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Herbicides for weed control in blessed thistle (Silybum marianum)

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Herbicides for Weed Control in Blessed Thistle (Silybum marianum)
1
VALTCHO D. ZHELJAZKOV, IVAN ZHALNOV, and NEDKO K. NEDKOV
2
Abstract: Blessed thistle is an important medicinal crop in Europe and recently has become more
significant in North America. A limiting factor in blessed thistle production is weed interference.
Field experiments were conducted near Plovdiv, Bulgaria, to study the effect of selected herbicides
on weed control, crop productivity, and crop quality. Seed yields of blessed thistle were increased
with metribuzin alone at 0.5 kg ai/ha, pendimethalin alone 1.32 kg ai/ha, pendimethalin at
1.32 kg ai/ha plus metribuzin at 0.5 kg ai/ha, trifluralin at 0.84 kg ai/ha plus linuron at 1.0 kg ai/
ha, and in the hand-weeded control compared to the nonweeded control (nontreated check).
Pendimethalin and metribuzin were safe both alone and in combination for weed control in
blessed thistle. Bentazon at 0.96 kg ai/ha inhibited blessed thistle development and reduced seed
yields compared to the untreated check. Generally, weed control increased the content of
silymarin and decreased the amount of seed oil. Overall, seeds contained 0.26 to 0.36%taxifolin,
0.69 to 0.99%silydianin plus silycristin, 1.31 to 1.78%silybin, and 0.27 to 0.39 %isosilybin.
Nomenclature: Bentazon; linuron; metribuzin; pendimethalin; trifluralin; blessed thistle, Silybum
marianum (L.) Gaertn. ‘Silmar’
#
3
SLYMA.
Additional index words: Medicinal plants, seed oil, seed yield, silymarin, taxifolin, silydianin,
silycristin, silybin, isosilybin.
INTRODUCTION
Blessed thistle, also known as milk thistle, has
become one of the most widely grown and econom-
ically viable medicinal plants in Europe including
Bulgaria (Zheljazkov et al. 1996), and recently is
coming to prominence in North America. Blessed
thistle achenes (seeds) contain the biologically active
flavonolignan complex silymarin, that consists of
silybin, silydianin, and silycristin. In addition, the
fruits contain seed oil composed of mainly linoleic
and oleic acids. Silymarin from blessed thistle fruits is
used for the production of hepatoprotectors for the
treatment of liver diseases, mainly cirrhosis (Boerth
and Strong 2002; He et al. 2002; Jacobs et al. 2002).
Recently, blessed thistle extract was shown to possess
anticarcinogenic properties (Kohno et al. 2002) and
silybin was found to suppress cholesterol synthesis
(Nassuato et al. 1991). Several commercial medicines
and plant extracts containing blessed thistle extract
are being produced and offered under different trade
names in Europe and recently in the United States
and Canada (including Nova Scotia).
Blessed thistle is very sensitive to most of the
herbicides used in other crops (Cacso et al. 1977;
Topalov et al. 1983). Blessed thistle seeds have pappi
and are easily dispersed before harvest (Hecht et al.
1992; Todorov et al. 1990), resulting in blessed thistle
emerging as a weed in the next crop. In North
America, blessed thistle is a noxious weed in Oregon
(category B), Texas (category S2), and Washington
(category A) (Plant Protection and Quarantine 2002),
but not in any of the provinces in Canada (USDA-
ARS 2005). Blessed thistle is being grown as a crop in
Saskatchewan and in Atlantic Canada.
A limiting factor in blessed thistle production in
Bulgaria and in other parts of Europe has been lack
of weed control (Topalov et al. 1983). There are few
publications on weed control in blessed thistle, but
some authors recommend the use of PRE applications
of alachlor at 1.0 to 1.5 kg ai/ha, linuron at 1.0 kg ai/
ha, trifluralin at 0.48 to 0.72 kg/ha, and a combination
of alachlor at 1.5 kg ai/ha plus linuron at 1.0 kg/ha
1
Received for publication September 25, 2005, and in revised form May
4, 2006.
2
Research professor, Mississippi State University, North Mississippi
Research & Ext. Center, 5421 Hwy. 145 South, Verona, MS 38879;
Associate professor, Department of Farming, University of Agriculture,
12 Mendeleev str., 4000 Plovdiv, Bulgaria; Senior Researcher at
the Research Institute for Roses and Medicinal Plants, 49 Osvobo-
jdenia Blv, 6100, Kazanlak, Bulgaria. Corresponding author’s E-mail:
vj40@pss.msstate.edu.
3
Letters following this symbol are a WSSA-approved computer code
from Composite List of Weeds, Revised 1989. Available only on computer
disk from WSSA, 810 East 10th Street, Lawrence, KS 66044-8897.
Weed Technology. 2006. Volume 20:1030–1034
1030
(Topalov et al. 1983). In Hungary, Cacso et al. (1977)
tested 58 herbicides in the greenhouse and 19 PRE
and 13 POST herbicides in small-plot experiments
and found that blessed thistle was highly sensitive to
many herbicides. They reported that best weed
control in blessed thistle was achieved with PRE
applications of isopropalin at 1.6 kg ai/ha and benefin
at 0.09 to 0.1 kg ai/ha. However, these herbicides did
not provide 100%weed control. The objectives of this
study were to evaluate five of the more promising
herbicides for weed control and the effect of weed
control on blessed thistle yield and quality.
