ORAL COMPOSITION

Abstract

An oral composition having a biofilm formation inhibitory action is provided. An oral composition, comprising a plant extract which is a hot water extract of Japanese mustard spinach, potherb mustard, mibuna, hot radish, cress, ostrich fern, Japanese angelica tree, or ice plant.

Description

TECHNICAL FIELD

The present invention relates to an oral composition having an inhibitory action by a plant extract on Actinomyces naeslundii (hereinafter referred to as “A. naeslundii”) biofilm formation.

BACKGROUND ART

Microorganisms attached on the surface of an object do not exist independently, but form a biofilm together with other microorganisms in the characteristic structure. The biofilm, which appears to work in favor of the human as seen in the use of immobilized microorganisms, is conversely revealed to cause tooth decay and food contamination, and has been extensively studied in recent years.

The dental biofilm includes 700 species or more of bacteria and 10⁸ or more bacteria are present per 1 mg of the dental biofilm. Of these, A. naeslundii has been receiving much attention in recent years as a key microorganism required when the initial stage plaque (cariogenic plaque) proceeds to the late stage plaque (periodontal disease plaque).

In the conventional periodontal disease prevention, the mainstream idea was to sterilize periodontal disease bacteria such as Porphyromonas gingivalis (hereinafter referred to as “P. gingivalis”) to inhibit the periodontal diseases. However, in reality, the periodontal disease foci are present with a biofilm deeply in the periodontal pocket, which prevents an antibacterial substance from permeation. Therefore, the conventional periodontal disease prevention fails to achieve an intended effect, and additionally always facing the risk of the resistant bacteria emergence. Thus, a safer and more effective prevention method has been in demand.

Also, mechanical removal such as brushing, and scaling, is believed to be the most effective method for inhibiting a biofilm, but it is difficult to practice suitable oral care using the current procedure for people having difficulties in such a mechanical control of dental biofilm such as the elderly in need of nursing care, whereby the development of biofilm removal procedures different from the convention procedures are in demand.

Short chain fatty acids (SCFA) such as butyric acid, are known to be present in a high concentration in the periodontal pocket and the dental plaque of periodontal disease patients, and the association thereof with the development and progress of the periodontal diseases became clear. In recent years, it was confirmed that acids such as SCFA produced by the periodontal disease bacteria such as P. gingivalis has a promoting effect on biofilm formation of A. naeslundii, and the studies on investigation of mechanism and pathogenic development control which targets this phenomenon are conducted (NIHON UNIVERSITY SCHOOL OF DENTISTRY, National Institute of Infectious Diseases, Japan).

In the present invention, with an attention on the influence by acids to the A. naeslundii biofilm formation, a substance, which is capable of inhibiting the biofilm formation depending on acids such as butyric acid thereby to inhibit the periodontal disease biofilm formation, was searched for, and a development of a novel periodontal disease biofilm inhibiting material with such substance was attempted.

An example of the literature regarding an oral composition exhibiting an antibacterial effect on the dental biofilm and an improvement effect on the gingivitis is PTL 1. PTL 1 discloses an oral composition containing (A) N-acylsarcosine or a salt thereof and (B) benzylisothiocyanate in a mass ratio (A)/(B) of 0.5 to 20, and also discloses that the oral composition has a good antibacterial effect on the dental biofilm causing the oral diseases and improvement effect on the gingivitis. However, PTL 1 does not disclose nor suggest any effects on the periodontal diseases.

CITATION LIST

Patent Literature

[0009]PTL 1: Japanese Patent Application Laid-Open No. 2008-174542

SUMMARY OF INVENTION

Technical Problem

Conventionally, in the methods for inhibiting the periodontal diseases which employ a certain antibacterial agent, the dental biofilm prevents the permeation of antibacterial agents and thus makes it difficult to achieve the intended periodontal disease inhibitory effects. Further, the use of antibacterial agents involves a high risk of resistant bacteria emergence, hence is not preferable. For these reason, controlling biofilm formed by A. naeslundii, which related to the initial stage of periodontitis is considered to be a periodontal disease prevention method which is safer and more effective than sterilizing the periodontal disease bacteria.

