296 Advances in Environmental Biology, 3(3): 296-301, 2009 ISSN 1995-0756

296
Advances in Environmental Biology, 3(3): 296-301, 2009
ISSN 1995-0756
© 2009, American-Eurasian Network for Scientific Information
This is a refereed journal and all articles are professionally screened and reviewed
O RIGINAL A RTICLE
Essential Oils Yield and Heavy Metals Content of Some Aromatic Medicinal Plants
Grown in Ash-Shoubak Region, South of Jordan.
Mohammad Sanad Abu-Darwish
Ash-Shoubak University College, Al-Balqa Applied University, Al Salt 19117, Jordan
Mohammad Sanad Abu-Darwish; Essential Oils Yield and Heavy Metals Content of Some Aromatic
Medicinal Plants Grown in Ash-Shoubak Region, South of Jordan; Adv. Environ. Biol., 3(3): 296-301,
2009
ABSTRACT
The use of aromatic medicinal herbs to relieve and treat many human diseases is increasing in Jordan and
worldwide due to their mild features and low side effects. It is important to have a good quality control for
aromatic medicinal herbs in order to protect consumers from contamination. The aim of the present study was
to carry out a comparative evaluation of essential oils yield and heavy metals content in some medicinal herbs
such as Thymus vulgaris L., Thymus serpyllum L. and salvia officinallis L. grown in Ash-Shoubak region-south
of Jordan. The essential oils were hydro-distilled from studied dried aerial herbs using Clevenger- type system.
The heavy metals content in collected herbal samples were analyzed by using atomic absorption flame emission
spectrometry by method described by Al-Alawi & mandiwana .Analytical results have evaluated by statistical
analysis system. The mean values of essential oils yields of T.vulgaris, T. serpyllum, and S. officinalis were
4.0, 2.5 and 1.9 %, respectively. The contents of heavy metals in the samples were determined in the ranges
of 1.26-32.03, 0.47-23.85, 7.66-13.23, 14.7-44.0, 15.8-114.91, 141.3-756.17ppm for Pb, Ni, Cu, Mn, Zn, Fe,
respectively .Cobalt has been detected only in T. serpyllum, while Cd and Cr were not detectable in all studied
samples. The highest Pb, Ni and Cu content has been detected in T. vulgaris (32.03ppm, 23.85ppm and 13.23
ppm, respectively. S. officinalis had The highest Mn, Zn and Fe content 44.0ppm, 114.91ppm and 756.17 ppm,
respectively. The essential oils and heavy metals contents in studied plants are affected by environmental
conditions. Moreover, the obtained results showed that the studied plants grown in Ash-shoubak region (with
respect to the lead content in T.vulgaris) can safely be used for pharmaceutical and ethno-pharmacological
purposes without any hazardous effect.
Key words: essential oils, heavy metals, sage, thyme,
Introduction
The use of aromatic medicinal herbs to relieve
and treat many human diseases has been increased in
Jordan and around the world because of their mild
features and low side effects. [1,2]. At present, there
are many aromatic medicinal herbs widely cultivated
and consumed in Jordan. Among these herbs,
Thymus vulgaris L. (common thyme), Thymus
serpyllum L. (wild thyme), and Salvia officinallis L.
(sage) which are the most popular aromatic medicinal
herbs used for medical purposes or maintaining good
health [1,3,4].
T. vulgaris
and T. serpyllum are aromatic
producing high quality of essential oil required by the
pharmaceutical, food and cosmetic industry [5-8] The
pharmacological activities of this medicinal plant are
antispasmodic, expectorant, antiseptic, antimicrobial,
and antioxidant activity [9-11]. S.officinalis (Sage) is
a herb considered mainly for its content of essential
Corresponding Author
Mohammad Sanad Abu-Darwish, Department of Basic and Applied Sciences, Al-Shouback
University College, Al-Balqa` Applied University, Jordan Work
TeleFax: 00962 03 2164035
E-mail: [email protected]
Adv. Environ. Biol., 3(3): 296-301, 2009
oil, it has been credited with a long list of medicinal
uses: e.g. spasmolytic, antiseptic, astringent, antioxidant and antimicrobial [12-15]. Also, it is largely
used as an infusion where polar compounds play a
central role [15]. In Jordan, there are twenty species
of Salvia cultivated or grow wildly [4,16] used to
improve the taste of tea and included in many
phytopreparations, for the treatment of inflammations,
catarrhs, mouth and throat gargling [15,17].
Medicinal herbs can be easily contaminated with
heavy metals from the environment (soil, water, or
air) during growth and the manufacturing processes
when the ready-made products are produced [18].
Additional sources of heavy metal contamination are
rainfall, atmospheric dust, plant protective agents, and
fertilizers [19-21]. The level of essential elements in
plants is conditional, the content being affected by
the geochemical characteristics of the soil and by the
ability of plants to selectively accumulate some of
these elements [22-23].