MATERIALS AND METHODS
Field experiments were conducted near Plovdiv,
Bulgaria, in 1995 and 1996 with the blessed thistle
cultivar ‘Silmar’, the most widely grown cultivar in the
country (Zheljazkov et al. 1996). The experiments were
conducted as a randomized complete block design with
3.0 by 10.0 m (30 m
2
) plots, in four replications. Treat-
ments evaluated were: (1) nontreated check (control
without weeding), (2) hand weeded (single hand
removal of the weeds), (3) trifluralin at 0.84 kg/ha
plus linuron at 1.0 kg/ha, (4) trifluralin at 0.84 kg/ha
plus bentazon at 0.96 kg/ha, (5) pendimethalin at
1.32 kg/ha, (6) metribuzin at 0.5 kg/ha, and (7) pendi-
methalin at 1.32 kg/ha plus metribuzin at 0.5 kg/ha.
Prior to planting, nitrogen (100 kg N/ha as NH
4
),
phosphorus (66 kg/ha as P
2
O
5
), and potassium
(83 kg/ha as K) were applied to the test site as
recommended for blessed thistle fertilization in the
region (Topalov et al. 1983) and based on the amount
of available P and K in the soil prior to seeding. The
soil was a calcareous alluvial-meadow soil (Koinov
1968) or calcaric fluvisols upon the FAO-UNESCO
(1974) classification of world soils. The sand, silt, and
clay contents of the soils were approximately 21, 41,
and 38%, respectively, making it a clay loam. The soil
was fall plowed to a 25- to 30-cm depth, and the next
spring tillage was done to 8- to 10-cm depth, 3 to 5 d
before seeding. In both years, blessed thistle was
seeded on March 12 at an interrow space of 45 cm
(Foldesi and Barsi 1983), a seeding rate of 15 kg/ha,
and at 2- to 3-cm depth (Topalov et al. 1983).
Herbicides were applied with a compressed air
backpack sprayer fitted with a flat-fan nozzle tips
4
calibrated to deliver 250 L water/ha at 200 kPa.
Trifluralin was applied PPI and incorporated 12 cm
deep by disking twice. Linuron, pendimethalin, and
metribuzin were applied PRE after seeding, and
bentazon was applied POST at the two- to five-leaf
stage of the weeds. Bentazon treatments included
Tween 20
5
at 0.25%v/v.
Specific composition and density of weeds was
established by counting the weeds from 2 m
2
in each
plot, just before harvest. Blessed thistle plants from the
whole plots, each 3.0 by 10.0 m, were harvested with
a swatter and left on the field for 3 to 4 d to allow all
the seeds to mature and dry. Subsequently, seeds were
threshed using a small plot research combine
6
and
dried to uniform 9%moisture. The extraction of active
compounds from blessed thistle seeds is usually a two-
step process; the first step is the extraction of the seed
oil (the lipids) and the second step is the extraction of
flavonolignan complex with organic solvents. Research
has demonstrated that prior removal of seed oil
(defattening) and higher extraction temperatures im-
prove the yields of silymarin from the seed meal
(defatted seeds) (Wallace et al. 2005). The seed oil
content was established by a 4-h extraction of the
achenes with hexane in a Soxhlet apparatus, with
a subsequent drying of the hexane extract at 105 C to
a constant weight. The content of silymarin was
obtained by acetone extraction for 12 h of the seed
meal, was conducted by a commercial company
7
using
its own method. The acetone in the extract was distilled
off under vacuum. The dry residue was dissolved in
methanol and brought up to 50 ml in a volumetric flask.
Five milliliters of this solution was diluted five times
with methanol (to 25 ml). Ten milliliters from the latter
was further diluted five times with methanol (to 50 ml).
The absorption of the resulting solution was measured
at a 288-nm wavelength and compared against a control
sample of 1-cm-thick methanol layer. The final percent-
age of silymarin was calculated using the formula:
Silymarin%~Asample|Bst:|12:5G
Ast:|Bsample
where:
A
sample
5extinction of the sample
A
st.
5extinction of the standard
B
sample
5weight of the sample
B
st.
5weight of the standard
5
Tween 20 (polyoxyethylenesorbitan monolaurate) from Agria, Plov-
div, Bulgaria.
6
Winterstieger Nurserymaster, Zentrale, Austria.
7
Bulgarska Rosa Sevtopolis, Kazanluk, Bulgaria.
4
Zavod za Selskostopanska Technica, Russe, Bulgaria.
WEED TECHNOLOGY
Volume 20, Issue 4 (October–December) 2006 1031
G5concentration of the internal
standard substance
The percentages of taxifolin, silydianin, silycristin,
silybin, and isosilybin were obtained using liquid
chromatography
8
with an UV detector and tetrahy-
drofuran modifier, using a mobile phase of 0.02 M
phosphate buffer and 0.05 M potassium nitrate in
35%tetrahydrofuran-water at pH 3.0 and run at
1.0 ml/min.
