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Article

Integrated Analysis by GC/MS and 13C NMR of Moroccan Cladanthus mixtus Essential Oil; Identification of Uncommon Epoxyfarnesanes

by
Souad El Hafidi
1,2,
Khadija Bakhy
2,
Mohammed Ouhssine
1,
Abderrahim Benzakour
1,
Joseph Casanova
3,
Mathieu Paoli
3 and
Félix Tomi
3,*
1
Laboratory of Natural Resources and Sustainable Development, Faculty of Science, University Ibn Tofail, BP 242, Kenitra 14000, Morocco
2
Research Unit on Aromatic and Medicinal Plant, INRA, Rabat-Instituts, BP 6570, Rabat 10101, Morocco
3
Laboratoire Sciences Pour l’Environnement, Université de Corse-CNRS, UMR 6134 SPE, Route des sanguinaires, 20000 Ajaccio, France
*
Author to whom correspondence should be addressed.
Compounds 2023, 3(2), 365-375; https://doi.org/10.3390/compounds3020028
Submission received: 11 April 2023 / Revised: 10 May 2023 / Accepted: 15 May 2023 / Published: 17 May 2023
(This article belongs to the Special Issue Feature Papers in Compounds (2022–2023))
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Abstract

:
Cladanthus mixtus (L.) Chevall., Asteraceae, also known as Moroccan chamomile, is a spontaneous, annual plant growing wild in North-Western Morocco. Economically, the essential oil of C. mixtus is of high interest, Morocco being the only supplier on the international market. Two essential oil samples (EO) were isolated from aerial parts of Cladanthus mixtus (L.) Chevall., and analyzed by a combination of chromatographic and spectroscopic techniques (gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS), and 13C NMR spectroscopy). Computer matching against the in-house 13C NMR library allowed the identification of the eight components at appreciable contents, namely 3,6,6,9-bis-epoxy-farnesa-1,7(14),10-triene, and its 3-epi, 9-epi, and 3,9-diepi epimers, and 6,9-epoxy-farnesa-1,7(14),10-trien-3-ol and its 3-epi, 6-epi, and 3,6-diepi epimers. Our results confirm the tremendous chemical variability of Moroccan C. mixtus essential oil and the usefulness of 13C NMR analysis, in combination with GC(RI), for the identification of uncommon oxygenated sesquiterpenes that induce an original composition.

1. Introduction

Cladanthus mixtus (L.) Chevall. (synonyms: Anthemis mixta (L.), Chamaemelum mixtum (L.) All., Ormenis mixta (L.) Dumort, Ormenis multicaulis Braun-Blanq. & Maire), also known as Moroccan chamomile, Asteraceae, is a spontaneous, annual plant 10 to 40 cm tall with numerous erect, lying, or ascending stems terminated by fragrant flower heads with ligulate, white, and sterile external flowers decorated with yellow at their base and fertile yellow tuberous internal flowers. This species is a sialophyte that abounds in the voids of semi-arid and sub-humid bioclimates on sandy soils of the thermomediterranean stage. It is generally found in open forests, fields, sand and stone agricultural landscapes, and low mountains. In Morocco, this plant is known by the vernacular name “Hellâla” [1] and is mainly distributed in two disjointed areas, the first between Tangier, Ouezzane, Souk Larbaa, Moulay Bousselham, and Azilah, and the second between Kenitra, Sidi Slimane, Khémisset, and Rabat [2]. Economically, the essential oil of C. mixtus is of high interest. Morocco is the world’s leading producer [3]. In terms of quality, the essential oil of C. mixtus was ranked ninth among the 20 best essential oils produced in Morocco. In Morocco, C. mixtus is advised as an anxiolytic for the rebalancing of the central nervous system; it has great value in nervous breakdowns and for mild hepatic and gastric insufficiency and Colibacillary colitis [4]. Thanks to its pleasant smell, the essential oil of C. mixtus is sought after in perfumery, cosmetics, and medicine [4]. Concerning the chemical composition of the essential oil of Cladanthus mixtus (Moroccan chamomile), various studies have shown a very important chemical polymorphism.
The chemical composition of C. mixtus essential oil has been investigated, most of the time, by GC/MS in combination with retention indices on the non-polar or semi-polar chromatography column. Various chemical compositions have been reported describing an important chemical variability, and they have recently been reviewed [5]. The authors listed the 264 compounds that have been identified at least once in C. mixtus essential oil isolated from plants harvested all around the Mediterranean Sea (Algeria, Morocco, France, and Italy).
We focused our attention on Moroccan C. mixtus essential oil, which also displayed a fair chemical variability. According to the literature data, the reported essential oil compositions are distributed within two groups: (i) those that displayed a major component (Group 1) and (ii) those that contained various components with more or less similar content (Group 2).
-
The compositions of essential oils of group 1 were dominated either by santolina alcohol (24.1–66.0%) [6,7,8,9,10,11], camphor (17.8–33.0%) [12,13,14], 2-methyl-2-trans-butenyl methacrylate (32.0–35.2%) [12,15,16], (E)-β-farnesene (35.5–50.3%) [12,15], or (E)-nerolidol (44.1%) [13];
-
Samples of group 2 contained mainly monoterpenes (α-pinene, myrcene, 1,8-cineole, and camphor), irregular monoterpenes (santolina triene and santolina alcohol), sesquiterpene hydrocarbons (germacrene D and (E)-β-farnesene), or miscellaneous (2-tridecanone and (Z)-methyl isoeugenol) [12,13,17,18].
The aim of this paper that reports on the composition of two C. mixtus oil samples submitted to combined analysis by chromatographic and spectroscopic techniques is to demonstrate overall the importance of 13C NMR in identifying uncommon oxygenated sesquiterpenes, the presence of which induces an unusual composition.

