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Article

Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. Essential Oils—Chemical and Enantioselective Analyses of Three Unprecedented Volatile Fractions from the Ecuadorian Biodiversity

by
Yessenia E. Maldonado
1,
María del Carmen Rodríguez
2,
María Emilia Bustamante
2,
Stefanny Cuenca
2,
Omar Malagón
3,
Nixon Cumbicus
4 and
Gianluca Gilardoni
3,*
1
Programa de Doctorado en Química, Universidad Técnica Particular de Loja (UTPL), Calle Paris s/n y Praga, Loja 110107, Ecuador
2
Carrera de Bioquímica y Farmacia, Universidad Técnica Particular de Loja (UTPL), Calle Paris s/n y Praga, Loja 110107, Ecuador
3
Departamento de Química, Universidad Técnica Particular de Loja (UTPL), Calle Paris s/n y Praga, Loja 110107, Ecuador
4
Departamento de Ciencias Biológicas y Agropecuarias, Universidad Técnica Particular de Loja (UTPL), Calle Paris s/n y Praga, Loja 110107, Ecuador
*
Author to whom correspondence should be addressed.
Plants 2025, 14(5), 659; https://doi.org/10.3390/plants14050659
Submission received: 31 January 2025 / Revised: 18 February 2025 / Accepted: 19 February 2025 / Published: 21 February 2025
(This article belongs to the Special Issue Chemical Analysis and Biological Activities of Plant Essential Oils)
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Abstract

:
The present study is the first report on the chemical and enantiomeric compositions of essential oils from the Ecuadorian species Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. All the volatile fractions presented a sesquiterpene-based chemical profile, typical of other volatile fractions from this genus. Both qualitative (GC-MS) and quantitative (GC-FID) chemical analyses were carried out on two stationary phases of different polarity (non-polar and polar). The main constituents of G. hallii essential oil on the two columns, respectively, were α-pinene (33.6–31.5%), (E)-β-caryophyllene (6.2–6.4%), germacrene D (35.7–38.3%), and bicyclogermacrene (3.8–4.0%). In G. calyculisolvens, the major compounds were α-pinene (11.2–11.0%), p-cymene (4.0–3.7%), α-copaene (3.6–3.7%), (E)-β-caryophyllene (8.1–8.3%), germacrene D (20.8–22.0%), and germacrene D-4-ol (8.4–8.6%). Finally, the main components of G. azuayensis were α-pinene (4.5–4.1%), germacrene D (14.1–12.4%), bicyclogermacrene (2.6–3.0%), tridecanal (6.4–6.2%), and spathulenol (7.8–7.1%). Furthermore, enantioselective analyses were conducted on the three volatile fractions, using two stationary phases based on β-cyclodextrins. As a result, twelve chiral components were investigated, detecting both enantiomerically pure compounds and scalemic mixtures with various enantiomeric excess.

1. Introduction

According to the United Nations, Ecuador has been defined as a megadiverse country, whose outstanding biodiversity includes thousands of phytochemically unstudied botanical species [1,2,3]. For this reason, our group has been studying the secondary metabolites of native and endemic Ecuadorian plants for more than twenty years, with the aim of discovering new natural products of pharmaceutical and biochemical interest [4]. In recent years, we have especially focused on the description of unprecedented essential oils (EOs), describing their chemical and enantiomeric compositions, olfactometric profiles, and biological activities [5]. With these premises, an unfunded project about the volatile fractions of genus Gynoxys in southern Ecuador is currently in progress, based on the chemical compositions and enantiomeric profiles of the EOs from this taxon. The focus of this project is strictly academic and chemotaxonomic due to the low distillation yields that usually characterise these EOs. A total of twelve unprecedented species were selected in the Province of Loja, Ecuador: Gynoxys miniphylla Cuatrec., Gynoxys laurifolia (Kunth) Cass., Gynoxys rugulosa Muschl., Gynoxys buxifolia (Kunth) Cass., Gynoxys cuicochensis Cuatrec., Gynoxys sancti-antonii Cuatrec., Gynoxys szyszylowiczii Hieron., Gynoxys reinaldii Cuatrec., Gynoxys pulchella (Kunth) Cass., Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. The first nine species have already been studied and their EOs published, whereas G. hallii, G. calyculisolvens, and G. azuayensis are the object of the present research [6,7,8,9,10,11,12].
Botanically, the genus Gynoxys Cass. (Asteraceae) is an endemic taxon of the Andean region, diffused from Venezuela to Bolivia, with Ecuador being the country with the highest number of collected specimens [13]. Among the Ecuadorian species, G. hallii, G. calyculisolvens, and G. azuayensis have been reported in the Province of Loja. According to the Catalogue of the Vascular Plants of Ecuador, G. hallii is an endemic treelet growing between 2500–3500 m above sea level and described in the provinces of Azuay, Cañar, Carchi, Chimborazo, Cotopaxi, Imbabura, Pichincha, and Tungurahua. In the same source, G. calyculisolvens is a native shrub growing between 2000–3500 m above sea level (m a.s.l.) and occurring in the provinces of Loja and Morona-Santiago. Finally, G. azuayensis is an endemic tree growing in the range 2500–3500 m a.s.l. that has been observed in the provinces of Azuay and Loja [14]. None of these three species are reported with botanical synonyms or relevant traditional use. To the best of the authors’ knowledge, the present study is the first description of EOs obtained from G. hallii, G. calyculisolvens, and G. azuayensis.