Data analyses were performed using two-way
ANOVA with SAS (SAS Institute 2000). Where the
main effects or interactions were found to be
significant, Duncan’s multiple range test was used to
separate means.
RESULTS AND DISCUSSION
Sixteen weed species, typical for the region, were
identified prior to harvest, of which 11 were annual
(including nine dicotyledonous and two monocotyle-
donous) and five perennial (including three dicotyle-
donous and two monocotyledonous). Of these, most
abundant were redroot pigweed (Amaranthus retro-
flexus L.),green foxtail [Setaria viridis (L.) Beauv.],
and bermudagrass [Cynodon dactylon (L.) Pers.]. The
other weeds species included the annual dicotyledon-
ous prostrate pigweed (Amaranthus blitoides S.Wats.),
common lambsquarters (Chenopodium album L.),
jimsonweed (Datura stramonium L.), wild buckwheat
(Polygonum convolvulus L.), prostrate knotweed
(Polygonum aviculare L.), black nightshade (Solanum
nigrum L.), common cocklebur (Xanthium strumarium
L.), velvetleaf (Abutilon theophrasti Medik.), and the
monocotyledonous large crabgrass (Digitaria sangui-
nalis L.). The perennials included dicotyledonous field
bindweed (Convolvulus arvensis L.), motherwort
(Leonurus cardiaca L.), and Canada thistle (Cirsium
arvense L.), and the monocotyledonous johnsongrass
[Sorghum halepense (L.) Pers.]. The annual weed
density at harvest varied significantly (Table 1) with
the highest weed infestation found in the nontreated
check. A single weeding at the three- to five-leaf stage
of weeds reduced weeds by 50%at the end of
vegetation period (i.e., prior to harvest). All herbicide
treatments significantly lowered weed density com-
pared to the nontreated check. The best control of
annual weeds was achieved with the herbicide
combinations of pendimethalin plus metribuzin for
dicots and trifluralin plus linuron for monocots,
indicating that linuron is more effective than benta-
zon for control of monocots. Perennial weed density
was not affected by the herbicides tested or by the
single hand removal of weeds, since the tested
herbicides are not active on established perennial
monocotyledonous and dicotyledonous weeds (Fet-
vadjieva et al. 1994; Mitchell and Abernethy 1993). At
harvest, annual weed infestation was lowest in the
metribuzin treatment, followed by pendimethalin and
pendimethalin plus metribuzin treatments; hence, the
herbicides pendimethalin and metribuzin could pro-
vide weed control in blessed thistle.
A single hand removal of the weeds gave a seed
yield increase of 27 and 40%in 1995 and 1996,
respectively, compared to the nontreated check
(Table 2). Differences in seed yields between the
nontreated check and the hand-weeded treatment
were significant and support previous reports that
blessed thistle plants develop and grow very quickly
and successfully suppress the weeds in later stages, but
plants are very sensitive to weed interference in their
initial stages of growth (Chiavari et al. 1991; Topalov
et al. 1983). Our results support those of Schunke
(1992) that if hand hoeing is done at this time (i.e., the
initial stages of blessed thistle growth), weed control
in blessed thistle crop would not be a significant
8
PYE Unicam 4100 liquid chromatograph.
Table 1. Effect of treatments on weed density in blessed thistle crops (pooled data for 1995 and 1996).
Treatments Rate
Annual weeds Perennial weeds
Monocots Dicots Monocots Dicots
kg ai/ha -------------------------------------------------------------------------------- n o . weeds/m
2
------------------------------------------------------------------------------
Nontreated check (without weeding) 32 a
a
41 a 4 b 1 b
Single hand weeding 23 b 19 b 3 b 1 b
Trifluralin plus linuron 0.84 +1.0 3 d 9 c 13 a 3 b
Trifluralin plus bentazon 0.84 +0.96 7 c 12 bc 3 b 7 a
Pendimethalin 1.32 6 cd 13 bc 0 0
Metribuzin 0.50 10 c 4 d 2 b 4 b
Pendimethalin plus metribuzin 1.32 +0.50 7 cd 4 d 5 b 3 b
a
Means with the same letter within a year (column) are not significantly different at P #0.05 using Duncan’s multiple range test.
ZHELJAZKOV ET AL.: WEED CONTROL IN SILYBUM MARIANUM L.
1032 Volume 20, Issue 4 (October–December) 2006
problem. All herbicide treatments except bentazon,
which exhibited phytotoxicity on blessed thistle, had
higher yields than the nontreated check (Table 2).
Pendimethalin and metribuzin treatments in combi-
nation increased yield by up to 25%over trifluralin
plus linuron treatment. These results suggest that the
herbicides pendimethalin and metribuzin can success-
fully be used either alone or in combination for weed
control in blessed thistle.
The seed oil content was highest in blessed thistle
seeds when no herbicides were used (in the nontreated
check and in the hand-weeded treatment, respectively)
in both years (Table 3). Pendimethalin or metribuzin
alone decreased seed oil content relative to the
nontreated check in both years, while trifluralin plus
bentazon decreased seed oil in 1995 but not in 1996.
Content of seed oil is important, since after extrac-
tion, blessed thistle seeds are used as feed for domestic
animals (Potkanski et al. 1991). The oil content in the
seeds from our experiment varied from 18.4 to 26.2%,
which is lower than that reported by Hamid et al.
