.alpha.-glycosyl quercetin, and its preparation and uses

A novel .alpha.-glycosyl quercetin, wherein at least equimolar D-glucose residues are attached to quercetin via the .alpha.-bond, has a satisfactory water-solubility, light tolerance and stability, and exerts the inherent activity of quercetin in vivo. The .alpha.-glycosyl quercetin is prepared by a process comprising subjecting a solution containing quercetin and an .alpha.-glucosyl saccharide to the action of a saccharide-transferring enzyme to form an .alpha.-glycosyl quercetin, and recoverying the resultant .alpha.-glycosyl quercetin. The .alpha.-glycosyl quercetin can be advantageously used in combination with other materials in food products, cosmetic compositions and pharmaceutical compositions as a highly-safe and natural vitamin P-enriched agent, yellow-color-imparting agent, antioxidant, deodorant, stabilizer, quality-improving agent, antiseptic, prophylactic agent, therapeutic agent and ultraviolet-absorbing agent.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a novel .alpha.-glycosyl quercetin, and 
its preparation and uses, more particularly, it relates to (i) an 
.alpha.-glycosyl quercetin wherein at least equimolar D-glucose residues 
are attached to quercetin via the .alpha.-bond; (ii) a process for 
preparing .alpha.-glycosyl quercetin comprising subjecting a solution 
containing quercetin and an .alpha.-glucosyl saccharide to the action of a 
saccharide-transferring enzyme to form an .alpha.-glycosyl quercetin; and 
recoverying the resultant .alpha.-glycosyl quercetin, and (iii) a 
composition, for example, food products, cosmetics and pharmaceuticals for 
susceptive diseases, into which said .alpha.-glycosyl quercetin is 
incorporated. 
2. Description of the Prior Art 
Usually, quercetin is widely distributed in the plant kingdom as a 
glycoside, i.e. rutin wherein a saccharide is attached to quercetin via 
the .beta.-bond, and can be prepared by extracting and separating such a 
glycoside from plants and hydrolyzing the resultant glycoside with an acid 
or an enzyme to remove saccharides therefrom. 
Quercetin has a relatively-large resonance structure in terms of the 
chemical structure, and this exhibits a yellow-color-imparting ability, 
antioxidation activity, vitamin-P activity and ultraviolet-absorbing 
activity. Thus, quercetin could be useful in the fields of food products, 
pharmaceuticals and cosmetics. 
Quercetin, however, is soluble in a readily water-soluble organic solvent, 
but insoluble or scarcely soluble in water, and this renders the 
handleability very difficult. 
Propolis is an example of the fact that a large amount of quercetin is 
present in the natural world. As described in Propolis in natural 
therapeutics (1983), published by Maloine Editeur S. A., Paris, France, 
and Fragrance Journal, No. 83, pp. 36-39 (1987), propolis is a resin-like 
product which is stored by bees in a beehive, said propolis containing 
resins, beeswaxes, essential oils, pollens and flavonoids, and has been 
used in a variety of folk medicines for a long time. 
Recently, it was found that flavonoids in propolis were mainly composed of 
flavon aglycons such as chrysin, and flavonol aglycons such as galangin 
and quercetin, said flavonoids having been noticed as a major effective 
component of propolis. 
The flavonoids are prepared by the extraction of propolis with a readily 
water-soluble organic solvent such as methanol and ethanol, and an extract 
prepared in this manner has been commercially available in these days as a 
propolis extract or a propolis tincture. 
The flavonoids, however, dissolve in a water-soluble organic solvent, but 
are insoluble or scarcely soluble in water, and this strongly restricts 
their actual use. 
SUMMARY OF THE INVENTION 
There has been a great demand to overcome conventional drawbacks of 
quercetin and to realize a quercetin derivative which has a satisfactory 
water-solubility and which exerts a satisfactory physiological-activity in 
vivo without fear of causing side effects. 
The present invention was made to overcome the above drawbacks, more 
particularly, the present inventors studied to obtain a novel quercetin 
derivative by using a biochemical technique. 
As a result, the present inventors found that a novel .alpha.-glycosyl 
quercetin having a satisfactory water-solubility, as well as being readily 
hydrolyzed in vivo to exert the inherent physiological activity of 
quercetin without fear of causing side effects, was formed by subjecting a 
solution containing quercetin and an .alpha.-glucosyl saccharide to the 
action of a saccharide-transferring enzyme, and the preparation of the 
.alpha.-glycosyl quercetin and its uses in food products, cosmetics and 
pharmaceuticals for the prevention and/or the treatment of susceptive 
diseases was established. This .alpha.-glycosyl quercetin is not 
hydrolyzed by .beta.-glucosidase. Thus, the present inventors accomplished 
this invention. 
The present inventors also found that an .alpha.-glycosyl quercetin formed 
by a saccharide-transferring reaction and which is not hydrolyzed by 
.beta.-glucosidase was readily purified by allowing a post-reaction 
solution to contact a synthetic macroporous resin wherein the difference 
of adsorbing ability of substances on the resin was utilized. 
The preparation of the present .alpha.-glycosyl quercetin which is not 
hydrolyzed by .beta.-glucosidase overcomes all conventional drawbacks in 
the prior art and strongly facilitates the realization of an 
industrial-scale preparation of an .alpha.-glycosyl quercetin.

DETAILED DESCRIPTION OF THE INVENTION 
The quercetin usable in the invention includes both a quercetin specimen 
prepared by the hydrolysis of rutin and a mixture of quercetin and 
flavonoids, e.g. propolis. 
The quercetin prepared from propolis suitably usable in the invention 
includes a highly-purified quercetin, as well as an extract extracted from 
propolis with a readily water-soluble organic solvent or a 
partially-purified product prepared by dewaxing the extract, a suspension 
boiled out of propolis, and an extract extracted from propolis with an 
alkaline solution. If necessary, commercially-available quercetin products 
and those obtained by a chemical synthesis can be favorably used in the 
invention. 
The .alpha.-glucosyl saccharides which can be used in the present invention 
are those which can be utilized for the formation of an .alpha.-glycosyl 
quercetin by a saccharide-transferring enzyme. For example, partial starch 
hydrolysates such as amylose, dextrins, cyclodextrins and 
maltooligosaccharides, as well as a liquefied- or gelatinized-starch, can 
be suitably chosen. 
A specific .alpha.-glucosyl saccharide suitable for a 
saccharide-transferring enzyme is chosen in order to facilitate the 
formation of an .alpha.-glycosyl quercetin. 
