Chemical Compositions and Antibacterial Activity of the Essential Oils of
Thymus vulgaris and Tanacetum parthenium
Aromatic and medicinal plants are widespread throughout world. Essential oils
obtained from different aromatic and medicinal plants parts have been shown
antibacterial, antifungal, antiviral and antioxidant properties The experiment
was started in season 2010-2011. This work was conducted for determination of
the phytochemistry and antibacterial activity of the essential oil from leaves
of Thymus vulgaris and Tanacetum parthenium growing in Iran. Antibacterial
effects of the extracts were tested on six Gram-positive and nine Gram-negative
human pathogenic bacteria. The major compounds in the leaves of Thymus vulgaris
and Tanacetum parthenium were α-pinene followed by camphene, β-
pinene, 1,8-cineole, camphor, thymol and carvacrol. The results of the Minimal
Inhibiting Concentration (MIC) and Minimum Bactericidal Concentration (MBC)
varied from one bacterium to another. The highest and broadest activity was
shown by Thymus vulgaris oil. Thymol and carvacrol possessed the highest
antibacterial activity among the tested components.
Received: March 08, 2012;
Accepted: May 11, 2012;
Published: July 03, 2012
The essential oils medicinal and aromatic plants have shown pharmaceutical,
pharmaceutical, antibacterial properties (Bari et al.,
2010). Thyme (Thymus vulgaris L.) is a plant belonging to the Lamiaceae
family (Matiljan, 2008). Atti-Santos
et al. (2004) reported that Thymus vulgaris oil have to act
as antioxidant, antimicrobial agent and antifungal properties (Inouye
et al., 2001; Hernandez et al., 2004;
Boskabady et al., 2006; Bolukbasi
and Erhan, 2007; Abu-Darwish and Abu-Dieyeh, 2009).
Ismail et al. (2011), Ahmad
et al. (2005), Ganjewala and Luthra (2007a,
b), Reza and Abbas (2007), Musyimi
and Ogur (2008), Swamy and Rao (2008), Imelouane
et al. (2009), Soltan et al. (2009),
Abd El-Mageed et al. (2011), Fortes
et al. (2011), Louis et al. (2011),
Patra (2011) and Upadhyay and Patra
(2011) reported that essential oils Thymus species have strong antibacterial,
antifungal, antiviral, antiparasitic and antioxidant activities. Tanacetum
parthenium is a medicinal plant that have essential oils and it is belongs
to Asteraceae family (Bernath, 2000; Burt,
2004; Izadi et al., 2010). Composition of
the oils extracted from the aerial parts of Tanacetum parthenium has
also been reported by Izadi et al. (2010). This
study evaluated the antimicrobial activities of Thymus vulgaris and
Tanacetum parthenium, leaves essential oil against fifteen human pathogenic
MATERIALS AND METHODS
The leaves of Thymus vulgaris and Tanacetum parthenium have been
collected during March-August 2010 in western regions of Iran. The essential
oils were extracted by hydrodistillation, using an apparatus of Clevenger. For
this, mixing 250 g of plants was used in 1600 mL of distilled water. The extraction
took 3 h. After filtration the solvent is eliminated by reduced pressure distillation
in rotary evaporator and pure oil was stored at 4°C in obscurity till the
beginning of analysis. GC analysis was performed, using a Shimadzu GC-9A gas
chromatograph equipped with a DB-5 fused silica column (30 mx0.25 mm i.d., film
thickness 0.25 μm). The oven temperature was held at 50°C for 5 min
and then programmed to 250°C at a rate of 3°C min-1. Injector
and detector (FID) temperatures were 290°C; helium was used as carrier gas
with a linear velocity of 32 cm sec-1. The percentages were calculated
by electronic integration of FID peak areas without the use of response factors
correction. Linear retention indices for all components were determined by co-injection
of the samples with a solution containing homologous series of C8-C22
n-alkanes. GC-MS analyses were carried out on a Varian 3400 GC-MS system equipped
with a DB-5 fused silica column (30 mx0.25 mm i.d.); oven temperature was 40°C
to 240°C at a rate of 4°C. Transfer line temperature was 260°C.