(1983) and Omer et al. (1993) and might be due to
differences in the tested cultivars or to environmental
conditions.
Weed control by herbicides increased silymarin
content of seeds for all herbicide combinations but
less strongly when metribuzin was applied alone
(Table 3). Our data seem to suggest that the increase
in silymarin content in the herbicide treatments may
be due to the direct effect of herbicides on blessed
Table 2. Seed yield of blessed thistle in response to hand weeding and weed control with herbicides.
Treatments Rate
Seed yield Percent of check
1995 1996 1995 1996
kg ai/ha ---------------------------------------- kg/ha------------ ---------------------------- ----------------------------------------- %---------------------------------------
Nontreated check (no weeding) 655.3 c
a
737.5 c 100 100
Single hand weeding 832.5 b 1032.1 b 127 140
Trifluralin plus linuron 0.84 +1.0 1070.0 a 977.8 b 163 133
Trifluralin plus bentazon 0.84 +0.96 462.4 d 620.1 d 71 84
Pendimethalin 1.32 1080.3 a 1026.4 b 165 139
Metribuzin 0.50 1094.8 a 1141.0 ab 167 155
Pendimethalin plus metribuzin 1.32 +0.50 1133.2 a 1273.1 a 173 173
a
Means with the same letter within a year (column) are not significantly different at P #0.05 using Duncan’s multiple range test.
Table 3. Seed oil and silymarin content in seeds of blessed thistle in response to hand weeding and weed control with herbicides.
Treatments Rate
Seed oil Silymarin
1995 1996 1995 1996
kg ai/ha ------------------------------------------------------------------------------------------------- %-------------------------------------------------------------------------------------------------
Nontreated check (no weeding) 24.6 a
a
25.9 a 2.3 b 2.0 b
Single hand weeding 24.1 a 26.2 a 2.2 b 2.1 b
Trifluralin plus linuron 0.84 +1.0 22.8 ab 23.6 ab 2.7 a 3.0 a
Trifluralin plus bentazon 0.84 +0.96 20.8 b 22.1 ab 2.6 a 3.2 a
Pendimethalin 1.32 19.7 b 18.4 b 2.7 a 2.9 a
Metribuzin 0.50 19.5 b 20.2 b 2.5 ab 3.1 a
Pendimethalin plus metribuzin 1.32 +0.50 22.8 ab 21.8 ab 2.9 a 2.8 a
a
Means with the same letter within a year (column) are not significantly different at P #0.05 using Duncan’s multiple range test.
Table 4. Taxifolin, silydianin and silycristin, silybin, and isosilybin content in seeds of blessed thistle in response to hand weeding and weed control with
herbicides (average for 1995 and 1996).
Treatment Rate Taxifolin Silydianin +silycristin Silybin Isosilybin
kg ai/ha ------------------------------------------------------------------------------------------- %------------------------------------------------------------------------------------------
Nontreated check (no weeding) 0.36 0.99 1.78 0.39
Single hand weeding 0.27 0.75 1.39 0.30
Trifluralin plus linuron 0.84 +1.0 0.31 0.86 1.58 0.34
Trifluralin plus bentazon 0.84 +0.96 0.26 0.69 1.31 0.27
Pendimethalin 1.32 0.31 0.82 1.54 0.31
Metribuzin 0.50 0.31 0.84 1.49 0.31
Pendimethalin plus metribuzin 1.32 +0.50 0.27 0.70 1.36 0.28
WEED TECHNOLOGY
Volume 20, Issue 4 (October–December) 2006 1033
thistle plants, rather than to the removal of stress with
weeds being controlled. Indeed, previous research has
demonstrated that herbicides may increase plant
secondary metabolites synthesis and accumulation in
some other crops (Cosio et al. 1985; Ko¨mives and
Casida, 1996; Lydon and Duke, 1989; Zheljazkov and
Zhalnov, 1995).
Overall, seeds contained 0.26 to 0.36%taxifolin,
0.69 to 0.99%silydianin plus silycristin, 1.31 to 1.78%
silybin, and 0.27 to 0.39 %isosilybin (Table 4). Due
to the high variation within a treatment, there were no
differences in the content of taxifolin, silydianin plus
silycristin, silybin, and isosilybin between the treat-
ments at P #0.05. Silymarin content in the seeds
varied depending on the level of weed control. This
supports the studies of Cacso et al. (1977) of
significant variation in total flavonoids, induced by
weed control with some herbicides.
Our results suggest that weed control in blessed
thistle could be obtained by single weed removal at
initial stages of crop development or by using
herbicides pendimethalin and metribuzin either alone
or in combination.
ACKNOWLEDGMENTS
This work was partially supported by the Bulgarian
Ministry of Agriculture grant awarded to V. Zheljaz-
kov and I. Zhalnov, and by AgriFutures Nova Scotia
grant
#
190 awarded to V. D. Zheljazkov (Jeliazkov).
Authors thank Dr. Claude D. Caldwell and Ms.
Stephanie Butler from the Nova Scotia Agricul-
tural College for their helpful corrections and sugges-
tions.