In case of using .alpha.-glucosidase (EC 3.2.1.20) as a 
saccharide-transferring enzyme, maltooligosaccharides such as maltose, 
maltotriose and maltotetraose, as well as partial starch hydrolysates 
having a dextrose equivalent (DE) of about 10-70, can be favorably used as 
an .alpha.-glucosyl saccharide; in case of using cyclomaltodextrin 
glucanotransferase (EC 2.4.1.19), cyclodextrins or amylaceous substances 
having a DE of about 60 or lower, i.e. gelatinized starch having a DE of 
one or lower and partial starch hydrolysates having a DE of about 60, can 
be favorably used; and in case of using .alpha.-amylase (EC 3.2.1.1), 
amylaceous substances having a DE of about 30 or lower, i.e. gelatinized 
starch having a DE of one or lower and dextrins or partial starch 
hydrolysates having a DE of about 30, can be favorably used. 
The concentration of an .alpha.-glucosyl saccharide suitable for an 
enzymatic reaction is about 0.5-100-fold, preferably, about 2-20-fold of 
that of quercetin. 
The quercetin-containing solutions suitable for an enzymatic reaction are 
those which contain the possible highest level of quercetin, for example, 
those having a relatively-high concentration of quercetin in the form of 
suspension or solution which is prepared by dissolving quercetin in the 
presence of an organic solvent or under a relatively-high temperature 
condition or under an alkaline condition exceeding pH 7.0, said solutions 
having a concentration of about 0.01 w/v % or higher, preferably, about 
0.1-10.0 w/v % of quercetin. 
The saccharide-transferring enzymes usable in the invention include those 
which can form an .alpha.-glycosyl quercetin without decomposing quercetin 
when allowed to act on a solution containing quercetin and an 
.alpha.-glucosyl saccharide having a suitable property for the enzymes. 
Examples of such a saccharide-transferring enzyme appropriately used in the 
invention are .alpha.-glucosidases derived from animal and plant tissues 
such as pig liver and buckwheat seed, and from a culture obtainable by 
cultivating in a nutrient culture medium microorganisms including 
bacteria, molds and yeasts such as those of the genera Mucor, Penicillium 
and Saccharomyces; cyclomaltodextrin glucanotransferases derived from a 
culture of bacteria such as those of the genera Bacillus and Klebsiella; 
and .alpha.-amylases derived from a culture of fungi such as those of the 
genus Aspergillus. 
The saccharide-transferring enzymes should not necessarily be purified 
prior to use as long as they fulfill the above requirements, and, usually 
crude saccharide-transferring enzymes can attain the object of the 
invention. 
If necessary, the saccharide-transferring enzymes can be purified by 
conventional methods, prior to use. Furthermore, commercially-available 
saccharide-transferring enzymes can be used in the invention. 
The amount of a saccharide-transferring enzyme and a reaction time are 
closely depended on each other. From an economical viewpoint, a 
saccharide-transferring enzyme is usually used in an amount of which 
completes an enzymatic reaction within about 5-80 hours. 
Immobilized saccharide-transferring enzymes can be appropriately used 
batchwise and in a continuous manner. 
it is recommendable to effect an enzymatic reaction under a light-shielded 
condition as much as possible in order to prevent the decomposition of 
quercetin in a reaction solution. 
A post-reaction solution containing an .alpha.-glycosyl quercetin obtained 
in this manner can be used intact as a product containing an 
.alpha.-glycosyl quercetin without any further treatment. Usually, a 
post-reaction solution is filtered and concentrated into an 
.alpha.-glycosyl quercetin syrup which is then dried and pulverized into 
an .alpha.-glycosyl quercetin powder, if necessary. 
The product thus obtained can be advantageously used as a vitamin 
P-enriched agent, as well as a highly-safe and natural 
yellow-color-imparting agent, antioxidant, deodorant, stabilizer, 
quality-improving agent, antiseptic, prophylactic agent, therapeutic agent 
and ultraviolet-absorbing agent, in combination with other materials in 
food products, cigarettes, tobaccos, feeds, pet foods, agents for 
susceptive diseases, cosmetics and plastics. 
In case of preparing a purified .alpha.-glycosyl quercetin product, it can 
be prepared by separating an .alpha.-glycosyl quercetin from a crude 
.alpha.-glycosyl quercetin containing concomitants such as 
.alpha.-glucosyl saccharides with a synthetic macroporous resin wherein 
the difference of adsorbing ability of substances on the resin is 
utilized. 
The wording "synthetic macroporous resin" as referred to in the invention 
means non-ionic and porous synthetic-resins which have a relatively-large 
adsorptive area such as a styrene divinyl benzene copolymer, 
phenol-formaldehyde resin, acrylic resin and methacrylate resin. Examples 
of such a resin are "Amberlite XAD-1", "Amberlite XAD-2", "Amberlite 
XAD-4", "Amberlite XAD-7", "Amberlite XAD-8", "Amberlite XAD-11" and 
"Amberlite XAD-12", products of Rohm & Haas Company, Philadelphia, USA; 
"Diaion HP-10", "Diaion HP-20", "Diaion HP-30", "Diaion HP-40" and "Diaion 
HP-50", products of Mitsubishi Chemical Industries Ltd., Tokyo, Japan; and 
"Imac Syn-42", "Imac Syn-44" and "Imac Syn-46" products of Industri de 
Maatshappily activate N.V., Amsterdam, Netherlands. 
The purification method of a post-reaction solution containing the present 
.alpha.-glycosyl quercetin is effected by feeding the solution to a column 
packed with a synthetic macroporous resin, whereby the .alpha.-glycosyl 
quercetin and intact quercetin are adsorbed on the resin, while a large 
amount of concomitant .alpha.-glucosyl saccharides and water-soluble 
saccharides are eluted from the column without adsorbing on the resin. 
After completion of an enzymatic reaction, two or more purification methods 
such as filtration to remove insoluble substances formed in a reaction 
solution by neutralizing or heating the solution; adsorption to remove 
proteinaceous substances formed in a reaction solution by treating the 
solution with magnesium alumino silicate or magnesium aluminate; and 
deionization using ion-exchange resin (H- and OH-forms) can be 
advantageously used in combination before contacting a post-reaction 
solution to a synthetic macroporous resin, if necessary. 
The .alpha.-glycosyl quercetin and intact quercetin, which have been 
selectively adsorbed on a synthetic macroporous resin in a column, are 
first washed with a solution such as water, then the column is fed with a 
solution such as aqueous methanol- and ethanol-solutions, followed by the 
elution of the .alpha.-glycosyl quercetin. Thereafter, intact quercetin 
adsorbed on the resin is eluted from the column with an increase of the 
volume of the eluate or the concentration of the organic solvent. 
