Kurosaki F, Kizawa Y, Nishi A
Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
Eur J Biochem. 1989 Oct 20;185(1):85-9. doi: 10.1111/j.1432-1033.1989.tb15085.x.
Synthetic activity of 6-hydroxymellein, the immediate precursor of carrot phytoalexin 6-methoxymellein, from acetyl-CoA and malonyl-CoA was induced in carrot cell extracts when the root disks were treated with CuCl2 or oligogalacturonide elicitor. These elicitors showed specific inducing activity of phytoalexin production and did not affect fatty acid synthesis in carrot tissues which may share some common properties with 6-hydroxymellein biosynthesis. 6-Hydroxymellein production was an NADPH-dependent process and, in the absence of the reagent, triacetic acid lactone was produced as a derailment product of the reaction process. This finding suggested that the reduction of the double bond at the 3,4-position of the phytoalexin takes place during the elongation of the poly(oxomethylene) chain. This NADPH-dependent reduction seems to occur at the triacetate stage before the condensation of the third malonyl-CoA as the conversion of carbonyl to hydroxyl group.
当用氯化铜或寡聚半乳糖醛酸激发子处理胡萝卜根盘时，胡萝卜细胞提取物中会诱导出6-甲氧基甜没药素（胡萝卜植保素6-甲氧基甜没药素的直接前体）从乙酰辅酶A和丙二酰辅酶A的合成活性。这些激发子显示出植保素产生的特异性诱导活性，并且不影响胡萝卜组织中的脂肪酸合成，而脂肪酸合成可能与6-甲氧基甜没药素生物合成具有一些共同特性。6-甲氧基甜没药素的产生是一个依赖于NADPH的过程，并且在没有该试剂的情况下，三乙酸内酯作为反应过程的偏离产物产生。这一发现表明，植保素3,4位双键的还原发生在聚（甲醛）链延长过程中。这种依赖于NADPH的还原似乎发生在第三个丙二酰辅酶A缩合之前的三乙酸酯阶段，即羰基向羟基的转化。