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ZHELJAZKOV ET AL.: WEED CONTROL IN SILYBUM MARIANUM L.
1034 Volume 20, Issue 4 (October–December) 2006
... Weeds adversely affect the product's commercial value both by competition and by mixing with the product (Upadhyay et al., 2012). Even if uncontrolled weeds are subsequently controlled during critical periods, there is a decrease in the content of metabolites, such as in coriander and milk thistle (Gil et al., 1998;Kothari et al., 2002;Sarrou et al., 2016;Zheljazkov et al., 2006). ...
... Removal of weeds cumin, musk sage, coriander, chamomile, mint, thistle "Mary thorn," fennel, sage, marjoram "Istanbul thyme," and thyme has been found helpful in the biomass and quality properties of medicinal and aromatic plants (Mitchell and Abernethy, 1993;Mitchell et al., 1995;Pank, 1992;Singh et al., 2011;Zheljazkov et al., 2006Zheljazkov et al., , 2010Zumelzu et al., 1999). ...
... For this reason, this plant can be used for phytoremediation of soils contaminated with heavy metals. The results show that a small amount of heavy metals remain in the roots of lavender and most of the heavy metals are transferred to the shoots of the plant(Angelova et al., 2015).Studies show that the concentration of aluminum in Rosmarinus officinalis, cobalt concentration in Alpinia officinarum, nickel concentration in Mentha piperita, lead concentration in Malva sylvestris, chromium concentration in Cuminum cyminum and cadmium concentration in Thymus vulgaris are higher (Esetlili et al., 2014).The medicinal plants basil, peppermint and dill are able to grow in soils contaminated with the heavy metals cadmium, lead and copper.Also, heavy metals accumulated in plants are not transferred to essential oils and do not change the composition of essential oils(Zheljazkov et al., 2006).In a study, three medicinal plants, Thymus vulgaris, Thymus serpyllum and Salvia officinalis, were compared in terms of metal content. Thymus vulgaris L. had the highest concentrations of lead, nickel and copper. ...
... Weeds adversely affect the product's commercial value both by competition and by mixing with the product (Upadhyay et al., 2012). Even if uncontrolled weeds are subsequently controlled during critical periods, there is a decrease in the content of metabolites, such as in coriander and milk thistle (Gil et al., 1998;Kothari et al., 2002;Sarrou et al., 2016;Zheljazkov et al., 2006). ...
... Removal of weeds cumin, musk sage, coriander, chamomile, mint, thistle "Mary thorn," fennel, sage, marjoram "Istanbul thyme," and thyme has been found helpful in the biomass and quality properties of medicinal and aromatic plants (Mitchell and Abernethy, 1993;Mitchell et al., 1995;Pank, 1992;Singh et al., 2011;Zheljazkov et al., 2006Zheljazkov et al., , 2010Zumelzu et al., 1999). ...
... For this reason, this plant can be used for phytoremediation of soils contaminated with heavy metals. The results show that a small amount of heavy metals remain in the roots of lavender and most of the heavy metals are transferred to the shoots of the plant(Angelova et al., 2015).Studies show that the concentration of aluminum in Rosmarinus officinalis, cobalt concentration in Alpinia officinarum, nickel concentration in Mentha piperita, lead concentration in Malva sylvestris, chromium concentration in Cuminum cyminum and cadmium concentration in Thymus vulgaris are higher (Esetlili et al., 2014).The medicinal plants basil, peppermint and dill are able to grow in soils contaminated with the heavy metals cadmium, lead and copper.Also, heavy metals accumulated in plants are not transferred to essential oils and do not change the composition of essential oils(Zheljazkov et al., 2006).In a study, three medicinal plants, Thymus vulgaris, Thymus serpyllum and Salvia officinalis, were compared in terms of metal content. Thymus vulgaris L. had the highest concentrations of lead, nickel and copper. ...
Chapter
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Abiotic stresses affect the growth, development and productivity of plants, especially medicinal plants, and also cause the plant to undergo various morphological reactions such as leaf area decline, premature aging, physiological and metabolic processes such as stomatal closure, and reduction in growth rate, accumulation of antioxidants and solutes, and activity of specific genes (Hughes et al., 1989; Sabagh et al., 2021). Plants' response to abiotic stresses depends on the type, intensity and duration of stress, the stage of stress occurrence, as well as plant species, age and developmental stage of the plant (Pagter et al., 2005). In response to stress, specific genes are expressed and enzymes are produced to trigger certain metabolic pathways that ultimately increase the concentration of soluble substances such as proline, sugar, glycine betaine in cells, and the conditions for water moves into the cells, resulting in increased turgor pressure. Plant cells also have antioxidant mechanisms that protect against oxidative damage (Lima et al., 2002). Protection against photo-oxidation by removing excess energy by nonenzymatic defense systems such as carotenoids, ascorbic acid, anthocyanin, glutathione, tocopherol or by increasing the degradation of reactive oxygen species by enzymatic defense systems of antioxidant enzymes such as superoxide dismutase, catalase, peroxidase, glutathione peroxidase, ascorbate peroxidase (Al-Aghabary et al., 2004). In this chapter, some abiotic stresses are investigated on the accumulation of secondary metabolites in medicinal plants.