A syrup containing an .alpha.-glycosyl quercetin as a main component can be 
obtained by distilling a high-.alpha.-glycosyl quercetin content solution 
to remove an organic solvent and concentrating the resultant solution to 
give a prescribed concentration. A powder containing an .alpha.-glycosyl 
quercetin as a main component can be prepared by drying and pulverizing 
the syrup. 
The elution step of the .alpha.-glycosyl quercetin and intact quercetin 
with an organic solvent enables the regeneration and the repeated use of a 
synthetic macroporous resin. 
The present purification step with a synthetic macroporous resin has an 
advantageous feature in that it can simultaneously remove concomitants 
such as .alpha.-glucosyl saccharides, water-soluble saccharides and 
water-soluble salts. The .alpha.-glycosyl quercetin thus obtained has the 
following features: 
(1) It has a higher level of water-solubility by a large margin than intact 
quercetin; 
(2) It has a higher level of light tolerance and stability than intact 
quercetin; 
(3) It exhibits substantially the same- or a slightly-lower level of 
yellow-color-imparting ability than intact quercetin; 
(4) It is hydrolyzed by the in vivo enzyme into quercetin and glucose to 
exert the inherent physiological activity of quercetin (vitamin P 
activity). When it is used in combination with vitamin C, the 
physiological activity is more augmented; and 
(5) When it contains an .alpha.-glucosyl saccharide, it exerts the inherent 
activity of .alpha.-glycosyl quercetin, and the .alpha.-glucosyl 
saccharides act as a filler, diluent or sweetener. When it is a purified 
product free of .alpha.-glucosyl saccharides, the product exerts the 
inherent activity of .alpha.-glycosyl quercetin without substantially 
acting as a filler or diluent. 
These features render the present .alpha.-glycosyl quercetin advantageously 
usable as a highly-safe and natural vitamin P-enriched agent, 
yellow-color-imparting agent, antioxidant, deodorant, stabilizer, 
quality-improving agent, antiseptic, prophylactic agent, therapeutic 
agent, and ultraviolet-absorbing agent, in combination with other 
materials in food products, cigarettes, tobaccos, feeds, pet foods, agents 
for susceptive diseases, plastics and cosmetics such as skin-refining 
agents and skin-whitening agents. 
More particularly, the vitamin-P activity of the present .alpha.-glycosyl 
quercetin can be advantageously more augmented by combining it with one or 
more derivatives of flavonoid saccharides such as rutin, hesperidin and 
naringin which have been recently paid attention as a bioflavonoid, as 
well as their .alpha.-glycosyl saccharide derivatives. 
The taste of the present .alpha.-glycosyl quercetin well harmonizes with 
other substances having a sour, saltiness, astringency, bitterness or 
deliciousness, and has a satisfiable acid-tolerance and thermal 
resistance, and these render the .alpha.-glycosyl quercetin advantageously 
useful in general food products, cigarettes and tobaccos such as 
seasonings, Japanese-style confectoneries, western-style confectoneries, 
ice creams, sherbets, beverages, spreads, pastes, pickled products, canned 
products, processed marine products, processed meat and fish meat 
products, processed milk and egg products, processed vegetable products, 
processed fruit products and processed cereal products. The 
.alpha.-glycosyl quercetin can be advantageously used to improve its taste 
and flavor in combination with one or more sweeteners, for example, those 
from plants such as stevioside, .alpha.-glycosyl stevioside, rebaudioside 
A, glycyrrhizin, .alpha.-glycosyl glycyrrhizin and dihydrochalcone; those 
of amino acids such as glycine, alanine and L-aspartyl-L-phenylalanine 
methyl ester; and those of saccharides such as sucrose, partial starch 
hydrolysate (thick malt syrup), glycosyl sucrose, glucose, isomerised 
sugar, fructose, honey, maltose, sorbitol, maltitol and lactose. The 
.alpha.-glycosyl quercetin prevents the crystalization and sedimentation 
of flavonoids present in a fruit juice, and this renders it advantageously 
useful as a turbidity- or dim-preventing agent for beverages and jellies 
containing a fruit juice. The .alpha.-glycosyl quercetin can be also 
advantageously used in feeds and pet foods for domestic animals, bees, 
silkworms and pet fishes as a vitamin P-enriched agent or a 
taste-improving agent. 
Furthermore, the .alpha.-glycosyl quercetin can be advantageously used in 
cigarettes, tobaccos, pharmaceuticals and cosmetics in the form of solid, 
paste and liquid, for example, troche, cod-liver oil, complex vitamin, 
sublingual tablet, cachou, oral refrigerant, gargle, intubation nutrition, 
crude drug, dentifrice, internal medicine, injection, lipstick, lip cream, 
sun-screening, prophylactic and/or therapeutic-agent for susceptive 
diseases, skin-refining agent, skin-whitening agent and hair-restorer. In 
addition, the .alpha.-glycosyl quercetin can be used in plastics as an 
ultraviolet-absorbing agent and deterioration-preventing agent. 
The wording "susceptive diseases" as referred to in the invention means 
those which can be prevented and/or treated with the present 
.alpha.-glycosyl quercetin. Examples of such susceptive diseases are viral 
diseases, bacterial diseases, traumatic diseases, immunopathies, 
rheumatisms, diabetes, diseases of circulatory organs, malignant tumors 
and nervous diseases. The form of such a prophylactic and/or therapeutic 
agent for susceptive diseases can be freely chosen to meet to its final 
use. Examples of such a form are liquid agents such as nebula, collyrium, 
collunarium, gargle and injection; agents in the form of a paste such as 
ointment, cataplasm and cream; and agents in the form of a solid such as 
powder, granule, capsule and tablet. In the preparation of these agents, 
the present .alpha.-glycosyl quercetin can be suitably used in combination 
with one or more other substances such as therapeutic agents, biologically 
active substances, antibiotics, adjuvants, fillers, stabilizers, 
color-imparting agents and flavor-imparting agents, if necessary. 
The dose of the prophylactic and/or therapeutic agents for susceptive 
diseases can be adequately controlled dependently on the content of the 
present .alpha.-glycosyl quercetin in the agents and their administration 
route and frequency. Usually, a dose in the range of about 0.001-10.0 
g/day/adult of .alpha.-glycosyl quercetin, on the dry solid basis 
(d.s.b.), is favorably used. 
