Synthesis of Various Kinds of Isoflavones, Isoflavanes, and Biphenyl-Ketones and Their 1,1-Diphenyl-2-picrylhydrazyl Radical-Scavenging Activities
作者:Hideyuki Goto、Yoshiyasu Terao、Shuji Akai
DOI:10.1248/cpb.57.346
日期:——
Forty-eight kinds of isoflavones (8), thirty-one isoflavanes (9), and forty-seven biphenyl-ketones (10, 10′) were synthesized from eleven kinds of substituted phenols (11) and six phenylacetic acids (12). Among them, seventy-five compounds are new. The radical scavenging activities of these compounds were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) at pH 6.0. We found that thirty-nine out of forty-three compounds having a catechol moiety on either the A- or the B-ring exhibited a high activity (ED50=12—54 μM) similar to that of catechin. In these cases, the remaining part of their structure seemed to have little effect on their activity. Many 6- or 8-hydroxyisoflavanes (9E—I) and their biphenyl-ketone derivatives (10E—H) also showed a high activity (ED50=<50 μM), while all of their corresponding isoflavones (8E—I) were not active at all. The 7-hydroxyisoflavanes having either an additional hydroxyl group at the C5-position (9D) or a methoxy group at the C6-position (9J) presented a high activity (ED50=26—32 μM). This study suggests that natural isoflavones have the possibilities of exhibiting antioxidant activities through the hydroxylation at the C6-, C8-, or C3′-position or the formation of the isoflavanes (9) and/or the biphenyl-ketone derivatives (10′) by metabolism or biotransformation.
合成了四十八种异黄酮(8)、三十一种异黄烷(9)以及四十七种联苯酮(10, 10′),这些化合物是由十一种取代酚(11)和六种苯乙酸(12)合成的。其中,有七十五种化合物是新发现的。这些化合物的自由基清除活性在pH 6.0下使用1,1-二苯基-2-吡唑啉酮(DPPH)进行了评估。我们发现,在四十三种含有儿茶酚基的化合物中,三十九种在A环或B环上表现出与儿茶素相似的高活性(ED50=12—54 μM)。在这些情况下,它们结构的其他部分似乎对活性影响不大。许多6-或8-羟基异黄烷(9E—I)及其联苯酮衍生物(10E—H)也显示出高活性(ED50=<50 μM),而它们对应的异黄酮(8E—I)则完全没有活性。具有在C5位增加羟基(9D)或在C6位增加甲氧基(9J)的7-羟基异黄烷则展现出高活性(ED50=26—32 μM)。本研究表明,天然异黄酮通过在C6、C8或C3′位置的羟基化,或通过代谢或生物转化形成异黄烷(9)和/或联苯酮衍生物(10′),具有表现抗氧化活性的可能性。