Solution to Problem

The present inventors conducted extensive studies and found that each of the plant extracts of potherb mustard, Japanese mustard spinach, hot radish and peppergrass belonging to the Brassicaceae family, Japanese angelica tree belonging to the Araliaceae family, and ice plant belonging to the Aizoaceae family has an inhibitory effect on the A. naeslundii biofilm formation induced by acid, whereby the present invention was accomplished.

The biofilm formation of A. naeslundii increases by the acid stimulation, but when 1000 ppm of the above plant is added to the culture system, the biofilm formation was found to be reduced to about 30%. At this time, some plant extracts did not affect the growth of A. naeslundii, suggesting that this biofilm formation inhibitory effect has a different mechanism from the antibacterial action.

A. naeslundii is a Gram-positive bacillus found in the sites of gingivitis and root surface caries and believed to be the pathogenic bacterium of the initial periodontal disease. Since A. naeslundii coaggregates with Streptococcus and the periodontal disease bacteria, it is considered to be a bacterium which is the key to the transition of bacterial flora to the periodontal plaque, which suggests that the control of A. naeslundii leads to the effective periodontal disease prevention.

The present inventors have validated that the biofilm formation was increased by the acids produced by the oral bacteria.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention provides a periodontal disease preventive agent with a new perspective, and is believed, when compared with the existing antibacterial agents, to have a lower risk of resistant bacteria emergence, and the like, hence advantageous.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph showing the A. naeslundii biofilm formation by the acid addition.

FIG. 2 is a graph showing the difference in the biofilm formation inhibitory activity by the extractant of a hot radish.

DESCRIPTION OF EMBODIMENTS

The present invention is directed to prevent the periodontal diseases by inhibiting the periodontal disease biofilm formed by A. naeslundii, an initial stage periodontal disease bacterium, and based on the findings such a periodontal disease biofilm inhibitor in the extracts of a part of the Brassicaceae family plants such as potherb mustard, Japanese mustard spinach and hot radish; Japanese angelica tree; and ice plant.

Being unlike the conventional antibacterial agents used for periodontal disease bacteria, the present inhibitor inhibits the biofilm formation, which is the dwelling of periodontal disease bacteria, and is believed to be effective and safe.

The present inhibitor is also applicable to chewing gums and candies as a novel oral composition. More specifically, the present invention relates to an oral composition containing a plant extract, wherein the plant extract is a hot water extract of Japanese mustard spinach, potherb mustard, mibuna (Brassica campestris var, laciniifolia), hot radish, cress, ostrich fern, Japanese angelica tree, or ice plant.

Further, the present invention relates to an acid-induced biofilm formation inhibitor containing a plant extract, wherein the plant extract is a hot water extract of Japanese mustard spinach, potherb mustard, mibuna, hot radish, cress, ostrich fern, Japanese angelica tree, or ice plant.

Furthermore, the present invention relates to mouthwashes, toothpastes, inhalants, troches, and food products such as chewing gums, candies, and tablets, comprising an oral composition containing a plant extract, which is a hot water extract of Japanese mustard spinach, potherb mustard, mibuna, hot radish, cress, ostrich fern, Japanese angelica tree, or ice plant.

EXAMPLE

Example 1

(Extract Preparation)

Each of the plant samples was a commercially purchased product. After freeze-dried, 1 g of each of the plant samples was finely ground using a grinder, and extracted with 50 ml of water at 70° C. for 2 hours. The obtained extract was centrifuged at 3000 rpm for 10 minutes, the supernatant thereof was filtered and freeze-dried to be tested as a hot water extract of each plant.

Example 2

(Evaluation on the Biofilm Formation Inhibitory Activity)

1. Biofilm Formation

A. naeslundii ATCC19039 strain was anaerobically cultured in 5 ml of Brain Heart Infusion (BHI) liquid media at 37° C. for 10 hours. Then, the bacteria collected by the centrifugal separation at 3000 rpm for 10 minutes was treated with PBS to adjust to OD_{550 nm}=0.5 and used as a test sample suspension.

