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Article

Comparative Study of the Chemical Composition of the Essential Oil of Plectranthus amboinicus from Different Sectors of Southern Ecuador

by
Susana Blacio
1,
Gabriela Avecillas
1,
Jordy Maldonado
1,
Katty Gadvay
1,
Martha Porras
1,
Wilson León
1 and
James Calva
2,*
1
Facultad de Ciencias Químicas y de la Salud, Universidad Técnica de Machala, Km.5 1/2 Via Machala Pasaje, Machala 070151, Ecuador
2
Departamento de Química, Universidad Técnica Particular de Loja, Calle Paris s/n y Praga, Loja 110107, Ecuador
*
Author to whom correspondence should be addressed.
Horticulturae 2025, 11(2), 173; https://doi.org/10.3390/horticulturae11020173
Submission received: 28 December 2024 / Revised: 28 January 2025 / Accepted: 4 February 2025 / Published: 6 February 2025
(This article belongs to the Special Issue Wild and Cultivated Culinary Plants)
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Abstract

:
The aim of this study was to demonstrate the variability of essential oils (EOs) extracted from the culinary plant Plectranthus amboinicus in different locations, in order to determine their optimal utilization. The EO was extracted from fresh leaves by steam distillation at three locations in the south of Ecuador: Paccha (PAC), El Guabo (GUA), and Arenillas (ARE). Qualitative and quantitative analyses were performed by gas chromatography coupled with mass spectrometry (GC-MS) and flame ionization detection (GC-FID). A total of 41 compounds were identified in Paccha (97.37%), 38 compounds in Arenillas (97.43%), and 41 compounds in El Guabo (98.31%). The most abundant compounds identified were germacrene D (17.60%, 14.59%, and 12.85%), alfa humulene (10.88%, 4.65%, and 5.08%), alfa-terpinene (10.66%, 13.85%, and 6.79%), and carvacrol (5.11%, 5.97%, and 9.13%), in PAC, ARE, and GUA, respectively. In addition, the antioxidant activity was evaluated by ABTS and DPPH assays, as well as the total phenol content of the EOs. Finally, a principal compound analysis (PCA) was performed in order to evaluate the variation in compounds using the geographical location of the samples as a variable.

