Structure Elucidation, Enantioselective Analysis, and Biogenesis of Nerol Oxide in Pelargonium Species

Abstract

A novel enantioselective synthesis of nerol oxide (3, 6-dihydro-4-methyl-2-(2-methyl-1-propenyl)-2H-pyran) was used for the determination of the absolute configuration at C-2. The order of elution of the enantiomers on octakis-(2, 3-di-O-butyryl-6-O-tert-butyldimethylsilyl)-gamma-cyclodextrin in OV 1701-vi as the chiral stationary phase in enantioselective GC was determined as (2R) before (2S). Enantioselective multidimensional GC/MS (enantio-MDGC/MS) was used for the determination of the enantiomeric ratios of nerol oxide in different geranium oils. As a result, in all investigated oils nerol oxide occurs as a racemate. The biogenesis of nerol oxide in Pelargonium species was investigated by feeding experiments using deuterium-labeled neryl glucoside as the precursor. The Pelargonium plants were able to convert the fed precursor into racemic nerol oxide, which has to be considered as a "natural racemate".

Identification and Quantification of Dimethylamylamine in Geranium by Liquid Chromatography Tandem Mass Spectrometry

“…The results in the current study show that 1,3-DMAA (1) in geranium plants and geranium oils appears to be an exception to this notion. Indeed, this is not the first report demonstrating the presence of a racemate in a plant tissue 18–20. In fact, the presence of a racemate (ie, nerol oxide) has been demonstrated once before in the geranium plant as well 19.…”

“…Indeed, this is not the first report demonstrating the presence of a racemate in a plant tissue. 18–20 In fact, the presence of a racemate (ie, nerol oxide) has been demonstrated once before in the geranium plant as well. 19 Further study is needed to elucidate the biosynthetic pathway of DMAAs in the geranium plant.…”

The Nose as a Stereochemist. Enantiomers and Odor

“…Other cases using enantiomeric compositions concern pulegone isomers (mint odors) and monoterpenes in oils of Salvia sp . In a study of Pelargonium species, the monoterpene nerol oxide was added to the list of naturally occurring racemates …”

Physicochemical, microbial, and aroma characteristics of Chinese pickled red peppers (Capsicum annuum) with and without biofilm

“…The formation of these compounds was related to the metabolism of microorganisms in biolm. 46 Three compounds with low concentrations, namely, geraniol, 4-ethylguaiacol, and 4vinylguaiacol, contributed the most to the aroma prole due to their low thresholds. Geraniol had an OVA value of 2389 and contributed to sweet and oral aromas.…”