2. Materials and Methods

2.1. Plant Material and Essential Oil Isolation

Aerial parts of C. mixtus have been collected in two locations (Figure 1, Table 1). Hydrodistillation (2 h) using a Clevenger-type apparatus of C. mixtus aerial parts (300 g) in 2 L flask yielded 0.3 mL of essential oil for both samples. To avoid any damage, the samples were stored at 5 °C in amber vials.

2.2. GC-FID Analysis

GC-FID analyses were carried out using a Clarus 500 Perkin Elmer (Perkin Elmer, Courtaboeuf, France) chromatograph equipped with two FID and two fused-silica capillary columns (50 m length × 0.22 mm internal diameter, film thickness 0.25 μm), BP-1 (polydimethylsiloxane), and BP-20 (polyethylene glycol). The oven temperature was programmed from 60 °C to 220 °C at 2 °C/min and then held isothermal at 220 °C for 20 min; injector temperature, 250 °C; detector temperature, 250 °C; carrier gas, H2 (0.8 mL/min); split, 1/60; and injected volume, 0.5 μL. The relative proportions of the essential oil constituents were expressed as percentages obtained by peak-area normalization without using correcting factors. Retention indices (RI) were determined relative to the retention times of a series of n-alkanes (C8–C28) with linear interpolation (Target Compounds software from Perkin Elmer, V1.2019, Courtaboeuf, France).

2.3. GC/MS Analysis

GC/MS analyses were performed on a Clarus SQ8S Perkin Elmer TurboMass detector (quadrupole), directly coupled to a Clarus 580 Perkin-Elmer Autosystem XL chromatograph, equipped with a BP-1 (polydimethylsiloxane) fused-silica capillary column (50 m length × 0.22 mm internal diameter, film thickness 0.25 µm). The oven temperature was programmed from 60 to 220 °C at 2°/min and then held isothermal at 220 °C for 30 min; injector temp., 250 °C; ion source temp., 150 °C; carrier gas, He (1 mL/min); split ratio, 1:80; injection volume, 0.5 μL; and ionization energy, 70 eV. The electron ionization (EI) mass spectra were acquired over the mass range of 35–350 Da.

2.4. Nuclear Magnetic Resonance

13C NMR spectra were recorded on a Bruker AVANCE 400 Fourier Transform spectrometer equipped with a 5 mm probe operating at 100.63 MHz for 13C, in CDCl3, with all shifts referred to internal Tetramethylsilane (TMS) at room temperature (298 °C). The following parameters were used: pulse width = 4 μs (flip angle 45°); acquisition time = 2.7 s for 128 K data table with a spectral width of 25,000 Hz (250 ppm); CPD mode decoupling; and digital resolution = 0.183 Hz/pt. For each sample (40 mg of essential oil in 0.5 mL of CDCl3), 3000 scans were recorded.

2.5. Identification of Individual Components

Identification of the individual components was carried out (i) by comparison of their GC retention indices (RI) on non-polar and polar columns with those of reference compounds compiled in the in-house library and with literature data [19,20,21]; (ii) on computer matching against commercial mass spectral libraries [21,22,23]; and (iii) on comparison of the signals in the 13C NMR spectra of the samples with those of reference spectra compiled in the laboratory spectral library, with the help of a laboratory-made software [24,25] (Figure 2).

3. Results

3.1. Methods for Identification of Individual Components of Essential Oils

Identification of individual components of essential oils is routinely performed by using a fast-scanning mass spectrometer associated with a gas chromatograph. The mass spectrum of every component is compared with those of reference compounds compiled in commercial or in-house libraries. Two-dimensional GC coupled with MS may be useful for the analysis of complex essential oils in order to individualize components that are co-eluted when a unique column is employed and then to record more reliable mass spectra. Commercial libraries contain mass spectra of thousands of compounds (covering all fields of research); among these, a few thousand belong to volatile components of essential oils. In-house MS libraries are constructed with pure compounds or compounds whose identity is ascertained in one essential oil sample by spectroscopic techniques. Therefore, the reference MS spectra of various new compounds identified in essential oils and reported in the literature are not directly available to be introduced in a given MS library. In most analyses, identification of the compounds suggested by MS is confirmed by comparison of its retention indices (RI) on non-polar and polar chromatography columns with those of reference compounds compiled in the literature and/or homemade RI libraries.
In parallel, it has been shown that 13C NMR can be used for the non-destructive, non-separative identification of individual components of essential oils. In this computerized procedure developed at the University of Corsica, an individual component is identified by comparison of the signals of the mixture spectrum with those of reference spectra compiled in a library [24,25] (Figure 2). It should be pointed out that structural elucidation of every new compound proceeds, inter alia, via 13C NMR spectroscopy, and therefore, the 13C NMR spectrum is fully reported in the publication. It could be added that nowadays, a high-field spectrometer allows us to record the 13C NMR spectrum of isolated compounds at the mg level. The diluted solutions avoid intermolecular influence, and therefore, chemical shifts are perfectly reproducible. In practice, two spectral data libraries were constructed; the first one contains spectra recorded in the lab, and the second contains spectra reported in the literature for every new compound isolated from plants or obtained by synthesis. Both libraries are continuously implemented. Each component is identified considering three parameters directly available from the in-house computer program: (i) the number of observed carbons with respect to the number of expected signals, (ii) the number of overlapped signals of carbons that possess the same chemical shift, and (iii) the difference of the chemical shift of each signal in the mixture spectrum and in the reference (Figure 2). A compound is considered as identified when at least 50% of its signals belonging solely to that molecule are observed [24,25].
The benefit of using various chromatographic and spectroscopic techniques for the analysis of essential oil has been demonstrated and exemplified. For instance, the key role of 13C NMR analysis in the identification of individual components of Ivoirian Polyalthia longifolia leaf oil and of Xanthocyparis vietnamensis wood oil has been highlighted [26,27]. 13C NMR analysis also appeared suited for the identification of stereoisomers [28,29].