2. Results

2.1. Chemical Composition of the EOs

The leaves of G. hallii, G. calyculisolvens, and G. azuayensis afforded, by analytical distillation, three EOs that, respectively, yielded 0.69 ± 0.105%, 0.08 ± 0.008%, and 0.02 ± 0.002% by weight of dry plant material. A total of 169 compounds were identified and quantified on at least one of the two employed columns. The quantified components, separately considered on the non-polar and polar stationary phase, respectively, and expressed as oil mass percent, corresponded to 93.2–92.7% for G. hallii, 94.9–93.8% for G. calyculisolvens, and 94.2–89.3% for G. azuayensis. All the volatile fractions were dominated by sesquiterpenes and sesquiterpenoids that, considered as a whole, corresponded to 56.8–58.5% for G. hallii, 60.7–59.8% for G. calyculisolvens, and 45.9–39.7% for G. azuayensis. In the EO of G. azuayensis, an important heavy aliphatic fraction is also present (about 30%), as typical of other species from this genus. On the other hand, in G. hallii and G. calyculisolvens, this fraction is absent or represented in a very low amount. Finally, a relevant monoterpene fraction, dominated by α-pinene, can also be observed in the three oils, reaching the maximum amount in G. hallii and the minimum value in G. azuayensis. Main constituents of G. hallii EO (≥3.0% on at least one column) were α-pinene (peak 2), (E)-β-caryophyllene (peak 75), germacrene D (peak 89), and bicyclogermacrene (peak 93). In G. calyculisolvens EO, the major compounds were α-pinene (peak 2), p-cymene (peak 15), α-copaene (peak 64), (E)-β-caryophyllene (peak 75), germacrene D (peak 89), and germacrene D-4-ol (peak 108). Finally, the main components of G. azuayensis EO were α-pinene (peak 2), germacrene D (peak 89), bicyclogermacrene (peak 93), tridecanal (peak 101), and spathulenol (peak 109). The detailed qualitative and quantitative compositions of these EOs are reported in Table 1, whereas the gas chromatographic profiles are represented in Figure 1 and Figure 2. The molecular structures of the nine major compounds are represented in Figure 3.

2.2. Enantioselective Analyses of the EOs

The enantioselective analyses of the three EOs permitted to evaluate the enantiomeric excess of a total of 12 enantiomeric pairs, using one of two available chiral selectors, depending on the chromatographic resolution. In this way, (1S,5S)-(−)-α-pinene, (R)-(−)-α-phellandrene, (R)-(−)-β-phellandrene, and (1S,2R,6R,7R,8R)-(+)-α-copaene resulted as enantiomerically pure in all the EOs where they were present. On the other hand, (R)-(−)-terpinen-4-ol and (S)-(−)-germacrene D were enantiomerically pure in G. azuayensis and G. hallii, respectively, but they were part of scalemic mixtures in the other species. Finally, all the others analysed chiral metabolites produced scalemic mixtures in all the volatile fractions where they were detected. The detailed results of the enantioselective analyses are shown in Table 2.

