-opened structure of 1 at the initial stage fo the decomposition of 1. Preliminary studies on the antibacterial activities of 1 showed moderate cell-killing activity, especially to Pseudomonas strains, and the activity was found to be related to the decomposition of 1.
在水介质中对4-烷氧基-1,4-二氢-2,3-苯并二恶英-1-醇(1, Bd)的分解进行了研究。随着介质中水含量的增加,1的分解速度加快,并且形成了相应的2-甲酰苯甲酸酯(2)作为分解产物。电子自旋共振(ESR)研究使用二甲基吡咯啉N-氧化物(DMPO)作为自旋捕获剂揭示了在1的分解过程中形成了羟基自由基(Matsugo等人,FEBS Lett., 184, 25 (1985))。因此,提出了1的水介导分解途径,产生酯2和羟基自由基。通过18O同位素示踪实验证实了水的直接参与,该实验揭示了18O完全融入了酯2的甲酰位置。可以合理地认为,在1的分解初期,水在开环结构的甲酰位置上形成了一个水合过氧化物(5)。对1的初步抗菌活性研究表明,它对细胞杀伤作用中等,特别是对铜绿假单胞菌,并且活性与1的分解有关。