In case of cosmetics, the present .alpha.-glycosyl quercetin can be used 
similarly as in the case of the above-mentioned agents. 
The .alpha.-glycosyl quercetin can be advantageously incorporated into a 
product before the completion of the processing by using conventional 
methods, for example, mixing, kneading, dissolving, soaking, penetrating, 
dispersing, applying, spraying and injecting. 
The following experiments will explain the present .alpha.-glycosyl 
quercetin in detail. 
EXPERIMENT 1 
Preparation of .alpha.-Glycosyl Quercetin 
EXPERIMENT 1-(1) 
Saccharide-Transferring Reaction 
One part by weight of quercetin and 6 parts by weight of dextrin (DE 20) 
were added with 500 parts by weight of water, and the mixture was adjusted 
to pH 9.5 and dissolved by heating under an anaerobic condition. 
Thereafter, the resultant mixture was cooled to 60.degree. C., added with 
40 units per g dextrin of a cyclomaltodextrin glucanotransferase specimen 
from Bacillus stearothermophilus, commercialized by Hayashibara 
Biochemical Laboratories, Inc, Okayama, Japan, and subjected to an 
enzymatic reaction at pH 8.5 or higher and at 60.degree. C. for 18 hours. 
After completion of the enzymatic reaction, the reaction solution was 
heated to inactivate the remaining enzyme to obtain a solution containing 
an .alpha.-glycosyl quercetin. 
EXPERIMENT 1-(2) 
Purification 
A post-reaction solution obtained by the method in Experiment 1-(1) was 
filtered and neutralized, and the resultant solution was fed at a flow 
rate of SV 2 to a column packed with "Diaion HP-10", a synthetic 
macroporous resin, commercialized by Mitsubishi Chemical Industries Ltd., 
Tokyo, Japan. The column was first washed with water, then fed with 50 v/v 
% ethanol, and the effluent was concentrated to remove ethanol and 
pulverized to obtain a yellow-colored .alpha.-glycosyl quercetin specimen 
[I] in the yield of about 220% against the weight of the material 
quercetin, d.s.b. 
EXPERIMENT 1-(3) 
Hydrolysis by Amylase 
An .alpha.-glycosyl quercetin specimen [I] prepared by the method in 
Experiment 1-(2) was dissolved in water into a 1 w/v % solution which was 
then added with 100 units per g specimen [I] of glucoamylse (EC 3.2.1.3), 
commercialized by Seikagaku-Kogyo Co., Ltd., Tokyo, Japan, and subjected 
to an enzymatic reaction for 5 hours while keeping the pH and temperature 
at 5.0.degree. and 55.degree. C. The reaction solution was heated to 
inactivate the remaining enzyme and fed at a flow rate of SV 2 to a column 
packed with "Diaion HP-10", a synthetic macroporous resin, commercialized 
by Mitsubishi Chemical Industries Ltd., Tokyo, Japan. As a result, an 
.alpha.-glycosyl quercetin and intact quercetin in the reaction solution 
were adsorbed on the resin, while glucose and salts were eluted from the 
column without adsorbing on the resin. Thereafter, the column was washed 
with water and fed with an aqueous ethanol solution while increasing the 
concentration of ethanol stepwise to effect fractionation, followed by 
recovering an .alpha.-glycosyl quercetin fraction. The resultant fraction 
was concentrated and pulverized to obtain a yellow-colored 
.alpha.-glycosyl quercetin specimen [II] in the yield of about 50% against 
the weight of the material quercetin, d.s.b. 
EXPERIMENT 2 
Physicochemical Properties of .alpha.-Glycosyl Quercetin 
(1) Solubility in solvent 
It is readily soluble in water and 0.1N sodium hydroxide; slightly soluble 
in methanol and ethanol; and insoluble in ether, benzene and chloroform. 
The solubility of the .alpha.-glycosyl quercetin specimen [I] in 
25.degree. C. water (pH 7) is about 10 w/v %, while that of intact 
quercetin is about 0.0002 w/v %. 
(2) Taste 
Intact quercetin and the .alpha.-glycosyl quercetin specimens [I] and [II] 
were respectively kept in the mouth directly and their tastes were 
compared. It was revealed that intact quercetin was tasteless as if you 
bite a grain of sand because intact quercetin did not melt in the mouth, 
while both of the specimens [I] and [II] smoothly melted in the mouth and 
exhibited a mild sweeteness. 
(3) Ultraviolet-absorption spectrum 
In order to compare the .alpha.-glycosyl quercetin specimen [I] or [II] 
with intact quercetin, their ultraviolet-absorption spectra were measured 
with methanol solution. The specimens [I] and [II] similarly as intact 
quercetin exhibited the first and the second maximum absorption peaks near 
253 nm and 373 nm respectively. 
(4) Infrared-absorption spectrum 
By using the KBr tablet method, the infrared-absorption spectrum of the 
.alpha.-glycosyl quercetin specimen [II] was studied. FIG.1 shows the 
result of the .alpha.-glycosyl quercetin specimen [II]. FIG. 2 shows the 
result of intact quercetin as a control. 
(5) Stability on hydrolysis 
(a) The .alpha.-glycosyl quercetin specimens are hydrolyzed by 
.alpha.-glucosidase (EC 3.2.1.20) from pig liver to form quercetin and 
D-glucose. 
(b) The .alpha.-glycosyl quercetin specimens are hydrolyzed by 
.beta.-glucosidase. 
(6) Analysis on high-performance liquid chromatography (HPLC) 
(a) Method of analysis 
Apparatus : WATERS MODEL M-6000A, a pump system commercialized by Japan 
Waters Ltd., Tokyo, Japan; 
Column: ODS-M column, a column product commercialized by Shimadzu 
Techno-Research, Inc., Kyoto, Japan; 
Column temperature : 53.degree. C.; 
Eluate : water:methanol : acetic acid =60:30:1 
Flow rate : 0.5 ml/min; and 
Detection wave length : at 255 nm. 
(b) Result 
As a result, the specimen [I] exhibited the inherent peak of quercetin at a 
retention time of 62 min and exhibited new peaks at 54, 44, 38, 33, 30, 
26, 25, 23, 21 and 19 min, while the specimen [II] exhibited two 
relatively-large peaks at 54 and 38 min in addition to a small peak 
corresponding to the inherent peak of quercetin at 62 min. 
Based on the results, a substance exhibiting new peaks contained in the 
specimen [I] was determined as an .alpha.-glycosyl quercetin wherein 
equimolar or more D-glucose residues are attached to quercetin via the 
.alpha.-bond. 
Two substances exhibiting new peaks contained in the specimen [II] were 
determined as .alpha.-glycosyl quercetins wherein equimolar or more 
D-glucose residues are attached to different positions of quercetin 
skeleton. As described above, the .alpha.-glycosyl quercetin according to 
the present invention is a novel saccharide derivative of quercetin having 
a satisfactory water-solubility wherein equimolar or more D-glucose 
residues are attached to quercetin via the .alpha.-bond. The 
.alpha.-glycosyl quercetin is readily hydrolyzed by .alpha.-glucosidase to 
exert the inherent physiological activity of quercetin when administered 
to a living body. 
(7) Antioxidation activity 
Ten ml of about one % linoleic acid in ethanol solution, 10 ml of 50 mM 
phosphate buffer and 5 ml water were mixed, and 5 ml aliquots of the 
mixture were distributed to 5 ml-flasks. Each flask was added with the 
.alpha.-glycosyl quercetin specimen [I] or [II] to give a concentration of 
200 ppm, sealed, and allowed to stand at 50.degree. C. under a 
light-shielded condition. As a control, d1-.alpha.-tocopherol which had 
been used as a typical antioxidant was used. A half ml of solution was 
sampled from each flask at a prescribed time interval, and the sampled 
solution was subjected to high-performance liquid chromatography (HPLC) to 
analyze the amount of hydroperoxide which was formed as a result of the 
oxidation of linoleic acid. The conditions used in the analysis of 
hydroperoxide were as follows: 
Apparatus : WATERS MODEL M-6000A, a pump system commercialized by Japan 
Waters Ltd., Tokyo, Japan; 
Column : ODS-M column, a column commercialized by Shimadzu Techno-Research, 
Inc., Kyoto, Japan; 
Column temperature : 35.degree. C. 
Eluate : water:methanol:acetic acid =75:25:0.1 
Flow rate : 0.5 ml/min 
Detection wave length: at 235 nm 
The results were as shown in Table 1. 
TABLE 1 
______________________________________ 
Antioxidation activity 
Sampling day 
Sample 0 4 7 8 
______________________________________ 
Control 0.3 1.5 5.3 7.1 
Added with dl-.alpha.-Tocopherol 
0.3 1.1 4.5 6.0 
Added with .alpha.-Glycosyl quercetin 
0.3 0.7 3.9 5.1 
specimen [I] 
Added with .alpha.-Glycosyl quercetin 
0.3 0.6 3.7 4.8 
specimen [II] 
______________________________________ 
Note: Each value indicates a relative intensity determined with the peak 
area corresponding to hydroperoxide. 
Based on the results in Table 1, the .alpha.-glycosyl quercetin specimens 
[I] and [II] exhibited a higher antioxidation activity than 
d1-.alpha.-tocopherol. 
EXPERIMENT 3 
Acute Toxicity 
An .alpha.-glycosyl quercetin specimen [I] prepared by the method in 
Experiment 1-(2) was tested on the acute toxicity by using 7 week-old dd 
mice. As a result, no mouse died up to a dose of 5 g of the specimen and a 
higher dose test was impossible. 
Thus, the acute toxicity of the specimen is extremely low. Similarly as 
above, an .alpha.-glycosyl quercetin specimen [II] prepared by the method 
in Experiment 1-(3) was tested on the acute toxicity to obtain the same 
result as in the specimen [I]. Thus, it was revealed that the acute 
toxicity of the specimen [II] was also extremely low. 
The preparations and uses of the present .alpha.-glycosyl quercetin will be 
described in the following Examples A and B. 
EXAMPLE A-1 
.alpha.-Glycosyl Quercetin 
To 200 parts by weight of water was added one part by weight of quercetin 
and 4 parts by weight of dextrin (DE 10), and the suspension was adjusted 
to pH 9.8, dissolved by heating under an anaerobic condition, cooled to 
60.degree. C., immediately added with 40 units per g dextrin of a 
cyclomaltodextrin glucanotransferase specimen from Bacillus 
stearothermophilus, commercialized by Hayashibara Biochemical Laboratories 
Inc., Okayama, Japan, and subjected to an enzymatic reaction at pH 8.5 or 
higher and at 55.degree. C. for 24 hours under anaerobic- and 
stirring-conditions. HPLC analysis of the reaction solution revealed that 
about 50% quercetin converted into .alpha.-glycosyl quercetins such as 
.alpha.-glucosyl quercetin, .alpha.-maltosyl quercetin and 
.alpha.-maltotriosyl quercetin. The reaction solution was neutralized, 
heated to inactivate the remaining enzyme and filtered, and the filtrate 
was in the usual manner deionized and purified by using an ion-exchange 
resin (H- and OH-forms), and concentrated to obtain an .alpha.-glycosyl 
quercetin syrup containing an .alpha.-glucosyl saccharide in the yield of 
about 80% against the weight of the material, d.s.b. 
The product can be advantageously used in combination with other materials 
in food products, cigarettes, tobaccos, feeds, pet foods, agents for 
susceptive diseases, cosmetics and plastics as a vitamin p-enriched agent 
with an improved water-solubility, as well as a highly-safe and natural 
yellow-color-imparting agent, antioxidant, stabilizer, quality-improving 
agent, prophylactic agents, therapeutic agents and ultraviolet-absorbing 
agents. 
EXAMPLE A-2 
.alpha.-Glucosyl Quercetin 
One part by weight of an .alpha.-glycosyl quercetin syrup containing an 
.alpha.-glucosyl saccharide, prepared in accordance with the method in 
Example A-1, was dissolved in 4 parts by weight of water, added with 100 
units per g .alpha.-glycosyl quercetin of glucoamylase (EC 3.2.1.3), 
commercialized by Seikagaku-Kogyo Co., Ltd., Tokyo, Japan, and subjected 
to an enzymatic reaction at 50.degree. C. for 5 hours. HPLC analysis of 
the reaction solution revealed that the .alpha.-glycosyl quercetin was 
converted into two types of .alpha.-glucosyl quercetin wherein a D-glucose 
residue is attached to a different position of quercetin moiety. The 
reaction solution was heated to inactivate the remaining enzyme and fed at 
a flow rate of SV 2 to a column packed with "Diaion HP-10", a synthetic 
macroporous resin commercialized by Mitsubishi Chemical Industries Ltd., 
Tokyo, Japan. As a result, the .alpha.-glucosyl quercetins and intact 
quercetin in the reaction solution adsorbed on the resin, while glucose 
and salts were eluted from the column without adsorbing on the resin. 
