Lactoferrin hydrolyzate for use as an antibacterial agent and as a tyrosinase inhibition agent

Lactoferrin hydrolyzates, having a decomposition rate between 6%-20% as measured by formol titration, for use as an antibacterial agent and which have remarkly more potent activity than unhydrolyzed lactoferrin; and lactoferrin hydrolyzates, having a decomposition rate between 4-50% as measured by formol titration, for use as a tyrosinase inhibition agent, are obtainable by conventional methods for hydrolysis with acids or enzymes, and are stable to heating.

FIELD OF THE INVENTION 
The present invention relates to lactoferrin hydrolyzate for use as an 
antibacterial agent and as a tyrosinase inhibition agent. In other words, 
the present invention relates to an antibacterial and/or tyrosinase 
inhibition agent consisting of or containing lactoferrin hydrolyzate as 
the effective components. 
BACKGROUND OF THE INVENTION 
Lactoferrin is known as an iron-binding protein occurring in lacrima, 
saliva, peripheral blood, milk and the like. It is known that lactoferrin 
has antibacterial activity against coliform bacillus (Escherichia coli), 
staphylococcus and other enterobacteria (or enteric bacteria) in a 
concentration within the range of 0.5-30 mg/ml (Nonnecke, B. J. and Smith, 
K. L.; Journal of Dairy Science; Vol. 67, pp.606; 1984). 
It has been considered in general that the antibacterial activity of 
lactoferrin is derived from the situation wherein environmental iron 
becomes unavailable to those microorganisms which require iron strongly, 
due to the chelation of lactoferrin with environmental iron. The 
antibacterial activity of lactoferrin is not necessarily strong enough, 
thus a considerable quantity of lactoferrin is required to utilize its 
antibacterial activity, especially when lactoferrin is added to, 
impregnated into, adhered to, or coated onto other materials. Thus, there 
is a limitation of its usefulness as an antibacterial agent. 
It has been attempted to increase the antibacterial activity of 
lactoferrin. For example, it has been proposed to use lactoferrin together 
with lysozyme (Japanese Unexamined Patent Application Gazette No. 
62(1987)-249931). It has been also reported that the copresence of 
lactoferrin and secretory IgA may multiplicatively augment antibacterial 
activity of the former (S. Stephens, J. M. Dolby, J. Montreuil and G. 
Spik; Immunology; Vol. 41; Page 597; 1980). 
To the best knowledge of the inventors, however, there has been no report 
indicating that chemical treatment of lactoferrin may improve its 
antibacterial activity. 
It is also known that lactoferrin is unstable to heating, and that the 
antibacterial activity of lactoferrin can be almost completely suppressed 
by heating it at 62.5.degree. C. for 30 minutes, and complete deactivation 
is achieved by heating it at 70.degree. C. for 15 minutes (Ford, J. E. et 
al; Journal of Pediatrics, Vol. 90, page 29; 1977). 
Therefore, sufficient thermal treatment cannot be applied to those 
materials which contain lactoferrin as an antibacterial agent. 
Also, it is known that lactoferrin is not stable to pH variation. 
The inventors of the present invention have exerted their efforts to 
increase the antibacterial activity of lactoferrin and to improve its 
stability to heating, and found that hydrolyzates of lactoferrin 
substances such as native lactoferrin, apolactoferrin, metal saturated 
lactoferrin, and mixtures thereof show much stronger antibacterial 
activity and superior stability to heating than unhydrolyzed lactoferrin. 
The present invention is based on this discovery. The words "native 
lactoferrin" used herein means that lactoferrin was just isolated from 
milk and the like, and that no chemical treatment such as iron removing 
and chelation with metals is made thereon. 
Meanwhile it has not been known that lactoferrin and its hydrolyzates have 
potent tyrosinase inhibition activity. 
Tyrosinase is known as an enzyme which may act as a catalyst for the 
oxidization of tyrosine, and other monohydric phenols and corresponding 
dihydric orthophenols with molecular oxygen. Tyrosinase widely occurs in 
plants such as mushrooms, potatoes, apples as well as in animal tissues. 
It is also known that tyrosinase is related to darkening phenomena at an 
injured portion of plant tissue, and is also related to the formation of 
melanin pigment in various tissues of animals, especially in epidermal 
cells (Editorial Committee of Encyclopedia Chimica, Encyclopedia Chimica, 
Vol. 5, page 976, Kyohritsu Shuppan; 1960). 
It is also known that pigmentation of melanin in epidermal cells or mucous 
membranes in Addison's disease results from a decrease in secretion of 
adrenal cortex hormones which antagonize melanotropin which in turn 
promotes tyrosinase activity (Editorial Committee of Encyclopedia Chimica, 
Encyclopedia Chimica, Vol. 1, Page 65, Kyohritsu Shuppan; 1960). 
Therefore, it has been strongly desired, in the industrial fields of 
pharmaceuticals, cosmetics, food and the like, to develop a tyrosinase 
inhibition agent for prevention and therapy of symptoms resulting from 
undesirable effects of tyrosinase activity. Especially in the cosmetics 
industry, research has been actively made on cosmetics or medicines for 
external use for effective inhibition of melanin-formation and for 
whitening of skin, and many products containing tyrosinase inhibition 
agents have been successively developed. There are known many tyrosinase 
inhibition agents, for example, cysteine and vitamin C (Yutaka Mishima et 
al, Fundamental Dermatology, page 258, Asakura Shoten; 1973), kojic acid 
(Nikkei Sangyo Newspaper, May 24th 1988), arbutin (Ken-ichi Tomita, 
Preliminary Text for 20th F. J. Seminar, page 21, Fragrance Journal 
Company, Mar. 14, 1990), products of microorganism belonging to the genus 
of Trichoderma (Unexamined Japanese Patent Application Gazette No. 
2(1990)-145189). 
The conventional tyrosinase inhibition agents, however, had more or less 
defects in that they are unstable in the products, they are excessively 
potent to melanocytes which produce melanin pigment, they are too 
expensive due to the difficulty in obtaining their raw materials, and they 
are not usable as cosmetics or medicines for external use from the view 
points of safety, economics, preservability, reliability for whitening 
effect and so on. 
The inventors of the present invention found that lactoferrin, especially 
its hydrolyzate, has potent tyrosinase-inhibition activity. The present 
invention is also based on this discovery. 
OBJECTS OF THE INVENTION 
Therefore, it is an object of the present invention to provide lactoferrin 
hydrolyzate for use as an antibacterial agent. 
More particularly, it is an object of the present invention to provide an 
antibacterial agent consisting of lactoferring hydrolyzate as the 
effective component. 
It is another object of the present invention to provide antibacterial 
agent comprising an effective amount of lactoferrin hydrolyzate as an 
effective component. 
It is a still further object of the present invention to provide various 
products containing the antibacterial and/or tyrosinase inhibition agent. 
