JPH06234652A - Preventive medicine for fish infectious disease - Google Patents

Abstract

PURPOSE:To obtain a preventive medicine having no problem of residual medicine when used with foods and capable of lowering fishes death by bacterial injections in a fish farm. CONSTITUTION:This preventive medicine for infectious decreases of fishes comprises an alkali soluble fraction which is extracted wing a sodium carbonate aqueous solution from a residue obtained by boiling and extracting a specific seaweed consisting of a brown algae or a red algae with dilute hydrochloric acid. The medicine is administered to a fish perorally by mixing it in a feed, intraperitoneally or intramuscularly, or the fish is dipped in the medicine solution in a water tank. By using the medicine, disease resistance and immunity of fishes are enhanced, leading to lowering of fishes death caused by bacterial injections. Fishes treated with this medicine give no problem of food hygienicity.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a relates to infectious prophylactic agent fish, particularly, Streptococcus (Streptococcus), class nodule bacteria (Pasteurella), Edwardsiella bacteria (Edwardsiella)
The present invention relates to a drug that reduces mortality due to fish infection caused by bacteria such as

[0002]

2. Description of the Related Art In fish farms, antibiotics and synthetic antibacterial agents are frequently used as countermeasures against frequent bacterial infections. However, these drugs not only lose their efficacy due to the emergence of resistant bacteria and multidrug-resistant bacteria, but also have an antibacterial agent remaining in cultured fish meat, which poses a food hygiene problem. Therefore, there is a strong demand for a method of reducing mortality due to bacterial infection without using these drugs.

In recent years, as a preventive method for preventing infection, a method of administering a large amount of various vitamins such as vitamin C, vitamin E, pantothenic acid and choline chloride has been proposed [Journal of the Fisheries Society of Japan, 54 ( 1), 141 ~ 144 (1988)
Etc.], some effects are recognized but they are not sufficient, and they do not actively prevent infection.

In addition, prevention of fish diseases based on immunopotentiating activity
FK-565 as a therapeutic agent (Japanese Patent Laid-Open No. 63-233923), a specific crude drug or its extract (Japanese Patent Laid-Open No. 64-75426, etc.),
Further, it has been reported that a polysaccharide having a β-1,3-glucan structure derived from fungi or yeast (Japanese Patent Laid-Open No. 2-218615) is effective for infectious diseases of fish.

On the other hand, with regard to seaweed polysaccharides, there are known examples showing effects on mammalian tumors [food and development, Vo.
L.25, No.3, 32-38 (1990)] is not reported to be effective for bacterial infection of fish.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the problems of conventional antibiotics and synthetic antibacterial agents, and is not inferior to the efficacy of antibacterial agents and synthetic antibacterial agents, and uses fish as a safe food. It intends to provide a drug that can prevent fish infections.

[0007]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventor has found that seaweed, particularly extracts from brown algae and red algae, have antibacterial activity and immunity possessed by fish. The present invention was completed by finding out that it strengthens.

[0008] That is, the present invention provides a drug containing a component extracted from seaweed of brown algae and red algae, which is effective for preventing fish infectious diseases, which can be used as a safe food for fish. is there.

The seaweed used in the present invention is brown algae,
Fukuronori, Habanori, sardine, seaweed, arame, Kajime, Mitsuishikonbu, Macombus, jolomoku, Hijiki, Akiyoremoku, Fushijimoku, Akamoku, Yanamoku, Yoremoku, Umitranoa, Iroro, Shiwanokawa, Chigaiso, Meatweed, Squirrel, Squirrel
Such as Yasumatamoku. In red algae, Susabinori,
Asakusanori, Matsunori, Ibaranori, Fukuro Funori,
They are Tsunomata and Shokenori.

Among these seaweed, especially Fukuronori,
Habanori, sardine, wakame, arame, kajime, mizushikonbu, mackerel, jolomoku, hijiki, akiyoremok, fujijimoku, akamoku, willowmoku, yeremok,
Umitranano, Asakusanori, and Tsunomata are preferable in terms of effects.

The drug of the present invention comprises the alkali-soluble fraction of these seaweeds. Even in the case of extracts from the same seaweed, there is a large difference in the effect of preventing bacterial infections in fish between the acid-soluble fraction and the alkali-soluble fraction,
The acid soluble fraction has little effect.

The alkali-soluble fraction is usually a fraction contained in a supernatant obtained by crushing dried seaweed into fine pieces, heat-extracting with dilute hydrochloric acid, and washing the precipitate with water, followed by alkali extraction.

Heat extraction with dilute hydrochloric acid is usually performed by drying dried algal pieces.
2 to 100 g of boiling hydrochloric acid (pH 2.8) 1-2 liters
Repeat 5 times, preferably about 3 times. As a result, 22 to 53% of the seaweed used is separated as an acid-soluble fraction.

After hot extraction with dilute hydrochloric acid, the mixture is allowed to stand to separate the supernatant liquid, and the precipitate is washed with water and subjected to alkali extraction.
Alkali extraction is usually carried out by immersing the above precipitate in a 1% aqueous solution of sodium carbonate, at room temperature, stirring, or shaking.
Soak for 6 to 24 hours, preferably 8 to 12 hours for extraction.

