Otani K., Takahashi T., Furuya T., Ayabe Si.
Department of Applied Biological Science, College of Agriculture and Veterinary Medicine, Nihon University, Fujisawa, Kanagawa 252, Japan (K.O., T.T., S.A.).
Plant Physiol. 1994 Aug;105(4):1427-1432. doi: 10.1104/pp.105.4.1427.
Cultured Glycyrrhiza echinata L. (Leguminosae) cells produce a retrochalcone echinatin (4,4[prime]-dihydroxy-2-methoxychalcone) and its biosynthetic intermediate licodione [1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)-1,3-propanedione, a dibenzoylmethane (keto form) or its enol tautomer ([beta]-hydroxychalcone)], when treated with elicitor-active substances, e.g. yeast extract. A microsomal fraction (160,000g pellet) prepared from yeast extract-induced suspension cultures of G. echinata catalyzed the formation of licodione from (2S)-liquiritigenin (7,4[prime]-dihydroxyflavanone) in the presence of NADPH and air. This licodione synthase activity was shown to be dependent on cytochrome P450 by its microsomal localization, requirement of NAD(P)H and O2 for activity, and inhibition by typical cytochrome P450 inhibitors. Licodione synthase activity transiently increased in the cells after treatment with yeast extract. When (2S)-naringenin (5,7,4[prime]-trihydroxyflavanone) and NADPH were incubated with the same microsomal preparation, a polar compound, which further converted into apigenin (5,7,4[prime]-trihydroxyflavone) when treated with acid, was produced. The reaction mechanism of licodione synthase is likely to be 2-hydroxylation of the flavanone molecule and subsequent hemiacetal opening and is possibly the same as the previously suggested mechanism of flavone synthase II from soybean and, furthermore, closely related to isoflavone synthase from Pueraria lobata.
用激发活性物质（如酵母提取物）处理培养的刺果甘草（豆科）细胞时，会产生反式查耳酮刺甘草查耳酮（4,4'-二羟基-2-甲氧基查耳酮）及其生物合成中间体甘草二酮[1-(2,4-二羟基苯基)-3-(4-羟基苯基)-1,3-丙二酮，一种二苯甲酰甲烷（酮式）或其烯醇互变异构体（β-羟基查耳酮）]。从酵母提取物诱导的刺果甘草悬浮培养物中制备的微粒体部分（160,000g沉淀）在NADPH和空气存在下催化(2S)-甘草素（7,4'-二羟基黄烷酮）形成甘草二酮。这种甘草二酮合酶活性通过其微粒体定位、活性对NAD(P)H和O2的需求以及典型细胞色素P450抑制剂的抑制作用，表明依赖于细胞色素P450。用酵母提取物处理后，细胞中甘草二酮合酶活性短暂增加。当(2S)-柚皮素（5,7,4'-三羟基黄烷酮）和NADPH与相同的微粒体制剂一起温育时，产生了一种极性化合物，用酸处理时该化合物进一步转化为芹菜素（5,7,4'-三羟基黄酮）。甘草二酮合酶的反应机制可能是黄烷酮分子的2-羟基化以及随后的半缩醛开环，并且可能与先前提出的大豆黄酮合酶II机制相同，此外，与野葛异黄酮合酶密切相关。