3. Discussion

The chemical composition of these three EOs presented the typical profile of most Gynoxys volatile fractions. Especially in G. azuayensis and, to a lesser extent in G. calyculisolvens, three characteristic groups of metabolites can be observed: a monoterpene fraction dominated by α-pinene (2); a sesquiterpene fraction with germacrene D (89) as the main component; and a heavy aliphatic fraction composed of alkanes and alkenes. Such a profile is very evident in G. rugulosa, G. szyszylowiczii, and G. pulchella but less important in G. laurifolia, G. sancti-antonii, and G. cuicochensis [7,8,10,11]. In the case of G. hallii, the heavy aliphatic fraction is practically absent, which was previously observed in G. miniphylla and G. buxifolia [6,9]. A comparison among the major constituents (≥3.0% in at least one oil) of G. hallii, G. calyculisolvens, and G. azuayensis volatile fractions is represented in Figure 4. It can be observed that α-pinene (2), (E)-β-caryophyllene (75), germacrene D (89), and bicyclogermacrene (93) are common to the three species, this pattern being characteristic of Gynoxys spp. Other compounds are abundant constituents of only one species, such as p-cymene (15) in G. calyculisolvens and tridecanal (101) and spathulenol (109) in G. azuayensis.
For what concerns the enantiomeric compositions of G. hallii, G. calyculisolvens, and G. azuayensis EOs (see Figure 5), three characteristics can be observed that are quite common to other species of this genus. First of all, a similar pattern can be observed for (1S,5S)-(–)-α-pinene and (S)-(–)-germacrene D. These compounds are in fact enantiomerically pure or close to optical purity in the three EOs, confirming a situation already seen before. Secondly, the oxygenated monoterpenoids are present as scalemic mixtures, with a quite low enantiomeric excess that makes their composition relatively close to a racemate. Finally, it can be observed that α-pinene and β-pinene, despite deriving from the common pinyl cation, exhibited a different enantiomeric excess. As a consequence, since the same absolute configuration should be expected for these two monoterpenes, the existence of some enantiospecific reaction could explain the loss of (1R,5R)-(+)-α-pinene [113].
Among the main components of G. hallii, G. calyculisolvens, and G. azuayensis EOs, five compounds were the most representative constituents. In fact, each one of the following metabolites, α-pinene (2), (E)-β-caryophyllene (75), germacrene D (89), germacrene D-4-ol (108), and spathulenol (109), reached at least 7% of the oil mass in at least one species, suggesting a possible relevant contribution to the properties of the corresponding volatile fractions in terms of biological activities.
According to literature, α-pinene (2), one of the most common monoterpenes, exhibited a wide range of biological capacities. For instance, it is known for its antibacterial potential, particularly against methicillin-resistant Staphylococcus aureus (MRSA). It also exhibited antifungal activity and has been found to be more effective than clotrimazole against Candida spp. This monoterpene also displayed anti-inflammatory properties, reducing the expression of inflammatory mediators like TNF-α and IL-1β. Additionally, it has demonstrated neuroprotective effects, enhancing learning and memory function in cases of scopolamine-induced memory deficit. Further studies have revealed its potential as an anticonvulsant and anti-leishmania agent. In addition, there is evidence of different biological activities exhibited by the enantiomers of α-pinene, highlighting the importance of monitoring enantiomeric distributions [114].
(E)-β-Caryophyllene (BCP, 75) is a natural bicyclic sesquiterpene, perhaps the most common sesquiterpene in plants, and has demonstrated a wide range of biological activities. In fact, BCP binds to CB2 cannabinoid receptors and interacts with peroxisome-proliferator-activated receptors (PPARs). Because of these interactions, BCP exhibited anti-inflammatory effects by reducing the production of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, and NF-κB. Additionally, BCP showed neuroprotective activity in models of Alzheimer’s disease, where it decreased NO synthesis and reduced the activation of astrocytes and microglia [115,116].
Germacrene D (89) is another natural sesquiterpene that acts as a key intermediate in the biosynthesis of many other metabolites from the same family. Furthermore, it has been shown to influence the behaviour of moths, for example, increasing attraction and oviposition on mated females of Heliotis virescens. In fact, germacrene D receptor neurons have been identified in the moths Helicoverpa armigera, H. assulta, and H. virescens, where an enantiospecific response for the laevorotatory enantiomer of germacrene D has been demonstrated [117,118].
Germacrene D-4-ol (108) is an oxygenated derivative of germacrene D, and few studies have been reported so far about its biological activities. This sesquiterpenoid is abundant in the leaves of Piper corcovadensis, from which it can be obtained by steam distillation or solvent extraction. Both the isolated compound and the oil exhibited significant larvicidal activity against the mosquito Aedes aegypti, with LC50 values of 18.23 ± 1.19 ppm and 6.71 ± 0.16 ppm, respectively. Additionally, both demonstrated oviposition deterrent activity at various concentrations. Molecular docking analysis suggested that germacrene-D-4-ol exerts its oviposition deterrent effect by interacting with the odorant-binding protein 1 (OBP1) of A. aegypti [119].
Finally, spathulenol (109), a major component of G. hallii EO, must be mentioned. It is a sesquiterpene alcohol quite common in many volatile fractions, but little investigated from the pharmacological point of view. One of the few studies about it dealt on the EO of Psidium guineense (EOPG). A total of 38 compounds were identified, with spathulenol (PG-1) being the most abundant (80.7%). Both EOPG and PG-1 demonstrated antioxidant activity in DPPH, ABTS, and MDA assays. They also exhibited anti-inflammatory effects in mice by significantly inhibiting carrageenan-induced paw oedema, pleural cell migration, and protein exudation. Furthermore, EOPG and PG-1 were evaluated for antiproliferative activity against various cancer cell lines, particularly against OVCAR-3 (ovarian cancer). Furthermore, both EOPG and PG-1 displayed moderate antimycobacterial activity against Mycobacterium tuberculosis [120].
Concerning some possible practical applications and based on this bibliographic information, the three EOs from G. hallii, G. calyculisolvens, and G. azuayensis would be expected to be anti-inflammatory products if their relatively low distillation yields did not prevent a sustainable exploitation of the wild species. Similarly, the high content of the laevorotatory germacrene D would suggest a possible use as insect attractants. On the other hand, in the only case of G. calyculisolvens, the latter property could be associated to a larvicidal capacity due to the presence of germacrene D-4-ol in a relatively high amount. Naturally, the same applications could be suggested for each major compound in its pure form.

4. Materials and Methods

4.1. Plant Materials

The leaves of the three species were gathered in the Province of Loja, Ecuador, within approximately 200 m of the following coordinates: 03°31′22″ S, 79°23′59″ W for G. hallii (elevation: 2810 m), 03°43′11″ S, 79°20′04″ W for G. calyculisolvens (elevation: 3490 m), and 03°59′26″ S, 79°09′39″ W for G. azuayensis (elevation: 2590 m). The botanical identification of the specimens was carried out by one of the authors (N.C.) based on reference samples with barcodes 01826294 (G. hallii), 01826134 (G. calyculisolvens), and 01826026 (G. azuayensis) and preserved at the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Following collection, a voucher for each species was also deposited at the herbarium of Universidad Técnica Particular de Loja, assigned the codes 14678 (G. hallii), 14673 (G. calyculisolvens), and 14816 (G. azuayensis). These collections were conducted in accordance with Ecuadorian law and authorised by the Ministry of Environment, Water, and Ecological Transition of Ecuador (MAATE) under permit code MAATE-DBI-CM-2022-0248.
On the same day they were collected, the plant materials were dried at 35 °C for 48 h and then stored in a cool, dark place until the distillation process.

4.2. Distillation of the EOs

The dry leaves were steam distilled using an analytical method, as described in the literature, with a modified Dean–Stark apparatus [8]. In this procedure, the plant material was distilled for four hours over 2 mL of cyclohexane, containing 1.4 mg of n-nonane as an internal standard. This process was carried out four times for each species, yielding samples in cyclohexane solutions that could be directly injected into the GC. Both n-nonane and cyclohexane were obtained from Merck (Sigma–Aldrich, St. Louis, MO, USA). The weights of dry leaves distilled in each repetition were as follows: 81.5 g, 84.5 g, 84.6 g, and 84.6 g for G. hallii; 100.8 g, 100.7 g, 101.1 g, and 109.7 g for G. calyculisolvens; and 57.8 g, 57.7 g, 46.6 g, and 50.0 g for G. azuayensis. Following distillation, all cyclohexane solutions were permanently stored at −14 °C.

