Synthesis of (14C)-labeled 5-deoxyflavonoids and their application in the study of dihydroflavonol/leucoanthocyanidin interconversion by dihydroflavonol 4-reductase
Synthesis of (14C)-labeled 5-deoxyflavonoids and their application in the study of dihydroflavonol/leucoanthocyanidin interconversion by dihydroflavonol 4-reductase
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DOI：
10.1016/j.plantsci.2005.10.013
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发表时间：
2006-03-01
期刊：
影响因子：
5.2
通讯作者：
Stich, K
中科院分区：
文献类型：
--
作者：
Halbwirth, H;Kahl, S;Stich, K
5-羟基黄酮（间苯三酚型）的生物合成已得到很好的阐明，但对于5-脱氧黄酮（间苯三酚型）的知识仍然有限。我们提供了详细的和优化的（C-14）-标记的6 '-脱氧查耳酮，5-脱氧黄烷酮，5-脱氧二氢黄酮醇和5-脱氧白花色素的合成方案。除了6 ′-脱氧查耳酮的形成外，所有步骤均使用通常参与5-羟基类黄酮形成的酶酶促进行。（C-14）标记的底物的可用性将促进未来的工作，迄今为止在很大程度上未知的5-脱氧黄酮类化合物的生物合成。特别是，5-脱氧leucoanthocyanidins，这是比相应的5-羟基化合物更稳定，可以提供很好的工具，研究酶，使用不稳定的5-羟基leucoanthocyanidins作为天然底物。作为第一个实施例，显示了在NADP（+）存在下（C-14）-标记的5-脱氧无色花色素向二氢黄酮醇的转化。使用具有或缺乏二氢黄酮醇4-还原酶活性的限定基因型的紫罗兰和表达紫罗兰酶的遗传修饰酵母的研究证实，该反应由众所周知的二氢黄酮醇4-还原酶催化，其催化二氢黄酮醇转化为无色花色素（正向反应）。因此，二氢黄酮醇4-还原酶的逆反应可以被首次证明。正向反应的最适pH值为6.25，反向反应的最适pH值为7.75。的影响的结果对调节类黄酮的积累进行了讨论。(c)2005爱思唯尔爱尔兰有限公司保留所有权利。
Biosynthesis is well elucidated for 5-hydroxyflavonoids (phloroglucinol type), but for 5-deoxyflavonoids (resorcinol type) the knowledge is still limited. We provide detailed and optimized protocols for the synthesis of (C-14)-labeled 6'-deoxychalcones, 5-deoxyflavanones, 5-deoxydihydroflavonols and 5-deoxyleucoanthocyanidins. With the exception of the formation of 6'-deoxychalcones, all steps were performed enzymatically using enzymes normally involved in the formation of 5-hydroxyflavonoids. The availability of (C-14)-labeled substrates will facilitate future work on the hitherto largely unknown biosynthesis of 5-deoxyflavonoids. In particular, the 5-deoxyleucoanthocyanidins, which are more stable than the corresponding 5-hydroxy compounds, may provide excellent tools for investigating enzymes, which use the unstable 5-hydroxyleucoanthocyanidins as natural substrates. As a first example, the conversion of(C-14)-labeled 5-deoxyleucoanthocyanidins to dihydroflavonols in the presence of NADP(+) was shown. Studies with defined genotypes of Matthiola incana possessing or lacking dihydroflavonol 4-reductase activity and genetically modified yeast expressing the Matthiola enzyme confirmed that the reaction is catalyzed by the well-known dihydroflavonol 4-reductase, which catalyzes the conversion of dihydroflavonols to leucoanthocyanidins (forward reaction). Thus, the reverse reaction of dihydroflavonol 4-reductase could be demonstrated for the first time. The forward reaction shows an optimum at pH 6.25, the reverse reaction at pH 7.75. The impact of the results on the regulation of flavonoid accumulation is discussed. (c) 2005 Elsevier Ireland Ltd. All rights reserved.