Thereafter, the column was first washed with water, then fed with aqueous 
ethanol solution while increasing the concentration of ethanol stepwise to 
fractionate the .alpha.-glucosyl quercetins. The resultant fraction 
containing .alpha.-glucosyl quercetins was concentrated in vacuo and 
pulverized to obtain an .alpha.-glucosyl quercetin powder in the yield of 
about 50% against the weight of the material quercetin, d.s.b. 
It was revealed that one mole of D-glucose was formed per mole of quercetin 
when the .alpha.-glucosyl quercetins were hydrolyzed with an acid, and the 
.alpha.-glucosyl quercetins were hydrolyzed into quercetin and D-glucose 
when subjected to the action of a partially-purified .alpha.-glucosidase 
specimen which had been extracted from pig liver and partially purified. 
The product can be advantageously used in combination with other materials 
in food products, cigarettes, tobaccos, agents for susceptive diseases, 
cosmetics and plastics, as a highly-purified vitamin p-enriched agent with 
an improved water-solubility, as well as a yellow-color-imparting agent, 
antioxidant, stabilizer, quality-improving agent, prophylactic agents, 
therapeutic agents and ultraviolet-absorbing agents. 
EXAMPLE A-3 
Mixture of .alpha.-Glycosyl Quercetin and Flavonoid 
One part by weight of a flavonoid mixture containing chrysin, galangin and 
quercetin, which had been prepared in conventional manner by dewaxing a 
propolis extract extracted with ethanol, and 10 parts by weight of dextrin 
(DE 8) were added with 200 parts by weight of water, and the suspension 
was adjusted to pH 9.8, dissolved by heating under an anaerobic condition, 
cooled to 60.degree. C., added with 50 units per g dextrin of 
cyclomaltodextrin glucanotransferase, and subjected to an enzymatic 
reaction at pH 8.5 or higher and at 55.degree. C. for 40 hours under 
anaerobic- and stirring-conditions. HPLC analysis of the reaction solution 
revealed that about 50% quercetin was converted into an .alpha.-glycosyl 
quercetin. 
The reaction solution was neutralized, heated to inactivate the remaining 
enzyme and filtered. Similarly as in Example A-1, the filtrate was in the 
usual manner purified, concentrated and spray-dried to obtain a powdery 
mixture of a flavonoid and an .alpha.-glycosyl quercetin containing an 
.alpha.-glucosyl saccharide in the yield of about 85% against the weight 
of the material, d.s.b. 
The product can be advantageously used in combination with other materials 
in food products, cigarettes, tobaccos, agents for susceptive diseases, 
cosmetics and plastics, as a vitamin p-enriched agent with an improved 
water-solubility, as well as a highly-safe and natural 
yellow-color-imparting agent, antioxidant, deodorant, stabilizer, 
quality-improving agent, antiseptic, prophylactic agents, therapeutic 
agents and ultraviolet-absorbing agents. 
EXAMPLE A-4 
Mixture of .alpha.-glycosyl Quercetin and Flavonoid 
A filtrate of a post-reaction solution, prepared in accordance with the 
method in Example A-3, was fed at a flow rate of SV 1.5 to a column packed 
with "Amberlite XAD-7", a synthetic macroporous resin commercialized by 
Rohm & Haas Company, Philadelphia, USA. 
As a result, an .alpha.-glycosyl quercetin and intact flavonoids in the 
filtrate adsorbed on the resin, while dextrin, oligosaccharides and salts 
were eluted from the column without adsorbing on the resin. 
The column was first washed with water, then fed with 50 v/v % methanol to 
elute the .alpha.-glycosyl quercetin and intact flavonoids. The effluent 
was concentrated and pulverized to obtain a powdery mixture of the 
.alpha.-glycosyl quercetin and flavonoids in the yield of about 55% 
against the weight of the material flavonoid mixture, d.s.b. 
The product can be advantageously used in combination with other materials 
in food products, cigarettes, tobaccos, agents for susceptive diseases, 
cosmetics and plastics, as a vitamin p-enriched agent with an improved 
water-solubility, as well as a highly-safe and natural 
yellow-color-imparting agent, antioxidant, deodorant, stabilizer, 
quality-improving agent, antiseptic, prophylactic agents, therapeutic 
agents and ultraviolet-absorbing agents. 
EXAMPLE A-5 
.alpha.-Glycosyl Quercetin 
EXAMPLE A-5(1) 
Preparation of .alpha.-Glucosidase Specimen 
A liquid culture medium consisting of 4 w/v % maltose, 0.1 w/v % potassium 
hydrogenphosphate, 0.1 w/v % ammonium nitrate, 0.05 w/v % magnesium 
sulfate, 0.05 w/v % potassium chloride, 0.2 w/v % polypeptone, 1 w/v % 
calcium carbonate (presterilized by heating and antiseptically added to 
the culture medium at a seeding time) and water was prepared, and 500 
hundred parts by weight of the culture medium was inoculated with a seed 
culture of Mucor javanicus IFO 4570 and incubated at 30.degree. C. for 44 
hours under shaking conditions. After completion of the cultivation, the 
resultant mycelia were recovered and 48 parts by weight of the wet mycelia 
was added with 50 parts by weight of 4M urea solution which had been 
prepared by dissolving urea in 0.5M phosphate buffer (pH 5.3), and the 
mixture was allowed to stand at 30.degree. C. for 40 hours and 
centrifuged. The resultant supernatant was dialyzed overnight against 
flowing water, added with ammonium sulfate to give a saturation degree of 
0.9, and allowed to stand at 4.degree. C. overnight, and the salted-out 
sediment was recovered by filtration, suspended and dissolved in 50 parts 
by weight of 0.01M acetate buffer (pH 5.3) and centrifuged, followed by 
recoverying the resultant supernatant, an .alpha.-glucosidase specimen. 
EXAMPLE A-5(2) 
Preparation of .alpha.-Glycosyl Quercetin 
Three parts by weight of quercetin and 20 parts by weight of dextrin (DE 
30) were added to 500 parts by weight of 20 v/v % aqueous ethanol 
solution, and the suspension was adjusted to pH 9.0, dissolved by heating 
under an anaerobic condition, cooled to 55.degree. C., immediately added 
with 15 parts by weight of an .alpha.-glucosidase specimen prepared by the 
method in Example A-5(1), and subjected to an enzymatic reaction at 
50.degree. C. and at pH 8.5 or higher for 40 hours under a stirring 
condition. HPLC analysis of the reaction solution revealed that about 30% 
quercetin was converted into an .alpha.-glycosyl quercetin. 