4.3. Qualitative Analyses of the EOs (GC-MS)

The qualitative analyses were carried out using a gas chromatograph (GC) model Trace 1310, supplied by Thermo Fisher Scientific (Waltham, MA, USA). The GC was coupled with a single quadrupole mass spectrometer (MS) model ISQ 7000, also obtained from the same provider. The electron impact ion source was set at 70 eV, with the mass analyser operating in SCAN mode over a mass range of 40–400 m/z. The ion source and quadrupole were heated to 250 °C, while the transfer line and injector were set to 230 °C. The samples were injected in split mode (40:1), introducing 1 μL of cyclohexane solution. Elution was performed according to the following thermal programme: 50 °C for 10 min, followed by an initial temperature gradient of 2 °C/min up to 170 °C and a second gradient of 10 °C/min up to 230 °C, which was maintained for 20 min. The carrier gas used was helium, maintained at a constant flow rate of 1 mL/min (Indura, Guayaquil, Ecuador). All essential oils (EOs) were analysed using two stationary phases with different polarities: one based on 5% phenyl-methylpolysiloxane (TR-5, non-polar) and the other one on polyethylene glycol (TR-WAX, polar). Both columns measured 30 m in length, with an internal diameter of 0.25 mm and a film thickness of 0.25 μm, and were purchased from Thermo Fisher Scientific (Waltham, MA, USA). The EO constituents were identified by comparing their linear retention indices (LRIs) and mass spectra with data available in the literature (see Table 1). The LRIs were calculated according to Van den Dool and Kratz, using a series of n-alkanes ranging from C9 to C26 (Sigma–Aldrich, St. Louis, MO, USA) [121].

4.4. Quantitative Analyses of the EOs (GC-FID)

The quantitative analyses were conducted using the same instrument, columns, thermal programme, carrier gas flow, injector temperature, and injection volumes as those used for the qualitative analyses. However, a flame ionisation detector (FID) was used instead of an MS, and the split ratio was set to 10:1. The components of the essential oils (EOs) were quantified by multiplying each peak area by a relative response factor (RRF), calculated based on combustion enthalpy, as described by Alain Chaintreau [122,123]. The corrected peak areas were then applied, for each column, to a six-point calibration curve, using isopropyl caproate as the calibration standard and n-nonane as the internal standard. The standard dilutions were prepared following the previously described methods in the literature, consistently achieving correlation coefficients greater than 0.998 [124]. The calibration standard was synthesised in the authors’ laboratory and purified to 98.8% (GC-FID).

4.5. Enantioselective Analyses of the EOs

The relative abundance of 12 enantiomeric pairs was determined using GC-MS, employing the same instrument, settings, and injection parameters as in the qualitative analyses, except for the carrier gas flow, which was maintained at a constant pressure of 70 kPa. The separations were performed using two enantioselective capillary columns, incorporating 2,3-diacetyl-6-tert-butyldimethylsilyl-β-cyclodextrin (DAC) and 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin (DET) as chiral selectors, both obtained from Mega (Milan, Italy). Elution was carried out following this thermal gradient: 50 °C for 1 min, followed by a temperature gradient of 2 °C/min up to 220 °C, which was then held for 10 min. The enantiomers were identified based on their mass spectra and by injecting enantiomerically pure standards under the same conditions. The LRIs of the enantiomers were also calculated for both columns according to Van den Dool and Kratz, using the same n-alkane mixture mentioned in Section 4.3. The choice of chiral selectors was based on the quality of separation achieved for each enantiomeric pair.

5. Conclusions

The leaves of Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. produced an EO with a yield by weight of 0.69%, 0.08%, and 0.02%, respectively. On the one hand, the yield of G. hallii was sufficiently high to be consistent with a possible practical application; on the other hand, the three EOs were characterised by the typical chemical profile of many other volatile fractions from this genus. Based on literature, these chemical compositions suggested a possible anti-inflammatory activity as the main biological property. Furthermore, the enantioselective analyses permitted to hypothesise that all these EOs are attractive for the insects of genus Helicoverpa, thanks to the extremely high enantiomeric excess of laevorotatory germacrene D.

Author Contributions

Conceptualisation, G.G.; investigation, Y.E.M., M.d.C.R., M.E.B., S.C. and N.C.; data curation, Y.E.M.; writing—original draft preparation, G.G.; writing—review and editing, O.M.; supervision, G.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The datasets presented in this article are not readily available because they are part of an ongoing study. Requests to access the datasets should be directed to the corresponding author.

Acknowledgments

We are grateful to the Universidad Técnica Particular de Loja (UTPL) for supporting this investigation and open access publication. We are also grateful to Carlo Bicchi (University of Turin, Italy) and Stefano Galli (MEGA S.r.l., Legnano, Italy) for their support with enantioselective columns.

Conflicts of Interest

The authors declare no conflicts of interest.