3.2. Chemical Composition of the Two Oil Samples

EOs were isolated from aerial parts of C. mixtus harvested in North-Western Morocco, at Souk Had (sample SH) and at Ain Chkef forest, near Sidi Slimane (Sample SS). Yields were measured as 0.10% (v/w) for both oil samples, which were submitted to GC(RI) on two column (non-polar and polar phases), GC/MS, and 13C NMR analyses.
We will detail below the identification of individual components of two Moroccan C. mixtus essential oil samples (Table 2) by (i) GC(RI), GC/MS, and 13C NMR (major components), (ii) GC(RI) and GC/MS (minor components), and (iii) by GC(RI) and 13C NMR (uncommon oxygenated sesquiterpenes).
In total, 81 compounds were identified. They accounted for 90.1 and 87.6% of the whole composition, respectively (Table 2). The chromatogram of the SS sample (non-polar column) is reported in Figure 3.
The identification of individual components was conducted as follows:
-
Mass spectrometry in combination with retention indices on two capillary columns (non-polar and polar phases) allowed the identification of 73 components (1–43, 48–63, 66, 69–81) from traces accounting for more than 21%;
-
In parallel, the identification of all the major components of both oil samples was ascertained by 13C NMR following the computerized methodology developed at the University of Corsica (2–4, 6, 8, 12, 14–18, 23, 24, 27, 29–31, 35, 40, 43, 48, 49, 53, 56, 58, 60, 61, 63, 73, and 75–77) [25,26]. Alismol 71 was identified by 13C NMR and RIs in both oil samples. Similarly, α-bisabolol 76 and epi-α-bisabolol 77 co-eluted on the non-polar column and were differentiated on the polar column. The occurrence of both epimers was confirmed by the observation of characteristic signals in the 13C NMR spectra;
-
Lastly, eight compounds (44–47, 64, 65, 67, and 68) that accounted for 0.2–8.3% each (percentages measured on the polar column due to overlapped GC signals on the non-polar column) remained unidentified regardless of the matching vs. MS commercial and homemade libraries at our disposal. Their retention indices were as follows: non-polar/polar column = 1451/1831, 1451/1834, 1460/1870, and 1460/1871 on the one hand, and 1600/2252, 1600/2255, 1613/2274, and 1613/2283 on the other hand. In parallel, computer alignment with the internal 13C NMR library allowed the presence of eight components in significant content. Components 44–47 were identified as 3,6,6,9-bis-epoxy-farnesa-1,7(14),10-triene (IUPAC nomenclature (2S,5S,7S)-2-methyl-9-methylene-7-(2-methylprop-1-en-1-yl)-2-vinyl-1,6-dioxaspiro [4.4]nonane, relative stereochemistry)), and its epimers, 3-epi (2R,5S,7S), 9-epi (2S,5S,7R), and 3,9-diepi (2R,5S,7R). Components 64, 65, 67, and 68 were identified as 6,9-epoxy-farnesa-1,7(14),10-trien-3-ol (IUPAC nomenclature (2S,3′R/S,5S)-(3′-hydroxy-3′-methylpent-4′-en)-3-methylene-5-isopropylidene tetrahydrofuran, relative stereochemistry)) and its epimers, 3-epi (2S, 3′R/S, 5S), 6-epi (2S, 3′R/S, 5R), and 3,6-diepi (2R, 3′R/S,5R) (Table 2, Figure 4).
The eight components were identified by comparison of their 13C NMR chemical shifts, measured in the recorded 13C NMR spectra of both oil samples with those of reference spectra compiled in our library (Figure 5, Table S1).

