著者

中村 優一 馬岡 秀陽 上岡 麗子 池田 剛 塚本 佐知子

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.52, pp.505-510, 2010

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We reported the structures and biosynthetic experiments of prenylated indole alkaloids, notoamides, which isolated from a marine-derived fungus Aspergillus sp. Among them, notoamides A and B (1 and 2) and stephacidin A (6) contain a bicyclo[2.2.2]diazaoctane ring, which is proposed to be constructed from notoamice E (8) by the intramolecular Diels-Alder (IMDA) reaction. We made a feeding experiment of ^<13>C-labeled-8 in the minimum medium. Contrary to our expectaton, compounds containing a bicyclo ring were not obtained at all. This result suggested that the formation of a pyrane ring would be constructed after the formation of the bicyclo ring. Then, we made a feeding experiment of ^<13>C, ^<15>N-labeled-7, which lacks a pyrane ring in 6. As the result, a pinacol-type rearrangement of the isoprenyl group in 7 occurred to give 11 and 12, and no metabolite containing a bicyclo ring was afforded. Now, feeding experiments of ^<13>C, ^<15>N-labeled-11 and -12 are in progress. Nortoamides O-R (14-17) were isolated from the same extract of the fungus, which yielded other notoamides. Notoamide O (14) possesses a novel hemiacetal/hemiaminal ether functionality hitherto unknown among this family of prenylated indole alkaloids. The structure represents an unusual branc point for the oxidative modification of other members in the family of prenylated indole alkaloids in the biogenetic pathway.