The test of biofilm formation was carried out using a 96-well microplate. In each well, 60 μl of the biofilm formation inhibitory sample, 20 μl of butyric acid, 20 μl of a test sample suspension containing A. naeslundiiand 100 μl of Toripticase soy broth with 0.5% sucrose added thereto were added and incubated for 16 hours at 37° C. under the conditions of 5% CO₂.

2. Quantitative Determination of Biofilm

The supernatant after the above incubation was removed and each well was washed twice with PBS. After washing, a 0.25% safranine solution was added to each well, allowed to stand for 15 minutes. The excess safranine solution was removed from each well and each well was washed twice with PBS. After washing, ethanol was added to each well, the stained safranine was eluted with shaking for 30 minutes and the absorbance at 492 nm was measured using a microplate reader to determine the amount of formed biofilm.

The amount of formed biofilm was shown in terms of the percentage, the amount formed with no sample added being 100.

(Result)

1. Biofilm Formation Inhibitory Effect of Natural Product Extract

Extracts of various natural products were examined for the biofilm formation inhibitory activity in a butyric acid added system. Hot water extracts of various plants were prepared and measured for the biofilm formation inhibitory activities, and it was confirmed that when the hot water extract of Japanese mustard spinach, potherb mustard, mibuna, hot radish, cress, ostrich fern, Japanese angelica tree, or ice plant was added to the test system, the biofilm formation amount remained substantially unchanged in the system to which butyric acid was not added, whereas the biofilm formation amount was reduced by 50 to 90% in the system to which butyric acid was added. The effect was outstanding particularly in the hot water extracts of plants of the Brassicaceae family (Table 1).

Subsequently, the A. naeslundii biofilm formation was investigated for any increase by the addition of acids other than butyric acid, and a potherb mustard extract was investigated for the acid-induced biofilm formation inhibition. As a result, it is revealed that the A. naeslundii biofilm formation was increased even with the addition of other acids than butyric acid, such as acetic acid, lactic acid, and hydrochloric acid, and the potherb mustard extract inhibits the biofilms thereof (FIG. 1).

Hot radish whose activity was validated was extracted using different extractants (hot water, 50% ethanol, 100% ethanol), and each of which was examined for the biofilm formation inhibitory activity, and it was found that all the extract had the concentration dependent biofilm formation inhibitory activity (FIG. 2). These results suggest that the hot radish is most likely to contain both water soluble active substance and lipid soluble active substance.

To develop a periodontal disease preventive material which works by a mechanism different from the conventional materials, a butyric acid-induced biofilm formation inhibitory substance was developed focusing on the phenomenon in which the A. naeslundii biofilm formation was increased by butyric acid.

On the premise that the material is used for food products, the search was carried out mainly in the plants commonly eaten and remarkable activities were found in several kinds of plant extracts. These extracts did not notably inhibit the biofilm formation in the system to which butyric acid was not added but inhibited in the system to which butyric acid was added, indicating that the extracts were likely to affect only the system associated with butyric acid. In the present tests, the activity was found in the Brassicaceae family plants. But some of the Brassicaceae family plants do not exhibit the biofilm formation inhibitory activity. So, the effect was not common in all of the Brassicaceae family plants.

Also, the significant biofilm formation inhibitory activity was found in the extract of ice plant, an Aizoaceae family plant. Ice plant (scientific name: Mesembryanthemum crystallinum) is a salinity tolerant halophilous plant, native to Europe, western Asia and Africa, and can be hydroponically cultivated in a sodium chloride aqueous solution having a saline concentration substantially equivalent to the seawater. Ice plant is sold at the vegetable section of department stores and grocery stores in recent years and has been receiving attention. If additional values such as the periodontal disease biofilm prevention effect, were found, even more attention will be paid thereto.