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Plants 14 00659 g001
Figure 1. Compared GC–MS profiles of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue) EOs on a 5% phenyl methylpolysiloxane stationary phase. The numbers refer to column N in Table 1.
Figure 1. Compared GC–MS profiles of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue) EOs on a 5% phenyl methylpolysiloxane stationary phase. The numbers refer to column N in Table 1.
Plants 14 00659 g001
Plants 14 00659 g002
Figure 2. Compared GC–MS profiles of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue) EOs on a polyethylene glycol stationary phase. The numbers refer to column N in Table 1.
Figure 2. Compared GC–MS profiles of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue) EOs on a polyethylene glycol stationary phase. The numbers refer to column N in Table 1.
Plants 14 00659 g002
Plants 14 00659 g003
Figure 3. Molecular structures of the major compounds whose abundance is ≥3.0% on at least one column in at least one EO. According to Table 1, these molecules are α-pinene (2), p-cymene (15), α-copaene (64), (E)-β-caryophyllene (75), germacrene D (89), bicyclogermacrene (93), tridecanal (101), germacrene D-4-ol (108), and spathulenol (109).
Figure 3. Molecular structures of the major compounds whose abundance is ≥3.0% on at least one column in at least one EO. According to Table 1, these molecules are α-pinene (2), p-cymene (15), α-copaene (64), (E)-β-caryophyllene (75), germacrene D (89), bicyclogermacrene (93), tridecanal (101), germacrene D-4-ol (108), and spathulenol (109).
Plants 14 00659 g003
Plants 14 00659 g004
Figure 4. Compared abundance of major compounds (≥3.0% in at least one oil) in the EOs of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue). Abundances correspond to the mean values of the quantitative results on both columns.
Figure 4. Compared abundance of major compounds (≥3.0% in at least one oil) in the EOs of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue). Abundances correspond to the mean values of the quantitative results on both columns.
Plants 14 00659 g004
Plants 14 00659 g005
Figure 5. Compared enantiomeric composition of some chiral compounds in the EOs of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue).
Figure 5. Compared enantiomeric composition of some chiral compounds in the EOs of G. hallii (black), G. calyculisolvens (red), and G. azuayensis (blue).
Plants 14 00659 g005
Table 1. Qualitative and quantitative compositions of G. hallii, G. calyculisolvens, and G. azuayensis EOs on two stationary phases of different polarity (5% phenyl methylpolysiloxane and polyethylene glycol).
Table 1. Qualitative and quantitative compositions of G. hallii, G. calyculisolvens, and G. azuayensis EOs on two stationary phases of different polarity (5% phenyl methylpolysiloxane and polyethylene glycol).
N.Compounds5% Phenyl Methyl PolysiloxanePolyethylene Glycol
LRIG. halliiG. calyculisolvensG. azuayensisLit.LRIG. halliiG. calyculisolvensG. azuayensisLit.
Calc.Ref.%σ%σ%σCalc.Ref.%σ%σ%σ
1heptanal9109010.10.02----[15]11581158trace-----[16]
2α-pinene93593233.62.3911.22.594.51.42[15]1015101531.52.3811.02.414.11.14[17]
3α-fenchene9489450.10.01----[15]107410730.30.04----[18]
4thuja-2,4(10)-diene953953trace-----[15]---------
5sabinene9769690.70.051.20.101.20.32[15]111311130.70.051.10.071.20.26[19]
6benzaldehyde978978----0.10.04[15]15141516----trace-[20]
7β-pinene9809790.30.020.30.020.20.11[15]11021102o.t.p. 3-0.30.020.10.08[21]
8myrcene9949880.20.020.40.030.60.10[15]115911590.20.010.50.020.50.06[22]
92-pentyl furan9979840.10.020.20.051.40.34[15]122912290.20.030.30.041.40.10[23]
10meta-mentha-1(7),8-diene10031000trace-----[15]---------
11α-phellandrene10071002--0.90.08--[15]11651164--0.70.02--[24]
12(2E,4E)-heptadienal10131005trace---0.60.10[15]14631463trace---o.t.p. 64-[25]
13n-octanal1015998----[15]12851286----0.20.07[23]
14α-terpinene10211014----0.10.03[15]11681167----0.10.01[26]
15p-cymene102710200.10.01----[15]12371237trace-----[27]
16o-cymene10281022--4.00.56--[15]12381234--3.70.42--[28]
17(2E,4Z)-heptadienal10281013----0.60.09[15]14881480----0.60.18[29]
18limonene10331024trace-1.40.060.40.04[15]118711860.10.011.30.040.20.02[30]
19β-phellandrene10311025trace-----[15]11621161trace-----[31]
20(Z)-β-ocimene10421032----0.10.02[15]12321232----0.20.18[32]
21(E)-β-ocimene10521044trace-0.10.011.40.35[15]12471247trace-0.10.011.40.18[33]
22γ-terpinene10601054trace-----[15]12211221trace-----[34]
23benzene acetaldehyde10611062----0.90.09[15]16391639----1.00.18[35]
24(2E)-octen-1-al10721049----0.20.05[15]14211421----0.10.05[36]
25cis-linalool oxide (furanoid)10781067----0.40.09[15]14421445----0.50.02[37]
26terpinolene10861086trace-----[15]12421239trace-----[38]
276-camphenone11041095--0.200.01--[15]1416---0.100.02--§
28linalool11101095--trace-1.30.06[15]15581560--trace-1.10.07[39]
29n-nonanal111611000.30.020.40.030.80.27[15]138913890.20.010.30.040.40.08[40]
30γ-campholene aldehyde113411220.10.02----[15]14351439trace-----[41]
31trans-pinocarveol11471135trace-----[15]---------
32(E)-epoxy-ocimene11481137trace-----[15]---------
33trans-verbenol115411400.10.020.20.03--[15]---------
34eucarvone11661146trace-0.20.02--[15]---------
35(2E)-nonen-1-al11731157--trace-0.20.03[15]15281528--trace-0.20.05[42]
36safranal11761197--trace---[15]---------
37p-mentha-1,5-dien-8-ol11851166----0.10.03[15]17311738----0.20.02[43]