It is a further object of the present invention to provide a method for 
treating materials with said antibacterial agent. 
It is another object of the present invention to provide lactoferrin 
hydrolyzate for use as a tyrosinase inhibition agent. 
It is a further object of the present invention to provide a tyrosinase 
inhibition agent consisting of lactoferrin hydrolyzate. 
It is a still further object of the present invention to provide tyrosinase 
inhibition agent comprising an effective amount of lactoferrin hydrolyzate 
as an effective component. 
It is a further object of the present invention to provide various types of 
products comprising an effective amount of lactoferrin hydrolyzate as a 
tyrosinase inhibition agent. 
SUMMARY OF THE INVENTION 
In accordance with one aspect of the present invention, lactoferrin 
hydrolyzate can be used as an excellent antibacterial agent. Preferable 
ranges in the decomposition rate of lactoferrin hydrolyzate for use as an 
antibacterial agent are 6-20%, especially 7-15%, as measured by the formol 
titration method (percentage of formol nitrogen to total nitrogen). 
In accordance with the other aspect of the present invention, lactoferrin 
hydrolyzate can be used as a tyrosinase inhibition agent. Preferable 
ranges in the decomposition rate of lactoferrin hydrolyzates for use as a 
tyrosinase inhibition agent are 4-50%, especially 6-40%, as measured by 
the same method. 
Lactoferrin hydrolyzate can be prepared by conventional methods (for 
example, hydrolysis of lactoferrin by organic or inorganic acids or by 
enzymes). 
Any lactoferrin substance can be used as the starting material for 
preparation of lactoferrin hydrolyzate, for example, lactoferrin 
obtainable in the market, native lactoferrin just isolated by conventional 
methods (for example, ion-exchange chromatography) from mammalian milk, 
apolactoferrin obtainable by removing iron from native lactoferrin with 
hydrochloric acid, citric acid and the like, metal saturated lactoferrin 
obtainable by chelating apolactoferrin with iron, copper, zinc, manganese 
and the like, or a mixture thereof (hereinafter these lactoferrin 
substances are abbreviated as LF). 
Any mammalian milk (for example, human breast milk as well as cow's, 
sheep's, goat's, horse's milk and the like) at any lactation stage (for 
example, colostrum, transitional milk, matured milk, milk in later 
lactation) can be used as the source of LF. Furthermore, processed milk or 
byproducts in milk-processing such as skim milk, whey and the like can be 
used as the source of lactoferrin (hereinafter they are referred to as 
milk and the like). 
Acid hydrolysis can be performed in accordance with conventional methods. 
For example, LF is dissolved into water or purified water in a 
concentration within the range of 0.1-20% (by weight, the same will be 
applied otherwise indicated), preferably 5-15%, followed by pH adjustment 
of the resultant solution to 1-4, preferably to 2-3, and hydrolysis 
reaction at a proper temperature depending upon the pH of the solution. 
For instance, when the pH is adjusted to 1-2, the solution is heated at 
80.degree.-130.degree. C., preferably at 90.degree.-120.degree. C.; when 
the pH is adjusted to 2-4, the solution is heated at 
100.degree.-130.degree. C., preferably at 100.degree.-120.degree. C.; 
respectively for 1-120 minutes, preferably 5-60 minutes until the 
decomposition rate (by formol titration) of the LF hydrolyzate is 6-20%, 
preferably to 7-15%. 
Enzymatic hydrolysis can be performed in accordance with conventional 
methods. For example, LF is dissolved into water or purified water in a 
concentration between 0.5-20%, preferably 5-15%, followed by pH adjustment 
of the resultant solution into the optimum pH range, and enzymatic 
hydrolysis is then conducted under proper conditions, for example, a 
temperature between 15.degree.-55.degree. C., preferably between 
30.degree.-50.degree. C. for 30-600 minutes, preferably for 60-300 
minutes. The reacted mixture is neutralized, followed by deactivation of 
the enzyme in accordance with conventional methods. 
In the case of the preparation of an antibacterial agent, any acidic 
enzymes such as MOLSIN F (trademark; by Seishin Seiyaku; optimum pH.: 
2.5-3.0), swine pepsin (by Wakoh Junyaku Kogyo; optimum pH: 2-3), SUMIZYME 
AP (trademark; by Shin Nihon Kagaku; optimum pH: 3.0), AMANO M (trademark; 
by Amano Seiyaku; optimum pH: 3.0) and the like can be used individually 
or in any combination thereof. Among them, good results are obtained by 
use of swine pepsin and SUMIZYME AP. 
In the case of the preparation of a tyrosinase inhibition agent, there is 
no limitation to the enzymes to be used. For example, Amano A (trademark, 
by Amano Seiyaku; optimum pH: 7.0), trypsin, exopeptidase originating from 
lactic acid bacteria recited in Japanese Examined Patent Application 
Gazette No. 48(1973)-43878 and commercial SHOHYU-ENZYME (soy sauce enzyme) 
comprising exopeptidase (by Tanabe Seiyaku) can be used, in addition to 
those enumerated above, individually or in any combination thereof. 
The quantity of enzymes to be used may be 0.1-5.0%, preferably 0.5-3.0% to 
the substrate used. 
Regardless of the method of hydrolysis, the resultant solution containing 
LF hydrolyzate is cooled by conventional methods, if necessary, followed 
by neutralization, demineralization, and decolorization. The resultant 
solution can be used as a liquid product as it is or if required, the 
solution is further concentrated and/or dried to obtain a concentrated 
liquid product or a powdery product. 
The conditions of hydrolysis referred to above are not critical, but can be 
modified depending upon the temperature, the period of time, the pressure 
as well as the kind and quantity of the acid or enzyme used. 
The LF hydrolyzate to the present invention is a mixture of the decomposed 
substances having different molecular weights. 
Thus obtained LF hydrolyzate is highly stable to heating, and is excellent 
in antibacterial activity compared to unhydrolyzed lactoferrin, and has 
tyrosinase inhibition activity.

DETAILED DESCRIPTION OF THE INVENTION 
Now some tests will be described hereunder for exemplifying the utility of 
LF hydrolyzate as an antibacterial agent. 
[TEST 1] 
The purpose of this test is to show relationships between the decomposition 
rate of LF hydrolyzate and antibacterial activity. 
1) METHOD 
1-1) Preparation of Samples 
Native LF sold in the market (by Oleofina, Belgium) was dissolved into 
purified water in 5% concentration. The resultant solution was divided 
into several lots which were adjusted into different pH, 1, 2, 3 and 4 by 
adding 1M hydrochloric acid thereto. The resultant solutions having 
different pH were subjected to hydrolysis reaction under different 
conditions in a combination of a temperature between 
60.degree.-130.degree. C. and a time between 5-60 minutes to thereby 
prepare samples of LF hydrolyzate having different decomposition rates as 
shown in Table 1. 
