摘要:

The configuration at C-18 of variabilin (1), isolated from a Caribbean sponge,Ircinia felix, was established to beR.Variabilin acetate (2) was oxidatively degraded and converted into di-(R)-MTPA ester of 2-methylheptane-1,6-diol, which was found to have 2R-configuration by1H-NMR studies in comparison with synthetic (2S, 6R S)- and (2R S, 6R S)-esters. The occurrence of (18R)-variabilin was demonstrated for the first time, whereas its (18S)-antipode were reported previously.

ISSN:1057-5634    

DOI:10.1080/10575639508044080

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The possibility for hydroxylations of androsta-1, 4-diene-3, 17-dione (ADD, II) was studied using different strains of the fungiPenicillium raistrickii, Aspergillus ochraceus, Curvularia lunata and Beauveria bassiana. The isolated products were 15α-hydroxy-ADD (III,P. raistrickii), 11α-hydroxy-ADD (IV,A. ochraceus, B. bassiana), 14-hydroxy-ADD (V,C. lunata) and 7α, 11α-dihydroxy-ADD (VI,B. bassiana). Yields were observed up to 70%. The structures were elucidated by1H-NMR,13C-NMR, 2d-NMR, MS and UV/VIS.

ISSN:1057-5634    

DOI:10.1080/10575639508044081

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Incubation of a monocyclic iridal (a triterpenoid fromIrisspecies) with rat liver microsomes in the presence of NADPH led to the degradation of this substrate and to the generation of 16-hydroxy-iridal (isoiridogermanal). This reaction which is inhibited by carbon monoxide seems to be mediated by cytochrome P-450. This observation strongly suggests that this monoxygenase, which is also present in intracellularIrismembranes, could be involved in plant iridal biosynthesis pathways.

ISSN:1057-5634    

DOI:10.1080/10575639508044082

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Four new phenalenone-type phytoalexins (2–5) have been isolated from rhizomes ofMusa acuminata(AAA) infected with the fungusFusarium oxysporum. The structures of the new phytoalexins were elucidated using spectroscopic evidence, chemical correlation, synthesis, and X-ray diffraction analysis. The major compound 2, has been previously described as a natural product, named anigorufone, but never as a phytoalexia. The chemical shift for all of the hydrogen and carbon atoms in the substances were unambiguously established by mono- and bidimensional, homo- and heteronuclear NMR experiments (1HNMR,13CNMR, COSY, HMQC and HMBC). In preliminaryin vitroassays, all of the four new phytoalexins have shown inhibitory activity on the growth of the germinative tube ofFusarium oxysporum f. sp. cubense race 4.

ISSN:1057-5634    

DOI:10.1080/10575639508044083

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Four new anti-microbial, unsaturated amino alcohols were isolated as their acetyl derivatives (1–4) from an extract of a South African marine ascidian (Pseudodistomaspecies). Standard spectroscopic methods were used to establish the structures of these compounds as 2S*-acetamido-3S*-acetoxy-5E, 13-tetradecadiene (1), 2S*-acetamido-3S*-acetoxy-5E-tetradecene (2), 1-acetamido-2-acetoxy-4E, 12-tridecadiene (3) and 1-acetamido-2-acetoxy- 4E-tridecene (4).

ISSN:1057-5634    

DOI:10.1080/10575639508044084

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

From the broth culture of the fungal pathogenHypoxylon mammatumresponsible for canker in aspen (Populusspecies) two new phytotoxins, hymatoxins K (2) and L (3), diterpenoid α-D-manno-pyranosides were isolated and their structures determined by mass spectrometry and 2D-NMR.

ISSN:1057-5634    

DOI:10.1080/10575639508044085

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

BZR-cotoxin III, a component of BZR-toxin produced byB. zeicolarace 3, which causes leaf spot disease in corn, was determined to be a cyclic nonadepsipeptide (1).

ISSN:1057-5634    

DOI:10.1080/10575639508044086

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Two new xenicane diterpenoids, 9-deoxyxeniolide-A (1) and 9-deoxyxeniolide-B (2), were isolated from a new species of the alcyonacean soft-coralXenia, collected in the Philippines. The structures of the new compounds were elucidated by interpretation of spectral data. The metabolites show weak antibacterial activities, with the conjugated lactone 9-deoxyxeniolide-A (1) showing the greatest potency.

ISSN:1057-5634    

DOI:10.1080/10575639508044087

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Two benzylisoquinoline and four aporphine alkaloids were isolated from roots of an oceanic Annonaceae,Xylopia papuana. The benzylisoquinoline alkaloids displayed a selectivity for dopamine receptors whereas aporphine alkaloids, specially anonaine, inhibited selectively dopamine uptake.

ISSN:1057-5634    

DOI:10.1080/10575639508044088

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The preferred conformation of a ring B-homo diterpene, obtained by the rearrangement of methyl 9α-hydroxy-11α-methanesulfonyloxy-(-)-kauran-10-oate 1 with potassium t-butoxide in t-butanol, was determined on the basis of the n.O.e. experiments and molecular dynamics calculations.

ISSN:1057-5634    

DOI:10.1080/10575639508044089

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor