JP2001039886A - Hop polyphenol having topoisomerase inhibitory activity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain from hop or hop bract polyphenols as a potent topoisomerase inhibitor, having topoisomerase inhibitory activity, and intended as a carcinostatic. SOLUTION: This substance, a polyphenol-like matter contained in hop bract, is a substance which highly inhibits topoisomerase I and III, is adsorbable to a gel-type synthetic resin and impermeable through an ultrafiltration membrane when treated therewith, and has a molecular weight cut off of >=1,000. This substance is a fraction which is obtained by the following process: hop bract is subjected to extraction treatment with water or an aqueous solution of an organic solvent miscible with water and the resultant extract liquid is then treated with a gel-type synthetic resin or ultrafiltration membrane. This substance thus obtained can be used as a carcinostatic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a topoisomerase inhibitor obtained from hop bracts, a method for producing the same, and uses thereof.

[0002]

2. Description of the Related Art Hops are perennial plants of the mulberry family, and their cones (mature of unfertilized female flowers) are generally called hops. The lupulin portion of this hop (yellow granules formed at the root of the inner bract of the cone) is the main component of the bitterness and aroma of the hop, and is an important beer raw material along with yeast and malt in beer brewing. Hops are also used in folk medicine as a sedative and anti-aphrodisiac.

On the other hand, hop bracts are obtained by removing lupulin from hop cones, and are not useful for beer brewing. In some cases, hop bracts are removed during beer brewing and are produced as by-products. At that time, hop bracts have not been found to be particularly effective in use other than being used as a fertilizer for soil improvement, and the development of a use method with higher added value has been desired. Note that Japanese Unexamined Patent Application Publication No.
-2917, JP-A-9-163969, JP-A-9-1997
295944 and JP-A-10-25232 confirm that hops, especially polyphenols derived from hop bracts, have an antioxidant effect, a foam stabilizing effect on a malted beer beverage, an anticarious effect, and a deodorant effect. However, for polyphenols derived from hops, especially hop bracts,
There is no example that reveals the topoisomerase inhibitory effect.

[0004]

In recent years in Japan,
Cancer is one of the most socially affected diseases, accounting for about one-quarter of the Japanese deaths. At present, surgical treatment, radiation therapy, chemotherapy and the like are performed as treatments for cancer, but these methods alone have not been able to obtain a sufficient therapeutic effect. Therefore, when an anticancer drug having an excellent effect is developed, its social significance is insignificant.

[0005] Since cancer cells have a property of proliferating more actively than normal somatic cells, a substance which is toxic to proliferating cells can be an anticancer agent. Recently, topoisomerase inhibitors have attracted attention as substances that are toxic to proliferating cells. In mammals, topoisomerase is classified into topoisomerase I and topoisomerase II according to the mechanism of action, and topoisomerase I undergoes single-strand breaks in DNA and topoisomerase II transmits D through a double-strand break.
This is to convert the NA structure. Since topoisomerase inhibitors inhibit DNA synthesis, they can selectively exert anticancer effects on cancer cells (Yamamoto et al., Chemotherapy, Vol. 14, S-1, 65-79, 1998). Examples of such compounds include camptothecin, which is a topoisomerase I inhibitor, and anthracycline and epipodophyllotoxin, which are topoisomerase II inhibitors. In addition, JP-A-6-72885 and JP-A-7-138165 disclose that edagiuragin and quebranin, which are ellagitannins, exhibit a topoisomerase I inhibitory action. Although these drugs are being used clinically, they have side effects and cannot be effective against all types of cancer. That is, when a new powerful topoisomerase inhibitor is developed, a great contribution to medical treatment can be expected.

Accordingly, an object of the present invention is to obtain polyphenols having a topoisomerase inhibitory effect from hops or hop bracts, and to utilize these as anticancer agents.

[0007]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that a polyphenol-like substance contained in hop bracts is adsorbed on a gel-type synthetic resin and has a molecular weight cut-off of 1,000 or more. A substance that does not pass through the membrane when treated with an ultrafiltration membrane, that is, hop bracts, is extracted with water or an aqueous solution of an organic solvent miscible with water, and then treated with a gel-type synthetic resin or an ultrafiltration membrane. The fraction obtained through the process was found to be a substance that strongly inhibits topoisomerase I and II, that is, a substance that can be used as an anticancer agent. Further, the present invention has been completed by utilizing this substance for pharmaceuticals.

