Chavicol formation in sweet basil (Ocimum basilicum): cleavage of an esterified C9 hydroxyl group with NAD(P)H-dependent reduction.
Chavicol formation in sweet basil (Ocimum basilicum): cleavage of an esterified C9 hydroxyl group with NAD(P)H-dependent reduction.
复制标题
甜罗勒 (Ocimum basilicum) 中 Chavicol 的形成：通过 NAD(P)H 依赖性还原裂解酯化的 C9 羟基。
DOI：
10.1039/b605407b
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Lewis,NormanG
中科院分区：
文献类型：
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作者：
Vassao,DanielG;Gang,DavidR;Koeduka,Takao;Jackson,Brenda;Pichersky,Eran;Davin,LaurenceB;Lewis,NormanG
丙烯基和烯丙基酚，如甲基chavicol，对醇和丁香酚，作为调味剂和在9,9 ' -脱氧木脂素的生物合成中假定的前体具有重要意义，其中许多具有潜在的药用价值。然而，尽管经过了几十年的研究，丙烯基/烯丙基酚的完整生物合成途径尚未被报道。我们对一种泰国罗勒品种进行了体内放射性标记前体和体外蛋白质制剂测定，该品种积累了相对大量的最简单的挥发性烯丙基酚，甲基查维醇。通过这些实验，证明了chavicol的生物合成是通过苯丙醇途径产生对香豆醇的。研究了导致后者脱氧的各种可能性，包括侧链双键还原形成对二氢香豆醇，然后脱水得到chavicol，以及形成对甲氧基肉桂醇，进一步侧链改性得到甲基chavicol。研究的第三种可能性是对香豆醇侧链醇的活化，例如通过酯化反应，通过还原消除形成更容易离开的基团。后者被证明是使用对香豆基酯作为NAD(P) h依赖性还原酶的潜在底物来提供chavicol，然后将其o甲基化以提供甲基chavicol。
Propenyl- and allyl-phenols, such as methylchavicol, p-anol and eugenol, have gained importance as flavoring agents and also as putative precursors in the biosynthesis of 9,9′-deoxygenated lignans, many of which have potential medicinal applications. In spite of several decades of investigation, however, the complete biosynthetic pathway to a propenyl/allylphenol had not yet been reported. We have subjected a Thai basil variety accumulating relatively large amounts of the simplest volatile allylphenol, methylchavicol, to in vivo administration of radiolabeled precursors and assays of protein preparations in vitro. Through these experiments, the biosynthesis of chavicol was shown to occur via the phenylpropanoid pathway to p-coumaryl alcohol. Various possibilities leading to deoxygenation of the latter were examined, including reduction of the side-chain double bond to form p-dihydrocoumaryl alcohol, followed by dehydration to afford chavicol, as well as formation of p-methoxycinnamyl alcohol, with further side-chain modification to afford methylchavicol. A third possibility studied was activation of the side-chain alcohol of p-coumaryl alcohol, e.g.via esterification, to form a more facile leaving group via reductive elimination. The latter was shown to be the case using p-coumaryl esters as potential substrates for a NAD(P)H-dependent reductase to afford chavicol, which is then O-methylated to afford methylchavicol.