Novel 6-formylpterin derivatives: chemical synthesis and O2 to ROS conversion activities
作者:Mitsuru Nonogawa、Toshiyuki Arai、Nobuyuki Endo、Seung Pil Pack、Tsutomu Kodaki、Keisuke Makino
DOI:10.1039/b602778d
日期:——
6-Formylpterin (6FP) has been demonstrated to have strong neuroprotective effects against transient ischemia-reperfusion injury in gerbils. Also it has been shown that in rats, 6FP protected retinal neurons even when it was administered after the ischemic insult. Since there is a significant need for such a compound that effectively suppresses the events caused by the lack of oxygen supply, 6FP has attracted further investigation. Unfortunately, however, 6FP is hardly soluble in water at neutral pH and in organic solvents because of its self-assembling ability. Although a several mM solution of 6FP is available in alkaline water, it is unstable. In the present study, a novel chemical derivatization of 6FP has been developed which maintains the formyl group on the 6-position of 6FP, which is essential for the physiological activities of 6FP, and increases solubility in water and organic solvents. In the method, the 2- and 3-positions of 6FP were modified by a three component coupling reaction: 6FP was subjected to the reaction with acid chloride and N,N-dimethylformamide. The derivatives synthesized here, 2-(N,N-dimethylaminomethyleneamino)-6-formyl-3-pivaloylpteridine-4-one 1, 2-(N,N-dimethylaminomethyleneamino)-6-formyl-3-isobutyrylpteridine-4-one 2, and 2-(N,N-dimethylaminomethyleneamino)-6-formyl-3-o-toluoylpteridine-4-one 3, showed high solubility in water (1.0–5.6 mM) and organic solvents. The O2 conversion property has also been determined for the derivative 1. Using an oxygen electrode, it has been found that O2 is consumed in the presence of 1 and NADH at around pH 7.4 and that the rate of O2 consumption is enhanced by UV-A irradiation. Electron paramagnetic resonance (EPR) analysis coupled with DMPO spin trapping has also revealed that in the presence of NADH, 1 converts O2 to ˙O2−, which is further reduced to ˙OH. By UV-A illumination in the analogous systems, 1O2 formation was observed. These results are similar to those reported previously for 6FP.
研究表明,6-甲酰基蝶呤(6FP)对沙鼠的短暂性缺血再灌注损伤具有很强的神经保护作用。此外,在大鼠体内,即使在缺血损伤后给药,6FP 也能保护视网膜神经元。由于目前亟需一种能有效抑制缺氧引起的事件的化合物,6FP 引起了进一步的研究。但遗憾的是,6FP 由于具有自组装能力,在 pH 值为中性时几乎不溶于水,也不溶于有机溶剂。虽然在碱性水中可以获得几毫微米的 6FP 溶液,但它并不稳定。本研究开发了一种新的 6FP 化学衍生方法,既保留了 6FP 生理活性所必需的 6 位甲酰基团,又增加了 6FP 在水和有机溶剂中的溶解度。在该方法中,6FP 的 2 位和 3 位通过三组份偶联反应进行了修饰:6FP 与氯化酸和 N,N-二甲基甲酰胺发生反应。在此合成的衍生物 2-(N,N-二甲基氨基亚甲基氨基)-6-甲酰基-3-特戊酰基蝶啶-4-酮 1、2-(N,N-二甲基氨基亚甲基氨基)-6-甲酰基-3-异丁酰基蝶啶-4-酮 2 和 2-(N,N-二甲基氨基亚甲基氨基)-6-甲酰基-3-邻甲苯酰基蝶啶-4-酮 3 在水中的溶解度很高(1.0-5.6 mM)和有机溶剂中表现出较高的溶解度。还测定了衍生物 1 的氧气转化特性。通过使用氧电极发现,在 1 和 NADH 存在的情况下,pH 值在 7.4 左右时会消耗 O2,而紫外线-A 的照射会提高 O2 的消耗速率。电子顺磁共振(EPR)分析和 DMPO 自旋捕获也显示,在 NADH 的存在下,1 将 O2 转化为 ˙O2-,然后进一步还原为 ˙OH。在类似的系统中,通过紫外线-A 的照射,可以观察到 1O2 的形成。这些结果与之前报道的 6FP 相似。