1. Introduction

In recent years, there has been a growing interest in studying the chemistry and effects of medicinal plants, which promises advances in the field of health [1]. Among the enormous diversity of plants, which includes at least 10,000 species, about 3000 belong to the families Asteraceae, Lamiaceae, and Apiaceae, which are known for their ability to produce essential oils [2].
The genus Plectranthus contains more than 300 species, 62 of which are known to have medicinal, antiseptic, repellent, food, flavouring, and other properties [3]. According to the taxonomy of Plectranthus (or Coleus), it was deduced that the species Plectranthus amboinicus originated in tropical Africa, from where the Arabs and Portuguese introduced it to India and Southeast Asia, and then to Europe and from there to the New World where it was christened ‘Broadleaf Oregano’ [4,5].
P. amboinicus is one of the most popular medicinal plants in Latin America. It belongs to the Lamiaceae family, also known as the mint or dead nettle family [6], which is characterized by generally including herbs, shrubs, and trees with a worldwide distribution. It comprises approximately 200 genera and about 3200 species, with important uses in the treatment of diseases and in culinary uses [7]. In Ecuador, approximately 27 genera and 219 species have been recorded, of which 29 are endemic. The species P. amboinicus grows in warm, dry, and sunny areas, tolerating temperatures between 15 °C and 30 °C, or even lower, down to about 5 °C, and suffers from stress that inhibits its growth [8]. In Ecuador, it is found in the provinces of Pichincha, Azuay, Cañar, Loja, and El Oro. It grows to a height of 0.5 to 1 m and has thick, oval, or round leaves with a characteristic aroma that last between 3 and 10 years. The stems are fleshy and can reach 90 cm [9].
P. amboinicus, also known as Coleus aromaticus, Coleus amboinicus Lour., and Plectranthus aromaticus (Benth.) Roxb. [10] Indian borage [11], French oregano [12], is an herbaceous plant commonly used in Chinese folk medicine for the treatment of cough, fever, mumps, skin disorders, mosquito bites, genito-urinary disorders, musculoskeletal disorders, sore throat, and it also shows the ability to treat arthritis [13,14]. The leaves have been studied for their potential antioxidant, antifungal, antimicrobial, antimutagenic, antitumor, and antigenotoxic activities [15].
Previous research has shown that P. amboinicus has the ability to restore glutathione in diabetic rats, more effectively than vitamin E [16]. It has high antioxidant power (98.88%) and anti-inflammatory activity from 83.37% to 88.66%. In addition, it shows analgesic activity between 90.33% and 80.65% compared to indo-methacin, and antibacterial activity on Gram-positive bacteria, especially oral pathogens such as Streptococcus mutans and Lactobacillus acidophilus, making it a potential use in mouthwashes and toothpastes [17]. Studies on the essential oil of the leaves showed high levels of bioactive compounds including carvacrol, thymol, β-caryophyllene, α-humulene, γ-terpinene, p-cymene, α-terpineol, β-selinene, α-cubebene, eudesma-4-11-diene, 4-terpineol, and caryophyllene oxide [18,19,20]. In addition, phytochemical evaluation of P. amboinicus extract revealed the presence of phenolics such as rosmarinic acid, caffeic acid, rutin, gallic acid, quercetin, and p-coumaric acid, as well as flavonoids and condensed tannins [21].
The aim of this study was to perform a comparative analysis of the chemical composition and biological activity of P. amboinicus EOs from three sectors south of Ecuador. This will enable us to assess the variability in the composition of P. amboinicus EOs in places with different soil and climatic conditions. Furthermore, the results will provide useful information for the design of potential pharmaceuticals and will contribute to a broader understanding of its uses in traditional medicine.

2. Materials and Methods

2.1. Collection of Plant Material

P. amboinicus leaves were collected in three different areas of southern Ecuador during summer season, see Figure 1. The collection was carried out in the canton Paccha (latitude 3°35′16′ S and longitude 79°40′02′ W) on 18 June 2022, at an altitude of 1583 m.a.s.l, where the average temperature was approximately 18 °C, and a relative humidity of 78. In El Guabo (latitude 3°13′35′ S and longitude 79°49′40′ W), on 4 June 2022, at an altitude of 15 m.a.s.l., the weather was characterized by a higher average temperature of 25 °C, and a relative humidity of 85%, Finally, in Arenillas (latitude 2°57′52′ S and longitude 79°44′29′ W) on 11 July 2022, at an altitude of 55 m.a.s.l, the average temperature was 28 °C, with a relative humidity of 75%. These environmental data, including temperature, humidity, and climatic conditions, were retrieved from the NASA POWER (Prediction of Worldwide Energy Resources) database https://power.larc.nasa.gov/ (accessed on 25 January 2025), providing reliable and site-specific meteorological information that contextualizes the ecosystems where the plant material was collected [22].

2.2. Extraction of Essential Oils

Leaves of P. amboinicus from the three sectors, were subjected to steam distillation for 2 h in a Clevenger apparatus from 7400 g of the sample from El Guabo 8300 g from Arenillas, and 6850 g from Paccha. The leaves were cut into small pieces to release more volatile compounds and distilled immediately. The EO was dried over Na2SO4 to remove moisture and stored at −7 °C until use.

