Ayabe S, Udagawa A, Furuya T
School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan.
Arch Biochem Biophys. 1988 Mar;261(2):458-62. doi: 10.1016/0003-9861(88)90362-1.
The crude extract prepared from Glycyrrhiza echinata cells treated with yeast extract catalyzed the formation of liquiritigenin (5-deoxyflavanone) and isoliquiritigenin (6'-deoxychalcone) in addition to naringenin (5-hydroxyflavanone) when incubated with 4-coumaroyl-CoA and malonyl-CoA in the presence of high concentrations (0.1 mM or higher) of NADPH. Incubation without NADPH, or with low concentrations (0.01 mM or lower), gave only naringenin as a reaction product. With NADH (1 mM), the major product was naringenin accompanied by a small quantity of liquiritigenin. The initial product of the assay with 1 mM NADPH was isoliquiritigenin, indicating a reaction catalyzed by 6'-deoxychalcone synthase (DOCS). Subsequent formation of liquiritigenin was attributed to the presence of chalcone isomerase in the crude extract. The results constitute the first demonstration in vitro of DOCS activity which, in G. echinata cells and other leguminous plants, is involved in the biosynthesis of retrochalcone and 5-deoxyisoflavonoid-derived phytoalexins.
用酵母提取物处理的刺果甘草细胞制备的粗提物，在高浓度（0.1 mM或更高）的NADPH存在下，与4-香豆酰辅酶A和丙二酰辅酶A一起孵育时，除了柚皮素（5-羟基黄烷酮）外，还催化了甘草素（5-脱氧黄烷酮）和异甘草素（6'-脱氧查耳酮）的形成。在没有NADPH或低浓度（0.01 mM或更低）的情况下孵育，反应产物只有柚皮素。使用NADH（1 mM）时，主要产物是柚皮素，并伴有少量甘草素。用1 mM NADPH进行测定的初始产物是异甘草素，表明该反应由6'-脱氧查耳酮合酶（DOCS）催化。随后甘草素的形成归因于粗提物中存在查耳酮异构酶。这些结果首次在体外证明了DOCS活性，在刺果甘草细胞和其他豆科植物中，DOCS活性参与了反式查耳酮和5-脱氧异黄酮衍生的植物抗毒素的生物合成。