The control of microorganisms and the conquer of infectious diseases using antibacterial agents, germicides, or the like, are the challenges against the resistant bacteria emergence, and the endless battles between novel antibiotics development and resistant bacteria emergence have been still ongoing at present. However, the biofilm formation inhibitory activity found in the plant hot water extracts obtained this time is verified only at the time of adding acids, and therefore, it is likely to be very safe in view of the resistant bacteria emergence.

Based on the results in this invention, investigation of the mechanism of the effect, identification of the active ingredient and effect tests on human will be carried out hopefully to develop a novel periodontal disease biofilm formation inhibitory material and apply such a material to oral care products.

Substances inhibiting the A. naeslundii biofilm formation induced by the addition of butyric acid were searched and it was found that the hot water extracts of 5 varieties belonging to the Brassicaceae plants such as Japanese mustard spinach and potherb mustard, and ice plant inhibited the biofilm formation by 50 to 90%. Further, it was suggested that the active ingredient of the Brassicaceae plants contains both of water soluble and lipid soluble substances.

TABLE 1
Biofilm formation inhibitory effect of hot water extracts of natural products
	Sample	Sample
	500 ppm	1000 ppm
	Butyric acid	Butyric acid
	Sample	Family	Genus	−	+	−	+
	—			100.0	100.0	100.0	100.0
1	Beet	Chenopodiaceae	Beta	87.3	104.5	132.0	96.4
2	Swiss chard	Chenopodiaceae	Beta	333.6	80.2	327.8	30.6
3	Raw coffee bean	Rubiaceae	Coffea	84.5	16.8	19.0	12.0
4	Coffee bean	Rubiaceae	Coffea	260.9	35.6	4.8	22.3
5	Indian mulberry	Rubiaceae	Morinda	231.3	93.6	584.8	92.3
6	Japanese mustard spinach	Brassicaceae	Brassica	537.7	93.2	87.9	6.8
7	Potherb mustard	Brassicaceae	Brassica	113.1	8.0	116.7	8.9
8	Mibuna	Brassicaceae	Brassica	94.1	13.2	138.1	33.8
9	Turnip	Brassicaceae	Brassica	455.8	77.7	367.0	71.4
10	Broccoli	Brassicaceae	Brassica	51.8	101.4	68.9	98.8
11	Rape blossom	Brassicaceae	Brassica	297.4	101.8	278.2	104.5
12	Kakina leaf	Brassicaceae	Brassica	156.7	115.4	325.7	115.8
13	Wasabi leaf	Brassicaceae	Brassica	86.7	110.9	45.6	118.9
14	Watercress	Brassicaceae	Nasturtium	44.2	50.9	7.9	26.8
15	Rucola	Brassicaceae	Arugula	11.8	30.1	7.8	38.0
16	Red radish	Brassicaceae	Raphanus	50.9	22.7	39.2	11.2
17	Hot radish	Brassicaceae	Raphanus	91.0	83.2	81.9	27.5
18	Radish	Brassicaceae	Raphanus	49.2	97.2	46.6	74.6
19	Cress	Brassicaceae	Lepidium	523.1	87.7	302.2	36.9
20	Horse radish	Brassicaceae	Wasabia	80.4	71.7	57.6	73.0
21	Ostrich fern	Woodsiaceae	Matteuccia	29.7	23.4	20.8	11.5
22	Japanese angelica tree	Araliaceae	Aralia	117.0	9.5	103.9	1.8
23	Zucchini	Cucurbitaceae	Cucurbita	337.9	86.4	329.9	91.9
24	Pumpkin	Cucurbitaceae	Cucurbita	63.3	129.7	70.1	140.6