2.3. Chemical Composition

2.3.1. GC-MS Analysis

The chemical analysis of the EOs was performed by gas chromatography (GC-MS) using a Thermo Scientific gas chromatograph Trace 1310 (Thermo Scientific, Wan-than, MA, USA) with electrical pressure control. The instrument was coupled to an ISQ 7000 single quadrupole mass spectrometry detector. A non-polar 5% phenyl-methylpolysiloxane-based DB-5ms column (30 m × 0.25 mm internal diameter and 0.25 mm layer thickness) was used. The column temperature was programmed starting at 50 °C for 3 min followed by a rate of 3 °C/min to a final temperature of 230 °C. The column temperature was then increased to 350 °C. Helio was used as the carrier gas at a flow rate of 1 μL/min from a nominal initial pressure of 6.49 psi and an average pressure of 35 cm/s. Injection was also performed in triplicate in split mode (50:1) [23].
The identification results were compared with the mass spectra and the calculated linear retention index (LRI) reported in the literature, with a value acceptable of ±20 units. The calculated linear retention indices (LRI) were obtained using the method of Van Den Dool and Kratz [24] and a mixture of n-alkanes (C10-C25) injected under the same chromatographic conditions as the EOs.

2.3.2. GC-FID Analysis

The GC-FID was performed with the same equipment used GC-MS analysis and the chromatographic analytical gas-chromatographic conditions were the same as described previously.

2.4. Antioxidant Analysis

2.4.1. ABTS Radical Method

The ABTS (2,2′-azinobis-3-ethylbenzothiazoline-6-sulphonic acid) assay was performed according to the method described by Thaipong [25] with minor modifications. The working solution was prepared using 40 µL of ABTS per millilitre of methanol. The absorbance was adjusted to 1.1 ± 0.02 and 270 µL working solution and 30 µL methanol were added to a multiwell plate and measured at 734 nm. Each sample was read in triplicate by adding 270 µL of ABTS working solution and 30 µL of each sample to be analyzed at the appropriate doses for the assay. Reaction kinetics were then measured in a BIOTEK Epoch2 microplate reader at 734 nm for 1 h in the dark at room temperature.

2.4.2. DPPH Radical Method

The DPPH (2,2-diphenyl-1-picrylhydrazyl) method was developed based on the method of Thaipong [25]. The blank was read in triplicate by adding 300 µL of methanol to each well. The working solution was prepared by adding 250 µL of DPPH (625 M) per millilitre of methanol. The absorbance was adjusted to 1.1 ± 0.02. Then, 270 µL of the working solution and 30 µL of methanol were added to a multiwell plate and measured at 515 nm. Samples were analyzed in triplicate with 270 µL of DPPH working solution and 30 µL of each sample to be analyzed. Reaction kinetics were determined at an absorbance of 515 nm in an Epoch2 microplate reader for 1 h in the dark at 25 °C.

2.4.3. Total Phenolic Content

The determination of total phenols was performed according to the procedure described by Thaipong [25] with modifications for reading in 96-well microplates and a final volume of 300 µL. The blank was read in triplicate. For each well, 255 µL of ultrapure water, 15 µL of Folin’s 0.25 N reagent solution, and 30 µL of 1 N sodium carbonate solution were prepared. The mixture was homogenized, and the reaction was carried out in an Epoch2 microplate reader for 2 h in the dark at 22 °C. Absorbance was read at 756 nm.

3. Results

3.1. Physical Properties of Essential Oils

The essential oil from the three different sectors showed yields ranging from 0.02 to 0.04%, as well as insignificant relative density and refractive index. These data are shown in Table 1. It is important to note that the samples collected had a slightly greenish appearance.

3.2. Chemical Composition of Plectrancthus amboinicus Essential Oils

The chemical analysis of P. amboinicus EOs from the three sectors is presented in Table 2, Figure 2. In total, 56 compounds were identified in the steam distillation of the three essential oils (EO) from the aerial parts of P. amboinicus. In Paccha 41 compounds were identified, representing 97.16% of the total, the main components (>3%) were as follows: Germacrene D (17.60%), γ-terpinene (11.25%), α-terpinene (10.66%), o-cymene (6.00%), carvacrol (5.11%), and (E)-caryophyllene (3.73%). In El Guabo, 39 compounds were identified, representing 97.43% of the total, the majority compounds (>5%) were as follows: germacrene D (14.59%), α-terpinene (13.85%), γ-terpinene (13.46%), carvacrol (5.97%), (E)-β-ocimene (5.88%), and ο-cymene (5.72%). Finally, in Arenillas 41 compounds were identified, representing 98.31% of the total, the main compounds (>6%) were as follows: γ-terpinene (15.52%), germacrene D (12.85%), carvacrol (9.13%), ο-cymene (8.17%), α-terpinene (6.79%), and (E)-caryophyllene (6.72%).

