Progress in Essential Oils:Thymol-rich Thymus vulgaris oils – Part 2

thyme

For part one of this column, click here.

Omidbaigi et al. (2008) analyzed oils produced from T. vulgaris grown in Iran. Oils produced in the laboratory by hydrodistillation of plants harvested from different ontogenetic (development) stages were analyzed by GC-FID and GC/MS (see T-2 for the results of this study).

Golmakani and Rezaei (2008) compared the composition of oils produced from the fresh aerial parts of T. vulgaris grown in Karaj assisted (northern Iran), by microwave-hydrodistillation and hydrodistillation. The oils, which were analyzed using GC/MS only, were found to be similar in composition. The composite results of the two analyses can be seen as follows:

α-thujene (0.5–0.6%)

α-pinene (0.9–1.0%)

camphene (0.5–0.6%)

1-octen-3-ol (2.6–2.7%)

myrcene (1.3–1.4%)

3-octanol (0.2%)

α-phellandrene (0.2%)

δ-3-carene (0.1%)

α-terpinene (1.7–1.9%)

p-cymene (16.9–17.6%)

1,8-cineole (1.3–1.4%)

γ-terpinene (8.5–9.1%)

cis-sabinene hydrate (0.9–1.1%)

terpinolene (0.3%)

linalool (2.4–2.5%)

borneol (1.1–1.2%)

isoborneol (1.4–1.9%)

terpinen-4-ol (0.6–0.7%)

α-terpineol (0.2–0.3%)

methyl thymol (0.1–0.2%)

geraniol (0.3–0.4%)

thymol (37.2–40.2%)

carvacrol (6.8%)

thymol acetate (0.1–0.2%)

β-caryophyllene (2.9–3.1%)

α-humulene (0.6%)

geranyl acetate (0.4%)

δ-cadinene (0.4%)

caryophyllene oxide (1.3–1.4%)

Thymus vulgaris plants that were collected from a cultivation site in Guadalajara (Spain) were subjected to hydrodistillation after drying and grinding. The oil yield was found to vary from 0.6–2.5% depending upon the harvest time. Analysis of the bulked oils using GC-FID and GC/MS by Arraiza et al. (2009) revealed that the following constituents were identified:

α-thujene (0.6%)

α-pinene (0.1%)

camphene (0.3%)

β-pinene (0.2%)

myrcene (0.7%)

α-terpinene (0.5%)

p-cymene (27.8%)

limonene (0.4%)

1,8-cineole (1.1%)

γ-terpinene (13.1%)

cis-sabinene hydrate (0.4%)

linalool (1.8%)

camphor (0.6%)

borneol (0.8%)

terpinen-4-ol (0.6%)

α-terpineol (0.1%)

methyl carvacrol (1.2%)

thymol (36.3%)

carvacrol (2.0%)

β-caryophyllene (0.6%)

α-amorphene (0.3%)

γ-cadinene (0.1%)

δ-cadinene (0.3%)

caryophyllene oxide (1.6%)

viridiflorol (0.4%)

γ-eudesmol (0.1%)

Thyme herbs grown in an experimental farm in Haistep (Cairo, Egypt) were subjected to a range of chemical and organic fertilizer treatments by Edris et al. (2009). Oils produced from the plants harvested at two different times were analyzed by GC-FID and GC/MS. The constituents of these oils were found to vary, irrespective of their fertilizer treatments, in the following way:

α-thujene (0.3–1.3%)

α-pinene (0.2–0.8%)

camphene (0.2–0.6%)

sabinene (0.1%)

3-octanol (0.6–1.5%)

β-pinene (0.1–0.4%)

myrcene (1.0–2.4%)

α-phellandrene (0.1–0.3%)

α-terpinene (0.7–1.3%)

p-cymene (14.8–31.7%)

limonene (0.3–0.7%)

(Z)-β-ocimene (0.5–1.2%)

(E)-β-ocimene (t–0.1%)