After extraction, the mixture is centrifuged to remove the residue, an equal amount of ethanol is added to the supernatant and mixed, and the deposited precipitate is washed with ethanol and ether, dried and dried to give a powdery alkali-soluble fraction. It is obtained as a solid in the form of fibers or fibers.

The yield of the alkali-soluble fraction thus obtained varies depending on the type of seaweed used and the extraction conditions, but is usually 10 to 45% of the seaweed used.

(Method of use) Examples of fishes and fish diseases to which the agent of the present invention is applied include vibrio diseases such as yellowtail, red sea bream, puffer fish, flounder, grouper, coho salmon, rainbow trout, eel, carp, ayu and tilapia ( Vibrio anguillarum ),
Edwardsiella tarda , Pasal tuberculosis ( Pas
teurella piscicida ), Streptococcus ( Streptococcus s)
p.), Nocardia campachi , gliding bacterium
( Flexibacter sp.), Aeromonas ( Aeromonas hydroph
ila , Aeromonas salmonicida ) and other bacterial infections.

The agent of the present invention can be used not only by oral administration or intraperitoneal administration to fish, but also by intramuscular administration or by immersing fish in the aqueous solution of the agent of the present invention.

In the case of oral administration, the alkali-soluble fraction is usually added to, for example, 0.001 to 10
%, Preferably 0.01 to 5%, and administered as a feed.

In the case of intraperitoneal administration or intramuscular administration, it is usually used as an aqueous solution in which an alkali-soluble fraction is dissolved in sterile physiological saline. In this case, even if it is not completely dissolved but partially suspended, it can be used as it is.

In the case of intraperitoneal administration, for example, 0.1-10%,
It is preferably administered by intraperitoneal injection as a 0.5-1.0% aqueous solution, or by intramuscular injection as a 1-10%, preferably 5-10% aqueous solution by injection into the muscle.

In both intraperitoneal and intramuscular administration, the dose is generally 1 to 100 mg / kg fish body weight of the alkali-soluble fraction, preferably 5 to 25 mg / kg fish body weight.

When the fish is immersed in the aqueous solution of the drug, the alkali-soluble fraction is usually 0.001 to 1%, preferably
Immerse in fresh water or seawater containing 0.01 to 0.5% for 1 minute to 12 hours, preferably 10 minutes to 5 hours.

[0024]

The present invention will be described in detail with reference to the following examples.

Examples and Comparative Examples (Preparation of Alkali-Soluble Fraction) Alame, Wakame, Willow Moku, Kajime, Hombu from Hokkaido, and Ascophilum from foreign brown algae collected on the coast of Fukuyoshi-cho, Saga Prefecture on February 20, 1991. ( Ascophyl lum nodosum ), and Asakusanori, Fukurofunori, Tsunomata, after air-drying overnight, freeze-dried 10 g each, add 100 ml of dilute hydrochloric acid of pH 2.8,
It was extracted by boiling for 3 hours and centrifuged to separate into a supernatant and a precipitate. The dilute hydrochloric acid extraction was repeated twice more to obtain about 300 ml of the supernatant and dilute hydrochloric acid hot extraction residue.

The supernatant was concentrated under reduced pressure, dehydrated with ethanol and ether, and dried to obtain an acid-soluble fraction.

The hot hydrochloric acid extraction residue was washed with 100 ml of water, then extracted with alkali with 500 ml of a 1% sodium carbonate aqueous solution overnight with shaking, and the insoluble residue was filtered off, and an equal amount of the separated supernatant was added. Alkali-soluble fraction was precipitated by mixing with ethanol, concentrated under reduced pressure, dehydrated with ethanol and ether, and dried to obtain an alkali-soluble fraction. The yield of each fraction is shown in Table 1.

[0028]

[Table 1]

(Protection test against carp) For each extract, 10 fish of each carp (average weight 25.6 ± 3.9 g) purchased from Yatsushiro Sugishima Fish Farm on May 22, 1991 and June 24, 1991 were used. The extract fraction aqueous solution (1 g / 100 ml physiological saline) was intraperitoneally administered twice every two days at a rate of 50 mg (dry weight of extract) per 1 kg of body weight. The control fish received the same amount of physiological saline alone. Edwa 3 days after the last dose
rdsiella tarda NG8104 (3 × 10 ⁷ CFU / 100g) was inoculated into the abdominal cavity, and the survival rate for 8 days after bacterial challenge was examined. The results are shown in Table 2.

[0030]

[Table 2]

[Table 3]

[0031]

EFFECTS OF THE INVENTION By using the agent of the present invention, it is possible to enhance the anti-disease and immunity of fish, effectively prevent bacterial infection of fish, and use fish as a safer food. In addition, it can be expected that the therapeutic effect is improved by using it together with a therapeutic drug.

Claims (3)

[Claims] 1. A drug for preventing infectious diseases of fish, which comprises a component extracted from seaweed of brown algae and red algae by alkali. 2. The agent according to claim 1, wherein the alkaline extractant is an aqueous sodium carbonate solution. 3. The drug according to claim 1, wherein the component to be extracted with alkali is the extracted component after the acid-soluble fraction has been separated and removed.