EP1897455A1

EP1897455A1 - Cigarette filter capable of removing harmful substance

Info

Publication number: EP1897455A1
Application number: EP05736754A
Authority: EP
Inventors: Xiang Dong Liu; Masaji Matsunaga; Norio Nishi
Original assignee: Hokkaido University NUC; Nissei Bio Co Ltd
Current assignee: Hokkaido University NUC; Nissei Bio Co Ltd
Priority date: 2005-04-28
Filing date: 2005-04-28
Publication date: 2008-03-12
Also published as: JPWO2006117862A1; US20090272392A1; WO2006117862A1; CN101166432A

Abstract

[PROBLEMS] To provide a cigarette filter that does not impair the distinctive flavor of a cigarette and the air permeability of filter while smoking, and at the same time, can more effectively remove harmful substances such as a pyrene that is generated from the cigarette.

[MEANS FOR SOLVING PROBLEMS] The cigarette filter comprising a filter fiber bundle body which cigarette smoke passes through; a fine powder with a high surface area ratio that are mixed and scattered in the filter fiber bundle body; and a double-stranded DNA molecule attached to the outer surface of the fine powder with a high surface area ratio, characterized in that harmful substances such as benzo[a]pyrene contained in the cigarette smoke can be removed by intercalation into the double-stranded DNA molecule.

Description

TECHNICAL FIELD

The present invention relates to a cigarette filter, and more particularly, to a cigarette filter capable of more effectively removing harmful substances in cigarette smoke such as pyrene while slightly imparing flavor of its own and air permeability of the filter during smoking.

BACKGROUND ART

A filter in a paper-wrapped cigarette has been developed to remove the tarry substance or tar of the cigarette in consideration with the influence of smoking cigarette to the human health. Recently, health problems caused by smoking have been increasingly focused, and the demand for filters capable of removing the harmful substances in cigarette smoke such as pyrene has been increased. Patent Document 1 proposes a cigarette filter to which DNA serving as an active constituent is directly adhered so as to trap carcinogenic and toxic components in cigarette smoke. Patent Document 2 proposes art in which UV ray is irradiated so as to fix DNA to the support such as the cigarette filter.
Patent Document 1: French Patent No. 2798302
Patent Document 2: JP-A 2001-81098

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

The cigarette filter capable of removing a harmful substance is required not only to remove the harmful substance in cigarette smoke as much as possible but also not to impair the distinctive flavor of the cigarette, that is, to allow smooth passage of a chemical substance which serves as the source of the flavor and further to keep the good air permeabilities. If the chemical substance as the source of the flavor is removed, the smoker may feel it as tasteless. If the air permeability of the filter is impaired, the smoker may feel uncomfortable in inhaling cigarette smoke, which may hurt the commercial value of the cigarette.
The cigarette filter disclosed in Patent Document 1 has been developed with no consideration for maintaining the flavor of the cigarette, and air permeability during smoking. Meanwhile, Patent Document 2 describes the art in which the filter with the DNA is used as the cigarette filter, but does not clarify the level of the effect for removing the harmful substance, the flavor of the cigarette, and the air permeability of the filter. Thus, the filter has not been applied to the practical use as the cigarette filter yet.