... Milk thistle has become one of the most cultivated and economically viable medicinal plants in some parts of Europe, including Bulgaria (Zheljazkov et al., 2006). Studies undertaken by Houachri et al. (2017) showed that milk thistle can also be a potential source of biofuel along with Citrullus colocynthis and Datura stramonium. ...
Article
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Milk thistle, a species mentioned from the time of Greek philosophers, is well known due to one of its constituents, silymarin, and used in the treatment of several liver disorders. Even though the majority of the documentary data on Silybum marianum focuses on its role in liver diseases, more information has recently become available regarding the herb's beneficial effects on a variety of other diseases, including protection for the kidneys, hypolipidemic and anti-atherosclerotic activities, cardiovascular protection, prevention of insulin resistance, particularly in cirrhotic patients, cancer prevention, and Alzheimer's and dementia prevention. Considering the preceding significance, in this paper, we present a synthesis of the knowledge related to the phytochemical constituents of the milk thistle fruits and their pharmaceutical activity, to the origin and spread of the species, to the systematics and cultivated varieties, as well as the influence of the environmental conditions and applied technology on the production and chemical composition of the fruits of these plants.
... This inhibition of EPSP synthase leads to increased accumulation of important metabolites, such as shikimate, benzoic acids, and benzoic acid derivatives (Lydon and Duke, 1989). Other herbicides, such as sulfonylureas and p-nitro-substituted diphenylether (DPE) have been reported to increase the level of cinnamate derivatives and terpenoids, respectively (Zheljazkov et al., 2006). Certain fungicides are believed to act by infuencing the plant's capacity to generate phytoalexins and other useful secondary metabolites (Majid et al., 2013). ...
... Ефектите и механизмът на действие на растението бял трън (Silybum marianum) все още не са достатъчно добре проучени в България. Той е обект на изследване на аграрния сектор [32,33]. Проведено е и проучване върху липидния му състав [34]. ...
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The regulation of lipid metabolism and glucose homeostasis is conducted through numerous processes and signaling pathways. Disorders in them are the reason for the development of a number of socially significant diseases. Silymarin is extracted from the plant Silybum marianum (milk thistle). It has many positive effects (antioxidant, anti-inflammatory, anti-tumor, antifibrotic, immunomodulatory, etc.), which make it a potential adjunct in the treatment of these conditions. Silymarin enhances lipolysis, inhibits TAG synthesis and lipogenesis, lowers levels of"bad∗ cholesterol and increases those of 'good0 cholesterol, thus improving lipid metabolism. These effects are manifested by milk thistle, affecting a number of enzymes-phosphatidate phosphatase (PAP), fatty acid synthase (FAS), diacylglycerol acyltransferase-1 (DGAT1) and others and transcription factors such as PPARa (peroxisome proliferator-activated receptor alpha). It regulates cholesterol levels through a double mechanism-suppression of its synthesis and the effect of resin in the enterchhepatic cycle. Regarding glucose homeostasis, milk thistle normalizes blood sugar levels, lowers glycated hemoglobin (HbA 1 c) levels and improves glucose tolerance. It manifests its effects through various mechanisms-supports the regeneration of fi-cells of the pancreas, regulates the signaling pathway of phosphatidylinositol-3-kinase (PI3K), inhibits major enzymes of gluconeogenesis. The numerous beneficial properties of silymarin make it the focus of alternative medicine and a means of adjunctive therapy to statin therapy However, more studies and clinical trials are needed to clarify its full potential and mechanism of action.
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This study is to evaluate the effectiveness of adding different concentrations of the hot and alcoholic aqueous extract of seeds of the local Kalgan plant ( Silybum marianum ) to water drinking on the performance productive of broilers and find the best ratios that achieve the highest results positive in productivity, It was used 315 of broiler chicks Ross 308 and It was randomly distributed to 21 (KN) with 7 trial transactions for each(3)bis transaction. The experiment treatments were as: T1(control) :free of any addition, and T2, T3, T4 : addition of 2 ml of hot water extract for the seeds of the Kalgan plant / liter of drinking water at a concentration of 2.5%, 5% and 7.5% respectively, and T5, T6, T7 : addition of 2 ml of alcoholic extract of the seeds of the Kalgan plant / liter of water drinking at a concentration of 2.5%, 5% and 7.5% respectively. The results showed a significant (p≤0.05) superiority for T6 and T7 coefficients in the average weight live body and the gain weight total compared T1 (control), the consumption total feed, the experimental coefficients (T6, T7, T4 and T3) achieved significant compared superiority T1 (control), recorded T7 the best cumulative food conversion with significant (p≤0.05) difference compared to treatments other. As for the carcass qualities, the treatment T7 achieved the best weight live body, and weight carcass and the net percentage, for the destruction, it was noted there were no significant differences between the experiment coefficients all. So the extract alcoholic of the seeds of the Kalgan plant at a concentration of 7.5% showed the best results In weight live body, the gain weight and consumption feed rate.