Similarly as in Example A-3, the reaction solution was purified, 
concentrated and pulverized to obtain an .alpha.-glycosyl quercetin powder 
containing an .alpha.-glucosyl saccharide in the yield of about 80%. 
Similarly as the product in Example A-3, the product can be advantageously 
used in combination with other materials in a variety of products as a 
vitamin P-enriched agent with an improved water-solubility, as well as a 
highly-safe and natural yellow-color-imparting agent, antioxidant, 
stabilizer, quality-improving agent, prophylactic agent, therapeutic 
agent, and ultraviolet-absorbing agent. 
EXAMPLE B-1 
Hard Candy 
One thousand and five hundred parts by weight of "MABIT.RTM.", a 
hydrogenated maltose syrup commercialized by Hayashibara Co., Ltd, 
Okayarea, Japan, was concentrated in vacuo up to give a moisture content 
of about 2% or lower, and admixed with an adequate amount of citric acid 
and one part by weight of a powdery mixture of an .alpha.-glycosyl 
quercetin and a flavonoid prepared by the method in Example A-4. The 
resultant mixture was in the usual manner molded and packed into a hard 
candy. 
The product is a relatively-low caloric vitamin p-enriched hard candy 
having a relatively-low dental-carries inducibility. 
EXAMPLE B-2 "Fuki-no-mizu-ni" (boiled big rhuharbs) 
Fresh bog rhuharbs were pared, cut into short sticks, soaked in a diluted 
salt solution for hours, and boiled down in a solution containing a 
green-coloring agent, which had been prepared by mixing food blue No.1 
(brilliant blue FCF) and an .alpha.-glycosyl quercetin syrup prepared by 
the method in Example A-1, to obtain the captioned product having a 
brilliant blue. 
The product having a natural taste is advantageously used as a material for 
Japanese-style foods. 
EXAMPLE B-3 
"Gyuhi" (starch paste) 
To one part by weight of glutinous rice starch was added 1.2 parts by 
weight of water, and the mixture was gelatinized by heating while admixing 
it with 1.5 parts by weight of sugar, 0.7 parts by weight of 
"SUNMALT.RTM.", a crystalline .beta.-maltose product commercialized by 
Hayashibara Co., Ltd., Okayama, Japan, 0.3 parts by weight of partial 
starch hydrolysate, and 0.02 parts by weight of an .alpha.-glycosyl 
quercetin powder prepared by the method in Example A-5. Thereafter, the 
resultant mixture was in an usual manner formed and packed to obtain the 
captioned product. 
The product having a natural taste is a Japanese-style confectionery like a 
"kibi-dango" (millet dumpling). 
EXAMPLE B-4 
Mixed Sweetener 
One hundred parts by weight of honey, 50 parts by weight of isomerized 
sugar, one part by weight of ".alpha.G sweet", an .alpha.-glycosyl 
stevioside product commercialized by Toyo Sugar Refining Co., Ltd., Tokyo, 
Japan, and 0.02 parts by weight of a powdery mixture of an 
.alpha.-glycosyl quercetin and a flavonoid prepared by the method in 
Example A-4. 
The product, a vitamin P-enriched sweetener, has a satisfactory 
taste-quality and about 2-fold higher sweetening power than sucrose, and 
these render the product advantageously useful as a health food. 
EXAMPLE B-5 
Cream Filling 
One thousand and two hundred parts by weight of "FINETOSE.RTM.", a 
crystalline .alpha.-maltose powder commercialized by Hayashibara Co., 
Ltd., Okayama, Japan, 1,000 parts by weight of shortening, 50 parts by 
weight of cacao mass, 3 parts by weight of an .alpha.-glycosyl quercetin 
powder prepared by the method in Example A-2, and one part by weight of 
lecithin were mixed in an usual manner to obtain a cream. 
The product is a vitamin P-enriched cream filling having a chocolate-like 
taste, as well as a satisfactory biting-property and meltability. 
EXAMPLE B-6 
Tablet 
Ten parts by weight of L-ascorbic acid was added with 19 parts by weight of 
crystalline .alpha.-maltose, 10 parts by weight of a powdery mixture of an 
.alpha.-glycosyl quercetin and a flavonoid prepared by the method in 
Example A-3, and one part by weight of ".alpha.G rutin", an 
.alpha.-glycosyl rutin product commercialized by Toyo Sugar Refining Co., 
Ltd., Tokyo, Japan, and the mixture was mixed to homogeneity and tabletted 
with a 20 R punch, diameter of 12 mm, to obtain a tablet. 
The product is an easily swallowable mixed-vitamin-agent containing 
L-ascorbic acid, .alpha.-glycosyl rutin and a mixture of an 
.alpha.-glycosyl quercetin and a flavonoid wherein the L-ascorbic acid is 
satisfiably stabilized. 
EXAMPLE B-7 
Capsule 
Ten parts by weight of calcium acetate monohydrate, 50 parts by weight of 
magnesium L-lactate trihydrate, 57 parts by weight of maltose, 20 parts by 
weight of a powdery mixture of an .alpha.-glycosyl quercetin and a 
flavonoid prepared by the method in Example A-4, and 12 parts by weight of 
a .gamma.-cyclodextrin inclusion complex containing 20% eicosapentaenoic 
acid were mixed to homogeneity, subjected to a granulator and encapsulated 
in gelatin in an usual manner to obtain capsules, 150 mg each. 
The product can be advantageously used as a blood-cholesterol-lowering 
agent, immunoactivator, skin-refining agent, prophylactic or therapeutic 
agent for susceptive disease, and food product for promoting health. 
EXAMPLE B-8 
Ointment 
One part by weight of sodium acetate trihydrate and 4 parts by weight of 
DL-calcium lactate were mixed to homogeneity with 10 parts by weight of 
glycerine, and the mixture was added with 50 parts by weight of 
petrolatum, 10 parts by weight of vegetable wax, 10 parts by weight of 
lanolin, 14.5 parts by weight of sesame oil, one part by weight of a 
powdery mixture of an .alpha.-glycosyl quercetin and a flavonoid prepared 
by the method in Example A-4, and 0.5 parts by weight of peppermint oil, 
and mixed to homogeneity to obtain the captioned product. 
The product can be advantageously used as a sun-screening, skin-refining 
agent, skin-whitening agent and promotor for healing injury and burn. 