4. Discussion

Despite the similarity of the structures and the low percentage of some components, the chemical shifts of all carbons were observed, except those of the quaternary carbons of the minor isomers. The difference in chemical shifts between the experimental spectra and the reference data was always acceptable, as well as the number of overlapped signals. It could be noticed that the eight components were first isolated from the essential oil of Tanacetum fruticulosum and spectroscopically characterized by Weyerstahl et al., who reported, inter alia, their 13C NMR data [46]. To the best of our knowledge, since that time, the eight compounds have only been identified, by using 13C NMR spectroscopy, in essential oil isolated from aerial parts of Corsican Dittrichia viscosa [38].
The composition of the SH oil sample was dominated by monoterpenes, 1,8-cineole (20.8%), and α-pinene (16.1%), followed by limonene (3.6%), terpinen-4-ol (3.5%), sabinene (3.2%), and α-terpineol (2.1%). Sample SS contained mainly (E)-nerolidol (13.9%), besides α-pinene (4.6%) and santolina alcohol (3.4%). A few compounds were present at appreciable content in both oil samples: myrcene (1.1/1.3%), 3-methylpentyl isobutyrate (0.8/0.2%), borneol (1.8/1.2%), caryophyllene oxide (1.7/0.9%), fokienol (1.1/2.9%), copaborneol (1.3/1.0%), and τ-muurolol (1.6/1.0%). Some components were noticeable in the SH oil sample, as follows: isobutyl isobutyrate (0.9%), α-thujene (0.7%), β-pinene (0.5%), 2-methylbutyl isobutyrate (1.1%), p-cymene (2.2%), isobutyl angelate (1.5%), linalool (0.6%), and 7α-silphiperfol-5-ene (0.4%). Components in the SS oil sample were as follows: santolina alcohol (3.4%), β-elemene (0.9%), (E)-β-caryophyllene (0.9%), and (E)-β-farnesene (2.2%). It is noticeable that irregular monoterpene alcohols, santolina alcohol (3.4%) and artemisa alcohol (0.2%), and diterpenes, neophytadiene (0.1%), (Z)-phytol (0.3%), and (E)-phytol (0.2%) were found only in SS sample. Various hemiterpene esters and analogs usually found in Cladanthus species [31] (up to 1.5%) were identified: isobutyl isobutyrate, isobutyl 2-methylbutyrate, isobutyl isovalerate, isopentyl isobutyrate, 2-methylbutyl isobutyrate, isobutyl angelate, 2-methylbutyl 2-methyl butyrate, 3-methylpentyl isobutyrate, and (Z)-2-hexenyl hexanoate. Lastly, it could be pointed out that the content of 3,6,6,9-bis-epoxyfarnesa-1,7(14),10-triene (44) and its three epimers (45, 46, and 47) were similar in both oil samples (8.3% vs. 9.7%), while the content of 6,9-epoxy-farnesa-1,7(14),10-trien-3-ol (64) and its epimers (65, 67, and 68) was substantially higher in sample SS than in sample SH (15.3% vs. 5.9%).

5. Conclusions

Although oil samples whose chemical composition was dominated by (i) α-pinene and/or 1,8-cineole, (ii) (E)-nerolidol, or (iii) (E)-β-farnesene have been reported, the occurrence of oxygenated farnesane derivatives at appreciable contents (up to 25%) brings originality to the investigated C. mixtus oil samples. Our results confirm the tremendous chemical variability of Moroccan C. mixtus essential oil and the potential of 13C NMR analysis, in combination with GC(RI), for the identification of uncommon oxygenated sesquiterpenes.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/compounds3020028/s1. Table S1: 13C NMR chemical shifts of compounds 44–47, 64, 65, 67, and 68.

Author Contributions

Conceptualization, K.B. and M.O.; methodology, K.B., M.P. and J.C.; validation, S.E.H. and K.B.; formal analysis, M.P. and J.C. investigation, S.E.H.; resources, M.O. and A.B.; writing—original draft preparation, K.B. and J.C.; writing—review and editing, J.C. and F.T.; visualization, K.B., F.T. and J.C.; project administration, K.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data are contained within the article.