That is, the first aspect of the present invention is a polyphenol-like substance contained in hop bracts, which is adsorbed on a gel-type synthetic resin and permeates through an ultrafiltration membrane having a molecular weight cut-off of 1,000 or more. It is a topoisomerase inhibitor that is not a substance.

A second aspect of the present invention is to extract hop bracts with water or an aqueous solution of an organic solvent miscible with water, pass the extract through a gel-type synthetic resin, and extract the aqueous solution of water or an organic solvent miscible with water. The topoisomerase inhibitor is obtained by eluting the fraction adsorbed on the resin with an aqueous solution of an organic solvent miscible with water after washing with water.

A third aspect of the present invention is that hop bracts are extracted with water or an aqueous solution of an organic solvent miscible with water, and the extract is treated with an ultrafiltration membrane having a molecular weight cut-off of 1,000 or more. It is a topoisomerase inhibitor obtained by removing a solvent from a liquid.

A fourth aspect of the present invention is an anticancer agent containing the above-mentioned topoisomerase inhibitor.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The hop bract, which is a raw material of the present invention, is obtained by removing the lupulin part from hop cones. Generally, hop cones are pulverized and then sieved to remove the lupulin part. Get hop bracts. However, in recent beer brewing, hop cones are formed directly into pellets without removing hop bracts that are not useful for beer brewing in order to eliminate the trouble of sieving and removing hop bracts, and beer brewing as hop pellets is performed. Tend to use it. Therefore, the raw material of the present invention is not particularly limited as long as it contains hop bracts, and there is no problem even if hop cones or hop pellets containing hop bracts are used as raw materials.

As a method for producing a topoisomerase inhibitor, hop bracts as raw materials or hop cones and hop pellets containing hop bracts are mixed with water or water such as 50% or less by volume of alcohol, acetone, or acetonitrile. Extract with an aqueous solution of an organic solvent. Preferable examples include water or ethanol containing 50 v / v% or less of ethanol. The ratio of raw material to extraction solvent is 1: 20-100 (weight ratio)
The extraction is preferably carried out at a temperature of 4 to 95 ° C. under stirring and 20 to 60.
It is desirable that this is performed for about a minute. An extract is obtained by filtration. If necessary, a filter aid such as pearlite can be used. The extract thus obtained is treated with a gel-type synthetic resin and / or an ultrafiltration membrane.

First, a method using a gel-type synthetic resin will be described. For the extract of the raw material obtained in the above extraction step, the adsorption step of adsorbing the topoisomerase inhibitor to the gel type synthetic resin, water or ethanol aqueous solution, preferably 1 to 10 v / v% ethanol aqueous solution to form the gel type synthetic resin. A washing step for washing and an elution step of eluting the topoisomerase inhibitor from the gel-type synthetic resin with an aqueous ethanol solution or ethanol of 60 v / v% or more are performed to obtain a topoisomerase inhibitor.

The adsorption step is a step of cooling the extraction solution to a room temperature of about 15 to 30 ° C., passing the same through a column filled with a gel type synthetic resin, and adsorbing the topoisomerase inhibitor on the resin. At that time, if necessary, the concentration of the organic solvent in the extract can be reduced in advance by concentration under reduced pressure or the like in order to increase the adsorption efficiency. Examples of the material of the gel type synthetic resin include a hydrophilic vinyl polymer, hydroxypropylated dextran, and styrene-divinylbenzene polymer. As for the liquid passing time, the SV value
It is preferable to set so that it is between 0.5 and 100.

Note that the SV value referred to here is a value defined by the following equation. SV value = (Poured amount (L)) / {(Resin amount (L)) × (Poured time (h))} The washing step is a step of washing the gel type synthetic resin holding the topoisomerase inhibitor. By this step, it is possible to remove contaminant components and to further improve the degree of purification of the topoisomerase inhibitor. As the solvent used for washing,
Water to 1 to 10 v / v% ethanol aqueous solution is preferred,
It is preferable to wash by passing a solvent amount of about 1 to 10 times the resin amount.

The elution step is a step in which the topoisomerase inhibitor is desorbed and eluted from the gel type synthetic resin holding the topoisomerase inhibitor. As the solvent used for the elution, aqueous alcohol, aqueous acetone, aqueous acetonitrile, etc. can be used. , 30 v / v% as a particularly preferred example
The above-mentioned ethanol aqueous solution or ethanol is mentioned. The flow rate of the elution solvent is desirably about 2 to 6 times the amount of the resin. The obtained elution solvent is removed by a usual method such as concentration, freeze-drying, spray-drying and the like, and the topoisomerase inhibitor can be obtained as a powder. At the time of concentration under reduced pressure, alcohol, acetone, acetonitrile, etc. can be collected and reused.

