Ashnagar A, Bruce J M, Dutton P L, Prince R C
Biochim Biophys Acta. 1984 Oct 16;801(3):351-9. doi: 10.1016/0304-4165(84)90138-7.
First and second half-wave reduction potentials of 11 1,4-naphthoquinones and 42 9,10-anthraquinones have been measured for solutions in dimethylformamide. The presence of hydroxy groups at the 5- and 8-positions of the 1,4-naphthoquinone nucleus, and at the 1-, 4-, 5- and 8-positions of the 9,10-anthraquinone (the alpha-positions) markedly raises both reduction potentials. Measurements on the corresponding methoxy- and acetoxyquinones indicate that internal hydrogen bonding in the alpha-hydroxyquinones makes a major contribution to stabilisation of the semiquinone, probably as a result of increased delocalisation due to exchange of the hydroxy hydrogen between the two neighbouring oxygen atoms. The bearing of this phenomenon on the mechanism of action of anthracycline antitumour quinones is discussed, and the stabilising effect on the semiquinone of hydroxy groups at the 1- and 5-positions of the 9,10-anthraquinone nucleus is highlighted.
已测定了11种1,4-萘醌和42种9,10-蒽醌在二甲基甲酰胺溶液中的第一和第二半波还原电位。1,4-萘醌核的5位和8位以及9,10-蒽醌的1位、4位、5位和8位（α位）存在羟基时，会显著提高这两个还原电位。对相应的甲氧基醌和乙酰氧基醌的测量表明，α-羟基醌中的分子内氢键对半醌的稳定起主要作用，这可能是由于羟基氢在两个相邻氧原子之间交换导致离域增加的结果。讨论了这一现象与蒽环类抗肿瘤醌作用机制的关系，并强调了9,10-蒽醌核1位和5位羟基对半醌的稳定作用。