Chapter
The medicinal plant Silybum marianum has long been utilised as a hepatoprotective treatment. It has been used to treat a variety of liver conditions marked by functional impairment or progressive necrosis. Silymarin compound mostly found in seeds of this plant that is helpful in curing of different diseases. Holy thistle is pharmacologically important and mostly use in treating the liver cancer in humans as well as in animals. Seeds of this plant improve antioxindant system in animals which increase resistance against the liver disease. Dihydro flavanol and flavonolignan, two derivatives of flavonoids, are mostly used in medical and therapeutic procedures. Some other components of this plant are silydianin, silibinin, and silybin. This plant is most effective in protection of the renal, hypolipidemic, anti-atherosclerosis activities cardiovascular protection, prevention of the insulin, cancer and Alzheimer prevention.
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Milk thistle Silybum marianum (L.) Gaertn. is one of the most researched medicinal plants, but at the same time it belongs to crops with wide industry potential whose growth requirements for marginal agroecological conditions or the response to agronomic interventions has not yet been sufficiently studied. The aim of the present research was to verify the effect of mineral nutrition (NPK 200 kg/ha) and humic acids applied to the soil (HUMAC Agro 250 kg/ha) on the main biometric parameters and the intensity of photosynthesis of milk thistle grown under less favourable climatic conditions of the semi-cold and humid foothills in Central Europe. The highest seed yield was achieved with the NPK variant in terms of dry matter 0.534 t/ha, in the HUMAC Agro variant 0.254 t/ha and with the untreated control 0.087 t/ha. The soil before the trial establishment was characterised by low nutrient content. The use of mineral fertiliser on NPK treatment eliminated the influence of low PK nutrients content of the soil, influencing the crop growth and yield/quality, while no doses of NPK were used on the HUMAC Agro variant and the untreated control. For both of the two sequences created (temperature and light), the highest photosynthesis rate was measured on untreated control (20.115 and 12.386 mmol/m2/s1), markedly lower on HUMAC Agro (16.386 and 9.653 mmol/m2/s1) – and the lowest on the NPK (10.933 and 7.813 mmol/m2/s1, respectively), in inverse proportion to the crop yield. Therefore, the size of the leaf area of the crop was decisive for the increased crop yield. The polynomial trend line of the photosynthesis rate according to the temperature sequence shows the photosynthesis rate and the torrential decrease by temperature increasing on untreated control compared with both treated variants. Both of these threats, mineral nutrition and use of humic preparations to soil, although they reduce the photosynthesis rate, have a wide range of complex effects that provide an opportunity to optimise the growth and yield of milk thistle. Ideally, the mineral nutrition and humic preparations should be used in combination with the crop of milk thistle for medicinal and energy purposes.
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The modifying effect of dietary administration of the polyphenolic antioxidant flavonoid silymarin, isolated from milk thistle [Silybum marianum (L.) Gaertneri], on AOM-induced colon carcinogenesis was investigated in male F344 rats. In the short-term study, the effects of silymarin on the development of AOM-induced colonic ACF, being putative precursor lesions for colonic adenocarcinoma, were assayed to predict the modifying effects of dietary silymarin on colon tumorigenesis. Also, the activity of detoxifying enzymes (GST and QR) in liver and colonic mucosa was determined in rats gavaged with silymarin. Subsequently, the possible inhibitory effects of dietary feeding of silymarin on AOM-induced colon carcinogenesis were evaluated using a long-term animal experiment. In the short-term study, dietary administration of silymarin (100, 500 and 1,000 ppm in diet), either during or after carcinogen exposure, for 4 weeks caused significant reduction in the frequency of colonic ACF in a dose-dependent manner. Silymarin given by gavage elevated the activity of detoxifying enzymes in both organs. In the long-term experiment, dietary feeding of silymarin (100 and 500 ppm) during the initiation or postinitiation phase of AOM-induced colon carcinogenesis reduced the incidence and multiplicity of colonic adenocarcinoma. The inhibition by feeding with 500 ppm silymarin was significant (p < 0.05 by initiation feeding and p < 0.01 by postinitiation feeding). Also, silymarin administration in the diet lowered the PCNA labeling index and increased the number of apoptotic cells in adenocarcinoma. beta-Glucuronidase activity, PGE(2) level and polyamine content were decreased in colonic mucosa. These results clearly indicate a chemopreventive ability of dietary silymarin against chemically induced colon tumorigenesis and will provide a scientific basis for progression to clinical trials of the chemoprevention of human colon cancer.
Article
Nitrogen and potassium fertilization and plant spacing affected seed yield and seed content of the active, antiheptotoxic flavonolignans silybin (silymarin), silidianin, and silicristin of Silybum marianum(L.) Gaertn. A narrow row spacing (25cm) produced higher yields of seeds, but reduced oil and flavonolignan content as compared with a wide row spacing (50cm). Potassium fetilization at 115 kg K2O/ha and nitrogen fertilization at 140 kg N/ha increased seed yield, oil yield, and percent oil, and flavonolignan content of seeds as compared with lower rates of fertilization. Cultivation of Silybum marianum at spacing of 50 cm between rows and with fertilization at 55 kg K2O/ha yielded the highest percentage of silybin in Silybum marianum seeds. Nitrogen had no effect on the percentage of silybin seeds at the 2 levels tested.
