Method for preparing an S-allylcysteine-containing composition

An Allium genus plant, typically garlic is extracted by adding water or alcohol to the garlic, subjecting a mixture of the solvent and the garlic to extraction, and collecting an extract liquid. A composition containing S-allylcysteine in the extract liquid from the garlic is obtained by adding cysteine to the solvent, the mixture of the solvent and the plant under extraction, or the extract liquid collected, and causing the cysteine to convert into S-allylcysteine which is effective controlling hepatopathy and oncogenesis.

This invention relates to a method for preparing an 
S-allylcysteine-containing composition from an Allium genus plant, and 
more particularly, to a method for preparing a composition containing 
S-allylcysteine in an extract from an Allium genus plant. The composition 
is useful as an ingredient or additive for medical preparations, cosmetic 
preparations, foods and the like. 
BACKGROUND OF THE INVENTION 
Allium genus plants include garlic, elephant garlic, scallion, onion, 
spring onion, green onion, leek, chives, and the like, and all have 
specific flavor. Since the ancient days, they have been cultivated all 
over the world as vegetables or medicinal plants. Among others, garlic is 
a perennial plant which is grown in Chine, Korea, Japan and many other 
countries. It is generally known as a tonic or restorative drug and has 
long been used as stomachic, diuretic, expectorant, intestinal 
controlling, bactericidal, and anthelmintic agents. There are many reports 
on characteristic sulfur components of garlic such as allicin, 
diallylsulfide, S-allylcysteine, ajoene, etc. Recent researches on the 
pharmaceutical action of these components are reported in the literature 
and patents, for example, Lancet, 1, 8212, 150-151 (1982), and Japanese 
Patent Application Kokai Nos. 42967/1980, 5203/1981, 209218/1982, 
140526/1986. Among others, S-allylcysteine has been reported as effective 
in controlling hepatopathy (Hiroshima, Journal of Medical Sciences, 34, 3, 
303-309 (1985)), in protecting against radiation (Z. Naturforsch, 35 c, 
726 (1980)), and in controlling oncogenesis (Proceedings of the American 
Association for Cancer Research, 30, 181 (1989)). Practical application of 
S-allylcysteine is expected. Also, elephant garlic is grown in Japan, 
U.S., and other countries and widely used like garlic. It was recently 
reported that elephant garlic contains steroid saponins having 
antibacterial action (see Chem. Pharm. Bull., 36, 3480-3486 (1988) and 
Japanese Patent Application Kokai No. 224396/1989). Regarding the 
treatments, typically deodorizing treatment of garlic and analogues, a 
number of reports have been available. 
However, in the production of a composition rich in a selected component 
derived from an Allium genus plant, few methods are known except for 
ajoene derived from garlic (see Japanese Patent Application Kokai No. 
129224/1987). No method for producing an S-allylcysteine rich composition 
is known. 
SUMMARY OF THE INVENTION 
An object of the present invention is to produce a composition containing a 
high content of S-allylcysteine in an extract from an Allium genus plant 
through simple operation at low cost. 
The inventors have found that the content of S-allylcysteine in an extract 
liquid from an Allium genus plant can be substantially increased by adding 
cysteine in any of the steps of extracting the Allium genus plant with a 
solvent. Although the reason why the content of S-allylcysteine can be 
increased by adding cysteine is not well understood, we presume that the 
enzymatic action of alliin (S-allylcysteine sulfoxide), which is a 
sulfur-containing amino acid, in the Allium genus plant produces allicin 
which reacts with the cysteine added to convert the cysteine into 
S-allylcysteine. 
Therefore, the present invention provides a method for preparing an extract 
liquid from an Allium genus plant, comprising the steps of adding a polar 
solvent to an Allium genus plant, subjecting a mixture of the solvent and 
the plant to extraction, and collecting an extract liquid. According to 
the present invention, cysteine is added to the polar solvent, the mixture 
of the solvent and the plant under extraction, or the extract liquid 
collected. Then the cysteine is converted into S-allylcysteine. There is 
obtained a composition containing S-allylcysteine in the polar solvent 
extract from the Allium genus plant.