γ-terpinene (8.8–11.7%)

cis-sabinene hydrate (0.7–1.1%)

terpinolene (0.1%)

linalool (2.1–2.3%)

trans-sabinene hydrate (0.2–0.4%)

camphor (0.1–0.3%)

borneol (1.1–1.7%)

terpinen-4-ol (0.1–2.6%)

α-terpineol (0.1%)

methyl thymol (0.1–1.0%)

methyl carvacrol (0.4–1.7%)

isobornyl acetate (0.1–0.2%)

thymol (31.7–51.1%)

carvacrol (2.9–3.7%)

thymol acetate (<0.1%)

α-copaene (t–0.1%)

β-bourbonene (t–0.1%)

β-caryophyllene (1.2–2.3%)

incorrect identification

The authors also found that both of the two applications of a chemical and organic fertilizer resulted in dramatic increases in biomass and a corresponding increase in oil content up to 1.8% oil yield.

Pavela et al. (2009) screened thyme oil against Colorado potato beetle (Leptinotarsa decemlineata). They found that the thymol-rich oil, although toxic to the Colorado beetle, was slightly less toxic than a carvacrol-rich oil. The lethal dose (LD50) of a carvacrol-rich oil such as Winter Savory (Satureja montana or Origanum oil (Origanum vulgare subsp. hirtum is lower than that of thymol-rich thyme oils even though both oils are potentially useful in controlling the Colorado beetle.

The composition of this thyme oil which was obtained from T. vulgaris grown locally in Prague (Czech Republic) was determined to be:

α-thujene (0.6%)

α-pinene (1.1%)

camphene (0.8%)

1-octen-3-ol (0.6%)

myrcene (1.6%)

α-phellandrene (0.1%)

α-terpinene (1.7%)

p-cymene (21.8%)

limonene (0.7%)

β-phellandrene (0.1%)

1,8-cineole (0.7%)

γ-terpinene (13.3%)

cis-sabinene hydrate (0.1%)

terpinolene (0.1%)

linalool (2.3%)

camphor (0.2%)

borneol (1.7%)

terpinen-4-ol (0.9%)

α-terpineol (0.1%)

methyl thymol (0.4%)

methyl carvacrol (0.5%)

bornyl acetate (0.1%)

thymol (46.3%)

carvacrol (2.0%)

β-caryophyllene (1.7%)

Pavela et al. also screened three supercritical fluid CO2 extracts (SFE) of the same batch of T. vulgaris produced under different extraction conditions. The compositions of the three extracts can be seen in T-3.

An oil that was produced from T. vulgaris plants that were grown in the Colombian Andes was analyzed by Roldan et al. (2010) using GC/MS only. The constituents characterized in this oil were:

α-thujene (1.6%)

α-pinene (1.2%)

camphene (1.1%)

sabinene (0.2%)

β-pinene (0.3%)

1-octen-3-ol (0.3%)

myrcene (2.3%)

α-phellandrene (0.2%)

p-cymene (10.9%)

limonene (1.0%)

1,8-cineole (1.9%)

(Z)-β-ocimene (0.8%)

(E)-β-ocimene (1.3%)

γ-terpinene (27.3%)

isoterpinolene (0.8%)

terpinolene (2.9%)

camphor (2.2%)

trans-sabinene hydrate (0.2%)

α-terpineol (0.2%)

methyl thymol (0.5%)

thymol (30.6%)

carvacrol (1.5%)

thymol acetate (0.3%)

β-caryophyllene (3.4%)

germacrene D (0.6%)

caryophyllene oxide (0.2%)

cadinene (0.5%)

incorrect identification

Viudα-Martos et al. (2010) used GC/MS to determine that a hydrodistilled oil produced from T. vulgaris cultivated in a plantation near the city of Bilbesis (northeastern Cairo, Egypt) was found to contain:

α-thujene (2.8%)

α-pinene (1.8%)

camphene (1.1%)

myrcene (3.0%)

α-terpinene (3.1%)

p-cymene (20.3%)

limonene (1.2%)

1,8-cineole (1.5%)

γ-terpinene (21.2%)

terpinolene (0.2%)

linalool (2.6%)

camphor (0.3%)

terpinen-4-ol (1.3%)

neral (0.1%)

geranial (0.2%)

thymol (32.2%)

carvacrol (2.1%)