3.3. Principal Component Analysis

Principal Component Analysis (PCA) was used to determine the correlation between the main compounds and the concentration of each sample of EOs from the different areas from south of Ecuador. The rotated component plot shows the similarity of the metabolites between the three samples of P. amboinicus EOs (Figure 3).
The PCA of the chemical composition of aerial parts showed different compounds found in the different collection sites. After the PCA, it was possible to determine the dispersion of the chemical composition obtained after chromatographic analysis on the DB-5ms column. The first component accounted for 56.7% with carvacrol, o-cymene, β-copaene, α-terpinene, among others, while the second component accounted for 43.3% of the variance, characterized by the compounds α-humulene, δ-cadinene, germacrene D, among others. In terms of similarity, the sectors of El Guabo and Arenillas showed greater variability than Paccha.

3.4. Antioxidant Activity

The EOs were tested for antioxidant activity using ABTS and DPPH radicals. Trolox was used as a positive control. The results obtained are shown below in Figure 4.

3.4.1. ABTS Radical Uptake

From the Trolox calibration curve with a correlation coefficient of R2 = 0.9995, an SC50 value of 29.09 µM was obtained, as shown in Figure 5. The graphs obtained for each sample analyzed by the ABTS test, where the concentration of the samples tested is plotted as a logarithmic function on the X-axis and the standardized response obtained from the absorbances recorded at the end of the monitoring is plotted on the Y-axis.

3.4.2. DPPH Radical Uptake

Results are expressed as the mean ± standard deviation of three replicates with three experiments (n = 9) and the Coefficient of Variation (CV) is expressed as a percentage, see Figure 6.
Following an analysis of the calibration curve using the Trolox correlation coefficient (R2 = 0.9971), an SC50 of 35.54 µM was determined.

3.4.3. Determination of Total Phenolics

Total Phenolic content was performed, and the results are shown in Figure 7. The absorbances obtained for each dilution of the essential oils in the presence of Folin’s reagent 0.25 N, and the results are expressed in mg/L.