Means for Solving the Problem

The inventor has been dedicated to develop a cigarette filter that is capable of more effectively removing the harmful substances in cigarette smoke such as pyrenes, as well as prevents impairment in the distinct flavor of the cigarette and in the air permeability of the filter during smoking. In the course of the development of such cigarette filter, the inventor selected the double-stranded DNA suitable as a substance for absorbing more amount of harmful substances such as pyrenes while absorbing less amount of substances such as nicotine and tasty constituents which constitute the source of the flavor of the cigarette. Considering the fact that the air permeability of the filter is likely to be impaired when the double-stranded DNA molecules are distributed in the entire filter fiber bundle so as to be adhered thereto, especially when a large amount of the double-stranded DNA molecules are distributed, the inventor studied various ways of scattering the double-stranded DNA in the filter fiber bundle partially rather than entirely. Then the double-stranded DNA is adhered to fine powder of the cellulose bead such that the fine powder of the cellulose bead to which the double-stranded DNA has been adhered is scattered in the filter fiber bundle. As a result, the harmful substance was effectively removed, and the substance that is the source of the distinct flavor of the cigarette smoothly passed through the filter while suppressing impairment in the air permeability of the filter. It is confirmed that more double-stranded DNA was adhered to the outer surface of the fine powder of the cellulose bead.
The present invention has been made in view of the aforementioned background to provide a cigarette filter that is capable of effectively removing harmful substances in cigarette smoke such as pyrenes and that suppresses impairment both in the distinct flavor of the cigarette and in the air permeability of the filter during smoking, by adhering the double-stranded DNA to the fine powder with large surface area, such as the cellulose bead, so as to mix the double-stranded DNA adhered to the fine powder into the filter fiber bundle.
According to an aspect of the present invention, a cigarette filter includes a filter fiber bundle through which cigarette smoke passes, fine powders with high specific surface area mixed into the filter fiber bundle to be scattered therein, and a double-stranded DNA molecule adhered to an outer surface of the fine powder with high specific surface area. In the cigarette filter, harmful substances such as benzo[a]pyrene are trapped by intercalation with the double-stranded DNA particle so as to be removed.
According to a preferable aspect of the present invention, the fine powder with high specific surface area is formed of the cellulose bead.
Preferably, the mean particle size of the fine powder with high specific surface area is in a range from 50 to 2000 µm, and more preferably, from 300 to 800 µm.
In the present invention, the cigarette filter contains the fine powder with high specific surface area in the range from 1 to 50% by weight, and the double-stranded DNA particle in the range from 0.01 to 10% by weight, based on the weight of the filter fiber bundle.
Still another aspect of the present invention relates to a paper-wrapped cigarette provided with the aforementioned cigarette filter.

Effects of the Invention

The cigarette filter according to the present invention includes the filter fiber bundle through which cigarette smoke passes, the fine powder with high specific surface area mixed in the filter fiber bundle, which allows the double-stranded DNA to be adhered to the outer surface, and the double-stranded DNA molecule adhered to the outer surface of the fine powder with high specific surface area. In the structure described above, it is possible to secure sufficient air permeability of cigarette smoke as well as to suppress absorption and removal of the tasty constituent contained in the smoke, such as tar, so as to maintain smoking feel. The harmful substances such as benzo[a]pyrene may be trapped by intercalation between the double-stranded DNA molecules effectively so as to be removed. As the double-stranded DNA molecule is adhered to the fine powder with high specific surface area so as to become unlikely to be desorbed compared to the case of direct adhesion to the cigarette filter. As a result, the effect of removing the harmful substance may be maintained for an extended period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of an electron micrograph showing fine powder with high specific surface area used in the present invention;
FIG. 2 is a view of an electron micrograph of the fine powder with high specific surface area to which the double-stranded DNA has been adhered in the present invention;
FIG. 3 is another view of an electron micrograph of the fine powder with high specific surface area to which the double-stranded DNA has been adhered in the present invention;
FIG. 4A is an explanatory view showing a longitudinal section of the cigarette filter according to the present invention; and
FIG. 4B is an explanatory view showing a longitudinal section of a cigarette filter having the double-stranded DNA directly adhered to the filter fiber bundle.