1-2) Measurement of Hydrolyzation Rate 
The decomposition rate (%) of the resultant LF hydrolyzate was determined 
in such a manner that the quantity of formol nitrogen in the respective 
samples was measured by formol titration method, then the resultant values 
were applied to the following formula: 
EQU decomposition rate (%)=100.times.(A/B) 
(wherein A denotes the quantity of formol nitrogen, and B denotes the 
quantity of total nitrogen). 
1-3) Preparation of Pre-Culture and Culture Medium 
1-3-1) Preparation of Pre-Culture 
From the stock culture of Escherichia coli, a loop of bacterial cells was 
taken out with a platinum loop and smeared onto a standard plate agar 
medium (by Nissui Seiyaku), followed by incubation at 35.degree. C. for 16 
hours under aerobic condition. The colonies grown on the surface of the 
culture were collected with a platinum loop and suspended into sterilized 
saline solution to prepare pre-culture having optical density of 1.0 (at 
660 nm) measured by a spectrophotometer (by Hitachi Seisakusho). 
1-3-2) Preparation of Basic Culture Medium 
Basic culture medium (liquid culture medium) was prepared by dissolving 
bactocasitone (by Difco) into purified water in 1% concentration, 
adjusting the pH of the resultant solution to 7.0 with 1M sodium 
hydroxide, then sterilizing at 115.degree. C. for 15 minutes. 
1-3-3) Preparation of Test and Control Culture Media 
The solutions of LF hydrolyzates previously prepared in item 1-1) were 
respectively filtered with membrane filters (by Advantech) to remove 
microorganisms which might be included therein. Different quantities of 
each of filtered solutions of LF hydrolyzates were respectively added to a 
portion of the basic culture medium to give 6 lots of test culture media 
containing LF hydrolyzate in different concentrations for each LF 
hydrolyzate having different decomposition rates as shown in Table 1. 
Control culture media containing unhydrolyzed LF in different 
concentrations were also prepared in the same manner as in the test 
culture media. 
1-3-4) Test for Antibacterial Activity 
To each of the test and control culture media, the pre-culture was 
inoculated in 1% concentration, followed by incubation at 35.degree. C. 
for 16 hours. The proliferation inhibition rate was determined by 
measuring the optical density of the culture broth in the same manner as 
previously described and calculating in accordance with the following 
formula: 
EQU proliferation inhibition rate (%)=100-(A/B.times.100) 
(wherein A denotes the difference of optical densities of the test culture 
media before and after 16 hours incubation, B denotes the difference of 
optical densities of the control culture media before and after 16 hours 
incubation respectively). 
2) RESULTS OF THE TEST 
The results are shown in Table 1. 
TABLE 1 
______________________________________ 
decomposition 
concentration (ppm) 
rate (%) 25 50 100 250 500 1000 
______________________________________ 
control 0 0 0 16 42 65 
6 8 26 40 94 100 100 
7 17 41 98 100 100 100 
8 21 60 100 100 100 100 
9 28 69 100 100 100 100 
10 23 74 100 100 100 100 
11 18 59 100 100 100 100 
12 11 45 100 100 100 100 
13 4 40 94 100 100 100 
14 2 38 86 100 100 100 
15 0 16 73 97 100 100 
16 0 9 47 84 96 100 
18 0 2 32 68 89 100 
20 0 0 20 56 82 93 
25 0 0 2 9 25 60 
30 0 0 0 0 1 5 
______________________________________ 
Note: the values indicate proliferation inhibition rates (%). 
As will be seen from the Table 1, the unhydrolyzed LF (control) showed 
antibacterial activity when more than 250 ppm of LF was added, but 
complete inhibition could not be achieved even when 1000 ppm of LF was 
added (weak antibacterial activity). In contrast to this, LF hydrolyzate 
having a 10% decomposition rate showed potent antibacterial activity at 
the concentration of 25 ppm, and proliferation of E. coli was completely 
inhibited at a concentration over 100 ppm. It will be understood that LF 
hydrolyzates of a decomposition rate between 6-20%, especially between 
7-15%, prepared by acid hydrolysis of LF have remarkably potent 
antibacterial activity in comparison with unhydrolyzed LF. 
[TEST 2] 
Ten samples of powdery LF hydrolyzates, nos. 1-10, were prepared by the 
following procedure: each of 5 kinds of commercial enzymes was added to 5% 
aqueous solution of commercial LF (by Oleofina), followed by adjustment of 
the pH to the optimum pH of the respective enzymes, enzymatic hydrolysis 
at 37.degree. C. for different reaction times, adjustment of the pH of the 
hydrolyzed solutions to 7, deactivation of the enzymes at 80.degree. C. 
for 10 minutes, and lyophilization of the resulting solutions. The kinds 
of enzymes and their quantities added to the substrate (LF), reaction 
times of hydrolysis and decomposition rates of the respective samples are 
shown in Table 2. The decomposition rates were determined by the same 
method as in Test 1. 
2) RESULT 
The results of this test are shown in Table 2. 
TABLE 2 
______________________________________ 
sam- reaction 
ple enzymes quantity of 
time decomposi- 
No. used enzyme (%) (minutes) 
tion rate (%) 
______________________________________ 
1 MOLSIN F 0.1 120 12.4 
2 MOLSIN F 1.0 300 14.7 
3 swine pepsin 0.3 30 6.3 
4 swine pepsin 3.0 180 11.4 
5 SUMIZYME AP 1.0 180 10.3 
6 SUMIZYME AP 3.0 180 13.5 
7 AMANO M 0.1 60 5.9 
8 AMANO M 3.0 120 12.6 
9 Trypsin 3.0 180 10.3 
10 Trypsin 6.0 360 12.5 
______________________________________ 
As will be seen from Table 2, decomposition rates of LF hydrolyzate by 
acidic proteases such as Molsin F, swine pepsin, Sumizyme AP, and Amano M 
fall between 5.9-14.7%, and those by trypsin which is a neutral protease 
were 10.3-12.5%. 
[TEST 3] 
The purpose of this test is to exemplify the antibacterial activity of LF 
hydrolyzate prepared by acid hydrolysis. 
Antibacterial activity against E. coli of LF hydrolyzate having a 12% 
decomposition rate prepared in the same manner as in Example 2 (hydrolysis 
by citric acid) and that of unhydrolyzed LF were determined in the same 
manner as in Test 1. 
The results are shown in Table 3. 
TABLE 3 
______________________________________ 
quantity added (ppm) 
sample 25 50 100 250 500 1000 
______________________________________ 
unhydrolyzed LF 
0 0 5 16 74 85 
LF hydrolyzate 
12 41 100 100 100 100 
______________________________________ 
Note: The values indicate proliferation inhibition rates (%). 
From the results of the foregoing test, it is exemplified that LF 
hydrolyzate prepared by organic acid hydrolysis, and inorganic acid 
hydrolysis have antibacterial activity. 
[TEST 4] 
The purpose of this test is to exemplify the effectiveness of the method 
for treatment of a material with antibacterial agent in accordance with 
the present invention. 
