A review of manufacture, bioavailability, safety and clinical efficacy of milk thistle phytosome

JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

A REVIEW OF MANUFACTURE, BIOAVAILABILITY, SAFETY
AND CLINICAL EFFICACY OF MILK THISTLE PHYTOSOME
Dang Truong Giang*; Nguyen Van Long*; Dang Van Diep*
Nguyen Thi Lan Huong*; Nguyen Thi Thu Hoai
SUMMARY
Milk thistle (Silybum marianum) is the most well-researched plant in the treatment of liver
diseases. Fruits of milk thistle contain flavonoids known for silymarin including silybin, silydianin
and silychristin. Although Silymarin has the most potent flavonoids in milk thistle, similar to other
flavonoids, it is not well-absorbed. In recent studies, the phytosome technology has increased
absorption of conventional herbal extract. This paper aims to review the researches about milk
thistle phytosome including: manufacturing, bioavailability, safety and clinical efficacy.
* Key words: Phytosome; Silybin; Bioavailability; Phosphatidylcholine.

INTRODUCTION
Milk thistle (Silybum marianum Asteraceae)
is the most well-researched plant in the
treatment of liver diseases. Fruits of milk
thistle contain flavonoids known for
silymarin including silybin, silydianin and
silychristin [4].
Although clinical trials have shown
silymarin is safe at high doses (> 1,500
mg/day) in humans over the past three
decades, the pharmacokinetic studies related
to absorption, distribution, metabolism
and excretion of silymarin have revealed
poor absorption, rapid metabolism and
ultimately poor oral bioavailability. For
optimum silymarin bioavailability, issues

of solubility, permeability, metabolism, and
excretion must be addressed [2]. An array
of methods have been described in recent
years that can improve bioavailability

of silymarin, including complexes with
β-cyclodextrins, solid dispersion method,
formation of microparticles and nanoparticles,
self-microemulsifying drug delivery systems,
micelles, liposomes and phytosomes
[2].
The phytosome technology is a novel
approach developed by Indena in an
attempt to combat the issue of poor
bioavailability. The term “phyto” means
plant and “some” means cell like. This
novel preparation comprises of incorporating
a standardized plant extracted into
phospholipids to produce lipid compatible
molecular complexes with enhanced
absorption and bioavailability [3].
This paper aims to review the researches
about milk thistle phytosome including:
manufacturing, bioavailability, safety and
clinical efficacy.

* Military Medical University
Corresponding author: Dang Truong Giang ()

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JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

MANUFACTURING MILK THISTLE
PHYTOSOME
Phytosome is prepared by reaction of
2 - 3 moles or 1 mole of phospholipid
preferably phosphatidylcholine or
phosphatidylserine
with
the
phytoconstituents like terpenoids or
flavonoids in an aprotic solvent such as
dioxane, ethyl acetate or acetone.
Lyophilization, freeze drying, precipitation
with aliphatic hydrocarbons or evaporation
of solvent under vacuum can be carried
out for the isolation of the complex [3].
YanYu X et al manufactured silybin
phytosome by evaporating anhydrous
ethanol [6]. The required amounts of
silybin and phospholipids were placed in a
100 mL round-bottom flask and dissolved
in anhydrous ethanol. After ethanol was
evaporated off under vacuum at 40°C, the
dried residues were collected and placed
in desiccators overnight, then crushed in
the mortar and sieved with a 100 mesh.
The resultant silybin-phospholipid complex

was transferred into a glass bottle, flushed
with nitrogen and stored at room
temperature. The content of silybin in the
phospholipid complex was 49.73% (w/w).
The silybin-phospholipid complex is stability.
The solubility of the silybin-phospholipid in
water, n-octanol, chlohydric acid (pH 1.2)
and phosphate buffer saline (pH 6.8) is
increasing more than the conventional
silybin [6].
Wina Maryana et al developed a
formulation of phytosome containing
silymarin for the oral route as well as the
characterization and stability studies [5].
Whereby, silymarin and SPC with 1:5
molar ratio was dissolved in 20 mL of

absolute ethanol. The mixture was stirred
at a temperature without an excess of
25°C for 2 hours. The mixture was then
evaporated under vacuum. The dried
residues were collected and placed in
desiccators overnight. The content of
silybin in the phospholipids complex was
95.63% (w/w). The preparation is stable
with good physical properties [5].
THE BIOAVAILABILITY OF MILK
THISTLE PHYTOSOME
The intermolecular bonding of silybin
with PC proved to be specific and stable

and the resulting molecular complex is
more soluble in lipophilic, organic solvents.
This property predicts the enhanced ability
of phytosomes to cross cell membranes
and enter cells [4].
1. Animal studies.
The superior bioavailability of complexed
silybin with PC over non-complexed one has
been documented through pharmacokinetic
studies conducted in rats.

Figure 1: Relative plasma levels of total
silybin in rats after dosing with silybin-PC
or non-phytosome silybin [1].
Figure 1 showed that when rats were
taken silymarin orally at a large dose of
silybin, the concentration of silybin in the
plasma for the six hour experiment was
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JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

virtually undetectable [1]. In contrast, it
was easily detected in plasma within minute
when the same number of silybin-PC was
given (200 mg per kg body weight) and its
level peaked by one hour. Its plasma
levels significantly maintained at the sixhour mark [1].
2. Human studies.