38terpinen-4-ol119011740.10.020.20.020.40.02[15]159915990.50.020.50.140.40.11[44]
39n-dodecane120012000.10.04--0.80.12-12001200----0.90.20-
40myrtenol120411940.10.11----[15]17401747trace-----[45]
41myrtenal12061195--0.30.05--[15]16011601--0.30.02--[46]
42α-terpineol12071207----0.80.10[15]16981700----o.t.p. 93-[47]
43verbenone12091204trace-0.30.06--[15]---------
44n-decanal121712010.10.030.30.021.10.27[15]14931495trace-0.70.060.90.08[48]
45nerol12371227----0.10.01[15]18051808----o.t.p. 101-[49]
46thymol, methyl ether12381232--0.20.2--[15]15431555--0.30.05--[50]
47cumin aldehyde12561238--trace---[15]17261738--trace---[51]
48geranial12621264--0.20.02--[15]17201718--trace---[52]
49geraniol12631249----1.10.06[15]18561856----1.10.12[53]
50(2E)-decanal127512600.10.010.50.020.10.04[15]163516380.40.020.70.030.10.02[54]
51nonanoic acid12931267----0.10.01[15]21892190----0.20.11[55]
52n-tridecane13001300----0.10.02-13001300----0.10.04-
53trans-pinocarvyl acetate13031298--0.10.01--[15]16381641--0.10.03--[56]
54(2E,4Z)-decadienal13091292trace---0.10.02[15]17601759trace---0.20.05[57]
55carvacrol13171315--2.00.03--[58]21862186--2.70.18--[59]
56undecanal13181305----0.40.07[15]16021598----0.50.09[60]
57p-vinylguaiacol132313091.00.322.20.35--[15]218221821.30.251.90.31--[61]
58δ-elemene133013350.10.02----[15]---------
59unidentified (MW = 150)1332-----0.90.04-1801-----0.70.11-
60(2E,4E)-decadienal13341334----[15]18011800----[62]
61α-cubebene13471348trace-0.10.01--[15]141614200.50.03trace---[63]
62neryl acetate13671359--0.30.02--[15]16821680--0.10.01--[49]
63α-ylangene137413730.50.02----[15]144714500.50.05----[64]
64α-copaene13771374--3.60.430.70.17[15]14691471--3.70.420.70.17[65]
65β-bourbonene13841387--0.20.01--[15]14971490--0.20.02--[66]
66α-isocomene13861387----0.10.06[15]15001510----0.20.03[65]
67geranyl acetate13861379--2.80.29--[15]17161713--2.90.25--[50]
68β-cubebene138613870.40.021.00.04--[15]15101508trace-0.80.07--[67]
69β-elemene138913890.20.01--[15]15541559trace-----[68]
70(E)-β-damascenone13891383----1.70.31[15]18081803----o.t.p. 101-[69]
71decanoic acid13911364----[15]22432244----1.60.56[70]
72n-tetradecane14001400trace-0.10.010.60.02-14001400--0.10.010.50.19-
73α-gurjunene140814090.40.020.30.040.20.04[15]15061507--0.30.020.10.01[71]
74methyl eugenol14161403--0.60.05--[15]---------
75(E)-β-caryophyllene141814176.20.278.10.331.20.25[15]155115506.40.208.30.460.70.17[72]
76dodecanal14201408----[15]17001698----o.t.p. 93-[73]
77unidentified (MW = 190)1420------2115-----0.60.10-
78β-duprezianene14211421----[15]2211-----o.t.p. 126-§
79β-copaene14331430--0.20.030.10.01[15]15491550--trace-0.20.04[64]
80allo-aromadendrene144614370.10.010.10.02--[15]--0.30.02----[74]
81α-humulene145214520.70.031.10.071.10.18[15]164316450.80.061.10.011.20.18[75]
82α-guaiene145514530.90.19----[15]158615831.10.05----[76]
839-epi-(E)-caryophyllene14631464----0.20.03[15]16181630----trace-[77]
84cis-cadina-1(6),4-diene14651461--0.20.07--[15]---------
854,5-di-epi-aristolochene146614710.20.05----[15]--o.t.p. 82------
86β-acoradiene147414690.70.16----[15]169116930.20.02----[78]
87trans-cadina-1(6),4-diene14791475--0.30.17--[15]1613---0.50.12--§
88γ-muurolene14801478----0.20.07[15]16651665----0.10.09[79]
89germacrene D1486148035.71.0220.80.6514.12.35[15]1684168438.31.6322.00.2312.41.69[80]
90(E)-β-ionone14901487----1.90.84[15]19251926----1.60.18[81]
91valencene14911496--0.20.02--[15]---------
92α-zingiberene14951493----0.70.14[15]17201721----0.60.22[82]
93bicyclogermacrene150015003.80.111.20.052.60.54[15]170817114.00.1710.033.00.66[83]
94α-muurolene150115000.20.031.20.05--[15]170517000.20.011.10.02--[84]
95β-himachalene15041500trace-----[15]17041704----[85]
96(E,E)-α-farnesene15091505--trace-2.41.03[15]17421745----2.51.01[49]
97germacrene A15111508--trace---[15]17371738--trace---[86]
98γ-cadinene151515130.30.070.50.04--[15]166616660.10.020.50.04--[87]
99δ-amorphene151915111.20.12----[15]170717101.30.12----[88]
100δ-cadinene15221522--2.40.16--[15]17131708--2.00.16--[89]
101tridecanal15221509----6.40.22[15]18101811----6.20.24[60]
102trans-cadina-1,4-diene15351533trace-----[15]---------
103cis-muurol-5-en-4-β-ol15541550--0.10.03--[15]---------
104(E)-nerolidol156515610.10.020.20.08--[15]200320050.10.020.20.02--[73]
105elemicin15651555--1.91.74--[15]22122214--1.50.09--[90]
106unidentified (MW = 220)1577-----0.40.05-1891-----0.20.03-
107β-copaen-4-α-ol15801590--0.20.02--[15]2226---0.10.01--§
108germacrene D-4-ol158115740.50.188.40.49--[15]203720380.60.078.60.43--[91]
109spathulenol158315770.60.14--7.81.26[15]21212121----7.11.08[92]
110unidentified (mw: 220)1591---0.90.28---2074---1.10.11---
111caryophyllene oxide159115820.50.151.80.263.10.16[15]195519550.20.071.80.221.90.16[89]
112unidentified (MW = 220)1595------1984-----0.30.09-
113unidentified (MW = 220)1596------2247-----0.50.16-
114n-hexadecane16001600----o.t.p. 111--16001600----0.20.04-
115guaiol16051600--0.60.06--[15]20542064--0.40.01--[93]
116ledol161016020.40.04----[15]201820160.30.03----[94]
117humulene epoxide II16211608----1.10.07[15]20122024----0.60.10[95]
118tetradecanal16231611----[15]19151919----0.50.04[96]
119junenol16271618trace---0.50.13[15]20282028trace---0.20.06[95]
120unidentified (MW = 220)1629-----1.10.17-2241-----o.t.p. 71--
121himachalol16411652--0.100.04--[15]---------
122allo-aromadendrene epoxide164116390.10.020.10.03--[15]209220950.10.020.10.01--[97]
123epi-α-cadinol165016380.30.050.70.11--[15]212621260.30.040.70.08--[38]
