- Isogermacrene A, a proposed intermediate in sesquiterpene biosynthesis
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A sesquiterpene hydrocarbon, isogermacrene A (5), which is structurally related to the gorgonanes and zieranes, was isolated from the essential oil of Saccogyna viticulosa (Hepaticae). This monocyclic compound is proposed as the biogenetic intermediate of some rare sequiterpene skeletons. In the essential oil of the liverwort Saccogyna viticulosa, collected on the island of Madeira, the new sesquiterpene hydrocarbons isogermacrene A (5) and its Cope rearrangement product iso-β-elemene (6) were identified. 5 is proposed to act as the biogenetic precursor of several new sesquiterpenes identified in the volatiles of S. viticulosa. These include iso-α-humulene, α-gorgonene, gorgona-1,4(15),11-triene and gorgon-11-en-4-ol. In addition, the Cope product of zierene, isozierene, allo-aromadendra-4(15),10(14)-diene, aromadendra-4(15),10(14)-dien-1-ol and a prenylguaiane diterpene alcohol, named viticulol, were identified as new natural products.
- Hackl, Thomas,K?nig, Wilfried A.,Muhle, Hermann
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p. 2261 - 2275
(2007/10/03)
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- Sesquiterpene constituents of the liverwort Calypogeia muelleriana
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The lipophilic constituents of the liverwort Calypogeia muelleriana were investigated. A new sesquiterpene hydrocarbon, maali-1,3-diene, and two sesquiterpene alcohols with an aromadendrane skeleton, 3-hydroxyledene and 4,5-dehydroviridiflorol, were isolated and identified. The structure elucidation was carried out mainly by NMR spectroscopic techniques (1H-, 13C-, 1H1H-COSY-, HMQC-, HMBC- and NOESY experiments). The majority of the constituents of the liverwort volatiles show a conspicuous biogeneric relationship, which becomes even more obvious in the stereochemical correlations.
- Warmers, Ute,Wihstutz, Kolja,Buelow, Nils,Fricke, Christiane,Koenig, Wilfried A.
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p. 1723 - 1731
(2007/10/03)
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- Metabolites from the Marine Sponge Epipolasis kushimotoensis
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Two isothiocyanates,epipolasin-A 1 and -B 2,and two corresponding thiourea derivatives,epipolasinthiourea-A 14 and -B 15, were isolated from the marine sponge E.kushimotoensis.Their structures were elucidated on the basis of chemical and spectral evidence.The thioureas 14 and 15 showed cell growth inhibition activity.Keywords-sponge;Epipolasis kushimotoensis;epipolasin-A,-B; epipolasinthiourea-A, -B; sesquiterpene; isothiocyanate; thiourea derivative; cell growth inhibition
- Tada, Haruhiko,Yasuda, Fumio
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p. 1941 - 1945
(2007/10/02)
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- Three ent-secoaromadendrane-type sesquiterpene hemiacetals and a bicyclogermacrene from Plagiochila ovalifolia and Plagiochila yokogurensis
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A new ent-secoaromadendrane-type sesquiterpene hemiacetal, plagiochiline G, was isolated from Plagiochila ovalifolia. Four new ent-sesquiterpene hemiacetals, plagiochiline H and I, and two pungent methoxyplagiochilines A1, A2 and non-pungent methoxyplagiochiline C were also isolated from P. yokogurensis. The methoxylated plagiochilines A1, A2 and C were derived from the plagiochilines A and C during the extraction procedure. A new germacrene, ent-3α-acetoxybicyclogermacrene, ent-maaliol and the previously known ent- aromadendrane-type sesquiterpenes have been obtained from P. yokogurensis. The structures of the new compounds were elucidated by 1H NMR spectral data and by chemical correlation.
- Asakawa, Yoshinori,Toyota, Masao,Takemoto, Tsunematsu
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p. 2141 - 2145
(2007/10/02)
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