BEST MODES FOR CARRYING OUT THE INVENTION

In the present invention, fine powder 2 with high specific surface area having a unique structure with plural gaps 1 formed in the outer surface as shown in FIG. 1 is used for the purpose of adhering more double-stranded DNA in a concentrated manner. A double-stranded DNA 3 is adhered to the outer surface of the fine powder 2 with high specific surface area (see FIGS. 2 and 3). Any type of the fine powder 2 with high specific surface area may be employed so long as it allows the double-stranded DNA molecules to be adhered thereto. The fold, wrinkle, or twist may be formed instead of the gap. The fine powder with high specific surface area according to the present invention may be formed to have the aforementioned gap, fold, wrinkle, or twist not only in the outer surface but also inside. The fine powder with high specific surface area may be arbitrarily configured, for example, the porous configuration.
The cigarette filter according to the present invention, in which the fine powder with high specific surface area holding more double-stranded DNA molecules is mixed and scattered, is much more advantageous compared to the generally employed cigarette filter having the DNA directly held in the filter in view of the performance for effectively maintaining the air permeability of the filter. The aforementioned advantage will be described below, in comparison with the generally employed cigarette filter in which the double-stranded DNA molecules are directly adhered to the filter fiber bundle.
Referring to FIG. 4A, the double-stranded DNA 3 is adhered to the outer surface of the fine powder with high specific surface area with the aforementioned structure. A cigarette filter 5 is formed by mixing into and scattering in a filter fiber bundle 4, the fine powder 2 with high specific surface area, to which the double-stranded DNA 3 has been adhered. In order to distribute a predetermined amount of the double-stranded DNA 3 in a filter fiber bundle 4, the fine powder 2 with high specific surface area holding the double-stranded DNA 3 is required to be mixed into the filter fiber bundle 4 while being scattered. As a result, the particles of the fine powder 2 with high specific surface area to which the double-stranded DNA 3 is adhered are apart from one another to ensure to form the sufficient passage for cigarette smoke 6.
Meanwhile, referring to FIG. 4B, in a cigarette filter 7 in which the double-stranded DNA 3 is directly adhered to the filter fiber bundle 4 (for example, the filter fiber bundle is impregnated in water solution of DNA, and then dried to hold the DNA), the double-stranded DNA 3 is substantially uniformly distributed all over the filter fiber bundle 4 for the purpose of distributing the same amount of the double-stranded DNA thereon. Consequently the respective molecules of the double-stranded DNA 3 are positioned adjacent with one another. The resultant narrow passage of the cigarette smoke 6 impairs air permeability of the filter.
The cigarette filter according to the present invention is designed to effectively maintain the air permeability of the filter.
Preferably, the mean particle size of the fine powder with high specific surface area according to the present invention is in the range from 50 to 2000 µm for the purpose of preventing clogging of the filter fiber bundle. More preferably, the mean particle size is in the range from 300 to 800 µm. The fine powder with high specific surface area is not particularly limited in terms of material and shape so long as it is pervious with respect to the cigarette smoke, and is structured to have a large specific surface area so as to allow adhesion of the double-stranded DNA molecules to the outer surface. For example, the fine powder with high specific surface area may be formed of a synthetic or natural polymer such as polystyrene, polyvinyl alcohol, polyvinyl chloride, polyethylene, cellulose, starch, natural rubber, gelatin, chitin, chitosan, and acetate, an inorganic substance such as silica, alumina, activated carbon, and diatom, and a mixture thereof. Preferably, the fine powder with high specific surface area is formed of the cellulose polymer, especially, cellulose acetate, for example. Preferably, the fine powder with high specific surface area has a bead-like form, and the most preferably, the cellulose bead form. It is sufficient to allow the fine powder with high specific surface area to be simply mixed in the filter fiber bundle. The double-stranded DNA molecules may be adhered to the fine powder with high specific surface area under the physical force such as intermolecular force and electrostatic force, through the chemical bonding such as covalent bonding, ion bonding and coordinate bonding, or combination of the physical forces and the chemical bondings. In the present invention, the state where the double-stranded DNA molecules exist on the fine powder with high specific surface area so as not to be desorbed therefrom may be considered as being adhered to the fine powder with high specific surface area.
Meanwhile, the double-stranded DNA employed in the present invention is formed of two polynucleotide chains (double helix) with the helical form. It is preferable to use the DNA derived from the milt (testis) of fish such as salmon, herring and codfish, or the double-stranded DNA derived from the thymus of mammal or birds such as cattle, hog, and chicken. In the double-stranded DNA, planar bases each having the structural complementation protrude from the sugar-phosphate frameworks of two polynucleotide chains toward the center of the helix perpendicularly to the axis thereof, and the bases are hydrogen bonded. In case of type B structure, a gap approximately 1.1 nm wide and 0.34 nm high is formed between the base pairs of the duplex, and so the gap is able to accommodate the small molecules with the planar structure. The above-described phenomenon is referred to as the intercalation which may be accelerated by the charge and hydrophobicity of the small molecules. As most of the substances harmful to the human health, such as dioxins are formed of plural benzene rings, and has the planar structure, the use of the double-stranded DNA is more effective for removing the harmful substance in cigarette smoke. The structure of the double-stranded DNA employed in the present invention is not particularly limited so long as it is capable of adhering to the outer surface of the fine powder with high specific surface area. Conceivable forms of the double-stranded DNA may include powder, fiber, and film, and the fine powder form is particularly preferable. The use of the fine powder as the double-stranded DNA allows its surface area to be larger with the same amount, thereby further improving the effect of absorbing/removing the harmful substance.
In view of the efficiency for removing the harmful substance, the respective contents of the fine powder with high specific surface area and the double-stranded DNA particles may be in the ranges from 1 to 50% by weight, and 0.01 to 10% by weight with respect to the filter fiber bundle, respectively.
The cigarette filter according to the present invention may further include an activated carbon, a substance other than the double-stranded DNA capable of removing the harmful substance, an aroma chemical, or the like.