124epi-α-muurolol165216400.50.090.70.120.40.06[15]218121820.90.060.80.100.50.14[98]
125α-muurolol165416440.10.080.40.130.50.12[15]216621650.30.050.40.030.50.14[99]
126α-cadinol166416520.50.181.90.231.20.07[15]22132211o.t.p. 124-1.80.292.00.13[100]
127unidentified (MW = 220)1673-----0.80.17-2067-----0.60.07-
128epi-zizanone167416680.10.02----[15]---------
12914-hydroxy-9-epi-(E)-caryophyllene168416680.5-----[15]2066-0.60.18----§
130khusinol169216790.10.020.40.04--[15]2237---0.40.02--§
131n-heptadecane17001700----0.20.08-17001700----0.10.07-
132amorpha-4,9-dien-2-ol170117000.10.04--0.90.27[15]2263-0.10.03--1.20.16§
133n-pentadecanal17251724--0.50.022.70.07[15]20232020--0.50.042.90.16[31]
134β-acoradienol17421762trace-----[15]---------
135unidentified (MW = 220)1781-----0.80.12-2231-----0.60.19-
136unidentified (MW = 220)1784-----0.50.03-2268-----0.20.05-
137avocadynofuran17841780--0.30.09 [15]---------
1381-octadecene17951789--0.10.01--[15]18351823--0.40.04--[101]
139n-octadecane18001800trace-trace-0.40.11-180018000.10.02trace-0.20.11-
14014-hydroxy-δ-cadinene18051803trace-----[15]---------
141n-hexadecanal183418300.10.020.10.020.80.22[15]21342137----1.10.04[102]
1426,10,14-trimethyl-2-pentadecanone18561855----0.90.08[15]21272125----0.60.06[103]
1431-nonadecene18931895--0.10.01--[15]19361938--0.10.02--[104]
144n-nonadecane19001900trace-0.50.010.20.03-19001900trace-0.80.02trace--
145(5E,9E)-farnesyl acetone19251913----0.90.06[15]2244-----1.10.22§
146n-heptadecanal19351930trace-0.10.011.50.10[15]2219-----1.60.42§
147methyl hexadecanoate19381921----0.20.02[15]21882191----0.40.17[105]
148unidentified (MW = 262)1978-----0.60.07-2235-----trace--
1491-eicosene19961987--0.20.01--[15]20372047--0.40.01--[106]
150n-eicosane20012000--trace-0.10.02-20002000----0.10.06-
151n-octadecanal20342033----0.20.02[15]23592357----0.20.04[107]
152unidentified (MW = 220)2085-----0.60.10-2294-----0.50.30-
1531-heneicosene20932098--0.10.01--[108]21372127--0.20.02--[109]
154unidentified (MW = 294)2096-----1.10.20-2376-----1.70.15-
155n-heneicosane210121000.10.070.40.060.40.01-21002100trace-0.30.020.50.06-
156(Z)-phytol21202114----2.50.53[53]2362-----2.90.90§
157unidentified (MW = 355)2152-----0.40.05-2323-----0.20.10-
1581-docosene21962189--0.20.030.10.01[15]2289-----0.70.02§
159n-docosane22002200--trace-0.10.01-22002200--0.20.020.10.06-
160n-eicosanal22372229----0.10.01[110]25752571----0.20.02[111]
1611-tricosene22952296trace-0.10.03trace-[108]2346-trace---0.50.05§
162n-tricosane23002300--0.50.060.40.03-23002300--0.30.060.10.01-
1631-tetracosene23962396--0.10.041.50.15[108]2467---0.20.020.40.15§
164n-tetracosane24002400--0.10.03-24002400--trace-1.10.17-
165n-docosanal24402434----0.50.25[110]2425-----0.40.05§
1661-pentacosene24962496--0.20.011.00.07[108]24762488--0.20.021.10.27[63]
167n-pentacosane25002500--0.20.011.00.10-25002500--0.30.071.10.19-
1681-hexacosene25962596--0.10.071.40.21[112]2551---0.50.061.60.29§
169n-hexacosane26002600--0.10.07---26002600--0.30.04---
monoterpenes 35.0 19.5 8.5 32.8 18.7 7.8
oxygenated monoterpenoids 0.4 7.0 4.2 0.5 7.0 3.3
sesquiterpenes 52.4 43.9 25.3 55.0 43.4 21.7
oxygenated sesquiterpenoids 4.4 16.8 20.6 3.5 16.4 18.0
others 1.0 7.7 35.6 0.9 8.3 38.5
total 93.2 94.9 94.2 92.7 93.8 89.3
LRI—linear retention index; calc.—calculated LRI; ref.—LRI from literature; lit.—reference literature; %—percent amount by weight; σ—standard deviation; trace—<0.1%; o.t.p.—overlapped to peak; MW—molecular weight; §—identified only by MS. The number and name of major compounds (≥3.0% on at least one column in at least one EO) are written in bold.
Table 2. Enantioselective analyses of G. hallii, G. calyculisolvens, and G. azuayensis EOs on 2,3-diacetyl-6-tert-butyldimethylsilyl-β-cyclodextrin and 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin chiral selectors.
Table 2. Enantioselective analyses of G. hallii, G. calyculisolvens, and G. azuayensis EOs on 2,3-diacetyl-6-tert-butyldimethylsilyl-β-cyclodextrin and 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin chiral selectors.
Chiral SelectorEnantiomersLRIG. halliiG. calyculisolvensG. azuayensis
Distribution (%)ee (%)Distribution (%)ee (%)Distribution (%)ee (%)
DAC(1S,5S)-(–)-α-pinene926100.0100.0100.0100.0100.0100.0
DAC(1R,5R)-(+)-α-pinene928---
DET(1R,5R)-(+)-β-pinene9499.181.99.082.069.939.7
DET(1S,5S)-(–)-β-pinene96090.991.030.1
DET(1R,5R)-(+)-sabinene97721.656.747.55.192.985.9
DET(1S,5S)-(–)-sabinene99278.452.57.1
DET(R)-(–)-α-phellandrene1022--100.0100.0--
DET(S)-(+)-α-phellandrene1025---
DET(R)-(–)-β-phellandrene1052100.0100.0----
DET(S)-(+)-β-phellandrene1063---
DET(S)-(–)-limonene105960.821.694.188.2--
DET(R)-(+)-limonene107539.25.9-
DET(R)-(–) cis-linalool oxide (furanoid)1099----30.838.4
DET(S)-(+) cis-linalool oxide (furanoid)1104--69.2
DET(R)-(–)-linalool1181----48.43.3
DET(S)-(+)-linalool1194--51.6
DET(S)-(−)-α-terpineol1300----39.421.2
DET(R)-(+)-α-terpineol1313--60.6
DET(1R,2S,6S,7S,8S)-(–)-α-copaene1321---100.0-100.0
DET(1S,2R,6R,7R,8R)-(+)-α-copaene1323-100.0100.0
DAC(R)-(–)-terpinen-4-ol133866.733.443.514.0100.0-
DAC(S)-(+)-terpinen-4-ol137533.357.5-
DET(R)-(+)-germacrene D1459-100.03.193.81.197.8
DET(S)-(–)-germacrene D1467100.096.998.9
DAC—2,3-diacetyl-6-tert-butyldimethylsilyl-β-cyclodextrin; DET—2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin; LRI—linear retention index; %—peak area percent; ee—enantiomeric excess.
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MDPI and ACS Style

