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

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.

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 (dangtruonggiang.hvqy@gmail.com)

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

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

six-hour 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

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 non-complexed 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]

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.239-249

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