Considering the complexity of these aromatic
medicinal herbs and their inherent biological
variation, it becomes necessary to evaluate their
safety, efficacy and quality [3]. W hile many
investigations of the quality values of aromatic
medicinal plants grown in Jordan are being reported
in the current literature [15,17,22] less emphasis has
been made on the metal content of herbal products.
As well as T. vulgaris L. T. serpyllum L. and S.
officinallis L. have various applications in ethno
pharmacology. It is important to have a good quality
control to protect consumers from contamination [4].
Therefore, the aim of the present study was to carry
out a comparative evaluation of essential oils yield
and heavy metals content in Thymus vulgaris L.,
Thymus serpyllum L. and salvia officinallis L. grown
in Ash-Shoubak, south environmental region in
Jordan.
M aterials and methods
Plant Material
Aerial parts of wild T.srpyllum, cultivated
T.vulgaris and S.officinalis have been collected at
vegetation during may, June and July 2008
respectively, from experimental area of the AshShoubak University Collage, in Ash-shoubak region
(30° 32N ,35° 33 E) in the southern altitudes of
Jordan, 1365 m above the sea level.
Ambient
temperature is 4.11 – 19.9C° and seasonal means of
rainfall is about 294.2mm/year. The collected plant
materials were dried in draughty place at about 20<C,
all specimens were identified on the basis of
macroscopic characteristics by comparison with
authentic sample and a voucher specimens were
deposited by the Herbarium of Ash-Shoubak
University College. The dried material of studied
297
plants were separately crushed and mild in to small
pieces and sieved through (0,5mm) mesh sieve.
Determination of Essential Oil
Essential oils contents of particular specimens of
studied plants were extracted separately by the hydrodistillation method utilizing Clevenger-type apparatus
similar to European Pharmacopoeia (EP) (22), using
50gr of the dried mild and sieved plant (0,5mm), 500
ml of water in 1000 ml round –bottomed flask. The
distillation time was 2 h at a rate of 2-3 min -1 .The
values reported are the mean of at least 3 distillations
[22]. There were three replications for each
specimen; all the results obtained were statistically
analyzed.
Determination of heavy metals content in medicinal
plant samples
Heavy metals content of particular collected
samples were analyzed using Atomic Absorption.
Flame Emission Spectrophotometer Model (Shimadzu,
Japan) AA-6200 [23]. The plant samples were oven
dried at 70 <C for 24 hours until the dry weight was
constant. The dried samples were then ground and
passed through a 0.2 mm plastic sieve. Then, 0.5g of
plant sample was wet digested with an Ultra-pure
nitric acid (HNO 3 (10-15ml) in a polyethylene test
tube using a heating block digestion unit at 120 C o .
The final solution was filtered into a 25 ml or 50 ml
volumetric flask through a 45-µm filter paper and
diluted to the mark with ultra-pure water. Ultra-pure
water was used for all dilutions and sample
preparation.
Results and discussion
Means of essential oil contents in the studied
aerial parts of T.vulgaris L., T.serpyllum L. and
S.officinalis L. are presented in table (1). The
essential oil contents in T.vulgaris L., T.serpyllum,
and S.officnalis were 4.0, 2.5, and 1.90 respectively.
The results showed that T. vulgaris L. and
T.serpyllum contain higher volumes of essential oil
than S.officnalis .However, The yields were found to
satisfy the requirements of Pharmacopeias such as
European Pharmacopoeia (EP), which requires a yield
of oil should be $ 1.2, 0.3, and 1.0% v/w for T.
vulgaris , T.serpyllum, and S.officnalis respectively
[23]. On the other hand, the results of previous
studies [7,8] revealed a wide variation in essential oil
contents in T.vulgaris cultivated in other neighboring
places located in the south and middle regions of
Jordan. However, Ash-shoubak region yielded higher
than these cultivated in other places located in the
south of Jordan such as in M aan 2.00±0.00% and in
Al-Tafelieh 2.30± 0.002%(8),or in Mshaqar (middle
Adv. Environ. Biol., 3(3): 296-301, 2009
298
M ean±SD of essential oil Y ields (% ) extracted from Thym us Vulgaris L, Tym us serpyllum L., and Saliva officinalis L. collected
from Ash-shouback region-south of Jordan.
Plant Species
Essential O il (% )
M oisture (% )
Thym us Vulgaris L*
4.0 ±0.007
6.00 ±0.020
Thym us serpyllum L
2.5 ±0.008
6.60 ±0.010
Saliva officinalis L.
1.9 ±0.002
9.40 ±0.012
*Results of T. vulgaris were delivered from previous paper for the sam e author [9].