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The effect of herbicides on the yield and quality of Coriandrum sativum L. and the weed density associated with it was examined. The best weed control was achieved with a combination of Pendimethalin (1320 cc/ha) and Metribuzin (500 g/ha); however, over a two-year period the herbicides exerted a toxic effect on the crop resulting in a poor seed yield. The highest seed yields were obtained with Trifluralin (840 cc/ha) + Linuron (1000 g/ha), Pendimethalin (320 cc/ha) or Metribuzin (500 g/ha). GC analysis of oils obtained from coriander seed produced from a variety of herbicide treatment did not appear to affect the chemical composition greatly although the oil produced from plants treated with Metribuzin (500 g/ha) was richest in linalool (44.47%).
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Leaves treated with acifluorfen [sodium 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate] contain greatly increased levels of N-feruloyl-3-methoxytyramine (spinach) and of 10 phytoalexins, i.e., glyceollins I, II, and III and glyceofuran (soybean), phaseollin (bean and pinto bean), pisatin (pea), medicarpin and wyerone (broad bean), xanthotoxin (celery), and hemigossypol (cotton). Enhanced synthesis of these compounds is related to the acifluorfen concentration and exposure time to light. The phytotoxicity of acifluorfen and oxyfluorfen [2-chloro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] to spinach is counteracted by appropriate treatments with (aminooxy)acetic acid, L-2-(aminooxy)-3-phenylpropionic acid, or silver nitrate and by heat shock. Under certain conditions soybean injury is ameliorated by combining (aminooxy)acetic acid with acifluorfen and silver nitrate with oxyfluorfen. These relationships for diphenyl ether (DPE) herbicides and protective treatments resemble those for other stress factors with associated increases in lipid peroxidation, membrane permeability, ethylene production, and phenylalanine ammonia-lyase (PAL) activity. Although increased PAL activity is not a primary lesion, it may play an important role in DPE herbicide action.
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Secondary compounds serve both endogenous and exogenous functions in higher plants because they are involved in plant growth and development as well as intraspecies and interspecies interactions. Documentation of the effects of pesticides on secondary compound biosynthesis in higher plants is increasing. While several herbicides have been reported to reduce levels of secondary compounds by non-specific mechanisms, a few herbicides, such as alachlor and glyphosate, directly affect specific biosynthetic steps. Alachlor reduces flavonoid synthesis at a step late in the biosynthetic pathway, and glyphosate blocks synthesis of all cinnamate derivatives by inhibiting 5-enolpyruvyl shikimate-3-phosphate (EPSP) synthase. Inhibition of EPSP synthase also leads to the accumulation of high levels of shikimate, benzoic acids and benzoic acid derivatives. The sulfonylureas and p-nitro-substituted diphenylether (DPE) herbicides can cause increases in the level of cinnamatederived phenolic compounds and the DPEs can cause dramatic increases in terpenoid stress metabolites. Certain fungicides are thought to act through enhancing the capacity of plants to produce phytoalexins. These and other data suggest that sublethal effects of pesticides on target and non-target plants can significantly affect agricultural ecosystems by altering the synthesis of compounds important in inter- and intraspecies interactions.
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The effect of Silymarin, a natural flavonoid, on biliary lipid composition, was studied in rats and humans. Bile flow, biliary cholesterol, phospholipid and total bile salt concentrations were measured in 23 control rats and in 27 rats treated with Silibinin, the active component of Silymarin, at the dose of 100 mg/kg body weight i.p. (n = 21) or 50 mg/kg body weight i.p. (n = 6) for 7 days. Biliary cholesterol and phospholipid concentrations were significantly reduced after the higher Silibinin dose (60.9 and 72.9% of the control values), whereas bile flow and biliary total bile salt concentration were unchanged. After the lower Silibinin dose all parameters remained unchanged. Total liver cholesterol content was not affected by Silibinin. On the other hand, in vitro determination of rat liver microsomal 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity showed a significant dose-dependent inhibition by Silibinin (0.5-8 mg/kg). Biliary lipid composition was also assayed in four gallstone and in 15 cholecystectomized patients before and after Silymarin (420 mg per day for 30 days) or placebo administration. In both groups, biliary cholesterol concentrations were reduced after Silymarin treatment and the bile saturation index significantly decreased accordingly. These data suggest that Silibinin-induced reduction of biliary cholesterol concentration both in humans and in rats might be, at least in part, due to a decreased synthesis of liver cholesterol.
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Silymarin, a mixture of flavonolignans isolated from Silybum marianum, is known for its hepatoprotective properties. We investigated the expression of cytokines in mouse liver following treatment with 0, 10, 50, and 250 mg/kg of silymarin once daily for 5 days. A dose-related but insignificant decrease of circulating alanine aminotransferase and aspartate aminotransferase after silymarin treatment was observed, suggesting that silymarin treatment did not induce hepatic damage. Silymarin treatment caused significant increases in the expressions of transforming growth factor (TGF) beta1 and c-myc in liver. No significant difference was detected among these treatments in the expression of hepatocyte growth factor, interferon gamma, tumor necrosis factor alpha, and class II major histocompatibility complex. These results suggest that alterations of TGFbeta1 and c-myc expression in the liver may be involved in the hepatoprotective effects of silymarin observed in other studies.