Acknowledgments

We thank all the farmers from the SH and SS locations for their kindness and help.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Bellakhdar, J. Médecine Arabe Ancienne et Savoirs Populaires, la Pharmacopée Marocaine Traditionnelle; Ibis Press: Paris, France, 1997. [Google Scholar]
  2. Aafi, A.; Achhal, A.K.; Benabid, A.; Rouchdi, M. Richesse et diversité floristique de l’écosystème de chêne-liège de la forêt de la Mamora. Acta Bot. Malacit. 2005, 30, 127–138. [Google Scholar] [CrossRef]
  3. Benjilali, B.; Zrira, S. Plantes Aromatiques et Médicinales, Atouts du Secteur et Exigences Pour Une Valorisation Durable; Actes Editions Institut Agronomique et Vétérinaire Hassan-II: Rabat, Morocco, 2005. [Google Scholar]
  4. Haddad, P.S.; Depot, M.; Settaf, A.; Chabli, A.; Cherrah, Y. Comparative study on the medicinal plants most recommended by traditional practitioners in Morocco and Canada. J. Herbs. Spices Med. Plants 2003, 10, 25–45. [Google Scholar] [CrossRef]
  5. Elouaddari, A.; El Amrani, A.; Cayuela Sánchez, J.A.; Ould Bellahcen, T.; Zouiten, A.; Jamal Eddine, J. Chemical Composition and Biological Activities of the Cladanthus mixtus Essential Oil: A Review. Anal. Chem. Lett. 2019, 9, 649–663. [Google Scholar] [CrossRef]
  6. Toulemonde, B.; Beauverd, D. Contribution à l’étude d’une camomille sauvage du Maroc: L’huile essentielle d’Ormenis mixta L. Parfum. Cosmétiques Arômes 1984, 68, 65–67. [Google Scholar]
  7. Satrani, B.; Ghanmi, M.; Farah, A.; Aafi, A.; Fougrach, H.; Bourkhiss, B.; Bousta, D.; Talbi, M. Composition chimique et activité antimicrobienne de l’huile essentielle de Cladanthus mixtus. Bull. Soc. Pharm. Bordx. 2007, 146, 85–96. [Google Scholar]
  8. Zrira, S.; Menut, C.; Bessiere, J.M.; Benjilalii, B. Chemical composition of the essential oils of Moroccan Ormenis mixta (L.) Dumort. ssp. Multicaulis. J. Essent. Oil Bear. Plants 2007, 10, 378–385. [Google Scholar] [CrossRef]
  9. Hajjaj, G.; Bahlouli, A.; Tajani, M.; Alaoui, K.; Cherrah, Y.; Zellou, A. Profil neuropharmacologique et analyse chimique d’Ormenis mixta (L.) marocain. Phytothérapie 2018, 16, S55–S64. [Google Scholar] [CrossRef]
  10. Zeroual, A.; Sakar, E.H.; Eloutassi, N.; Mahjoubi, F.; Chaouch, M.; Chaqroune, A. Wild Chamomile [Cladanthus mixtus (L.) Chevall.] Collected from Central-Northern Morocco: Phytochemical Profiling, Antioxidant, and Antimicrobial Activities. Biointerface Res. Appl. Chem. 2021, 11, 11440–11457. [Google Scholar]
  11. Chraibi, M.; Fadil, M.; Farah, A.; Lebrazi, S.; Fikri-Benbrahim, K. Antimicrobial combined action of Mentha pulegium, Ormenis mixta and Mentha piperita essential oils against S. aureus, E. coli and C. tropicalis: Application of mixture design methodology. LWT—Food Sci. Technol. 2021, 145, 111352. [Google Scholar] [CrossRef]
  12. Elouaddari, A.; El Amrani, A.; Jamal Eddine, J.; Correia, A.I.D.; Barroso, J.G.; Pedro, L.G.; Figueiredo, A.C. Yield and chemical composition of the essential oil of Moroccan chamomile [Cladanthus mixtus (L.) Chevall.] growing wild at different sites in Morocco. Flavour Fragr. J. 2013, 28, 360–363. [Google Scholar] [CrossRef]
  13. Elouaddari, A.; El Amrani, A.; Jamal Eddine, J. Effect of the Parts of Plant Material (Flowers and Leaves) on Essential Oil Chemical Composition of Ormenis mixta from Morocco. J. Essent. Oil Bear. Plants 2015, 18, 398–408. [Google Scholar] [CrossRef]
  14. Ainane, T.; Elkouali, M.; Ainane, A.; Talbi, M. Moroccan traditional fragrance based essential oils: Preparation, composition and chemical identification. Der Pharma Chem. 2014, 26, 84–89. [Google Scholar]
  15. Elouaddari, A.; El Amrani, A.; Jamal Eddine, J.; Barroso, J.G.; Pedro, L.G.; Figueiredo, A.C. Intraspecific variability of the essential oil of Cladanthus mixtus from Morocco. Nat. Prod. Commun. 2014, 9, 133–136. [Google Scholar] [CrossRef] [PubMed]
  16. Elouaddari, A.; El Amrani, A.; Moutia, M.; Oubrim, N.; Habti, N.; Jamal Eddine, J. Chemical composition and evaluation of antioxidant, antimicrobial and cytotoxic activities of Moroccan Cladanthus mixtus essential oil and extracts. J. Essent. Oil Bear. Plants 2019, 22, 1450–1466. [Google Scholar] [CrossRef]
  17. Wanner, J.; Schmidt, E.; Bail, S.; Jirovetz, L.; Buchbauer, G.; Gochev, V.; Girova, T.; Atanasova, T.; Stoyanova, A. Chemical composition, olfactory evaluation and antimicrobial activity of selected essential oils and absolutes from Morocco. Nat. Prod. Commun. 2010, 5, 1349–1354. [Google Scholar] [CrossRef] [PubMed]