The studies conducted on 1,900 people
showed that a group of eight healthy
volunteers of 16 - 26 years old took orally
single silybin at a dose of 360 mg, either
as phytosomes or non-complexed silymarin.
The silybin rose slightly in the plasma
beginning one hour after dosing and
declined to minimal levels by eight hours
(figure 3). By measuring the total area
under the curve (AUC) for each line, it
was determined that phytosomal silybin
was absorbed 4.6 times better than the
non-phytosome silybin [4].

Figure 2: Plasma silybin uptake in healthy
humans [4].
SAFETY OF MILK THISTLE
PHYTOSOME
This phytosomal form of silybin has been
studied for safety. According to researchers
Marena and Lampertico, healthy volunteers
(total number not disclosed) received 360 mg
silybin-phytosome complex three times
88

daily for three weeks without adverse
effect [4].
Another study on 232 patients with
“liver disorders” for up to four months with
either 240 or 360 mg of silybin-phytosome

complex daily, concluding that the
tolerability of the silybin-PC preparation
was excellent. Minor adverse effects
(nausea, heartburn, dyspepsia, transient
headache) were reported in 12 patients
(5.2% of the total studied), compared with
8.2% of patients who received noncomplexed silybin and 5.1% of patients on
placebo [4].
Phytosomal silybin has also proven to
be safe in traditional toxicological tests.
After 13-week subacute toxicity studies,
the preparation was found safe for rats
and monkeys at oral doses up to 2,000 mg
per kg per day. In 26-week sub-chronic
toxicity studies, oral doses up to 1,000 mg
per kg per day were well tolerated in rats
and dogs. In another 26-week oral toxicity
study, rats were fed a daily 2,000 mg per
kg dose of silybin-PC, equivalent to 160 g
daily for an 80 kg human. As published by
Indena, body weight, liver weight and
enzyme indicators of liver damage (AST,
ALT) remained within normal, healthy
range of the untreated control rats [1].
Pharmacological studies in mice, rats and
dogs indicate phytosomal silybin does not
adversely affect central nervous system,
cardiovascular or respiratory functions
and does not influence stomach emptying
or intestinal motility at oral doses as high

as 1,000 mg per kg. The silybin-PC complex
had no obvious adverse effects on
reproduction of rats and showed no
mutagenic effects in several testing models
[1].


JOURNAL OF MILITARY PHARMACO-MEDICINE N07-2016

CLINICAL EFFICACY OF MILK
THISTLE PHYTOSOME
In 1992, researchers at the Universities
of Milan and Bari reported in a controlled
study of chronic persistent hepatitis. The
study recruited only the patients with
biopsy-confirmed hepatitis. These patients
were randomized to receive either 240 mg
silybin phytosome (n = 31) or placebo
(n = 34), one capsule orally, twice daily
for three months. The phytosome group
experienced significant loss of both serum
ALT and AST while in the placebo group
both enzyme indicators got worse [4].
Data particularly useful in establishing
dosing recommendations came from a
larger 1993 hepatitis trial at the University
of Pavia involving 54 patients. Patients
with chronic hepatitis of either viral or
alcoholic origin were randomly assigned
to one of three groups. One group (n = 19)

received phytosomal silybin at 160 mg
daily; another group (n = 17) received 240
mg daily; and the third group (n = 18)
received 360 mg daily. The trial lasted two
weeks, with enzyme indicator testing
done after 1 and 2 weeks. Despite short
duration of the trial, AST was significantly
lowered by all dosages. At the two higher
doses of 240 and 360 mg daily (but not at
160 mg daily), ALT and GGT were also
significantly reduced [4].
CONCLUSION
Silymarin has the most potent flavonoids
in milk thistle, similar to other flavonoids, it
is not well-absorbed. Silybin-PC complex
was successfully prepared by a simple,
novel method. It had no obvious adverse

effects on reproduction of rats and showed
no mutagenic effects in several testing
models. The silybin-PC complex provides
significant liver protection and enhances
bioavailability when it was taken orally.
Because of remarkable effects of the
milk thistle and advanced bioavailability of
phytosome, reseachers in Vietnam Military
Medical University have studied phytosome
formulation from standardized extract of
milk thistle fruit. From these raw phytosome
of milk thistle, we can prepare several

products to servepublic and soldiers.
REFERENCES
1. Indena. Silybin-PC (TM). From silybum
marianum (L.) Gaertn a new natural preventive
targeted at the liver. Seattle, WA: Indena USA
Inc.; www. indenausa.com. 2004.
2. Javed S, Kohli, Ali M. Reassessing
bioavailability. Altern Med Rev. 2011, pp.239249.
3. Joseph A. Kareparamban et al. Phytosome:
A novel revolution in herbal drugs. International
Journal of Research in Pharmacy and Chemistry.
2012, pp.299-310.
4. Parris Kidd, Kathleen. A review of
bioavailability and clinical efficacy of milk
thistle phytosome: A silybin-phosphatidylcholine
complex (Siliphos®). Alternative Medicine Review.
2005, Vol 10, No 3, pp.193-203.
5. Wina Maryana, Heni Rachmawati, Dicky
Mudhakir. Formation of phytosome containing
silymarin using thin layer-hydration technique
aimed for oral delivery. Materials Today:
Proceedings 3. 2016, pp.855-866.
6. Yanyu X, Yunmei S, Zhipeng C, Quineng
P. The preparation of silybin-phospholipid
complex and the study on its pharmacokinetics
in rats. Int J Pharm. 2006, p.307, pp.77-82.

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