Carrier gas was helium with a linear velocity of 31.5 cm sec-1, split
ratio 1/60. In addition, ionization energy was 70 eV, scan time 1 sec and mass
range 40-300 amu. Identification of components in the oil was based on retention
indices relatives to n-alkanes and computer matching with the WILLEY 275. L
library, as well as by comparison of the fragmentation patterns of mass spectra
with those reported in the literature (Adams, 2001). The
chromatographic conditions were identical to those used for GC analysis.
Tests for antibacterial activity: The microorganisms used in the present
study were six Gram-positive (Staphylococcus aureus, Bacillus cereus, Bacillus
megaterium, Bacillus subtilis, Sarcina lutea and Streptococcus-β-haemolyticus)
and nine Gram-negative (Salmonella typhi, Shigella dysenteriae, Shigella
shiga, Shigella sonnei, Shigella boydii, Escherichia coli, Klebsiella sp.,
Pseudomonas aeruginosa and Proteus sp.) human pathogenic bacteria.
The antibacterial assays were carried out by the disc-diffusion (Verpoorte
et al., 1983) and microdilution method (Daouk
et al., 1995; Hanel and Raether, 1988; Espinel-Ingroff,
2001) in order to determine of the antibacterial activity of oils and their
components against the human pathogenic bacteria. The bacterial suspensions
were adjusted with sterile saline to a concentration of 1.0x105 CFU
mL-1. The inocula were prepared daily and stored at 4°C until
time of use. Dilutions of the inocula were cultured on solid medium to verify
the absence of contamination and to check the validity of the inoculum.
Disc-diffusion test: Compounds were investigated by the disc diffusion
using 4 mm filter discs. Bacteria were cultured overnight at 28°C in LB
medium and then adjusted with sterile saline to a concentration of 1.0x105
CFU mL-1. The suspension was added to the top of agar (6 mL) and
dissolved in Petri dishes (2 mL agar plate-1) with solid peptone
agar. Filter discs with essential oils and main components (1.0 μg mL-1)
were placed on agar plates (1 disc per agar plate). After 24 h of incubation
at 28°C for bacteria the diameter of the growth inhibition zones was measured.
Streptomycin was used as a positive control and 1 μL was applied to the
discs from stock solution (1 mg mL-1). All tests were done in duplicate.
Three replications were used for each oil and for each component (Sokovic
et al., 2009).
Microdilution test: The minimum inhibitory and bactericidal concentrations
(MICs and MBCs) were determined using microtitre plates. The bacterial suspension
was adjusted with sterile saline to a concentration of 1.0x105 CFU
mL-1. Compounds to be investigated were dissolved in broth LB medium
(100 μL) with bacterial inoculum (1.0x104 CFU per well) to achieve
the wanted concentrations (0.02-15.0 μg mL-1). The microplates
were incubated for 24 h at 28°C. The lowest concentrations without visible
growth (at the binocular microscope) were defined as concentrations that completely
inhibited bacterial growth (MICs). The MBCs were determined by serial sub-cultivation
of 2 μL into microtitre plates containing 100 μL of broth per well
and further incubation for 72 h. The lowest concentration with no visible growth
was defined as the MBC, indicating 99.5% killing of the original inoculum. The
optical density of each well was measured at a wavelength of 655 nm by Microplate
manager 4.0 (Bio-Rad Laboratories) and compared with a blank and the positive
control. Streptomycin was used as a positive control using the same concentrations
as in the disc diffusion test. Three replications were used for each oil and
each component (Sokovic et al., 2009).
RESULTS AND DISCUSSION
The chemical compositions of essential oils of Thymus vulgaris and
Tanacetum parthenium are presented in Table 1. In total,
thirty nine volatile compounds, representing 71.13% of the total composition,
were identified in the leaves oils of Thymus vulgaris (Table
1). The main one being α-pinene (6.54%), camphene (10.12%), thymol
(11.15%), 1.8-cineole (3.42%), β-pinene (3.91%) followed camphor (22.14%).