A quantity of sliced vegetables sold in the market was divided into three 
parts. Each of the parts was respectively dipped into a 1% aqueous 
solution of LF hydrolyzate prepared in the same manner as in Example 1 
(hydrolyzed by inorganic acid, decomposition rate: 9%), unhydrolyzed LF 
solution (control) and sterilized water (control) for 30 seconds. Each of 
the treated samples was drained then preserved at 5.degree. C. for 
observation. Viable bacterial count of the samples was periodically 
determined by the conventional method. 
The results of this test are shown in Table 4. 
TABLE 4 
______________________________________ 
preservation period (hours) 
Samples 0 12 24 36 
______________________________________ 
sterilized water 
5.1 .times. 10.sup.3 
4.9 .times. 10.sup.4 
5.0 .times. 10.sup.5 
9.2 .times. 10.sup.5 
unhydrolyzed LF 
5.1 .times. 10.sup.3 
2.0 .times. 10.sup.4 
1.8 .times. 10.sup.5 
2.2 .times. 10.sup.5 
LF hydrolyzate 
5.1 .times. 10.sup.3 
1.1 .times. 10.sup.3 
1.5 .times. 10.sup.3 
1.6 .times. 10.sup.3 
______________________________________ 
Note: the values indicate viable bacterial counts per 1 g of sliced 
vegetables. 
As will be seen from the Table 4, it is exemplified that LF hydrolyzate has 
remarkably stronger antibacterial activity than unhydrolyzed LF when they 
are used for treatment of materials. 
[TEST 5] 
The purpose of this test is to exemplify the effectiveness of inclusion of 
LF hydrolyzate in a food as the effective component for antibacterial 
activity. 
A quantity of raw milk was sterilized at 65.degree. C. for 30 minutes and 
dispensed into test tubes in 10 ml amounts. To each of the test tubes, LF 
hydrolyzate having a 9% decomposition rate (prepared in Example 1) or 
unhydrolyzed LF were added and homogeneously mixed in 0.1% concentration, 
and sealed to prepare samples No. 1 and No. 2. A sample which contains raw 
milk only was prepared as a control sample. These samples were preserved 
at 25.degree. C. to determine preservable days during which coagulation of 
raw milk was not observed. 
The results were that coagulation was observed in sample No. 1 on the 9th 
day, in sample 2 on the 4th day, and in control sample on the 2nd day. 
This means that LF hydrolyzate has excellent antibacterial activity. 
Meanwhile, an organoleptic test was carried out with respect to the 
control sample and sample No. 1 immediately after preparation of the 
samples, and confirmed that there was no difference in taste and 
appearance therebetween. 
[TEST 6] 
The purpose of this test is to exemplify antibacterial activity of LF 
hydrolyzate prepared by enzymatic hydrolysis. 
1) Method 
Aqueous solutions of 10 kinds of LF hydrolyzate (prepared using different 
enzymes) and an aqueous solution of unhydrolyzed LF prepared in the same 
manner as in test 2 were filtered with membrane filters (by Advantec) to 
remove bacterial cells which might be contaminated therein. Each of the 
solutions was added to basic culture media (the same with that in Test 1) 
in different concentrations (50, 100, 250, 500, and 1000 ppm) to prepare 
test cultures and control cultures. 
Antibacterial activity was tested for these cultures in the same manner as 
in test 1. 
2) Results 
The results are shown in Table 5. 
TABLE 5 
______________________________________ 
proliferation inhibition rate (%) 
sample quantity of LF hydrolyzate added (ppm) 
No. 50 100 250 500 1000 
______________________________________ 
1 20 78 100 100 100 
2 2 54 96 100 100 
3 0 5 24 78 100 
4 41 97 100 100 100 
5 35 93 100 100 100 
6 16 62 100 100 100 
7 0 3 15 38 61 
8 26 65 84 100 100 
9 0 0 0 0 0 
10 0 0 0 0 0 
control 0 0 7 25 46 
______________________________________ 
As will be seen from Table 5, addition of 250 ppm unhydrolyzed LF (control) 
showed weak antibacterial activity and complete inhibition against 
proliferation of E. coli could not be achieved even by addition of 1000 
ppm of unhydrolyzed LF. LF hydrolyzate having a decomposition rate over 
10% obtained from hydrolysis by MOLSIN F, swine pepsin, SUMIZYME AP and 
AMANO M, all of which are acidic proteases showed potent antibacterial 
activity at a concentration of only 100 ppm, and a concentration over 250 
ppm may inhibit proliferation of coliform bacillae perfectly. On the other 
hand, LF hydrolyzate resulting from hydrolysis by trypsin which is a 
neutral protease did not show any antibacterial activity even at a 
concentration of 1000 ppm. 
LF hydrolyzate having a decomposition rate of more than 10% as a result of 
hydrolysis by acidic proteases has stronger antibacterial activity against 
coliform bacillus than unhydrolyzed LF. 
[TEST 7] 
The purpose of this test is to confirm the antibacterial activity of a 
composition containing a hydrolyzate of metal saturated LF. 
The antibacterial activity of hydrolyzates of iron saturated LF was tested 
in the same manner as in test 5, except that hydrolyzates of iron 
saturated LF prepared in the same manner as in Example 5 and cow's milk 
sold in the market were used. 
Each of three kinds of samples, to one of which is added hydrolyzate of 
Fe-LF, to another one of which is added unhydrolyzed LF and the third of 
which is added nothing, were respectively distributed into 3 test tubes 
(in total 9) and preserved at 25.degree. C. for observation of any change 
in appearance. 
The results are shown in Table 6. 
TABLE 6 
__________________________________________________________________________ 
preservation (day) 
sample 9 3 7 10 14 
__________________________________________________________________________ 
hydrolyzate 
1 no change 
no change 
no change 
no change 
no change 
of Fe-LF 
2 no change 
no change 
no change 
no change 
no change 
3 no change 
no change 
no change 
no change 
no change 
unhydrolyzed 
1 no change 
no change 
no change 
no change 
coagulated 
Fe-LF? 2 no change 
no change 
no change 
no change 
coagulated 
3 no change 
no change 
no change 
no change 
coagulated 
control 
1 no change 
no change 
no change 
coagulated 
coagulated 
(added 2 no change 
no change 
no change 
no change 
coagulated 
nothing) 
3 no change 
no change 
no change 
coagulated 
coagulated 
__________________________________________________________________________ 
All of the samples (milk) to which was added hydrolyzate of Fe-LF did not 
show any change in appearance on the 14th day after initiation of the 
test. All of the samples to which was added unhydrolyzed LF did not show 
any change in appearance until 10th day after initiation of the test, but 
all of the samples showed coagulation on the 14th day. In the control 
samples, 2 samples showed coagulation on the 10th day, and all of the 
samples coagulated on the 14th day. It is exemplified that hydrolyzate of 
Fe-LF has excellent antibacterial activity in comparison with unhydrolyzed 
LF. 