β-caryophyllene (1.6%)

The composition of a laβ-distilled oil and a supercritical fluid CO2 extract of the flowering aerial parts of T. vulgaris grown in Ejea (Spain) was the subject of analysis by Grosso et al. (2010). Using GC-FID and GC/MS as their method of analysis, and the conditions for SFE production: particle size = 0.6 mm, pressure = 90 bar, temperature = 40°C, CO2 flow rate and amount consumed = 1.1 kg/hr and 4.4 kg, respectively, the composition of each isolate can be found in T-4.

Trace amounts (<0.05%) of (E)-β-ocimene, α-calacorene and geranyl butyrate were also characterized in the oil and SFE.

Ozcakmak et al. (2010) screened a commercial sample of thyme oil acquired in Turkey against two aflatoxigenic strains of Aspergillus flavus.

The main constituents of this oil, which was analyzed by GC/MS only, was found to be as follows:

camphene (1.8%)

myrcene (3.2%)

p-cymene (19.8%)

γ-terpinene (17.5%)

terpinolene (5.2%)

linalool (6.4%)

isoborneol (2.2%)

thymol (26.9%)

β-caryophyllene (2.5%)

In addition the authors also misidentified a further five compounds that will not be listed in this review. Also, they found (not unexpectedly) that thyme oil could be a useful food preservative against aflatoxigenic A. flavus.

A hydrodistilled oil of T. vulgaris of Romanian origin was analyzed by Grigore et al. (2010) using GC-FID and retention times. The constituents identified in this oil were:

α-pinene (1.2%)

camphene (0.6%)

sabinene (4.2%)

β-pinene (0.3%)

myrcene (1.6%)

α-terpinene (0.8%)

p-cymene (30.5%)

limonene (0.62%)

1,8-cineole (1.2%)

linalool (2.7%)

camphor (0.8%)

borneol (3.2%)

α-terpineol (1.2%)

geraniol (0.6%)

bornyl acetate (0.7%)

thymol (30.9%)

carvacrol (3.4%)

β-caryophyllene (2.5%)

Oils of T. vulgaris produced from plants grown using different organic fertilizer regimens in Egypt were analyzed by GC-FID and retention times by Hendawy et al. (2010).

The compositional range of constituents characterized were as follows:

α-pinene (1.0–4.0%)

myrcene (2.2–5.7%)

p-cymene (23.1–30.5%)

γ-terpinene (1.4–2.9%)

linalool (2.5–4.8%)

camphor (0.5–1.1%)

borneol (2.1–3.1%)

α-terpineol (0.3–2.1%)

thymol (44.1–52.1%)

carvacrol (0.1–1.2%)

β-bourbonene (<0.1–0.3%)

β-caryophyllene (0.3–1.0%)

germacrene D (0.2–0.7%)

cadinene* (0.4–1.7%)

caryophyllene oxide (0.1–0.4%)

carotol (0.1–0.4%)

incorrect identification

*correct isomer not identified

A commercial sample of thyme oil (originating from T. vulgaris) of unknown origin was determined. Bosquez-Molina et al. (2010) using GC-FID and GC/MS to possess the following composition:

α-thujene (0.1%)

α-pinene (0.5%)

camphene (1.0%)

sabinene (0.5%)

β-pinene (0.5%)

myrcene (0.1%)

p-cymene (15.0%)

limonene (0.6%)

1,8-cineole (0.3%)

(E)-β-ocimene (0.1%)

γ-terpinene (12.0%)

linalool (0.1%)

camphor (1.0%)

menthone (13.0%)

isomenthone (3.0%)

borneol (0.8%)

α-terpineol (0.6%)

methyl thymol (0.5%)

geraniol (2.0%)

thymol (47.0%)

carvacrol (0.1%)

geranyl acetate (0.2%)

β-caryophyllene (0.1%)

α-humulene (0.1%)

γ-muurolene (0.2%)

definitely not constituents of thyme oil

 

 

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