Examples

An example of the present invention will be described in detail, however, the present invention is not limited to the following explanation.

Example 1

A cigarette filter 5 having the structure as shown in FIG. 4A according to the present invention and a cigarette A provided with the cigarette filter 5 are produced as described below.
Firstly, 750 mg of the double-stranded DNA in the form of fine powder was applied to be adhered to approximately 100 g of the cellulose beads (mean particle size: 300 to 800 pm) as the fine powder with high specific surface area. Then 0.1 g of the cellulose beads to which the double-stranded DNA was adhered (content of the double-stranded DNA: 0.75 mg) was mixed into the filter fiber bundle formed of cellulose acetate (weight: approximately 1.0 g) using a cigarette filter manufacturing machine. Thereafter, by the use of the cigarette filter manufacturing machine, the mixture was wrapped with rice paper so as to be formed into a round-bar like shape, and thus the cigarette filter according to the present invention was obtained. The filter of Research Cigarette 2R4F (trade name, University of Kentucky, United States) was removed to be replaced by the above-obtained cigarette filter according to the present invention to produce the cigarette A.

Comparative Example 1

The filter of Research Cigarette 2R4F (trade name, University of Kentucky, United States) was removed to be replaced by the filter (no double-stranded DNA nor the cellulose beads holding the double-stranded DNA) formed of the filter fiber bundle used in Example 1 to produce a cigarette B.

Comparative Example 2

Approximately 1.0 g of the filter fiber bundle used for producing the cigarette B was impregnated in water solution containing the double stranded DNA of 5% by weight. Then the filter fiber bundle was taken out from the water solution of the double-stranded DNA, and sufficiently dried at approximately 37°C. The ultraviolet ray with the wavelength of 260 nm was irradiated to the fiber bundle to form the cigarette filter. The double-stranded DNA adhered to the cigarette filter measured approximately 1 mg. The thus obtained cigarette filter was wrapped with rice paper using the cigarette filter manufacturing machine so as to be formed into a round-bar like shape. The filter of the Research Cigarette 2R4F (trade name, University of Kentucky, United States) was removed to be replaced by the cigarette filter having the round-bar like shape to produce a cigarette C. '

Comparative Example 3

The water solution containing the double-stranded DNA of 5% by weight was sprayed to approximately 1.0 g of the filter fiber bundle used for producing the cigarette B, and sufficiently dried at 37°C to produce the cigarette filter. The double-stranded DNA adhered to the cigarette filter measured approximately 1 mg. The thus obtained cigarette filter was wrapped with rice paper using the cigarette filter manufacturing machine so as to be formed into a round-bar like shape. The filter of the Research Cigarette 2R4F (trade name, University of Kentucky, United States) was removed to be replaced by the cigarette filter having the round-bar like shape to produce a cigarette D.

Comparative Example 4

Approximately 1.0 g of the filter fiber bundle used for producing the cigarette B was impregnated in the water solution that contains 5% by weight of the double-stranded DNA and 0.1 % by weight of NaF for about 1 minute. Then the filter was taken out from the water solution of the DNA, and sufficiently dried at approximately 37°C to produce the cigarette filter. The DNA adhered to the cigarette filter measured approximately 3 mg. The thus obtained cigarette filter was wrapped with rice paper using the cigarette filter manufacturing machine so as to be formed into a round-bar like shape. The filter of Research Cigarette 2R4F (trade name, University of Kentucky, United States) was removed to be replaced by the above-obtained cigarette filter having the round-bar like shape to produce a cigarette E.