Other predominant components were myrcene (1.24%), P-cymene (1%), Linalool (1.11%),
borneol (1%) and terpinene-4-ol (1%). Other components were presents in amounts
less than 1% (Table 1). The essential oils yield of Thymus
vulgaris was 1.87%. Badi et al. (2004) and
Jordan et al. (2006) found that wild-growing
thyme in Jordan had higher concentrations of essential oil (5.40%) than recorded
in Egypt (1.07%), Chili (0.39%), Iran (1.4%) and Belarusian (1.75%) (Karawya
and Hifrawy, 1974; Hudaib and Aburjai, 2007; Khazaie
et al., 2008). The chemical compositions revealed that this leaves
had compositions similar to those of other thyme essential oils analyzed by
Imelouane et al. (2009) which the major constituent
in lab sample have been reported as α-pinene, camphene, followed camphor.
Phytochemical studies have reported the occurrence o f α-pinene, p-cymene
and terpinene in thyme essential oil (Ozcan and Chalchat,
2004). The above mentioned results are agreed with those recorded by Jordan
et al. (2006) who studied the oil composition of thyme of the same
specie sample in Spanish, the major components quantified were 1,8-cineole,
followed by terphenyl acetate, borneol, linalool, β-pinene, alphaterpineol
and camphor. In total, eighteen volatile compounds, representing 66.07% of the
total composition, were identified in the leaves oils of Tanacetum parthenium
(Table 1). The essential oils yield of Tanacetum parthenium
was 4.18%. It is relatively higher than other plants Tanacetum parthenium
(3.3%) (Izadi et al., 2010) and Tanacetum
argyrophyllum (3.13%) (Askari and Mirza, 1998).
Some investigators have shown that the major constituents of the essential oils
extracted from aerial parts of Tanacetum parthenium have been camphor
(56.9%) followed by camphene (12.7%) and p-cymene (5.2%) (Akpulat
et al., 2005). Camphor existed in the aerial parts of T. aucheranum
(11.6%), T. hiliophyllum (28.1%), T. argenteum (14%) and T.
argyrophyllum (22.3%) (Salamci et al., 2007;
Tabanca et al., 2007; Omidbeigi,
2007; Askari, 2008). The results of antibacterial
activity of tested essential oils are presented in Table 2,
3. The essential oils which showed the best antibacterial
activity in disc-diffusion method were related to Thymus vulgaris (20.0-38.0
mm) and Tanacetum parthenium (20.0-35.0 mm). Streptomycin at 1 μg
disc-1 showed inhibition zones in the range of 10.0- 22.0 mm (Table
2). It can be seen that essential oils Thymus vulgaris and Tanacetum
parthenium possess a higher antibacterial effect than streptomycin.
|| Chemical composition of essential oils investigated
|Total identified constituents (%) are mean of three replications
obtained from electronic measurements using flame ionization detection (FID),
0: Not detected
|| Antibacterial activity of essential oils (1.0 μg mL-1)
in disc-diffusion method
|The data show the diameter of inhibition zone growth in mm,
The diameter of paper disc was 6 mm
Thymus vulgaris and Tanacetum parthenium oils exhibited much
higher antibacterial activity with the same MIC (1-0.5 μg mL-1)
and MBC (0.5-0.5 μg mL-1). Streptomycin showed MIC at 3.0-1.5
μg mL-1 and MBC at 2.0-4.0 μg mL-1. The results
of antibacterial activity of essential oil components are presented in Table
4, 5. β-Pinene and 1,8-cineole showed the lowest
antibacterial activity among the tested components, with inhibition zones 6.0-18.0
mm; α-pinene and camphene possessed almost the same activity, with inhibition
zones 10.0-25.0 mm. Camphor inhibited bacterial growth of all bacteria and inhibition
zones were 15.0-30.0 mm, carvacrol reacted slightly better (inhibition zones
20.0-35.0 mm) while Streptomycin showed activity with inhibition zones 15.0-25.0
mm. Thymol showed inhibition with zones of 25.0-38.0 mm. β-pinene and 1,8-cineole
and showed the lowest antibacterial activity in the microdilution method, MIC
at 5.0-6.0 μg mL-1 and MBC at 7.0-10.0 μg mL-1.