The used gel-type synthetic resin can be repeatedly used after washing with an aqueous alcohol solution of 80 v / v% or more, an aqueous solution of about 0.05 N sodium hydroxide, or the like.

Next, a method using an ultrafiltration membrane will be described. The extract of the hop bract obtained in the above extraction step,
Treat with an ultrafiltration membrane with a molecular weight cut-off of 1,000 or more. At that time, if necessary, the extract can be concentrated under reduced pressure to reduce the concentration of the organic solvent. The recovered organic solvent can be reused.

As the material for the membrane, any material which is usually used as a material for an ultrafiltration membrane, such as cellulose, cellulose acetate, polysulfone, polypropylene, polyester, polyethersulfone, or PVDF, can be used without any particular limitation. If the molecular weight cut-off is 1,000 or more, it can be used without any problem.However, if a membrane having a high molecular weight cut-off is used, the yield is extremely reduced. An ultrafiltration membrane having a molecular weight cut-off of 10,000 to 50,000 is preferred because of its length. The treatment is preferably performed until the amount of the remaining liquid is about 1/10 to 1/100 of the amount at the start of the treatment, depending on the type of the extraction solvent and the ratio of the extraction solvent to the hop or hop bract. The pressure at that time depends on the ultrafiltration membrane and the filtration device, but is preferably about 0.1 to 10.0 kg / cm ² . If necessary, after the treatment, the remaining liquid can be diluted again with a suitable solvent such as water, and then re-treated in the same manner to increase the degree of purification.

The topoisomerase inhibitor can be obtained as a powder by removing the solvent from the resulting upper residue by a conventional method such as concentration, freeze drying, spray drying and the like.
At the time of concentration under reduced pressure, alcohol, acetone, acetonitrile, etc. can be collected and reused.

The thus obtained topoisomerase inhibitor is a slightly bitter, odorless flesh-colored, brown or pale yellow powder which is adsorbed on a gel-type synthetic resin and has a molecular weight cut off of 1,000 or more. It is a polyphenol-like substance that does not permeate through the membrane when treated with an ultrafiltration membrane. The yield is 0.5 to 20.0 w / w% in terms of hop bract weight, and 0.5 to 15.0 w / w% in terms of hop cone weight.

Since the active substances of the topoisomerase inhibitor obtained by the method using the gel type synthetic resin and the method using the ultrafiltration membrane are the same polyphenols, the topoisomerase obtained by the method using the gel type synthetic resin is used. The inhibitor can be dissolved in an appropriate solvent such as an aqueous alcohol solution, and the degree of purification of polyphenols as the active substance can be further increased by a method using an ultrafiltration membrane.
The reverse is also possible. Needless to say, a sufficiently useful topoisomerase inhibitor can be obtained by a method using a gel-type synthetic resin or a method using an ultrafiltration membrane alone.

The obtained topoisomerase inhibitor can be formulated as a carrier together with commonly used carriers, auxiliaries, additives and the like, and can be used as a drug as an oral or parenteral product according to a conventional method. Pharmaceuticals include tablets, capsules, granules, syrups and the like as oral preparations, external preparations such as ointments, creams and solutions as parenteral preparations and injections such as sterile solutions and suspensions. When these products are administered to the human body as medicines, 2 mg to 500 mg
It is administered once or several times a day, that is, in a total daily dose of 2 mg to 1000 mg, and the effect can be sufficiently exerted.

The pharmaceutical containing the topoisomerase inhibitor of the present invention can take the required unit dosage form together with physiologically acceptable vehicles, carriers, excipients, integrators, stabilizers, flavoring agents and the like. Adjuvants such as tragacanth, gum arabic, corn starch and gelatin, excipients such as microcrystalline cellulose, corn starch, whole gelatinized starch, and leavening agents such as alginic acid Lubricating agents such as magnesium stearate; sweeteners such as sucrose, lactose and saccharin; and flavoring agents such as peppermint, reddish oil and cherry. In the case of a capsule, the above-mentioned materials may further contain a liquid carrier such as oil and fat, and other materials may be used as a coating agent or to change the physical form of the preparation by another method. it can. For example, tablets may be coated with shellac, sugar. A syrup or elixir may contain sucrose as a sweetening agent, methyl or propylparabens as preservatives, a dye and flavoring such as cherry or orange flavor.

