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- Title
New Antifungal `Quinone Methide' Diterpenes from Bobgunnia madagascariensis and Study of Their Interconversion by LC/NMR.
- Authors
Schaller, Frédéric; Wolfender, Jean-Luc; Hostettmann, Kurt; Mavi, Steven
- Abstract
Two new `quinone methide' diterpenes with a cassane skeleton were isolated from the root bark of Bobgunnia madagascariensis ( Desv.) J. H. Kirkbr. & Wiersema (Leguminosae). The two compounds occurred as a diastereoisomer mixture 1/ 2. Their structure was established as (4 R,6a S,10a S)- and (4 S,6a S,10a S)- 1,4,6a,7,8,9,10,10a-octahydro-4,11-dihydroxy-7,7,10a-trimethyl-2 H-phenanthro[1,2- c]pyran-6,12-dione by spectroscopic methods and by comparison with the data obtained for another `quinone methide' diterpene isolated previously from the same plant and identified by single-crystal X-ray analysis. 1H- and 13C-NMR signals were assigned by extensive in-mixture 2D correlation experiments, and 1H-NMR spectra of the separated diastereoisomers 1 and 2 were recorded by on-flow LC/NMR. The interconversion of 1 and 2 was followed by repeated stop-flow LC/NMR experiments over a two-hour period. Compounds 1 and 2 showed moderate antifungal properties towards human pathogenic fungi, in particular the yeast Candida albicans.
- Publication
Helvetica Chimica Acta, 2001, Vol 84, Issue 1, p222
- ISSN
0018-019X
- Publication type
Article
- DOI
10.1002/1522-2675(20010131)84:1<222::AID-HLCA222>3.0.CO;2-R