[TEST 8] 
The purpose of this test is to confirm the antibacterial activity of LF 
hydrolyzate under the presence of iron. 
Antibacterial activity was tested with respect to some samples used in Test 
6, i. e. sample Nos. 1, 2, 5, 6 and the sample containing unhydrolyzed LF 
(control) in the same manner as in Test 6, except that 0.01 mM of ferrous 
sulfate (FeSO.sub.4) was further added to the respective culture media. 
The results are shown in Table 7. 
TABLE 7 
______________________________________ 
proliferation inhibition rate (%) 
sample quantity of LF hydrolyzate (ppm) 
No. 50 100 250 500 1000 
______________________________________ 
1 13 59 100 100 100 
2 0 26 87 100 100 
5 27 65 86 100 100 
6 14 40 93 100 100 
control 0 0 0 0 0 
______________________________________ 
The antibacterial activity of unhydrolyzed LF was deactivated in the 
presence of 0.01 mM of ferrous sulfate. However, all of the LF 
hydrolyzates resulting from hydrolysis by acidic proteases maintained 
their antibacterial activity in the presence of 0.01 mM of ferrous 
sulfate. 
Now some tests will be described hereunder for exemplifying the utility of 
LF hydrolyzate as a tyrosinase inhibition agent. 
[TEST 9] 
The purpose of this test is to exemplify the tyrosinase inhibition activity 
of LF hydrolyzate resulting from acid hydrolysis of LF. 
1) Preparation of Samples 
Native LF sold in the market (by Oleofina, Belgium) was dissolved into 
purified water in 5% concentration. The resultant solution was divided 
into several lots which were adjusted into different pH values, 1, 2, 3 
and 4 by adding 1M hydrochloric acid thereto. The resultant solutions 
having different pH values were subjected to hydrolysis reaction under 
different conditions in a combination of a temperature between 
60.degree.-130.degree. C. and a reaction time between 5-60 minutes, to 
thereby prepare 8 kinds of solutions of LF hydrolyzate having different 
decomposition rates as shown in Table 8. The resultant solutions were 
adjusted to pH 7 with 1M sodium hydroxide, then lyophilized to thereby 
obtain 8 kinds of powdery LF hydrolyzate in different decomposition rates 
between 4-30%. 
2) Method 
2-1) Determination of Decomposition Rate 
The decomposition rate (%) of the resultant LF hydrolyzate was determined 
in such a manner that the quantity of formol nitrogen in the respective 
samples was measured by formol titration method, then the resultant values 
were applied to the following formula: 
EQU Decomposition rate=100.times.(A/B) 
(wherein A denotes quantity of formol nitrogen, and B denotes quantity of 
total nitrogen). 
2-2) Measurement of Tyrosinase Inhibition Activity 
2-2-1) Preparation of Various Solutions 
2-2-1-1) Preparation of Substrate Solution 
L-tyrosine as guaranteed grade reagent (by Wakoh Junyaku Kogyoh) was 
dissolved into 0.1M phosphate buffer solution in 0.045% (W/V) 
concentration. 
2-2-1-2) Preparation of Enzyme Solution 
Tyrosinase derived from mushroom (by Sigma, 3,000 unit/mg) was dissolved 
into 0.1M phosphate buffer solution (pH 7.0) in 0.1% (W/V) concentration. 
2-2-1-3) Preparation of Copper Ion Solution 
Copper sulfate as guaranteed grade reagent (by Wakoh Junyaku Kogyoh) was 
dissolved into purified water in 1% (W/V) concentration. 
2-2-1-4) Preparation of Sample Solution 
Each of the solutions of LF hydrolyzate previously prepared in item 1) in 
different decomposition rates was respectively dissolved into 0.1M 
phosphate buffer solution (pH 7.0) to prepare sample solutions in 8 
different concentrations, so that when the sample solutions were added in 
the proportions described in the next item 2-2-2), 8 lots of test samples 
in different concentrations as shown in Table 8 were prepared for each of 
the LF hydrolyzates having different decomposition rates. 
2-2-2) Enzymatic Reaction 
Each of the resultant sample solutions, previously prepared substrate 
solution and the copper ion solution, which are previously heated to 
37.degree. C., were mixed in a test tube in the proportions as follows: 
______________________________________ 
sample solution 1.0 ml 
substrate solution 
0.9 ml 
copper ion solution 
0.02 ml 
______________________________________ 
To each of the mixtures, 0.08 ml of enzyme solution which was previously 
heated to the same temperature was added (in total 2.0 ml), and the 
enzymatic reaction was performed at 37.degree. C. for 3 minutes. After the 
reaction, 2 ml of 30% acetic acid solution was added to each of the 
reaction mixtures to terminate the enzymatic reaction, then the absorbancy 
of the respective reaction mixtures was measured with a spectrophotometer 
at the wave length of 640 nm (the values of the absorbancy are denoted as 
B). As a control, a solution was prepared substituting 1.0 ml of 0.1M 
phosphate buffer solution for the sample solution, and the resultant 
solution was subjected to the enzymatic reaction and measurement of 
absorbancy in the same manner as test samples No. 1-No. 8 (the value of 
the absorbancy of the control is denoted as A). When the sample solution 
was muddy, the absorbancy of a corresponding mixture which has the same 
composition as the muddy sample solution in question except that the 
enzyme solution was substituted with 0.08 ml of 0.1M phosphate buffer 
solution was measured (the value of the absorbancy is denoted as C), and 
the value of C is reduced from the value B to obtain the difference of 
absorbancy of the reaction mixture before and after enzymatic reaction. 
The measured values were applied to the following formula to obtain the 
tyrosinase inhibition rate (%): 
EQU inhibition rate=100.times.[1-(B-C)/A] 
3) Results 
The results are shown in Table 8. 
TABLE 8 
______________________________________ 
sample 
decomposition 
concentration of LF hydrolyzate (%) 
No. rate (%) 0.02 0.05 0.1 0.3 0.4 0.5 1.0 2.0 
______________________________________ 
control 
0 0 0 0 0 0 0 0 0 
1 4 -- -- 3 11 -- 19 30 50 
2 6 11 29 59 80 -- 100 -- -- 
3 8 9 33 61 79 -- 100 -- -- 
4 10 16 33 63 85 -- 100 -- -- 
5 15 10 32 61 81 -- 100 -- -- 
6 20 9 30 62 77 -- 100 -- -- 
7 25 9 28 60 82 -- 100 -- -- 
8 30 13 31 58 81 -- 100 -- -- 
______________________________________ 
Note: tyrosinase inhibition rate (%) 
Sample No. 1 which had a 4% decomposition rate showed a 10% tyrosinase 
inhibition rate with addition of 0.3% of the LF hydrolyzate. The 
inhibition activity increased as the concentration of LF hydrolyzate 
increased, such that a 30% inhibition rate was observed with addition of 
1% LF hydrolyzate, and a 50% inhibition rate was observed with addition of 
2% of the LF hydrolyzate. 