  18. Ouedrhiri, W.; Balouiri, M.; Bouhdid, S.; El Harki, H.; Moja, S.; Greche, H. Antioxidant and antibacterial activities of Pelargonium asperum and Ormenis mixta essential oils and their synergistic antibacterial effect. Environ. Sci. Pollut. Res. 2018, 25, 29860–29867. [Google Scholar] [CrossRef]
  19. Babushok, V.I.; Linstrom, P.J.; Zenkevich, I.G. Retention indices for frequently reported compounds of plant essential oils. J. Phys. Chem. Ref. Data 2011, 40, 043101–043147. [Google Scholar] [CrossRef]
  20. Terpenoids Library Website. Available online: https://massfinder.com/wiki/Terpenoids_Library_List (accessed on 14 April 2022).
  21. König, W.A.; Hochmuth, D.H.; Joulain, D. Terpenoids and Related Constituents of Essential Oils; Library of MassFinder 2.1; Institute of Organic Chemistry: Hamburg, Germany, 2001. [Google Scholar]
  22. National Institute of Standards and Technology. PC Version of the Mass Spectral Library; Norwalk: Connecticut, CT, USA, 2014. [Google Scholar]
  23. Adams, R.P. Identification of Essential Oils Components by Gas Chromatography/Mass Spectroscopy, 4th ed.; Allured: Carol Stream, IL, USA, 2007; p. 455. [Google Scholar]
  24. Tomi, F.; Bradesi, P.; Bighelli, A.; Casanova, J. Computer-aided identification of individual components of essential oil using carbon-13 NMR spectroscopy. J. Magn. Reson. Anal. 1995, 1, 25–34. [Google Scholar]
  25. Tomi, F.; Casanova, J. 13C-NMR as a tool for identification of individual components of essential oils from Labiatae—A review. Acta Hortic. 2006, 723, 185–192. [Google Scholar] [CrossRef]
  26. Ouattara, Z.A.; Boti, J.B.; Ahibo, A.C.; Sutour, S.; Casanova, J.; Tomi, F.; Bighelli, A. The key role of 13C NMR analysis in the identification of individual components of Polyalthia longifolia leaf oil. Flavour Fragr. J. 2014, 29, 371–379. [Google Scholar] [CrossRef]
  27. Bazzali, O.; Tran Huy, T.; Tran Minh, H.; Nguyen Sinh, K.; Nguyen Thi, H.; Casanova, J.; Bighelli, A.; Tomi, F. Wood oil from Xanthocyparis vietnamensis Farjon et Hiep. Integrated analysis by chromatographic and spectroscopic techniques. Molecules 2016, 21, 840. [Google Scholar] [CrossRef] [PubMed]
  28. Tomi, F.; Casanova, J. Contribution de la RMN du carbone-13 à l’analyse des huiles essentielles. Ann. Fals. Exp. Chim. 2000, 952, 313–330. [Google Scholar]
  29. Cavalli, J.F.; Tomi, F.; Bernardini, A.F.; Casanova, J. Composition and chemical variability of the bark oil of Cedrelopsis grevei H. Baillon from Madagascar. Flavour Fragr. J. 2003, 18, 532–538. [Google Scholar] [CrossRef]
  30. Binder, R.G.; Turner, C.E.; Flath, R.A. Comparison of yellow star thistle volatiles from different plant parts. J. Agric. Food Chem. 1990, 38, 764–767. [Google Scholar] [CrossRef]
  31. El Hafidi, S.; Bakhy, K.; Ouhssine, M.; Casanova, J.; Tomi, F.; Paoli, M. Essential oil composition of Cladanthus eriolepis (Coss. ex Maire) Oberpr. & Vogt, an endemic species to Morocco. J. Essent. Oil Res. 2021, 33, 369–375. [Google Scholar] [CrossRef]
  32. Blanc, M.-C.; Muselli, A.; Bradesi, P.; Casanova, J. Chemical composition and variability of the essential oil of Inula graveolens from Corsica. Flavour Fragr. J. 2004, 19, 314–319. [Google Scholar] [CrossRef]
  33. Binder, R.G.; Flath, R.A. Volatile components of pineapple guava. J. Agric. Food Chem. 1989, 37, 734–736. [Google Scholar] [CrossRef]
  34. Ashes, J.R.; Haken, J.K. Gas chromatography of homologous esters. IX. Structure-retention increments of unsaturated esters. J. Chromatogr. 1975, 111, 171–187. [Google Scholar] [CrossRef]
  35. Fröhlich, O.; Duque, C.; Schreier, P. Volatile constituents of curuba (Passiflora mollissima) fruit. J. Agric. Food Chem. 1989, 37, 421–425. [Google Scholar] [CrossRef]
  36. Paolini, J.; Muselli, A.; Bernardini, A.-F.; Bighelli, A.; Casanova, J.; Costa, J. Thymol derivatives from essential oil of Doronicum corsicum L. Flavour Fragr. J. 2007, 22, 479–487. [Google Scholar] [CrossRef]
  37. Paolini, J.; Costa, J.; Bernardini, A.F. Analysis of the essential oil from aerial parts of Eupatorium cannabinum subsp. corsicum (L.) by gas chromatography with electron impact and chemical ionization mass spectrometry. J. Chromatogr. A 2005, 1076, 170–178. [Google Scholar] [CrossRef] [PubMed]
  38. Blanc, M.C.; Bradesi, P.; Gonçalves, M.J.; Salgueiro, L.; Casanova, J. Essential oil of Dittrichia viscosa ssp. viscosa: Analysis by 13C-NMR and antimicrobial activity. Flavour Fragr. J. 2006, 21, 324–332. [Google Scholar] [CrossRef]
  39. Ferrari, B.; Tomi, F.; Casanova, J. Composition and chemical variability of Ferula communis essential oil from Corsica. Flavour Fragr. J. 2005, 20, 180–185. [Google Scholar] [CrossRef]