Maldonado, Y.E.; Rodríguez, M.d.C.; Bustamante, M.E.; Cuenca, S.; Malagón, O.; Cumbicus, N.; Gilardoni, G. Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. Essential Oils—Chemical and Enantioselective Analyses of Three Unprecedented Volatile Fractions from the Ecuadorian Biodiversity. Plants 2025, 14, 659. https://doi.org/10.3390/plants14050659

AMA Style

Maldonado YE, Rodríguez MdC, Bustamante ME, Cuenca S, Malagón O, Cumbicus N, Gilardoni G. Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. Essential Oils—Chemical and Enantioselective Analyses of Three Unprecedented Volatile Fractions from the Ecuadorian Biodiversity. Plants. 2025; 14(5):659. https://doi.org/10.3390/plants14050659

Chicago/Turabian Style

Maldonado, Yessenia E., María del Carmen Rodríguez, María Emilia Bustamante, Stefanny Cuenca, Omar Malagón, Nixon Cumbicus, and Gianluca Gilardoni. 2025. "Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. Essential Oils—Chemical and Enantioselective Analyses of Three Unprecedented Volatile Fractions from the Ecuadorian Biodiversity" Plants 14, no. 5: 659. https://doi.org/10.3390/plants14050659

APA Style

Maldonado, Y. E., Rodríguez, M. d. C., Bustamante, M. E., Cuenca, S., Malagón, O., Cumbicus, N., & Gilardoni, G. (2025). Gynoxys hallii Hieron., Gynoxys calyculisolvens Hieron., and Gynoxys azuayensis Cuatrec. Essential Oils—Chemical and Enantioselective Analyses of Three Unprecedented Volatile Fractions from the Ecuadorian Biodiversity. Plants, 14(5), 659. https://doi.org/10.3390/plants14050659

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