On the other hand, Samples No. 2-8 having decomposition rates 6-30% showed 
a 30% inhibition rate with addition of LF hydrolyzate only in 0.05% 
concentration. The inhibition rate increased as the concentration of LF 
hydrolyzate was increased, such that about a 60% inhibition rate was 
observed at 0.1% concentration, an 80% inhibition rate was observed at 
0.3% concentration, and 100% inhibition was observed at 0.5% 
concentration. 
It was also confirmed that acid hydrolyzates of other LF substances such as 
apolactoferrin, zinc-, copper-, and iron-LF showed similar tyrosinase 
inhibition rates. 
[TEST 10] 
The purpose of this test is to exemplify the tyrosinase inhibitory efficacy 
of LF hydrolyzate resulting from enzymatic hydrolysis of LF. 
1) Preparation of Sample 
LF sold in the market (by Oleofina) was dissolved into purified water in 5% 
concentration. The resultant LF solution was distributed into 8 lots to 
which different combinations of enzymes comprising swine pepsin, AMANO A 
and soy source enzyme containing peptidase sold in the market were added 
in different concentration between 0.1-6% to prepare samples Nos. 9-16. 
The resultant mixtures were kept at 37.degree. C. for different reaction 
times between 10 minutes-24 hours. The reacted solutions were adjusted to 
pH 7, heated to 80.degree. C. for 10 minutes for deactivation of enzymes, 
then lyophilized to obtain LF hydrolyzate having different decomposition 
rates between 6-50%. 
2) Method 
Decomposition rates and tyrosinase inhibition rates of the respective LF 
hydrolyzates were measured in the same manner as in Test 9. 
3) Results 
The results are shown in Table 9. 
TABLE 8 
______________________________________ 
sample 
decomposition 
concentration of LF hydrolyzate (%) 
No. rate (%) 0.02 0.05 0.1 0.3 0.5 1.0 2.0 
______________________________________ 
control 
0 0 0 0 0 0 0 0 
9 6 10 28 55 82 100 -- -- 
10 10 8 32 60 79 100 -- -- 
11 15 9 33 58 80 100 -- -- 
12 20 12 31 62 78 100 -- -- 
13 30 9 30 61 83 100 -- -- 
14 40 11 28 60 80 100 -- -- 
15 45 -- -- 2 11 23 35 54 
16 50 -- -- 3 10 27 33 52 
______________________________________ 
Note: tyrosinase inhibition rate (%) 
Sample Nos. 9-14 which had a decomposition rate between 6-40% showed about 
a 30% tyrosinase inhibition rate with addition of 0.05% LF hydrolyzate. 
The inhibition activity increased as the concentration of LF hydrolyzate 
increased. About a 60% inhibition rate was achieved with addition of 0.1% 
LF hydrolyzate, about 80% inhibition rate with addition of 0.3%, LF 
hydrolyzate and 100% inhibition rate with addition of 0.5% LF hydrolyzate. 
On the other hand, Sample Nos. 15 and 16 having decomposition rates of 45 
and 50% respectively showed about a 10% inhibition rate at 0.3% 
concentration of LF hydrolyzate. The inhibition rate increased as the 
concentration of LF hydrolyzate was increased, such that about a 30% 
inhibition rate was achieved at 1% concentration, and about a 50% 
inhibition rate at 2% concentration. 
It was also confirmed that enzymatic hydrolyzate of other LF substances, 
that is apolactoferrin, metal saturated LF chelated with metals such as 
zinc, copper, iron and the like showed substantially the same tyrosinase 
inhibition rate. More specifically it was found that the tyrosinase 
inhibition rate mainly depends upon the decomposition rate of LF 
hydrolyzate. 
Now, some examples will be described for better understanding of the 
present invention. 
EXAMPLE 1 
To 950 g of purified water, 50 g of native LF sold in the market (by 
Oleofina, Belgium) was dissolved, then the pH of the solution was adjusted 
to 2 with 1M hydrochloric acid. The resultant solution was heated to 
120.degree. C. for 15 minutes for acid hydrolysis, then cooled, thereby 
about 1000 g of a 5% solution of LF hydrolyzate having antibacterial 
activity was obtained. The decomposition rate of the LF hydrolyzate was 9% 
(determined by the same method as in Test 1). 
EXAMPLE 2 
To 850 g of purified water, 150 g of native LF sold in the market (by 
Oleofina, Belgium) was dissolved. The resultant solution was adjusted to 
pH 3 with 1M citric acid, then heated to 130.degree. C. for 60 minutes for 
hydrolysis. The resulting solution was cooled, adjusted to pH 7 with 1M 
sodium hydroxide, filtered, demineralized, then lyophilized (freezedried) 
thereby about 45 g of powdery LF hydrolyzate having antibacterial activity 
was obtained. 
The decomposition rate of this LF hydrolyzate was 12% (determined by the 
same method as in Test 1). 
EXAMPLE 3 
1) Preparation of Fe Saturated LF 
To 180 g of purified water, 20 g of native LF sold in the market (by 
Oleofina, Belgium) was dissolved. To the resultant solution, 200 mg of 
FeSO.sub.4.7H.sub.2 O was added. After maintaining at 25.degree. C. for 12 
hours, unreacted Fe was removed from the reacted solution by 
ultrafiltration module SEP-1013 (trademark, by Asahikasei), then the 
resultant filtrate was lyophilized to thereby obtain about 19 g of iron 
saturated LF. 
2) Hydrolysis of Fe Saturated LF 
To 285 g of purified water, 15 g of iron saturated LF was dissolved, the pH 
of the resulting solution was adjusted to 1.0 with 2M hydrochloric acid, 
heated at 90.degree. C. for 15 minutes for hydrolysis, then cooled, 
thereby yielding about 300 g of about 5% solution of LF hydrolyzate having 
antibacterial activity. 
The decomposition rate of the resulted LF hydrolyzate was 7% (determined by 
the same method as in Test 1). 
EXAMPLE 4 
1) Preparation of Column 
In a column (id. 10 cm), 500 ml of SEPABEADS FP-CM13 (trademark, by 
Mitsubishi Kasei) having a carboxymethyl group as an ion-exchange group 
was placed, then a 10% aqueous solution of sodium chloride was passed 
through the resulting column. The column was washed with water to thereby 
obtain a Na-type ion-exchanger. 
2) Preparation of Native LF 
To the resultant column, 60 l of cheese whey (pH 6.5) originated from goat 
milk was introduced at 4.degree. C. at the flow rate of 4 l/hour. After 
the column was washed with water to remove the unadsorbed components of 
the cheese whey, the adsorbed component of the cheese whey was eluted with 
a 10% aqueous solution of sodium hydroxide at the flow rate of 5 l/hour to 
thereby obtain about 5 l of eluate. The resultant eluate was concentrated 
with ultra-filtration module SEP-1013 (trademark, by Asahikasei) then 
water was added thereto to remove sodium chloride to thereby obtain about 
200 ml of LF solution containing 1% goat LF. 