  40. Lesueur, D.; Ninh Khac, B.; Bighelli, A.; Muselli, A.; Casanova, J. Analysis of the root oil of Fokienia hodginsii (Dunn) Henry et Thomas (Cupressaceae) by GC, GC–MS and 13C-NMR. Flavour Fragr. J. 2006, 21, 171–174. [Google Scholar] [CrossRef]
  41. Garcia, G.; Garcia, A.; Gibernau, M.; Bighelli, A.; Tomi, F. Chemical compositions of essential oils of five introduced conifers in Corsica. Nat. Prod. Res. 2017, 31, 1697–1703. [Google Scholar] [CrossRef]
  42. Pino, J.A.; Marbot, R.; Vázquez, C. Characterization of volatile in Costa Rican Guava [Psidium friedrichsthalianum (Berg) Niedenzu] fruit. J. Agric. Food Chem. 2002, 50, 6023–6026. [Google Scholar] [CrossRef]
  43. Werka, J.S.; Boehme, A.K.; Setzer, W.N. Biological activities of essential oils from Monteverde, Costa Rica. Nat. Prod. Commun. 2007, 2, 1215–1219. [Google Scholar] [CrossRef]
  44. Baser, K.H.C.; Demirci, B.; Kirimer, N.; Satil, F.; Tumen, G. The essential oils of Thymus migricus and T. fedtschenkoi var. handelii from Turkey. Flavour Fragr. J. 2002, 17, 41–45. [Google Scholar] [CrossRef]
  45. Bicchi, C.; Fresia, M.; Rubiolo, P.; Monti, D.; Franz, C.; Goehler, I. Constituents of Tagetes lucida Cav. ssp. lucida essential oil. Flavour Fragr. J. 1997, 12, 47–52. [Google Scholar] [CrossRef]
  46. Weyerstahl, P.; Marshall, H.; Thefeld, K.; Rustaiyan, A. Constituents of the essential oil of Tanacetum (syn. Chrysanthemum) fruticulosum Ledeb. from Iran. Flavour Fragr. J. 1999, 14, 112–120. [Google Scholar] [CrossRef]
Compounds 03 00028 g001 550
Figure 1. Cladanthus mixtus (L.) Chevall (Souk Had location).
Figure 1. Cladanthus mixtus (L.) Chevall (Souk Had location).
Compounds 03 00028 g001
Compounds 03 00028 g002 550
Figure 2. Identification of individual compounds using 13C NMR.
Figure 2. Identification of individual compounds using 13C NMR.
Compounds 03 00028 g002
Compounds 03 00028 g003 550
Figure 3. Chromatogram of SS sample (BP-1, non-polar column).
Figure 3. Chromatogram of SS sample (BP-1, non-polar column).
Compounds 03 00028 g003
Compounds 03 00028 g004 550
Figure 4. Structures of 3,6,6,9-bis-epoxy-farnesa-1,7(14),10-triene 44 and its epimers, 3-epi, 9-epi, and 3,9-diepi, and 6,9-epoxy-farnesa-1,7(14),10-trien-3-ol 64 and its epimers, 3-epi, 6-epi, and 3,6-diepi.
Figure 4. Structures of 3,6,6,9-bis-epoxy-farnesa-1,7(14),10-triene 44 and its epimers, 3-epi, 9-epi, and 3,9-diepi, and 6,9-epoxy-farnesa-1,7(14),10-trien-3-ol 64 and its epimers, 3-epi, 6-epi, and 3,6-diepi.
Compounds 03 00028 g004
Compounds 03 00028 g005 550
Figure 5. Part (104–108 ppm) of 13C-NMR spectrum of C. mixtus (C14, Csp2, methylene).
Figure 5. Part (104–108 ppm) of 13C-NMR spectrum of C. mixtus (C14, Csp2, methylene).
Compounds 03 00028 g005
Table
Table 1. Characteristics of localities of harvest.
Table 1. Characteristics of localities of harvest.
Oil SampleLocation of HarvestElevation (m)Longitude/LatitudeDate of Harvest
SHSouk Had14N: 34°51′13.81″6 April 2022
W: 6°39′04.82″
SSAin Chkef forest451N: 33°98′57.60″12 April 2022
Sidi Slimane W: 5°01′84.39″
Table
Table 2. Chemical composition of two oil samples from aerial parts of Moroccan Cladanthus mixtus.
Table 2. Chemical composition of two oil samples from aerial parts of Moroccan Cladanthus mixtus.
N°Components aRIa
Lit b		RIp
Lit b		RIaRIpSH%SS%Identification Mode
13-Methyl-1-pentanol825 c1327 c8291326-0.1RI, MS
2Isobutyl isobutyrate899109590110960.90.1RI, MS, 13C NMR
3α-Thujene 932102592410190.70.8RI, MS, 13C NMR
4α-Pinene9361026932101916.14.6RI, MS, 13C NMR
5Camphene 947106894510660.20.2RI, MS
6Sabinene 973112296711263.21.0RI, MS, 13C NMR
7β-Pinene 978111097211150.50.1RI, MS
8Myrcene 987116198211641.11.3RI, MS, 13C NMR
9Isobutyl 2-methylbutyrate 990 d1183 d99011830.2-RI, MS
10Isobutyl isovalerate992 d1179 d99211790.1-RI, MS
11Isopentyl isobutyrate996 d1195 d99911950.10.1RI, MS
122-Methylbutyl isobutyrate1003 d1201 d100312011.1-RI, MS, 13C NMR
13α-Terpinene1011117810101183-0.1RI, MS
14p-Cymene10151270101312762.20.2RI, MS, 13C NMR
15Limonene10251198102212053.6 *1.0 *RI, MS, 13C NMR
161,8-Cineole 102512111022121520.8 *3.9 *RI, MS, 13C NMR
17Santolina alcohol1019 e1391 e10221404-3.4 *RI, MS, 13C NMR
18Isobutyl angelate 1036 d1293 d103512931.5-RI, MS, 13C NMR
19γ-Terpinene 10511245105012490.30.2RI, MS
20Artemisia alcohol 1071151010701507-0.2RI, MS
21Nonanal1084139110831389-0.1RI, MS
22Linalool 10861544108415500.60.1RI, MS
23Hotrienol 1088160210861611-0.6RI, MS, 13C NMR
242-Methylbutyl 2-methyl butyrate1089 f1279 f109012830.5-RI, MS, 13C NMR
253-Methylpentyl isobutyrate1095 gnd1103nd0.80.2RI, MS
26α-Campholenal1107149611071486-0.1RI, MS
27trans-Pinocarveol11261661112516550.70.4RI, MS, 13C NMR
