Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Phytochemistry. 2010 Jul;71(10):1059-67. doi: 10.1016/j.phytochem.2010.02.012. Epub 2010 May 5.
Alkylresorcinols, produced by various plants, bacteria, and fungi, are bioactive compounds possessing beneficial activities for human health, such as anti-cancer activity. In rice, they accumulate in seedlings, contributing to protection against fungi. Alkylresorcylic acids, which are carboxylated forms of alkylresorcinols, are unstable compounds and decarboxylate readily to yield alkylresorcinols. Genome mining of the rice Oryza sativa identified two type III polyketide synthases, named ARAS1 (alkylresorcylic acid synthase) and ARAS2, that catalyze the formation of alkylresorcylic acids. Both enzymes condensed fatty acyl-CoAs with three C(2) units from malonyl-CoA and cyclized the resulting tetraketide intermediates via intramolecular C-2 to C-7 aldol condensation. The alkylresorcylic acids thus produced were released from the enzyme and decarboxylated non-enzymatically to yield alkylresorcinols. This is the first report on a plant type III polyketide synthase that produces tetraketide alkylresorcylic acids as major products.
烷基间苯二酚是由各种植物、细菌和真菌产生的具有生物活性的化合物，具有有益于人类健康的活性，如抗癌活性。在水稻中，它们在幼苗中积累，有助于抵御真菌。烷基间苯二羧酸是烷基间苯二酚的羧化形式，是不稳定的化合物，容易脱羧生成烷基间苯二酚。对水稻(Oryza sativa)的基因组挖掘鉴定出两种类型的 III 型聚酮合酶，分别命名为 ARAS1（烷基间苯二酚合酶）和 ARAS2，它们催化烷基间苯二羧酸的形成。这两种酶将脂肪酸酰基辅酶 A 与来自丙二酰辅酶 A 的三个 C(2)单元缩合，并通过分子内 C-2 到 C-7 醛缩合使生成的四酮中间体环化。由此产生的烷基间苯二酚从酶中释放出来，并在非酶促条件下脱羧生成烷基间苯二酚。这是第一个报道植物 III 型聚酮合酶产生四酮烷基间苯二酚作为主要产物的报告。