4. Discussion

EO was obtained by steam distillation of fresh samples of P. amboinicuos collected at three different sites in southern Ecuador. The average (w/w) yields were 0.036%, 0.049%, and 0.025% in Paccha, El Guabo, and Arenillas, respectively. In a study by Pino [27], P. amboinicus showed a yield of 0.55% (w/w) of EOs by steam distillation, while other publications reported yields of 0.05 and 0.078% by hydrodistillation and microwave-assisted hydrodistillation, respectively [28].
Chemical analysis by GC-MS and GC-FID identified a total of in Paccha 41 components representing 97.37% of the total of Eos, 39 compounds in El Guabo corresponding at 97.43%, and 41 compounds in Arenillas corresponding to 98.31%. The results indicated that the EOs consisted mainly by sesquiterpenes and monoterpenes hydrocarbons and the majority of chemical compounds included γ-terpinene, followed by germacrene D, α-terpinene, carvacrol, and ο-cymene. Slightly different chemical composition was reported in previous research on the same species in Magdalena, Colombia with thymol (49.7%) and p-cymene (13.2%) as the main compounds [12]. Other similar study in Colombia and India, where carvacrol (64.55% and 28.65%) and thymol (10.11% and 21.66%) followed by p-cymene (13.2% and 6.46%) and γ-terpinene (12.8% and 7.76%) [28,29]. A similar composition was determined in the Comaras Islands reported at carvacrol (23.0%), camphor (22.2%), δ-3-carene (15.0%), λ-terpinene (8.4%), o-cymene (7.7%), and α-terpinene (4.8%) as majority components [30].
Although the composition of the genus Plectranthus is not well defined, most species are composed of mono- and sesquiterpenes. For example, the EO of the species P.rugosus [31] showed a lower amount of monoterpenes among which p-cymene (3.2%), γ-terpinene (2.0%), α-terpineol (1.2%), limonene (1.0%), sesquiterpenes such as germacrene-D (9.7%), β-caryophyllene (7.6%), ar-curcumene (5.0%), (E)-β-farnesene (1.0%), humulene (0.2%), β-elemene (0.1%), and oxygenated sesquiterpenes such as α-bisabolol (41.9%), α-cadinol (3.2%), T-muurolol (2.5%), germacrene D-4-ol (0.6%), and spathulenol (0.5%) [32,33]. In contrast, compounds such as thymol (68.5%), terpinolene (5.3%), β-selinene (4.7%), β-caryophyllene (4.0%), δ-cadinol (2.1%), and ar-curcumene (1.7%) were identified in P. cylindraceus EO [34].
EO from Paccha showed poor antioxidant activity for DPPH and ABTS, with a DPPH SC50 of 1688.67 ± 1.03 µg/mL and an ABTS SC50 activity of 19.65 ± 1.02 µM. Similarly, the El Guabo EO showed zero DPPH removal with an SC50 of 1508.33 ± 1.02 µg/mL and a moderate ABTS activity SC50 of 21.03 ± 1.01 µM. Finally, the antioxidant activity reported for Arenillas EO was higher, with a DPPH SC50 of 816.57 ± 1.02 µg/mL and a positive result for ABTS activity SC50 24.15 ± 1.02 µM. Although P. amboinicus is known for its strong antioxidant activity, a study on P. amboinicus leaf extract in ethanol determined a considerably good DPPH (IC50 271.82 ± 29.23 µg/mL) [35]. In contrast, another study determined an IC50 of 500 µg/mL and a value of ABTS of IC50 750 µg/mL [36]. Furthermore, according to studies, the highest antioxidant activity was obtained in ethyl acetate (3085.8 ± 2.53 µM AAE/g extract) and acetone (3020.55 ± 0.18 µM AAE/g extract) [11]. Vijayanand et al. (2023) compared the antioxidant potential of stem and leaf extracts of P. amboinicus using methanolic extracts. They found that the methanolic stem extract showed higher antioxidant activity compared to the fresh and dried leaf extracts [37]. In another study, the antioxidant activity in EO at different doses and found a significant and stable antioxidant activity with values between 5.25% to 8.25% [38]. Our result showed that the antioxidant and free radical scavenging activities of P. amboinicus vary significantly across different locations and altitudes, which could be attributed to changes in the active components present in the plant [39,40].
Finally, the total phenolic content of the EOs was evaluated, the following values were obtained: 428.76 ± 13.27 mg GAE/L in El Guabo, 601.25 ± 14.88 mg GAE/L in Paccha, and 383.36 ± 14.10 mg GAE/L in Arenillas. Previous studies have determined a maximum concentration of 11.6 mg GAE/g dry matter using P. amboinicus leaves in different solvents such as petroleum ether, ethanol, and chloroform by cold maceration [41]. However, research by Koztowska [42] reported an average concentration of 146.77 mg GAE/g using leaves in 70% ethanol, probably this activity may be related to the compound carvacrol, one of the main compounds of our EO.
Principal Component Analysis (PCA) was used to understand the similarity between the essential oils in terms of the content of their chemical constituents [43]. The Principal Components Analysis (PCA) showed a better similarity in the composition of the EOs from El Guabo and Arenillas, which was slightly different from those from Paccha. These data may be related to volatile contributors during the flowering (pollination) and vegetative phases, the response of the species to pathogens or herbivores, as well as environmental variations [44].
This study examined the chemical composition, antioxidant capacity, and phenol content of P. amboinicus in three different sectors was reported, it provides valuable insight into how variations in temperature, harvesting time, and damage to the physical structure affect the chemical composition of the plant. This information is essential for evaluating the therapeutic properties and identifying potential alternatives that ensure a reliable supply chain, while minimizing health and environmental risks.