28Pinocarvone 11401575114215690.20.5RI, MS
29Borneol11531700115217031.81.2RI, MS, 13C NMR
30Terpinen-4-ol11641601116416053.50.5RI, MS, 13C NMR
31α-Terpineol11761694117516992.10.3RI, MS, 13C NMR
32Myrtenol 1182179011801790-0.4RI, MS
33Bornyl acetate 1270158012711583-0.1RI, MS
34(Z)-2-Hexenyl hexanoate1333 h1653 i13271655-0.1RI, MS
35δ-Elemene 1340146913351470-0.5RI, MS, 13C NMR
367α-Silphiperfol-5-ene 1348 j1454 j134714520.4 trRI, MS
37Geranyl acetate 1362175213601742-0.1RI, MS
38Cyclocopacamphene13681483136214830.4 0.6RI, MS
39α-Copaene1375149113751491- 0.3RI, MS
40β-Elemene13881591138915910.4 0.9RI, MS, 13C NMR
41Bornyl isobutyrate 1402 k1641 k14021643-0.1RI, MS
42(E)-β-Caryophyllene 1419159814161595- 0.9RI, MS
43(E)-β-Farnesene 14461664144616670.8 2.2RI, MS, 13C NMR
443,6,6,9-bis-epoxy-Farnesa-1,7(14), 10-triene 1450 l1831 l144918284.3 *5.8 *RI, 13C NMR
459-epi-3,6,6,9-bis-epoxy Farnesa-1,7(14), 10-triene 1450 l1834 l144918310.9 *0.9 *RI, 13C NMR
463,9-di-epi-3,6,6,9-bis-epoxy-Farnesa-1,7(14),10-triene 1458 l1865 l145718670.9 *1.9 *RI, 13C NMR
473 epi-3,6,6,9-bis-epoxy-Farnesa-1,7(14), 10-triene 1458 l1870 l145718682.2 * 1.1 *RI, 13C NMR
48Selina-4,11-diene 1474 m1670 m14701674-0.7RI, MS, 13C NMR
49Germacrene D 14761708147817090.3 4.0RI, MS, 13C NMR
50β-Selinene 1481171714811716-0.4RI, MS
51(Z,E)-α-Farnesene 1481172814861714-0.2RI, MS
52Bicyclogermacrene1490173414901726-0.2RI, MS
53α-Muurolene 14911723149217240.70.5RI, MS, 13C NMR
54(E,E)-α-Farnesene1496174414951749-0.2RI, MS
55γ-Cadinene1506176315051755-0.2RI, MS
56δ-Cadinene 15201756151617570.2 0.6RI, MS, 13C NMR
57β-Elemol1537208815332053-0.7RI, MS
58(E)-Nerolidol15502036155020423.4 13.9RI, MS, 13C NMR
59Spathulenol1566212615632119- 0.7RI, MS
60Caryophyllene oxide15701986157219831.7 0.9RI, MS, 13C NMR
61Fokienol1577 n2170 n157721681.1 2.9RI, MS, 13C NMR
62β-Oplopenone 1593208415882077-0.3RI, MS
63Copaborneol 1600 k2181 k159521761.3 1.0RI, MS, 13C NMR
646,9-epoxy-Farnesa-1,7(14),10-trien-3-ol1601 l2257 l159822542.75.4RI, 13C NMR
653-epi-6,9-epoxy-Farnesa-1,7(14),10-trien-3-ol 1601 l2255 l159822491.14.3RI, 13C NMR
66Junenol 1607 o2055 o16072046-0.6RI, MS
676-epi-6,9-epoxy-Farnesa-1,7(14),10-trien-3-ol 1614l2276 l161022700.92.3RI, 13C NMR
683,6-diepi-6,9-epoxy-Farnesa-1,7(14),10-trien-3-ol 1614 l2284 l161222791.23.3RI, 13C NMR
69epi-γ-Eudesmol 1608210616142107-0.4RI, MS
70γ-Eudesmol1616217616142186-0.5RI, MS
71Alismol 1620 l2295 l161722910.80.4RI, 13C NMR
72Caryophylla-4(12),8(13)-dien-5α-ol1622 l2294 l16192291-0.5RI, MS
73τ-Muurolol16312186162521851.6 1.0RI, MS, 13C NMR
74Torreyol (δ-Cadinol) 1631 p2167 p16292164-0.2RI, MS
75α-Cadinol 1643222716372226-1.1RI, MS, 13C NMR
76α-Bisabolol 1668221316652201-0.8 *RI, MS, 13C NMR
77epi-α-Bisabolol 1674221416652212-0.8 *RI, MS, 13C NMR
78Shyobunol 1687 q1953 r16751940-0.8RI, MS
79Neophytadiene 1827 s1933 s18351936-0.1RI, MS
80(Z)-Phytol2077 t2551 t20962558-0.3RI, MS
81(E)-Phytol2103 t2613 t21062609-0.2RI, MS
Total 90.187.6
a Components are listed following their order of elution on non-polar column BP-1; percentages on non-polar capillary column, except those with * (%) on polar capillary column BP-20). RIa, RIp: Retention indices on non-polar and polar columns, respectively; 13C NMR: compound identified by 13C-NMR, at least in one oil sample; nd: not determined; and tr: traces. b RIa lit, RIp lit: literature retention indices [19] otherwise stated. c [30]; d [31]; e [32]; f [33]; g [20]; h [34]; i [35]; j [36]; k [37]; l [38]; m [39]; n [40]; o [41]; p [42]; q [43]; r [44]; and s [45]. t RIs of pure compounds from Aldrich (Z/E mixture).
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El Hafidi, S.; Bakhy, K.; Ouhssine, M.; Benzakour, A.; Casanova, J.; Paoli, M.; Tomi, F. Integrated Analysis by GC/MS and 13C NMR of Moroccan Cladanthus mixtus Essential Oil; Identification of Uncommon Epoxyfarnesanes. Compounds 2023, 3, 365-375. https://doi.org/10.3390/compounds3020028

AMA Style

El Hafidi S, Bakhy K, Ouhssine M, Benzakour A, Casanova J, Paoli M, Tomi F. Integrated Analysis by GC/MS and 13C NMR of Moroccan Cladanthus mixtus Essential Oil; Identification of Uncommon Epoxyfarnesanes. Compounds. 2023; 3(2):365-375. https://doi.org/10.3390/compounds3020028

Chicago/Turabian Style

El Hafidi, Souad, Khadija Bakhy, Mohammed Ouhssine, Abderrahim Benzakour, Joseph Casanova, Mathieu Paoli, and Félix Tomi. 2023. "Integrated Analysis by GC/MS and 13C NMR of Moroccan Cladanthus mixtus Essential Oil; Identification of Uncommon Epoxyfarnesanes" Compounds 3, no. 2: 365-375. https://doi.org/10.3390/compounds3020028

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