DETAILED DESCRIPTION OF THE INVENTION 
The method for preparing an S-allylcysteine-containing composition 
according to the present invention starts with an Allium genus plant. The 
Allium genus plants used herein include plants belonging to the Allium 
genus of the Liliaceae family, for example, 
Allium sativum L. forma pekinense Makino commonly known as garlic, 
Allium cepa commonly known as onion, 
Allium chinense commonly known as scallion, and 
Allium ampeloprasum commonly known as great headed garlic or elephant 
garlic. Garlic and elephant garlic are preferred Allium genus plants. The 
Allium genus plants may be used alone or in admixture of two or more. 
A portion of the plant from which the end product is obtained is preferably 
a bulb which may be used in raw form although dry or frozen form is 
acceptable. In processing steps, the bulb may be used as such although 
crushing is preferred for efficient extraction. It is also possible to use 
a culture product obtained by subjecting the plant to tissue culture in a 
conventional manner. 
According to the present invention, the plant in any desired form as 
described above is subjected to extraction. Extraction may be carried out 
by any conventional techniques commonly used in the extraction of crude 
drugs. 
The extracting solvent used herein is a polar solvent. Often extraction is 
carried out with water and monohydric lower aliphatic alcohols. The 
preferred lower alcohols used as the extracting solvent are hydrous or 
anhydrous alcohols having 1 to 3 carbon atoms, most preferably ethanol. 
The solvent may be used alone or in admixture of two or more. In the case 
of a hydrous alcohol, it may have any desired content of alcohol, 
typically contain 0 to 50% by weight of alcohol. The amount of the 
extracting solvent used is not particularly limited although the weight of 
the solvent used is preferably 0.1 to 10 times, more preferably 0.5 to 5 
times the weight of the plant. 
Extraction may be effected at room temperature or elevated temperatures. 
Since it takes a long time at room temperature, it is desired to process 
the mixture of the plant and the solvent at a temperature of 30.degree. to 
50.degree. C. for several hours to several days. 
At the end of extraction, the solid matter is removed from the extract 
mixture by suitable separation techniques such as filtration and 
centrifugal separation, collecting the extract liquid. This extract liquid 
typically contains sulfur-containing amino acids, polysaccharides, 
water-soluble components, and fat-soluble sulfides as major components. 
According to the present invention, cysteine is added at any stage of the 
above-mentioned extraction process. More particularly, cysteine may be 
added to the extracting solvent. Then cysteine is contained in the 
extracting mixture from the start of extraction. Also, cysteine may be 
added to the extracting mixture at an intermediate stage of extraction. 
Alternatively, cysteine may be added to the extract liquid resulting from 
extraction. In this way, cysteine can be added at any stage of the 
extraction process. Preferably, cysteine is added to the extract liquid 
resulting from extraction. The amount of cysteine added preferably ranges 
from 0.1 to 20%, more preferably from 1 to 5% by weight based on the 
weight of the plant. 
The cysteine added converts into S-allylcysteine in the extract liquid. 
This reaction can be promoted by maintaining the extract liquid neutral or 
alkaline, preferably at pH 7-12, more preferably pH 8-10. For pH 
adjustment, any of commonly used basic or acidic substances may be used if 
desired. Such pH adjusting substances include sodium hydroxide, aqueous 
ammonia, hydrochloric acid, acetic acid, and citric acid. The pH 
adjustment is not essential for the present process and may be carried out 
at any stage of the process. Preferably, the extract liquid resulting from 
extraction is subject to pH adjustment. It is possible to carry out 
extraction in the above-defined pH range if extraction is not adversely 
affected, so that there is obtained an extract liquid having the desired 
pH value. Preferably, cysteine is added immediately after pH adjustment. 
Of course, it is possible to extract an Allium genus plant with a solvent 
having cysteine already added thereto, and thereafter adjust the pH of the 
resulting cysteine-containing extract liquid. 
The reaction of cysteine may be effected by agitating the extract liquid at 
room temperature to 50.degree. C., preferably 30.degree. to 50.degree. C. 
The reaction time, after the addition of cysteine, generally ranges from 1 
to 10 days, preferably from 1 to 5 days at a temperature of 30.degree. to 
50.degree. C. A longer reaction time will be necessary at room 
temperature. 
