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Monoterpene biosynthesis in Agathosma crenulata (Buchu)
Author(s) -
Fuchs Sabine,
Sewenig Sabine,
Mosandl Armin
Publication year - 2001
Publication title -
flavour and fragrance journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 70
eISSN - 1099-1026
pISSN - 0882-5734
DOI - 10.1002/ffj.970
Subject(s) - pulegone , chemistry , menthone , monoterpene , enantiopure drug , essential oil , chromatography , organic chemistry , stereochemistry , enantioselective synthesis , catalysis
Young plants of Agathosma crenulata (L.) Pillans were stem fed with aqueous solutions of 2 H 2 and 18 O/ 2 H 2 ‐labelled monoterpene ketone precursors. The essential oil was extracted by solid phase microextraction and subsequently analysed with enantioselective multidimensional gas chromatography–mass spectrometry. Both labelled pulegone precursors were converted into corresponding labelled menthone, isomenthone and menthofuran with different enantioselectivity. Feeding experiments with 18 O/ 2 H‐labelled pulegone proved an enzymatic conversion of pulegone to menthofuran and the loss of the pulegone oxygen. Stereoselective analysis of all four isopulegone stereomers using octakis(2,3‐di‐ O ‐butyryl‐6‐ O ‐ tert ‐butyldimethylsilyl)‐γ‐cyclodextrin or heptakis(2,3‐di‐ O ‐acetyl‐6‐ O ‐ tert ‐butyldimethylsilyl)‐β‐cyclodextrin allowed the detection of enantiopure (1 S )‐ cis ‐ and (1 S )‐ trans ‐isopulegone (>99%) in A. crenulata and buchu samples. Labelled isopulegone is discussed as a suitable pulegone precursor. Feeding experiments regarding the biosynthesis of 3‐oxo‐ p ‐menthan‐8‐thiol and 3‐oxo‐ p ‐menthan‐8‐thiol acetate are also reported. Copyright © 2001 John Wiley & Sons, Ltd.