3) Acid Hydrolysis 
The resultant LF solution was adjusted to pH 2.0 with 1M hydrochloric acid, 
heated to 120.degree. C. for 20 minutes, then cooled, to thereby obtain 
about 200 g of a 1% solution of LF hydrolyzate having antibacterial 
activity. The decomposition rate of the LF hydrolyzate was 10% (determined 
by the same method as in Test 1). 
EXAMPLE 5 
1) Preparation of Fe Saturated LF 
To 9 kg of purified water, 1 kg of native LF (by Oleofina, Belgium) was 
dissolved. To the resultant solution, 10 g of FeSO.sub.4.7H.sub.2 O was 
added, and maintained at 25.degree. C. for 12 hours. From the resultant 
solution, unreacted iron was removed by ultrafiltration module SEP-1013 
(trademark, by Asahikasei). 
2) Enzymatic Hydrolysis 
After adjusting the resultant solution to pH 3.5 with 0.5N hydrochloric 
acid, 10 g of MOLSIN F (trademark, by Seishin Seiyaku, 42,000 unit/g of 
protein) sold in the market was added to the solution and homogeneously 
mixed. The resultant mixture was maintained at 37.degree. C. for 180 
minutes, neutralized, heated to 85.degree. C. for 10 minutes for 
deactivation of the enzyme, then cooled, thereby yielding about 10 kg of 
LF hydrolyzate solution having antibacterial activity. 
The decomposition rate of the resultant LF hydrolyzate was 13.5% 
(determined by the same method as in Test 1). 
EXAMPLE 6 
To 9 kg of purified water, 1 kg of native LF (by Oleofina, Belgium) was 
dissolved. The resultant solution was adjusted to pH 2.5 with 2M citric 
acid, then 30 g of swine pepsin sold in the market was added (10,000 
unit/g of protein: by Wakoh Junyaku Kogyo), homogeneously mixed, 
maintained at 37.degree. C. for 180 minutes for hydrolysis, heated to 
85.degree. C. for 10 minutes for deactivation of the enzyme, cooled, then 
concentrated by the conventional method to thereby obtain about 10 kg of a 
solution of the LF hydrolyzate having antibacterial activity. 
The decomposition rate of the resultant LF hydrolyzate was 11.3% 
(determined by the same method as in Test 1). 
EXAMPLE 7 
1) Preparation Cu Saturated LF 
Copper saturated LF was prepared as follows. To 50 l of goat skim milk, 5 l 
of 0.1M citric acid solution containing 0.003M ferric chloride 
(FeCl.sub.3) was added and homogeneously mixed. To the resultant solution, 
5 l of CM-Sephadex C-50 (H.sup.+ type, by Pharmacia) was added and stirred 
for 1 hour. After removing unadsorbed components of the goat skim milk by 
washing the ion-exchange resin with water, the resin was suspended in 
0.05M tris-hydrochloride buffer solution (pH 8.2). The resultant 
suspension was placed in a column (20.times.50 cm), then washed with the 
same buffer solution. The adsorbed components of goat skim milk were 
eluted with 0.05M tris-hydrochloric acid buffer solution containing sodium 
chloride in a gradient of 0-2M to thereby collect about 800 ml of an 
LF-containing fraction. The resultant LF-containing fraction was 
concentrated to 150 ml with ultrafiltration membrane PM-10 (trademark, by 
Amicon), then dialyzed against 0.05M tris-acetate buffer solution (pH 8.2) 
containing 0.5M sodium chloride. The resultant dialyzed solution was 
introduced into a column (10.times.30 cm) filled with copper chelating 
SEPHAROSE 6B (trademark, by Pharmacia) which was previously equilibrated 
with the same buffer solution to adsorb LF. After washing the column with 
the same buffer solution, the adsorbate was eluted with acetate buffer 
solution (pH 4.0) containing 0.5M sodium chloride. The resultant eluate 
was dialyzed against purified water, then lyophilized to thereby obtain 
about 2 g of powdery LF. 
2) Enzymatic Hydrolysis 
To 17 g of purified water, 2 g of the resulting powdery LF was added. The 
resultant solution was adjusted to pH 3.5 with 1M lactic acid. To the 
resultant solution, 60 mg of SUMIZYME AP sold in the market (trademark, by 
Shinnihon Kagakukogyo, 50,000 unit/g of protein) was homogeneously added, 
maintained at 50.degree. C. for 180 minutes, neutralized, then the 
resultant reaction mixture was heated to 85.degree. C. for 10 minutes for 
deactivation of the enzyme, cooled, concentrated then lyophilized to 
thereby obtain about 2 g of powdery LF hydrolyzate having antibacterial 
activity. 
The decomposition rate of the resulted LF hydrolyzate was 13.8% (determined 
by the same method as in test 1). 
EXAMPLE 8 
LF solution was prepared by dissolving 80 g of an LF sold in the market (by 
Oleofina) into 1000 ml of purified water, then the pH of the resultant LF 
solution was adjusted to 2 with 1M hydrochloric acid. The resultant 
solution was heated to 115.degree. C. for 10 minutes, adjusted to pH 7 
with 1M sodium hydroxide solution, then lyophilized to thereby obtain 
about 77 g of LF hydrolyzate powder having a 15% decomposition rate as 
measured by the same method as in Test 1. 
Having homogeneously mixed 50 g of the resultant LF hydrolyzate, 900 g of 
glycine (by Wakoh Junyaku Kogyo), and 50 g of lysozyme (by Wakoh Junyaku 
Kogyo), about 1000 g of a tyrosinase inhibition agent to be used for 
keeping freshness of food was prepared. 
The tyrosinase inhibition rate of a 20% aqueous solution of the resultant 
tyrosinase inhibition agent was 100% as measured in the same method as in 
Test 9. 
EXAMPLE 9 
After dissolving 270 g of LF sold in the market (by Oleofina) into 6300 ml 
of purified water, the pH of the resultant solution was adjusted to 2.5 
with a 10% aqueous solution of citric acid, and kept at room temperature 
for 1 hour for removal of iron. The reacted solution was subjected to 
ultrafiltration, and the resultant concentrate was lyophilized to thereby 
obtain about 260 g of apolactoferrin. 
Sixty g of the resultant apolactoferrin was dissolved into 1000 ml of 
water, and the resultant solution was adjusted to pH 3 with 2M phosphoric 
acid solution. The resultant solution was heated to 121.degree. C. for 25 
minutes, its pH adjusted to 7 with 1M sodium hydroxide solution, then 
lyophilized to thereby obtain about 55 g of powdery LF hydrolyzate having 
a 23% decomposition rate as measured by the same method as in Test 9. 