5. Conclusions

The comparative study of the essential oils obtained from the fresh leaves of Plectranthus amboinicus by steam distillation, showed that the chemical composition of the different EOs was slightly different depending on the sector of collection. The majority of components included germacrene D (17.60%, 14.59%, and 12.85%), α-humulene (10.88%, 4.65%, and 5.08%), α-terpinene (10.66%, 13.85%, and 6.79%) and carvacrol (5.11%, 5.97%, and 9.13%), in Pacha, Arenillas, and El Guabo, respectively. In addition, antioxidant activity analysis revealed moderate to strong ABTS+ radical scavenging activity and high DPPH values. A high content of total phenolics (>300 mg/L) was also found. The differences in the chemotype and biological activity of EOs can be attributed to environmental factors such as altitude, soil type, temperature, precipitation amount and sun exposure, its known that this factors directly influence the secondary metabolism of plants. The PCA and the subsequent analyses of the Clusters, based on the different chemical classes, represent a useful tool towards a complete taxonomic investigation, also leading to an understanding of the diversification of the genus Plectranthus.

Author Contributions

Conceptualization, S.B. and J.C.; methodology, G.A. and J.M.; formal analysis, J.C.; investigation, K.G., M.P. and W.L.; writing—original draft preparation, S.B.; writing—review and editing, J.C. All authors have read and agreed to the published version of the manuscript.

Funding

The APC was funded by Universidad Técnica de Machala, El Oro, Ecuador.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in the study are included in the article. Further inquiries can be directed to the corresponding author.

Acknowledgments

Authors would like to thank the Universidad Técnica de Machala for funding this open access publication.

Conflicts of Interest

The authors declare no conflicts of interest.

