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. 2022 Sep 23;27(19):6277.
doi: 10.3390/molecules27196277.

Authentication of Citrus spp. Cold-Pressed Essential Oils by Their Oxygenated Heterocyclic Components

Noura S Dosoky  1 , Prabodh Satyal  1 , William N Setzer  1   2
Affiliations

Authentication of Citrus spp. Cold-Pressed Essential Oils by Their Oxygenated Heterocyclic Components

Noura S Dosoky et al. Molecules. .

Abstract

Citrus essential oils are routinely adulterated because of the lack of regulations or reliable authentication methods. Unfortunately, the relatively simple chemical makeup and the tremendous price variations among Citrus varieties encouraged the interspecies adulteration of citrus oils. In this study, a sensitive UPLC-MS/MS method for the quantitation of 14 coumarins and furanocoumarins is developed and validated. This method was applied to screen the essential oils of 12 different Citrus species. This study, to our knowledge, represents the most comprehensive investigation of coumarin and furanocoumarin profiles across commercial-scale Citrus oils to date. Results show that the lowest amount was detected in calamansi oil. Expressed oil of Italian bergamot showed the highest furanocoumarin content and the highest level of any individual furanocoumarin (bergamottin). Notable differences were observed in the coumarin and furanocoumarin levels among oils of different crop varieties and origins within the same species. Potential correlations were observed between bergapten and xanthotoxin which matches with known biosynthetic pathways. We found patterns in furanocoumarin profiles that line up with known variations among the Citrus ancestral taxa. However, contrary to the literature, we also detected xanthotoxin in sweet orange and members of the mandarin taxon. Using multivariate analysis, we were able to divide the Citrus oils into 5 main groups and correlate them to the coumarin compositions.

Keywords: Citrus; UPLC-MS/MS; coumarins; essential oils; furanocoumarins.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Chemical structure of key non-volatile components in expressed Citrus essential oils.
Figure 2
Figure 2
LC-MS/MS chromatogram (MRM acquisition mode) of 14 targeted coumarins using a Shimadzu LCMS8060.
Figure 3
Figure 3
Dendrogram obtained by cluster analysis of the coumarin composition of Citrus essential oils, based on correlation and using the unweighted pair-group method with arithmetic average (UPGMA).
Figure 4
Figure 4
Principal component biplot of PC1 and PC2 scores and loadings indicating the coumarin chemical relationships of Citrus essential oils.
See this image and copyright information in PMC

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