α-pinene and camphor exhibited inhibitory activity at 2.0-1.5 μg mL-1
and was bactericidal at 1.5-3.0 μg mL-1 while, streptomycin
exhibited inhibitory activity at 7.0-5.0 μg mL-1 and was bactericidal
at 6.0-9.0 μg m L-1. Among the seven essential oil components
tested, thymol (MIC at 0.5-0.5 μg mL-1 and MBC at 1.0-1.5 μg
mL-1) and carvacrol (MIC at 1.0-1.5 μg mL-1 and MBC
at 1.5-1.5 μg mL-1) showed the highest activity. Many studies
have reported that phenolic compounds in medicinal plants and herbs significantly
contributed to their antioxidant and pharmaceutical properties (Cai
et al., 2004; Shan et al., 2005; Wu
et al., 2006). The antimicrobial activities of phenolic compounds
may involve multiple modes of action. For example, essential oils degrade the
cell wall, interact with the composition and disrupt cytoplasmic membrane (Ultee
et al., 1999; Lambert et al., 2001),
damage membrane protein, interfere with membrane integrated enzymes (Raccach,
1984), cause leakage of cellular components, coagulate cytoplasm, deplete
the proton motive force, change fatty acid and phospholipid constituents, impair
enzymatic mechanisms for energy production and metabolism, alter nutrient uptake
and electron transport , influence the synthesis of DNA and RNA and destroy
protein translocation and the function of the mitochondrion in eukaryotes (Raccach,
1984; Nychas, 1995).
|| Antibacterial activity of essential oils (MIC and MBC μg
mL-1), microdilution method
|MBC test: Minimum bactericidal concentration, MIC test: Minimum
Borneol has been reported to have significant antimicrobial activity (Tabanca
et al., 2001; Vardar-Unlu et al., 2003).
Pinene-type monoterpene hydrocarbons (α-Pinene and β-Pinene) are well-known
chemicals having antimicrobial potentials (Dorman and Deans,
2000). The essential oils containing terpenes are also reported to possess
antimicrobial activity (Dorman and Deans, 2000) which
are similar with our present studies. The antifungal and antibacterial activity
exhibited by Thymus genus essential oil has been demonstrated by several
researchers (Karaman et al., 2001; Rasooli
and Mirmostafa, 2003). This oil also showed very strong antibacterial activity
against food spoilage bacteria (Sokovic et al., 2007).
Feverfew essential oils affected on the growth of bacteria and C. albicans
that potentially causes infection (Izadi et al.,
2010). Significant difference was observed between Gram-positive and Gram
-negative bacteria in terms of their susceptibility, so that Gram-positive bacteria
were more sensitive to antimicrobial activity of feverfew essential oil. The
higher sensitivity of Gram-positive bacteria may be explained according to their
cell wall structure. The antimicrobial activity of the essential oil from Tanacetum
parthenium may be associated with its major components such as Thymol, carvacrol
and α-Pinene. In previous studies, the antimicrobial effect of these components
has been confirmed (Sokovic et al., 2007; Izadi
et al., 2010). Camphor is most commonly used externally to relieve
arthritic and rheumatic pains.
|| Antibacterial activity of essential oils components (1.0
μg mL-1) in disc-diffusion method, inhibition zones in mm
|The data show the diameter of inhibition zone growth in mm,
The diameter of paper disc was 6 mm
|| Antibacterial activity of essential oils components (MIC
and MBC μg mL-1) microdilution method
|MBC test: Minimum bactericidal concentration, MIC test: Minimum
It is often used in steam vaporizers to help control coughs by producing a
local anesthetic action to the throat and to loosen congestion due to colds
(Baser et al., 2001). α-Pinene is used by
the fragrance industry as a starting material in the syntheses of terpineols,
borneol and camphor (Bauer et al., 1997). Camphor
and chrysanthenyl acetate were the main components of the essential oil of Tanacetum
parthenium originated from England (Christensen et
al., 1999) but in the region of Turkey (Adams, 2001),
the main constituents of Tanacetum parthenium essential oil were camphor,
camphene and p-cymene. In conclusion Present findings on the components of essential
oil from the leaves of Thymus vulgaris and Tanacetum parthenium
were in agreement with the previous report (Bendahou et
al., 2008; Izadi et al., 2010). Essential
oil of Thymus species and Tanacetum contain mainly aromatic monoterpenes,
carvacrol, thymol and p-cymene and their activity are often attributed to these
compounds (Daouk et al., 1995; Izadi
et al., 2010).
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