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Horticulturae 11 00173 g001
Figure 1. (a) Plectranthus amboinicus species. (b) Map of the leaf collection of Plectranthus amboinicus in the three sectors from south of Ecuador.
Figure 1. (a) Plectranthus amboinicus species. (b) Map of the leaf collection of Plectranthus amboinicus in the three sectors from south of Ecuador.
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Horticulturae 11 00173 g002
Figure 2. Gas chromatogram of Plectranthus amboinicus leaves EOs from (a) Paccha, (b) El Guabo, and (c) Arenillas using DB-5ms column.
Figure 2. Gas chromatogram of Plectranthus amboinicus leaves EOs from (a) Paccha, (b) El Guabo, and (c) Arenillas using DB-5ms column.
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Horticulturae 11 00173 g003
Figure 3. PCA of (GC−MS) P. amboinicus essential oil from different sectors from south of Ecuador.
Figure 3. PCA of (GC−MS) P. amboinicus essential oil from different sectors from south of Ecuador.
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Horticulturae 11 00173 g004
Figure 4. Antioxidant activity of Plectrancthus amboinicus essential oils from three different locations. SC50; Clearance capacity of half expressed as µg/mL-µM.
Figure 4. Antioxidant activity of Plectrancthus amboinicus essential oils from three different locations. SC50; Clearance capacity of half expressed as µg/mL-µM.
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Horticulturae 11 00173 g005
Figure 5. Calibration curve of ABTS analysis of P. amboinicus essential oils obtained by steam distillation from (a) Paccha, (b) El Guabo, and (c) Arenillas.
Figure 5. Calibration curve of ABTS analysis of P. amboinicus essential oils obtained by steam distillation from (a) Paccha, (b) El Guabo, and (c) Arenillas.
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Horticulturae 11 00173 g006
Figure 6. Calibration curve of the DPPH analysis of P. amboinicus essential oils obtained by steam distillation from (a) Paccha, (b) El Guabo, and (c) Arenillas.
Figure 6. Calibration curve of the DPPH analysis of P. amboinicus essential oils obtained by steam distillation from (a) Paccha, (b) El Guabo, and (c) Arenillas.
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Horticulturae 11 00173 g007
Figure 7. Total phenol content from Plectrancthus amboinicus essential oils from three locations.
Figure 7. Total phenol content from Plectrancthus amboinicus essential oils from three locations.
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Table 1. Physical properties of three different samples of Plectranthus amboinicus collected from three locations.
Table 1. Physical properties of three different samples of Plectranthus amboinicus collected from three locations.
Location%
(v/w)		RD
(g/mL)		RI
Paccha0.03650.91671.4896
El Guabo0.04920.91331.4916
Arenillas0.02250.92431.4828
%: Yield; RD: Relative Density; RI: Refractive index.
Table 2. Chemical composition of Plectranthus amboinicus essential oil from aerial parts collected at South of Ecuador.
Table 2. Chemical composition of Plectranthus amboinicus essential oil from aerial parts collected at South of Ecuador.
N°CompoundLRIcalc aLRIref bCollection Location
PacchaGuaboArenillas
% ± SD% ± SD% ± SD
1α-thujene9259240.27 ± 0.010.27 ± 0.050.24 ± 0.09
2α-pinene934932n.d.0.20 ± 0.10n.d.
33-octanone986979n.d.0.45 ± 0.03n.d.
4myrcene9919881.55 ± 0.00n.d.0.70 ± 0.05
5δ-3-carene101010080.32 ± 0.02n.d.0.29 ± 0.10
6α-terpinene1021101410.66 ± 0.0113.85 ± 0.036.79 ± 0.05
7ο-cymene103310226.00 ± 0.085.72 ± 0.148.17 ± 0.00
8limonene103210290.31 ± 0.00n.d.0.28 ± 0.03
9β-phellandrene103510250.39 ± 0.030.31 ± 0.050.35 ± 0.05
10(Z)-β-ocimene103810320.27 ± 0.010.26 ± 0.110.24 ± 0.11
11(E)-β-ocimene104910441.67 ± 0.015.88 ± 0.113.99 ± 0.02
12γ-terpinene1061105411.25 ± 0.0713.46 ± 0.0515.52 ± 0.08
13trans-sabinene hydrate110610980.40 ± 0.02n.d.0.36 ± 0.00
14linalool11071095n.d.1.23 ± 0.06n.d.