At the end of reaction of cysteine, the extracting solvent may be removed. 
The extract liquid is ready for use without removing the extracting 
solvent if the solvent is not detrimental. 
The resulting composition is the (polar solvent) extract liquid of the 
Allium genus plant that contains a relatively high concentration of 
S-allylcysteine which has been converted from cysteine through reaction in 
the extract liquid. The concentration of S-allylcysteine is generally 0.1 
to 3%, preferably 0.5 to 3% by weight based on the weight of the 
composition from which the extracting solvent has been removed. 
Consequently, with only a simple step of adding cysteine, the present 
invention can efficiently produce an Allium genus plant-derived 
composition containing a relatively high concentration of S-allylcysteine 
which is effective in controlling hepatopathy, protecting against 
radiation and controlling oncogenesis. Thus the present invention greatly 
contributes to the supply of medicinal, cosmetic and food stock materials. 
EXAMPLE 
Examples of the present invention are given below by way of illustration 
and not bay way of limitation. 
EXAMPLE 1 
To 100 grams of frozen garlic was added 300 ml of water. The mixture was 
homogenized for about 3 minutes in a blender. The mixture was passed 
through a gauze filter and the filtrate was adjusted to pH 9.1 using 6 N 
NaOH. Test tubes were charged with 10 ml portions of the pH adjusted 
filtrate, to which 0, 2.5, 10, 25, 75 and 250 mg of cysteine were added. 
The contents were fully agitated. The test tubes were closed with plugs 
and allowed to stand at 37.degree. C. for several days. Samples were taken 
out after 1, 3 and 7 days from the cysteine addition. The amount of 
S-allylcysteine produced was quantitatively determined by high-pressure 
liquid chromatography (HPLC) using a post column method. 
The results are shown in FIG. 1. 
EXAMPLE 2 
To 159 grams of frozen garlic was added 476 ml of water. The mixture was 
homogenized for about 3 minutes in a blender. The mixture was passed 
through a gauze filter and the filtrate was adjusted to pH 9.0 using 6 N 
NaOH. The pH adjusted filtrate was divided into four portions. One portion 
is a control. To the three portions, 2.5 mg/ml of cysteine was added 
immediately after the pH adjustment (0 day), and after 1 and 2 days from 
the pH adjustment. The portions were allowed to stand at 37.degree. C. for 
several days. Samples were taken out of each portion after 1, 2, 3 and 4 
days from the cysteine addition. The amount of S-allylcysteine produced 
was quantitatively determined by HPLC using a post column method. 
The results are shown in FIG. 2. 
EXAMPLE 3 
To about 60 grams of frozen garlic were added a three times weight of water 
and 5%, 10%, 20% and 50% ethanol. Each mixture was homogenized for about 3 
minutes in a blender. Each mixture was passed through a gauze filter. Test 
tubes were charged with 10 ml of the filtrates, to each of which 25 mg of 
cysteine was added. The contents were fully agitated. The test tubes were 
closed with plugs and allowed to stand at 37.degree. C. for several days. 
Samples were taken out after 1, 3 and 7 days from the cysteine addition. 
The amount of S-allylcysteine produced was quantitatively determined by 
HPLC using a post column method. 
The results are shown in FIG. 3. 
EXAMPLE 4 
To 47 grams of frozen elephant garlic was added 140 ml of water. The 
mixture was homogenized for about 3 minutes in a blender. The mixture was 
passed through a gauze filter and the filtrate was adjusted to pH 9.0 
using 6 N NaOH. A test tube was charged with 10 ml of the filtrate, to 
which 25 mg of cysteine was added. The contents were fully agitated. As a 
control, another test tube was charged with 10 ml of the filtrate to which 
no cysteine was added. The test tubes were closed with plugs and allowed 
to stand at 37.degree. C. for several days. Samples were taken out after 
0, 3 and 5 days from the cysteine addition. The amount of S-allylcysteine 
produced was quantitatively determined by HPLC using a post column method. 
The results are shown in FIG. 4. 
Although some preferred embodiments have been described, many modifications 
and variations may be made thereto in the light of the above teachings. It 
is therefore to be understood that within the scope of the appended 
claims, the invention may be practiced otherwise than as specifically 
described.