Isolation, Structure Determination, and Synthesis of Allo-RA-V and Neo-RA-V, RA-Series Bicyclic Peptides from Rubia cordifolia L.
Isolation, Structure Determination, and Synthesis of Allo-RA-V and Neo-RA-V, RA-Series Bicyclic Peptides from Rubia cordifolia L.
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DOI：
10.1002/chem.201103185
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发表时间：
2012-03-01
影响因子：
4.3
通讯作者：
Takeya, Koichi
中科院分区：
文献类型：
--
作者：
Hitotsuyanagi, Yukio;Odagiri, Masumi;Takeya, Koichi
从茜草（Rubia cordifolia L.）的根中分离得到两个双环六肽（allo-RA-V（4）和neo-RA-V（5））和一个环六肽（O-seco-RA-V（6））。化合物5的光谱分析和X-射线晶体学鉴定了它们的结构。通过全合成确定了化合物4和5的绝对立体化学，通过与脱氧布瓦丁（3）的化学关联确定了化合物6的绝对立体化学。高活性RA-VII（1）与低活性化合物4和5的3D结构的比较表明，Tyr-5和/或Tyr-6苯环的取向在其生物活性中起重要作用。肽46的分离，沿着化合物3，以及它们的结构的比较似乎表明肽6可能是植物中双环肽35的共同前体。
Two bicyclic hexapeptides, allo-RA-V (4) and neo-RA-V (5), and one cyclic hexapeptide, O-seco-RA-V (6), were isolated from the roots of Rubia cordifolia L. Their gross structures were elucidated on the basis of spectroscopic analysis and X-ray crystallography of compound 5. The absolute stereochemistry of compounds 4 and 5 were established by their total syntheses, and the absolute stereochemistry of compound 6 by chemical correlation with deoxybouvardin (3). Comparison of the 3D structures of highly active RA-VII (1) with less-active compounds 4 and 5 suggests that the orientation of the Tyr-5 and/or Tyr-6 phenyl rings plays a significant role in their biological activity. The isolation of peptides 46, along with compound 3, and the comparison of their structures seem to indicate that peptide 6 may be the common precursor to bicyclic peptides 35 in the plant.