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Absolute Configuration of a Diterpene Lactone from Parinari capensis
Author(s) -
Garo Eliane,
Maillard Marc,
Hostettmann Kurt,
StdecktiEvans Helen,
Mavi Steven
Publication year - 1997
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19970800218
Subject(s) - diterpene , chemistry , absolute configuration , stereochemistry , lactone , phytochemical , derivative (finance) , biochemistry , financial economics , economics
Abstract Phytochemical investigation of Parinari capensis (Chrysobalanaceae) led to the isolation of three diterpene lactones 1–3. The structures of these compounds have been established by NMR spectroscopy and X‐ray crystal‐structure analysis. Addition of bromine onto the exocyclic methylidene group of 1 yielded the brominated derivative 1‐Br . X‐Ray analysis of 1‐Br established unambiguously the absolute configuration, and 1 was then identified as the (4 R , 9 R )‐10‐hydroxy‐13‐methoxy‐9‐methyl‐15‐oxo‐20‐norkaur‐16‐en‐18‐oic acid γ‐lactone. Diterpenes 2 and 3 were identified as the C(13)‐demethoxylated and the C(13)‐demethylated derivatives of diterpene 1 , respectively. Antifungal activity against Cladosporium cucumerinum was determined for 1–3 .