25	Cucumber	Cucurbitaceae	Cucumis	316.3	82.7	313.3	82.6
26	Melon cucumber	Cucurbitaceae	Cucumis	291.8	87.8	327.3	90.0
27	Okinawan yellow cucumber	Cucurbitaceae	Cucumis	107.1	124.5	97.5	117.1
28	Bitter melon	Cucurbitaceae	Momordica	522.6	77.5	568.1	79.8
29	Wax gourd	Cucurbitaceae	Benincasa	134.5	96.7	117.1	95.3
30	Chicory	Asteraceae	Cichorium	175.8	103.7	315.3	103.6
31	Gynura bicolor	Asteraceae	Gynura	145.0	100.4	137.6	105.7
32	Nigana	Asteraceae	Ixeris	94.7	91.1	87.4	95.4
33	Butterbur scape	Asteraceae	Petasites	509.7	124.9	511.2	129.3
34	W blueberry	Ericaceae	Vaccinium	168.6	98.8	212.8	102.0
35	Chinese wolfberry fruit	Solanaceae	Lycium	187.7	87.6	476.1	84.6
36	Sweet green pepper	Solanaceae	Capsicum	137.1	73.6	544.3	64.8
37	Manganji pepper	Solanaceae	Capsicum	102.7	81.0	118.5	82.0
38	Green pepper	Solanaceae	Capsicum	129.9	91.4	221.1	83.7
39	Green chili	Solanaceae	Capsicum	64.9	87.3	37.3	84.1
40	Jalapeno pepper	Solanaceae	Capsicum	103.7	98.9	72.7	85.9
41	Eggplant	Solanaceae	Solanum	235.5	70.2	579.3	66.1
42	Potato	Solanaceae	Solanum	166.2	95.7	229.8	97.2
43	Cherry tomato	Solanaceae	Solanum	193.8	102.9	372.1	102.9
44	Mizunasu eggplant	Solanaceae	Solanum	127.7	117.0	151.7	108.3
45	Tomato	Solanaceae	Solanum	164.4	103.1	131.4	110.7
46	Beinasu eggplant	Solanaceae	Solanum	217.5	106.2	259.0	111.4
47	Pepino	Solanaceae	Solanum	93.7	81.7	109.8	55.4
48	Red onion	Alliaceae	Allium	447.4	111.3	660.6	96.0
49	Ice plant	Aizoaceae	Mesembryanthemum	504.8	34.2	213.7	11.0
50	Prune	Rosaceae	Prunus	263.8	107.6	401.7	66.0
51	Apricot	Rosaceae	Prunus	126.0	108.6	388.5	112.7
52	Cherry	Rosaceae	Prunus	313.5	124.3	485.0	183.3
53	Kidney bean	Fabaceae	Phaseolus	240.3	86.9	320.0	86.5
54	Red kidney bean	Fabaceae	Phaseolus	66.2	122.8	55.7	103.3
55	Feijoada bean	Fabaceae	Phaseolus	82.3	120.8	106.5	103.6
56	Black kidney bean	Fabaceae	Phaseolus	122.8	104.2	162.7	115.1
57	White flower bean	Fabaceae	Phaseolus	102.4	116.4	84.8	122.3
58	Red pea	Fabaceae	Pisum	182.3	123.1	275.5	121.6
59	Mung bean	Fabaceae	Vigna	70.6	95.5	45.9	37.9
60	Dainagon azuki	Fabaceae	Vigna	87.1	96.5	69.5	48.2
	bean
61	Bean sprout	Fabaceae	Vigna	99.5	97.3	106.1	100.8
62	Black-eyed pea	Fabaceae	Vigna	132.2	110.9	103.3	114.2
63	Winged bean	Fabaceae	Psophocarpus	72.1	89.0	131.4	88.4
64	Lentil bean	Fabaceae	Lens	244.9	120.4	457.2	115.8
65	Asparagus	Liliaceae	Asparagus	106.1	97.1	150.3	100.0
66	Dogtooth violet	Liliaceae	Erythronium	168.7	81.7	240.7	65.7
67	Hosta montana	Liliaceae	Hosta	229.7	100.0	325.4	98.2

Subsequently, a mouthwash, toothpaste, breath freshening spray, troche, chewing gum, candy, tablet candy, gummy jelly, and beverage, all containing the acid-induced biofilm formation inhibitor containing the plant extract of the present invention, were produced by a conventional method. The formulae are shown below.

However, the scope of the present invention is not limited thereto.