Table 1:
region of Jordan), 1.6% [7], but less than these
cultivated in the north region of country ,where
T.vulgaris cultivated in Jeresh and Ajlune yielded
5.4±0.12 and 5.2± 0.09%, respectively [8]. However
T.vulgaris cultivated in Ash-shoubak region yielded
higher than those cultivated in other regions of the
world, where in
Egypt, Iran, Brazil, Iraq, and
Turkey yielded 1.07, 1.45, 0.56, 1.67 and 1.6%,
respectively) [24-28]. The higher volumes of essential
oil in T.vulgaris was observed with a lower content
in T.serpyllum. However, the results showed that,
T.serpyllum grown in Ash-shoubak region yielded
higher volumes of essential oil than these
investigated from other regions of the world, where
in Estonia, the yield of essential oil was ranged
between 0.6-4.4 ml/kg, while in Russia, Latvia and
Armenia was ranged between 1.9 and 8.2 ml/kg,
[29]. This variation of essential oil yielded from a
particular species of thyme plant could be explained
by the effect of harvesting season [25,26],
geographical environment and other agronomical
factors [8,30-32].
The essential oils content in S.officnalis was
1.90%. This result is in agreement with others who
reported that S.officnalis cultivated in other locations
from the middle region of Jordan; Hfashiet Al
Dbajbe and Al Fesalia, yielded essential oil ranged
from 1.18 to 2.13% [15]. However, this variation in
essential oil yield of S.officnalis cultivated in Ashshoubak region in south and other regions of Jordan
could be ascribed according to climate variations
among regions [30], growth region [7,8,24] and
cultivation practices such as spacing [31], irrigation
regimen (25), and harvesting time [26,32].
The results of heavy metal concentrations (ppm)
in T.vulgaris, T.serpyllum, and S.officnalis grown in
Ash-shoubak region are presented in table (2). In all
investigated medicinal herbs, Cadmium (Cd) and
Chromium (Cr) were not detectable. The un
detectable concentration of Cd and Cr in all
investigated herbs may be due to a low soil content
of Cd in suburbanized areas in Jordan or due to
cultivation these herbs in locations free off industrial
activities such as steel and glass industries that have
been shown to be a source of chromium pollution
(33,34). However, high Cd content was detected in
urban areas in Jordan [33] near the road and their
level increased with increasing traffic densities [35].
On the other hand, Cd was not detectable in
T.vulgaris cultivated in other regions of Jordan [8]
and had not yet determined in S.officnalis cultivated
in the middle region of Jordan [15]. Comparing Ash-
shoubak region to other locations of the world, it was
obtained that the studied species grown in that
locations are contaminated with Cd and Cr [36,3739].
The average concentrations of Pb in T.vulgaris,
and T.serpyllum, were 32.03 and 1.26, respectively.
The concentration of Pb in T.vulgaris cultivated
in Ash-shoubak region was higher than that detected
in wild T.serpyllum at the same region and exceeded
the level (< 10 ppm) recommended by W HO [3].
However, it was lower than that detected in the north
regions [9]. On the other hand, Pb was not detectable
in S.officinalis cultivated in Ash-shoubak region
while, it was characterized by higher level of these
trace elements in the middle region [15]. The
contamination of studied T.vulgaris by Pb, could be
clarified according to location of cultivation area of
these species, especially it was known that motor
vehicles are the leading factor in Pb contamination
[15,18,21,33-38] while, in wild T.serpyllum grown in
natural habitat Pb was low and below the toxic level
[3]. On the other hand, the variation in Pb content in
studied plants may be due the type of soil, species of
plant, the availability of plant to absorb the metal
and accumulate it [38-40].
The average content of Ni was 23.85 ppm in
T.vulgaris and not detectable in wild grown
T.serpyllum. In S.officinalis, it was within normal
range (0.47 ppm) since the toxic level ranges from
10 to 100 ppm. Also, the Copper (Cu) contents in all
studied plants were within normal level (2-20 ppm).
The detected level of Cu was ranged from 10.4 ppm
in T.serpyllum to 13.23 ppm in T.vulgaris, while it
decreased to 7.66 ppm in S.officinalis. This variation
of Cu content in the studied samples, could be due
to genetic differences between plant species [41], or
different plant selectivity for heavy metals [33].
These results are in agreement with the results of
others who found that the contents of Cu in some
medicinal plants in the same family such as salvia
officinalis, Mentha piperita, Melissa officinalis,
Ocimum basilicum, and Origanum vulgaris were
varying from 5.92 to 14.79 mg/kg [42]. On the other
hand, the concentration of Cu detected in S.
officinalis cultivated in Ash-shoubak is less than that
detected in the middle of Jordan, where it was varied
from 61 to 70 mg/kg [15], and less than cultivated in
other regions of the world. [37,38]. This indicates the
effect of anthropogenic activities and heavy traffic
activities by which the Cu metal may accumulate in
the soil [33,43].
