Novel terpenyl esters from Australian finger lime (Citrus australasica) peel extract

Abstract

The volatile constituents of the peel solvent extract of the Australian finger lime Citrus australasica were analysed by GC-MS. Besides limonene, isomenthone was a major component, which is rare in Citrus species. Six new terpenyl esters were also identified and confirmed by chemical synthesis: citronellyl 2-methylbutanoate; 1,8(10)-p-menthadien-9-yl propanoate; 1,8(10)-p-menthadien-9-yl 2-methylbutanoate; 1,8(10)-p-menthadien-9-yl 3-methylbutanoate; 1-p-menthen-9-yl 2-methylbutanoate; and 1-p-menthen-9-yl 3-methylbutanoate. To the best of our knowledge, the last four compounds have never before been identified in a natural product extract.

Confined direct analysis in real time ion source and its applications in analysis of volatile organic compounds of Citrus limon (lemon) and Allium cepa (onion)

“…Table lists the molecular formula identifications of the dominant peaks observed in Fig. based on accurate mass match and results reported in the literature . These volatile compounds observed in this study mainly consist of mono‐, sesqui‐ and diterpene hydrocarbons and oxygenated molecules.…”

“…For peel, the ions at m/z 135.12 (C 10 H 14 H + ) and 153.13 (C 10 H 16 OH + ) are the strongest peaks, while, for flesh, the dominant ions are at m/z 137.13 (C 10 H 16 H + ) and 205.20 (C 15 H 24 H + ). The C 10 H 14 H + , C 10 H 16 OH + , C 10 H 16 H + and C 15 H 24 H + ions are tentatively identified as protonated 3‐isopopyltoluene, piperitone, limonene and valencene, respectively, based on results from the literaure . No tandem mass spectrometry (MS/MS) measurements were performed; therefore, no structural information can be obtained in this study.…”

“…The confined DART ion source was then applied in the analysis of VOCs of Citrus limon (lemon) fruits. As an important nutrition resource, the VOCs of Citrus limon (lemon) have been studied by several groups and more than 160 different volatile molecules have been identified …”

Simple preparative gas chromatographic method for isolation of menthol and menthone from peppermint oil, with quantitative GC‐MS and 1H NMR assay

“…From this result, 50 mg can still be adequately analysed by using 1 H NMR on the 600 MHz instrument, and data suggests about 10 mg could be detectable by increasing spectral acquisition time in NMR, but this has not been established as a quantitative rule. Delort et al [19] proposed the use of preparative NMR to characterize components in Australian finger lime extracts, but the aroma compounds were considered of insufficient abundance, hence they had to rely on MS interpretation for structural identification. Thus NMR sensitivity is a key factor in determining the applicability of the prep-GC method.…”

Secondary Metabolites

“…This included citronellyl and geranyl esters, commonly found in lime peel oils, but also several less common (Z)-3-hexenyl esters and bornyl esters. In finger limes these compounds, together with isomenthone, menthol, carvone, cis-3-hexenol and methyl salicylate, may also contribute to the characteristic fresh green aroma of the fruits (Delort et al, 2009). …”