15terpinen-4-ol11891174n.d.0.21 ± 0.05n.d.
16carvacrol131412985.11 ± 0.035.97 ± 0.049.13 ± 0.07
17α-ylangene137913732.46 ± 0.06n.d.4.46 ± 0.00
18α-copaene13801374n.d.3.36 ± 0.09n.d.
19β-bourbonene138713870.27 ± 0.07n.d.0.24 ± 0.02
20β-cubebene139113870.33 ± 0.010.32 ± 0.030.30 ± 0.05
21β-elemene139313890.50 ± 0.000.60 ± 0.020.45 ± 0.00
22α-gurjunene141014090.47 ± 0.040.43 ± 0.000.42 ± 0.03
23(E)-caryophyllene142514173.73 ± 0.014.45 ± 0.046.72 ± 0.09
24β-copaene143714302.33 ± 0.050.21 ± 0.103.2 ± 0.00
25α-humulene1463145210.88 ± 0.044.65 ± 0.005.08 ± 0.03
26trans-cadina-1(6).4-diene148214750.17 ± 0.09n.d.0.15 ± 0.05
2710-epi-β-acoradiene14831474n.d.1.47 ± 0.00n.d.
28germacrene D1485148017.60 ± 0.0114.59 ± 0.0512.85 ± 0.03
29β-selinene149714890.24 ± 0.060.20 ± 0.070.22 ± 0.01
30trans-muurola-4(14).5-diene149914930.20 ± 0.08n.d.0.18 ± 0.17
31α-zingiberene15001493n.d.0.84 ± 0.07n.d.
32bicyclogermacrene150315001.45 ± 0.024.51 ± 0.001.31 ± 0.08
33α-muurolene150615000.52 ± 0.090.28 ± 0.100.47 ± 0.11
34β-curcumene15161514n.d.0.59 ± 0.09n.d.
35not identified1523 n.d.0.23 ± 0.03n.d.
36not identified1523 0.32 ± 0.08n.d.0.29 ± 0.14
37δ-cadinene152615227.72 ± 0.023.34 ± 0.055.31 ± 0.00
3810-epi-cubebol153315330.18 ± 0.01n.d.0.16 ± 0.05
39(Z)-nerolidol153615310.19 ± 0.05n.d.0.17 ± 0.03
40(E)-nerolidol15701561n.d.1.83 ± 0.05n.d.
41germacrene D-4-ol158915741.21 ± 0.081.56 ± 0.101.09 ± 0.05
42spathulenol15911577n.d.0.01 ± 0.03n.d.
43caryophyllene oxide159215820.64 ± 0.10n.d.0.58 ± 0.14
44viridiflorol15991592n.d.0.22 ± 0.03n.d.
45β-oplopenone161916070.16 ± 0.01n.d.0.14 ± 0.22
46cis-cadin-4-en-7-ol164314350.21 ± 0.00n.d.0.19 ± 0.02
47not identified1658 0.26 ± 0.010.37 ± 0.030.23 ± 0.02
48not identified1659 n.d.0.67 ± 0.00n.d.
49α-cadinol166116561.60 ± 0.03n.d.1.44 ± 0.02
505-neo-cedranol16731684n.d.1.35 ± 0.05n.d.
518-cedren-13-ol167316844.16 ± 0.05n.d.2.89 ± 0.07
52not identified169816880.43 ± 0.09n.d.0.39 ± 0.02
53not identified1699 n.d.0.40 ± 0.05n.d.
54shyobunol170716881.95 ± 0.004.65 ± 0.023.52 ± 0.00
55not identified1732 0.84 ± 0.010.68 ± 0.030.76 ± 0.11
5614-hydroxy-α-muurolene178617790.79 ± 0.080.37 ± 0.020.71 ± 0.01
Total identified (%) 97.3797.4398.31
Monoterpene hydrocarbons (%) 32.6972.2436.93
Oxygenated monoterpenoids (%) 5.514.219.13
Sesquiterpene hydrocarbons (%) 48.878.0041.36
Oxygenated sesquiterpenes (%) 10.39.9910.89
Others (%) 1.850.661.67
LRIcal a: linear (arithmetic) calculated retention index; LRIref b: linear (arithmetic) retention index according to Adams [26]; % ± SD: area percentage and standard deviation of triplicate injections; n.d.: not detectable.
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Blacio, S.; Avecillas, G.; Maldonado, J.; Gadvay, K.; Porras, M.; León, W.; Calva, J. Comparative Study of the Chemical Composition of the Essential Oil of Plectranthus amboinicus from Different Sectors of Southern Ecuador. Horticulturae 2025, 11, 173. https://doi.org/10.3390/horticulturae11020173

AMA Style

Blacio S, Avecillas G, Maldonado J, Gadvay K, Porras M, León W, Calva J. Comparative Study of the Chemical Composition of the Essential Oil of Plectranthus amboinicus from Different Sectors of Southern Ecuador. Horticulturae. 2025; 11(2):173. https://doi.org/10.3390/horticulturae11020173

Chicago/Turabian Style

Blacio, Susana, Gabriela Avecillas, Jordy Maldonado, Katty Gadvay, Martha Porras, Wilson León, and James Calva. 2025. "Comparative Study of the Chemical Composition of the Essential Oil of Plectranthus amboinicus from Different Sectors of Southern Ecuador" Horticulturae 11, no. 2: 173. https://doi.org/10.3390/horticulturae11020173

APA Style

Blacio, S., Avecillas, G., Maldonado, J., Gadvay, K., Porras, M., León, W., & Calva, J. (2025). Comparative Study of the Chemical Composition of the Essential Oil of Plectranthus amboinicus from Different Sectors of Southern Ecuador. Horticulturae, 11(2), 173. https://doi.org/10.3390/horticulturae11020173

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