Sterile compositions for injection include an active substance in a vehicle such as water for injection, a naturally occurring vegetable oil such as sesame oil, coconut oil, peanut oil, cottonseed oil, or a synthetic fatty vehicle such as ethyl oleate. It can be formulated by a usual method of dissolving or suspending. Further, a buffer, a preservative, an antioxidant and the like can be blended as required. As an external preparation, vaseline, paraffin, oils and fats, lanolin, macrogol, etc. were used as base materials,
Ointments, creams and the like can be prepared by ordinary methods.

[0027]

The drug containing the topoisomerase inhibitor of the present invention has an effect of suppressing the growth of cancer that has occurred in a living body, and is therefore effective for treating cancer.

[0028]

The present invention is not limited to the following examples.

Example 1 (Preparation of topoisomerase inhibitor from hop cones by gel-type synthetic resin) 20 g of hop cones was ground in a mortar and stirred with 2 L of water under stirring.
Extracted at 40 ° C for 40 minutes. After filtration, allow to cool, and extract the extract with a hydrophilic vinyl polymer resin (Toyopearl HW40, manufactured by Tosoh Corporation) 80 ml
For 2 hours (SV = 12.
5) Then, it was washed with 400 ml of a 5% aqueous ethanol solution.
Further, 400 ml of an 80% aqueous ethanol solution was passed through the column, and the eluate was collected and freeze-dried to obtain 800 mg of a topoisomerase inhibitor as a pale yellow powder having an odorless and slightly bitter taste. The yield from hops was 4%.

Example 2 (Preparation of Topoisomerase Inhibiting Substance from Hop Bract Using Gel Type Synthetic Resin) 20 g of hop bract was stirred with 600 ml of 50% ethanol aqueous solution.
Extraction was performed at 80 ° C. for 40 minutes. After filtration, the solution was concentrated under reduced pressure until the volume reached 300 ml, and the concentrated solution was passed through a column filled with 80 ml of styrene-divinylbenzene resin (Sepabeads 825 manufactured by Mitsubishi Chemical Corporation) over 1 hour (SV = 3.75), and poured. At 400
Washed with ml of water. Further, 400 ml of an 80% aqueous ethanol solution was passed through the column, and the eluate was collected and freeze-dried to obtain 1.6 g of a topoisomerase inhibitor as a pale yellow powder having an odorless and slightly bitter taste. The yield from hop bracts was 8%.

Example 3 (Preparation of topoisomerase inhibitor from hop cones by ultrafiltration membrane) 20 g of hop cones was ground in a mortar and stirred with 2 L of water under agitation.
Extracted at 40 ° C for 40 minutes. After filtration, the mixture was allowed to cool, and the extract was treated with an ultrafiltration membrane (XM50 manufactured by Amicon) having a molecular weight cut-off of 50,000 at 1.0 kg / cm ² at room temperature until the volume became 20 ml. The resulting upper residue was dried under reduced pressure to give 200 mg of a topoisomerase inhibitor as a pale yellow powder having an odorless and slightly bitter taste. The yield from hops was 1%.

Example 4 (Preparation of Topoisomerase Inhibitor from Hop Bract by Ultrafiltration Membrane) 20 g of hop bract was stirred with 600 ml of a 50% ethanol aqueous solution.
Extraction was performed at 80 ° C. for 40 minutes. After filtration, the extract has a molecular weight cut off.
3.0k by ultrafiltration membrane of 10,000 (YM10 manufactured by Amicon)
The treatment was performed at 60 g / cm ² at room temperature until the volume reached 60 ml. The obtained upper remaining solution is freeze-dried, and 0.8 g of a topoisomerase inhibitor is obtained.
Was obtained as a pale yellow powder having an odorless and slightly bitter taste. The yield from hop bracts was 4%.