Adv. Environ. Biol., 3(3): 296-301, 2009
299
Table 2: Concentration of heavy metals (ppm) in Thymus Vulgaris L, Tymus serpyllum L. and Saliva officinalis L. collected from Ash-shouback south region, Jordan.
Plant species
Cd
Cr
Pb
Ni
Cu
Mn
Zn
Fe
Co
Thymus vulgaris*
ND
ND
32.03 ±0.04
23.85 ±0.03
13.23 ±0.13
15.52 ±0.16
16.18±0.24
141.3±0.67
ND
Thymus serpyllum
ND
ND
1.26±0.01
ND
10.40±0.150
14.7±0.06
15.80±0.02
142.00±0.879
0.40±0.003
Saliva officinalis
ND
ND
ND
0.47±0.23
7.66±0.77
44.0±0.46
114.91±0.36
756.17±5.82
ND
Detection limit µg/L
0.002
0.004
0.050
0.070
0.014
0.028
0.150
0.060
0.011
*Results of Cd, Cr, Pb, Ni, Cu, Mn, Zn, contents in T. vulgaris were delivered for Comparison from a previous paper for the same author [9].
As well as Cu is one of important constituent of
many enzymes essential for living organisms, Also
Zn has the same role and considered an important
factor in the biosynthesis of enzymes and some
proteins. [18,44,45]. The concentration of Zn in plant
may vary between 30-150 ppm, but usually it is 2050 ppm. In the investigated plant materials the
highest concentration was found in S.officinalis, while
the lowest was detected in T.serpyllum. These results
indicated that S.officinalis cultivated in Ash-Shouback
south environment is rich with Zn content compared
with the middle growth area in Jordan (114.19 vs.
22-29 ppm) [15].The concentrations of Manganese
(Mn) were found to be closely relative to each other
in T.serpyllum, and T.vulgaris. They were 14.7 and,
15.52 ppm, respectively, where the highest
concentration (44.0ppm) was found in S. officinalis.
However, the concentration of Mn in S. officinalis
was lower than that detected in S. officinalis
cultivated in middle of Jordan which was ranged
from 92 mg/kg to 108 mg/kg [15]. The high content
of Mn could be ascribed as a cultivation of plant in
industrial and residential sites rich of Mn and Ni ,due
to their using as fuel additives just like Pb [45] since
the critical threshold for M n deficiency in plants is
<10 ppm, it is obvious that studied plants were
sufficiently provided with Mn.
Ferrous (Fe) concentration in dry plant material
typically reaches 1000 ppm or more [38]. In the
studied herbs, Fe content was in the following order
T.vulgaris <T.serpyllum < S. officinalis. The highest
content of Fe was been detected in S.officinalis
(756.17 ppm), while the lowest was detected in T.
vulgaris (142.3ppm). The variation in Fe content in
Salvia species and thymus species may be due to
plant availability of the essential micronutrients and
plant uptake of micronutrients which vary and depend
on genetic differences between plant species [20,41].
On the contrary, a low Fe content ranged from 122
mg/kg to 184 mg /kg was found in S.officinalis
grown in the middle region of Jordan (near highway
between Amman and Sahab) [15]. These differences
in Fe contents could be ascribed to a well-supplied
soil in Ash-shoubak south region, and according to
the neighborhood location the cement factory in the
south of Jordan [46].
Cobalt (Co) concentration in T.serpyllum was
within the optimum range 0.02-1.0 mg/kg in the plant
[47]. It was 0.40 ppm and not detectable in
T.vulgaris and S.officinalis. In 303 samples, which
represent 20 different types of spices and medicinal
plants that were collected from areas of exportation
in Egypt, Co was not detectable [48]. Also in
infusion of S.officinalis consumed in Turkey these
metal was not detected [37].The presence of Co in
T.serpyllum and its absence in other studied herbs
could be ascribed that cobalt distribution in plants is
entirely species-dependent. The uptake is controlled
by different mechanisms in different species. Physical
conditions like salinity, temperature, pH of the
medium, and presence of other metals influence the
process of uptake and accumulation of Co in
medicinal plant [49].
Conclusion
The essential oils yields in Thymus vulgaris L.,
Thymus serpyllum L. and Salvia officinallis L. grown
in Ash-shoubak region were found to satisfy the
requirement of European pharmacopoeia.
The contents of heavy metals in Ash-Shouback
south environment are variable and mainly affected
by plant species. Thymus vulgaris is rich in Pb
content, Thymus serpyllum and Salvia officinallis are
more safely and rich sources of Fe. Further studies of
heavy metals concentrations in medicinal plants
grown in Jordan environment are recommended.
Acknowledgment
The author express his thanks to the deanship of
scientific research and Al-Balqa`Applied University
for their financial support and advice, and to
agricultural engineer Sanaa Al-shqerat for technical
assistant.
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