EXAMPLE B-9 
Injection 
An .alpha.-glycosyl quercetin powder prepared by the method in Example A-2 
was dissolved in water and sterilely filtered in an usual manner to obtain 
a pyrogen-free solution which was then distributed to 20 ml-glass-vials to 
give an .alpha.-glycosyl quercetin content of 10 mg, freeze-dried and 
sealed to obtain an injection. 
The product is intramuscularly or intravenously administrable to a 
recipient alone or in combination with other vitamins and minerals. The 
product does not require a cold storage and it readily dissolves in 
physiological saline when in use. 
EXAMPLE B-10 
Injection 
Six parts by weight of sodium chloride, 0.3 parts by weight of potassium 
chloride, 0.2 parts by weight of calcium chloride, 3.1 parts by weight of 
sodium lactate, 45 parts by weight of maltose, and one part by weight of 
an .alpha.-glucosyl quercetin powder prepared by the method in Example A-2 
were dissolved in 1,000 parts by weight of water. The resultant solution 
was sterilely filtered in an usual manner to obtain a pyrogen-free 
solution, and 250 ml aliquots thereof were distributed to plastic 
containers to obtain the captioned product. 
The product, which is an injection for supplementing vitamin P, energy and 
minerals, is advantageously useful for promoting the treatment and the 
recovery of health during or after diseases. 
EXAMPLE B-11 
Intubation Nutrition 
A composition consisting of 20 parts by weight of crystalline maltose, 1.1 
parts by weight of glycine, 0.18 parts by weight of sodium glutamate, 1.2 
parts by weight of salt, one part by weight of citric acid, 0.4 parts by 
weight of calcium lactate, 0.1 part by weight of magnesium carbonate, 0.01 
part by weight of a powdery mixture of an .alpha.-glycosyl quercetin and a 
flavonoid prepared by the method in Example A-3, 0.01 part by weight of 
thiamine, and 0.01 part by weight of riboflavin was prepared. Twenty-four 
g aliquots of the composition were injected to laminated aluminum-bags and 
heat sealed to obtain the captioned product. 
The product can be advantageously used as an oral or parenteral intubation 
nutrition by dissolving one bag of the product in about 300-500 ml water 
and administering the solution to the nasal cavity, stomach or intestine. 
EXAMPLE 12 
Bath Salts 
A mixture consisting of 21 parts by weight of DL-sodium lactate, 8 parts by 
weight of sodium pyruvate, 5 parts by weight of an .alpha.-glycosyl 
quercetin syrup prepared by the method in Example A-1, and 40 parts by 
weight of ethanol was mixed with 26 parts by weight of refined water and 
adequate amounts of a color-imparting agent and a flavor-imparting agent 
to obtain the captioned product. 
The product can be suitably used as a skin-refining agent and 
skin-whitening agent and used by diluting it 100-10,000-fold with hot 
water in a bathtub, when in use. The product can be advantageously used by 
diluting it similarly as above with a cleansing liquid or lotion, prior to 
use. 
EXAMPLE B-13 
Milky Lotion 
One half part by weight of polyoxyethylene behenyl ether, one part by 
weight of polyoxyethylene sorbitol tetraoleate, one part by weight of 
oil-soluble glyceryl monosterate, 0.5 parts by weight of pyruvic acid, 0.5 
parts by weight of behenyl alcohol, one part by weight of avocado oil, one 
part by weight of an .alpha.-glycosyl quercetin syrup prepared by the 
method in Example A-1, and adequate amounts of an antiseptic and vitamin E 
were dissolved by heating in an usual manner, and the resultant solution 
was added with one part by weight of L-sodium lactate, 5 parts by weight 
of 1,3-butylene glycol, 0.1 part by weight of carboxy vinylpolymer and 
85.3 parts by weight of refined water. The resultant mixture was 
emulsified by a homogenizer, added with an adequate amount of a flavoring 
agent and mixed while stirring to obtain a milky lotion. 
The product can be advantageously used as a sun-screening, skin-refining 
agent and skin-whitening agent. 
EXAMPLE B-14 
Cream 
Two parts by weight of polyoxyethylene glycol monostearate, 5 parts by 
weight of self-emulsifying glycerine monostearate, 2 parts by weight of a 
powdery mixture of an .alpha.-glycosyl quercetin and a flavonoid prepared 
by the method in Example A-3, one part by weight of liquid paraffin, 10 
parts by weight of glyceryl trioctanate and an adequate amount of an 
antiseptic were dissolved by heating in an usual manner, and the resultant 
solution was added with 2 parts by weight of L-lactic acid, 5 parts by 
weight of 1,3-butylene glycol and 66 parts by weight of refined water. The 
resultant mixture was emulsified by a homogenizer, added with an adequate 
amount of a flavoring agent and mixed while stirring to obtain a cream. 
The product can be advantageously used as a sun-screening, skin-refining 
agent and skin-whitening agent. 
As described above, the present invention has the following advantageous 
features: (i) An .alpha.-glycosyl quercetin is readily formed by a 
biochemical technique which contains a step of subjecting a solution 
containing quercetin and an .alpha.-glucosyl saccharide to the action of a 
saccharide-transferring enzyme; (ii) the .alpha.-glycosyl quercetin 
diminishes the drawback of intact quercetin, i.e. intact quercetin is 
substantially not soluble or insoluble in water; and (iii) the 
.alpha.-glycosyl quercetin exerts a yellow-color-imparting ability as 
intact quercetin and it is readily hydrolyzed in vivo into quercetin and 
D-glucose to exert the inherent physiological activity of quercetin 
without fear of causing side effects. 
Thus, the .alpha.-glycosyl quercetin according to the present invention can 
be advantageously used as a highly-safe and natural vitamin P-enriched 
agent, yellow-color-imparting agent, antioxidant, deodorant, stabilizer, 
quality-improving agent, prophylactic agent, therapeutic agent, and 
ultraviolet-absorbing agent, and deterioration-preventing agent, in 
combination with other materials in food products, cigarettes, tobaccos, 
feeds, pet foods, agents for susceptive diseases, plastics and cosmetics 
such as skin-refining agents and skin-whitening agents. 
Accordingly, the establishment of the present industrial-scale preparation 
of an .alpha.-glycosyl quercetin and its uses has a great significance in 
the fields of food products, cosmetics, pharmaceuticals and plastics. 
While there has been described what is at present considered to be the 
preferred embodiments of the invention, it will be understood the various 
modifications may be made therein, and it is intended to cover in the 
appended claims all such modifications as fall within the true spirits and 
scope of the invention.