Having homogeneously mixed 20 g of the resultant LF hydrolyzate, 400 g of 
propylene glycol (by Wakoh Junyaku Kogyo), 4 g of oleyl alcohol (by Wakoh 
Junyaku Kogyo), 200 g of ethanol (by Wakoh Junyaku Kogyo) and 3376 g of 
purified water, about 4000 g of tyrosinase inhibition agent for use in 
cosmetics was obtained. 
The apparent inhibition rate against tyrosinase of the resultant agent was 
75%, but a substantial inhibition rate against tyrosinase was calculated 
to be 100% in consideration of LF hydrolyzate concentration. 
EXAMPLE 10 
Having homogeneously mixed 100 g of LF sold in the market (by Oleofina) and 
1000 ml of purified water, the pH of the resultant solution was adjusted 
to 2 with 1M hydrochloric acid. To the resultant solution, 5 g of swine 
pepsin sold in the market (by Wakoh Junyaku Kogyo) was added and reacted 
at 37.degree. C. for 60 minutes. The reacted solution was heated to 
80.degree. C. for 10 minutes for deactivation of the enzyme, then 
lyophilized to thereby obtain about 95 g of LF hydrolyzate having a 12% 
decomposition rate as measured by the same method as in Test 9. 
About 2000 g of a tyrosinase inhibition agent for cosmetic use was prepared 
by homogeneously mixing 30 g of the resultant LF hydrolyzate, 200 g of 
propylene glycol (by Wakoh Junyaku Kogyo), 2 g of oleyl alcohol (by Wakoh 
Junyaku Kogyo), 100 g of ethanol (by Wakoh Junyaku Kogyo) and 1668 g of 
purified water. 
The tyrosinase inhibition rate of the resultant tyrosinase inhibition agent 
was 100% as measured by the same method as in Test 9. 
EXAMPLE 11 
One hundred and fifty g of LF sold in the market (by Oleofina) was 
dissolved into 150 g of purified water, the pH of the resultant solution 
was adjusted to 6 with 1M sodium hydroxide solution, then the solution was 
pasteurized at 60.degree. C. for 10 minutes. The resultant solution was 
cooled to 50.degree. C., and 15 g of trypsin (by Nobo) and 30 g of soy 
sauce enzyme containing peptidase sold in the market (by Tanabe Seiyaku) 
were added and reacted at 50.degree. C. for 5 hours. The reacted solution 
was heated at 80.degree. C. for 10 minutes for deactivation of the 
enzymes, then lyophilized to thereby obtain about 145 g of powdery LF 
hydrolyzate having a 38% decomposition rate as measured by the same method 
as in Test 9. 
Having homogeneously mixed 12 g of sodium hyaluronate (by Wakoh Junyaku 
Kogyo), 15 g of placenta extract (by Botoger, West Germany), 10 g of 
glycerin (by Wakoh Junyaku Kogyo) and 962 g of purified water, about 1000 
g of tyrosinase inhibition agent was obtained. 
The tyrosinase inhibition rate of the resultant agent was 100% as measured 
by the same method as in Test 9. 
EXAMPLE 12 
About 78 g of Fe-LF was prepared by dissolving 90 g of LF sold in the 
market (by Oleofina) into 2100 ml of purified water, then reacting with 
755 ml of a 2.6 mM aqueous solution of ferrous sulfate at room temperature 
for 24 hours. The resultant reacted solution was subjected to 
ultrafiltration, then the resultant concentrate was lyophilized. 
Forty g of the resultant Fe-LF was dissolved into 500 ml of purified water, 
and the pH of the resultant solution was adjusted to 3 with 1M 
hydrochloric acid solution. To the resultant solution, 5 g of SUMIZYME AP 
(by Shin Nihon Kagaku) was added and the resultant mixture was subjected 
to hydrolysis at 30.degree. C. for 3 hours. The reacted mixture was heated 
at 80.degree. C. for 10 minutes for deactivation of the enzyme, then 
lyophilized to thereby obtain about 35 g of LF hydrolyzate having an 18% 
decomposition rate as measured by the same method as in Test 9. 
About 500 g of a tyrosinase inhibition agent to be used for keeping 
freshness of food was prepared by homogeneously mixing 30 g of the 
resultant LF hydroplyzate, 450 g of glycine (by Wakoh Junyaku Kogyo), and 
20 g of lysozyme (by Wakoh Junyaku Kogyo). 
The tyrosinase inhibition rate of a 20% aqueous solution of the resultant 
agent was 100% as measured by the same method as in Test 9. 
EFFECTS OF THE INVENTION 
The effects of the present invention are as follows: 
1) The LF hydrolyzates for use as an antibacterial and/or tyrosinase 
inhibition agent of the present invention are safe for humans and animals, 
since it is a natural antibacterial and/or tyrosinase inhibitory substance 
derived from hydrolysis of milk components and the like. 
2) The LF hydrolyzates for use as an antibacterial and/or tyrosinase 
inhibition agent of the present invention have much stronger antibacterial 
activity than unhydrolyzed LF and have remarkably potent tyrosinase 
inhibition activity. 
3) The LF hydrolyzates for use as an antibacterial and/or tyrosinase 
inhibition agent of the present invention are stable to heating, and can 
be provided in liquid and powdery forms, thus it has wider application. 
4) The antibacterial and/or tyrosinase inhibition agent comprising LF 
hydrolyzate of the present invention can be prepared by mixing them with 
one or more of excipients or other medicines, inclusive of other 
antibacterial agents and/or other tyrosinase inhibition agents. 
5) The antibacterial agent and the tyrosinase inhibition agent consisting 
of or comprising LF hydrolyzate of the present invention can be utilized 
as a component of various products such as cosmetics, foods, feeds and 
other products which are desirable to be prevented or inhibited from 
qualitative deterioration due to proliferation of microorganisms and/or 
undesirable effects of tyrosinase activity. It is specifically noted that 
inclusion of the antibacterial and/or tyrosinase inhibition agent 
consisting of or comprising LF hydrolysate of the present invention in 
such products is effective not only for preservation of the products, but 
also is effective for therapy or prevention of bacterial infection and/or 
pigmentation of melanin therefrom when the products are given to humans 
and other animals or applied to the body surface thereof. 
6) The antibacterial and/or tyrosinase inhibition agent consisting of or 
comprising LF hydrolyzates of the present invention can be utilized for 
treatment of various materials, for example washing or dipping the 
materials in a solution of the agent so that the agent adheres to or is 
coated onto or impregnated into those materials, for maintenance of 
sanitary conditions and for prevention from deterioration in freshness 
thereof. It is specifically noted that the materials treated are also 
effective for therapy and prevention against bacterial infection or 
pigmentation of melanine or prevention therefrom when they are taken into 
or applied onto the body surface of human or animals subject to the 
condition that an effective amount of LF hydrolyzate is accompanied 
therewith (or remained therein).