Example 3

A mouthwash was produced according to the following formulation.

Ethanol                          2.0% by weight
Japanese mustard spinach extract 1.0
Flavor                           1.0
Water                            Balance
                                 100.0

Example 4

A toothpaste was produced according to the following formulation.

Calcium carbonate      50.0% by weight
Glycerol               19.0
Mibuna extract         1.0
Carboxymethylcellulose 2.0
Sodium lauryl sulfate  2.0
Flavor                 1.0
Saccharin              0.1
Chlorhexidine          0.01
Water                  Balance
                       100.0

Example 5

A breath freshening spray was produced according to the following formulation.

Ethanol            10.0% by weight
Glycerol           5.0
Hot radish extract 1.0
Flavor             0.05
Coloring agent     0.001
Water              Balance
                   100.0

Example 6

A troche was produced according to the following formulation.

Cress extract              92.3% by weight
Gum Arabic                 6.0
Flavor                     1.0
Sodium monofluorophosphate 0.7
                           100.0

Example 7

A chewing gum was produced according to the following formulation.

Gum base                20.0% by weight
Xylitol                 54.7
Maltose                 15.0
Sorbitol                9.3
Flavor                  0.5
Potherb mustard extract 0.5
                        100.0

Example 8

A candy was produced according to the following formulation.

Sugar                   50.0% by weight
Reduced sugar syrup     33.0
Citric acid             1.0
Flavor                  0.2
L-Menthol               1.0
Potherb mustard extract 0.4
Water                   Balance
                        100.0

Example 9

A tablet candy was produced according to the following formulation.

Sugar                    74.7% by weight
Lactose                  18.9
Ice plant extract        2.0
Fatty acid sucrose ester 0.15
Water                    4.25
                         100.0

Example 10

A gummy jelly was produced according to the following formulation.

Gelatin                        60.0% by weight
Reduced sugar syrup            32.4
Japanese angelica tree extract 0.5
Vegetable oil and fat          4.5
Malic acid                     2.0
Flavor                         0.5
                               100.0

Example 11

A beverage was produced according to the following formulation.

Orange juice         30.0% by weight
Ostrich fern extract 0.5
Citric acid          0.1
Vitamin C            0.04
Flavor               0.1
Water                Balance
                     100.0

INDUSTRIAL APPLICABILITY

The oral composition of the present invention is a periodontal disease preventive agent with a new perspective which exhibits the acid-induced periodontal disease biofilm formation inhibitory action, different from the conventional antibacterial agents against periodontal disease bacteria. Consequently, the oral composition of the present invention is likely to render advantages of having a lower risk of resistant bacteria emergence, or the like, when compared with the existing antibacterial agents, and the like, and thus applicable to various products.

This application claims the priority from Japanese Patent Application No. 2011-196315, filed on Sep. 8, 2011, and the disclosure of which is hereby incorporated by reference as a part of the present application.

Claims

1. An oral composition, comprising a plant extract.

2. The oral composition according to claim 1, wherein the plant extract is a hot water extract of Japanese mustard spinach, potherb mustard, mibuna, hot radish, cress, ostrich fern, Japanese angelica tree, or ice plant.

3. An acid-induced biofilm formation inhibitor, comprising a plant extract.

4. The acid-induced biofilm formation inhibitor according to claim 3, wherein the plant extract is a hot water extract of Japanese mustard spinach, potherb mustard, mibuna, hot radish, cress, ostrich fern, Japanese angelica tree, or ice plant.

5. A mouthwash comprising the oral composition according to claim 1.

6. A toothpaste comprising the oral composition according to claim 1.

7. An inhalant comprising the oral composition according to claim 1.

8. A troche comprising the oral oral composition according to claim 1.

9. A food product containing the oral composition according to claim 1.

10. A mouthwash comprising the oral composition according to claim 2.

11. A toothpaste comprising the oral composition according to claim 2.

12. An inhalant comprising the oral composition according to claim 2.

13. A troche comprising the oral composition according to claim 2.

14. A food product containing the oral composition according to claim 2.