Test Example 1

Experiment with respect to each effect for removing the benzo[a]pyrene generated by smoking the respective cigarettes A, B, C, D and E was implemented.
(Test procedure)
A Hamburg II automatic smoking machine was allowed to take the mainstream smoke (air : cigarette smoke = 7 : 3) 10 times under the condition where 1. puff/ 35 ml per two seconds of 20 cigarettes per day with respect to the above-produced cigarettes A, B, C, D and E. The amount of the benzo[a]pyrene contained in the total air discharged outside after smoking was measured. The measurement results are shown in Table 1.
[Table 1] Table 1

Outflow amount of benzo[a]pyrene (ng/UNK)

A 0.15

B 0.45

C 0.25

D 0.31

E 0.41

(Results)
From the results shown in Table 1, compared to each outflow amount of benzo[a]pyrene discharged outside after smoking of the cigarettes B, C, D and E, that is, 0.45 ng/UNK, 0.25 ng/UNK, 0.31 ng/UNK, and 0.41 ng/UNK, the outflow amount in case of smoking the cigarette A provided with the cigarette filter according to the present invention measured only 0.1 S ng/LJNK. Although the cigarette A contains only 0.75 mg of the double-stranded DNA, the effect for removing the benzo[a]pyrene was higher than those of the cigarettes C, D and E each holding the double-stranded DNA of 1 mg, 1 mg, and 3 mg, respectively. In other words, the cigarette A produced by mixing the cellulose beads holding the double-stranded DNA into the fiber bundle exhibits the higher effect for removing the benzo[a]pyrene than those of the cigarettes C and D produced by directly adhering the double-stranded DNA to the fiber bundle through impregnating in the water solution or spray. The cigarette filter according to the present invention which holds a large amount of the double-stranded DNA on the cellulose beads to be mixed into the fiber bundle provides further excellent effect for absorbing/removing the pyrenes such as the benzo[a]pyrene.

Test Example 2

The test was performed with respect to the smoking feel level derived from smoking the cigarettes A, B, C, D and E produced as Example 1 and Comparative Examples 1 to 4.
Test Procedure:
In the test, 30 subjects smoked the cigarettes A, B, C, D and E such that the comparison with respect to the flavor and smoke inhaling feel was made between the cigarettes A, C, D, E each holding the double-stranded DNA and the cigarette B holding no double-stranded DNA. The evaluation was performed based on impairment level in the flavor and in the smoke inhaling feel resulting from smoking of the cigarettes A, C, D, and E in reference to the cigarette B. If the subjects determined that the flavor and smoke inhaling feel derived from smoking the cigarette A, C, D or E hardly changed or they did not notice such change, a score of 3 points was given. If they slightly felt discomfort during smoking, a score of 2 points was given. If they clearly felt discomfort during smoking, a score of 1 point was given. Each average score of the cigarettes A, B, C, D and E was calculated, and the results are shown in Table 2.
[Table 2] Table 2

Flavor Smoke inhaling level

A 2.7 2.8

B 2.7 2.8

C 2.2 2.3

D 2.1 2.2

E 2.1 2.2

The test results of the cigarette A with the cigarette filter according to the present invention holding the double-stranded DNA with respect to the ease of smoke inhaling and the flavor are substantially the same as those of the cigarette B provided with the cigarette filter having no double-stranded DNA. It also becomes clear that the cigarettes C, D and E each having the double-stranded DNA directly adhered to the filter fiber bundle could suppress impairment in the smoke inhaling feel less compared to the cigarette A. The aforementioned effect is assumed to be obtained due to the form of the cigarette filter, in which the double-stranded DNA is adhered to the fine powder with high specific surface area such as the cellulose beads in the concentrated manner rather than the direct adhesion such that the particles of fine powder with high specific surface area are scattered in the filter fiber bundle of the cigarette at sufficient intervals with one another.

Claims

A cigarette filter comprising:
a filter fiber bundle through which smoke of a cigarette passes;

fine powder with high specific surface area mixed into the filter fiber bundle to be scattered therein; and

a double-stranded DNA molecule adhered to an outer surface of the fine powder with high specific surface area, wherein

harmful substances such as benzo[a]pyrene contained in the smoke of the cigarette is trapped by intercalation with the double-stranded DNA molecule so as to be removed.
The cigarette filter according to claim 1, wherein the fine powder with high specific surface area is formed of a cellulose bead.
The cigarette filter according to claim 1, wherein a mean particle size of the fine powder with high specific surface area is in a range from 50 to 2000 µm.
The cigarette filter according to claim 1, wherein a mean particle size of the fine powder with high specific surface area is in a range from 300 to 800 µm.
The cigarette filter according to any one of claims 1 to 4, wherein the fine powder with high specific surface area in a range from 1 to 50% by weight and the double-stranded DNA molecule in a range from 0.01 to 10% by weight based on the weight of the filter fiber bundle are contained.
A paper wrapped cigarette provided with the cigarette filter according to any one of claims 1 to 5.