Example 5 (Further purification and qualitative analysis of topoisomerase inhibitor) 0.8 g of the topoisomerase inhibitor obtained in Example 2 was added to 500 m
dissolved in 10% aqueous ethanol solution and the molecular weight cut off is 10,000
1.0 kg / c by ultrafiltration membrane (YM10 manufactured by Amicon)
The mixture was treated under m ² at room temperature until the volume became 20 ml. The obtained upper residue was freeze-dried to obtain 0.4 g of a topoisomerase inhibitor as a flesh-colored powder having an odorless and slightly bitter taste. When this powder is analyzed by HPLC under the following conditions, a characteristic chromatogram as shown in FIG. 1 is obtained. In addition, catechin quantification (official method of food analysis), which is one of the general methods for quantifying polyphenols, is performed. As a result, a value of 40.6% was obtained in terms of catechin content. Further, when the molecular weight was roughly estimated by a gel filtration method, the molecular weight was about 40,000.

(HPLC conditions) Apparatus: Shimadzu LC-10A system, column: ODS-80TM (Tosoh, 4.6 mm ID × 25c)
m), mobile phase: (solution A: solution B) = (100: 0) to (50: 5
0) linear gradient for 30 minutes, solution A: 5% acetonitrile (containing 0.1% HCl), solution B: acetonitrile, sample injection amount: 20 μg, detection: multi-wavelength detection at 200 to 300 nm.

Example 6 (Tablets, Capsules) The substance obtained in Example 5 10.0 mg Lactose 75.0 mg Magnesium stearate 15.0 mg Total 100.0 mg Tablets and capsules were prepared according to the method. Note that tablets and capsules to which the substances obtained in Examples 1, 2, 3, and 4 were respectively added instead of the substances obtained in Example 5 were similarly obtained.

Example 7 (powders, granules) The substance obtained in Example 5 20.0 mg Starch 30.0 mg Lactose 50.0 mg Total 100.0 mg The above parts by weight were uniformly mixed and mixed according to a conventional method. Powders and granules were prepared. Instead of Example 5, powders and granules to which the substances obtained in Examples 1, 2, 3, and 4 were added were also obtained in the same manner.

Example 8 (Injection) The substance obtained in Example 5 1.0 mg Surfactant 9.0 mg Physiological saline 90.0 mg Total 100.0 mg Each of the above parts by weight was heated, mixed and sterilized. It was used as an injection. Powders and granules to which the substances obtained in Examples 1, 2, 3, and 4 were respectively added instead of the substances obtained in Example 5 were similarly obtained.

Example 9 (Topoisomerase I inhibitory effect) The topoisomerase inhibitor obtained in Example 5 (hereinafter referred to as "HB
P-HMW ") was examined for its inhibitory effect on topoisomerase I. As an index of the topoisomerase I inhibitory effect, the method of Ishii et al. (Ishii et al., J. Biol. Che
m., 258, 12728-12732 (1983)), the relaxation inhibitory activity of the circular plasmid DNA was measured. Camptothecin was used as a control. The concentration was calculated assuming that the molecular weight of the substance of Example 5 was 40,000.

That is, a mixed solution (10 μl of 2 × RB buffer, water
2 μl, Topo I enzyme solution 2 μl, sample diluent 1 μl, ColE
5 μl of 1 DNA (0.2 μg) was prepared, incubated at 37 ° C. for 15 minutes, and then electrophoresed by SDS-PAGE. However, 2 ×
The composition of the RB buffer is as follows. After the electrophoresis, the amount of circular and relaxed DNA due to ethidium bromide color development was examined.

The sample solution was HBP-HMW at 0.1-30 μg / ml.
Was prepared by three-fold serial dilution at a concentration of The positive control was camptotensin (CPT). The result is shown in FIG. As can be seen, the CPT had an IC ₅₀ of about 3 μM (lanes 2-6). HBP-HMW started already inhibition observed at 0.1 [mu] g / ml, the inhibition rate with increasing concentration also increased, IC ₅₀ is
It was found to be between 3.0 and 10 (lanes 7-12).
The result was quantified with a densitometer, and the IC ₅₀ was determined.
μg / ml. When the concentration to calculate the molecular weight of HBP-HMW as 40,000, IC ₅₀ of the HBP-HMW is 3.1 nM, the positive control
Compared to CPT, it was found to have significantly stronger topoisomerase I inhibitory activity.

Example 10 (Topoisomerase II inhibitory effect) With respect to the topoisomerase inhibitor obtained in Example 5, the inhibitory effect of topoisomerase II was examined. As an index of the topoisomerase II inhibitory effect, the method of Marina et al.
ni et al., J. Biol. Chem., 255, 4976-4979 (1980))
In accordance with the method described above, the activity of the linked circular DNA for inhibiting the disassembly ring was measured. ICRF-193 was used as a control.

That is, a mixed solution (10 μl of 2 × RB buffer, 200 μl
mM MgCl ₂ + 20mM ATP 1μl, water 1μl, TopoII enzyme solution 2
μl, 1 μl of sample diluent, and 5 μl of kDNA).
After incubation at 15 ° C for 15 minutes, electrophoresis was performed by SDS-PAGE. After the electrophoresis, the amount of circular and relaxed DNA due to ethidium bromide color development was examined. The sample solution was HBP
-HMW was prepared by serial three-fold dilution at a concentration of 0.1-30 μg / ml. The positive control was ICRF193. The result is shown in FIG.
Shown in As can be seen, the IC ₅₀ of ICRF193 was less than 5 μM (about 3.0). Inhibition of HBP-HMW was already observed at 0.1 μg / ml, and the inhibition increased with increasing concentration. Lanes 2,3 and lanes 8-13 subjected to a densitometer, to give an IC ₅₀ extrapolated, was 0.075 / ml. HBP-H
When the molecular weight of MW is 40,000 and the concentration is calculated, the IBP of HBP-HMW
C ₅₀ is 1.9 nM, which is higher than that of the positive control ICRF193.
It was clarified that it has a remarkably strong topoisomerase II inhibitory activity.

[0043]

According to the present invention, a topoisomerase inhibitor can be obtained using hop bracts and hop cones containing hop bracts as raw materials. Further, it could be easily used as a drug material.

[Brief description of the drawings]

FIG. 1 is a chromatogram of the substance obtained in Example 5 by HPLC analysis. The vertical axis indicates absorbance, and the horizontal axis indicates time (minutes). The upper part of the figure shows the absorbance at UV 220 nm, and the lower part of the figure shows the absorbance at UV 280 nm.

FIG. 2: SDS-PAGE showing inhibitory activity of topoisomerase I
It is an electrophoretogram. Lane 1 contains substrate only, lane 2,
3 shows only the substrate and topoisomerase I, lanes 4-6 show the results obtained by adding camptotensin (CPT) to the substrate and topoisomerase I, and lanes 7-12 show the substrates and topoisomerase I added to the topoisomerase inhibitor obtained in Example 5 Is shown. a: circular DNA relaxed by topoisomerase I, b: supercoiled DNA
(Substrate).

FIG. 3 SDS-PAGE showing inhibitory activity of topoisomerase II
It is an electrophoretogram. Lane 1 contains substrate only, lane 2,
3 shows only the substrate and topoisomerase II, lane 4-7 shows the result of adding ICRF193 to the substrate and topoisomerase II, and lane 8-12 shows the result of adding the substrate and topoisomerase II to which the topoisomerase inhibitor obtained in Example 5 was added. Is shown. c indicates linked circular DNA (substrate), and d indicates DNA delinked by topoisomerase II.

Claims (7)

[Claims] 1. A topoisomerase inhibitor which is a polyphenol-like substance contained in hop bracts and which is adsorbed on a gel-type synthetic resin. 2. A topoisomerase inhibitor which is a polyphenol-like substance contained in hop bracts and which does not permeate through an ultrafiltration membrane having a cut-off molecular weight of 1,000 or more. 3. A polyphenol-like substance contained in hop bracts, which is a substance adsorbed on a gel-type synthetic resin and which does not permeate through an ultrafiltration membrane having a molecular weight cut-off of 1,000 or more. A topoisomerase inhibitor. 4. The hop bract is extracted with water or an aqueous solution of an organic solvent miscible with water, and the extract is passed through a gel-type synthetic resin, washed with water or an aqueous solution of an organic solvent miscible with water, and then further extracted. A method for producing a topoisomerase inhibitor, which is obtained by eluting a fraction adsorbed on the resin with an aqueous solution of an organic solvent miscible with water. 5. A hop bract is extracted with water or an aqueous solution of an organic solvent miscible with water, and the extracted solution has a molecular weight cut-off of 1,00.
The method for producing a topoisomerase inhibitor according to claim 1, wherein the substance is obtained by treating with a zero or more ultrafiltration membrane and removing the solvent from the remaining liquid. 6. A method for producing a topoisomerase inhibitor, comprising obtaining a polyphenol-like substance by combining the method according to claim 4 and the method according to claim 5. 7. An anticancer agent comprising the topoisomerase inhibitor according to any one of claims 1, 2, and 3.