Composition for suppressing aflatoxin production and antibacterial composition

Abstract

To provide a composition for inhibiting aflatoxin production or an antimicrobial composition against an aflatoxin-producing fungus, each containing a plant-derived component.SOLUTION: A composition for inhibiting aflatoxin production by an aflatoxin-producing fungus of the present invention contains at least one selected from the group consisting of Gordonia axillaris extract, garden huckleberry extract, Wallum Banksia extract and Welwitschia mirabilis extract. An antimicrobial composition against an aflatoxin-producing fungus of the present invention contains at least one selected from the group consisting of Gordonia axillaris extract, garden huckleberry extract and Wallum Banksia extract.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition for suppressing aflatoxin production and an antibacterial composition against aflatoxin-producing bacteria, and particularly to such a composition containing a specific plant extract.

Background Art

[0002] Aflatoxin is a fungal toxin with strong toxicity including carcinogenicity. Contamination of agricultural crops including grains by aflatoxin has become a major problem worldwide, and the economic loss due to the disposal of contaminated food and feed is also enormous. Since aflatoxin contamination is derived from aflatoxin-producing bacteria that are present in fields, soil, etc., the development of control technologies for such bacteria is required. Patent Document 1 describes that a specific compound can be used for inhibiting aflatoxin production and controlling aflatoxin contamination, and Non-Patent Document 1 also describes that another compound has an antibacterial effect and an aflatoxin production inhibitory effect against aflatoxin-producing bacteria.

[0003] On the other hand, Non-Patent Document 2 describes that an extract of Camellia japonica var. formosana has an antioxidant effect. Non-Patent Document 3 describes that resveratrol and the like are contained in the methanol extract of the stem or root of Welwitschia mirabilis. However, Non-Patent Documents 1 and 2 do not describe an antibacterial effect or an aflatoxin production inhibitory effect against aflatoxin-producing bacteria. Further, Non-Patent Document 4 describes that an essential oil extracted from the leaves of Artemisia princeps Pamp. by steam distillation has an antibacterial effect, but does not describe an alcohol extract of Artemisia princeps Pamp.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005] [Non-Patent Document 1] JSM Mycotoxins(2019),69(2),81-83 [Non-Patent Document 2] Molecules(2010),15,8602-8617 [Non-Patent Document 3] Chemistry & Biodiversity(2005),2(6),773-779 [Non-Patent Document 4] Phytomedicine(2010),17,771-774 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] Although various mold inhibitors are used as post-harvest pesticides, problems such as persistence and toxicity have arisen, and safer materials are required. Therefore, an object of the present invention is to provide a composition for suppressing aflatoxin production containing a plant-derived component or an antibacterial composition against aflatoxin-producing bacteria. [Means for Solving the Problems]

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that a specific plant extract exhibits an aflatoxin production inhibitory effect or an antibacterial effect against aflatoxin-producing bacteria, and have completed the present invention. That is, the present invention provides the following composition for suppressing aflatoxin production, an antibacterial composition against aflatoxin-producing bacteria, and a method for suppressing the production of aflatoxin or the growth of aflatoxin-producing bacteria. [1] A composition for suppressing aflatoxin production of aflatoxin-producing bacteria, comprising at least one selected from the group consisting of Camellia japonica L. extract, Vaccinium vitis-idaea L. extract, Banksia integrifolia extract, and Welwitschia mirabilis extract. 〔2〕An antibacterial composition against aflatoxin-producing bacteria, comprising at least one selected from the group consisting of Taiwanese camellia extract, garden huckleberry extract, and wallum banksia extract. 〔3〕The composition according to 〔1〕 or 〔2〕 above, wherein the extract is an alcohol extract. 〔4〕A composition for suppressing aflatoxin production, comprising a Gymnema sylvestre extract, wherein the Gymnema sylvestre extract is an alcohol extract, and the composition is for suppressing aflatoxin production by aflatoxin-producing bacteria. 〔5〕An antibacterial composition comprising a Gymnema sylvestre extract, wherein the Gymnema sylvestre extract is an alcohol extract, and the composition is for antibacterial use against aflatoxin-producing bacteria. 〔6〕The composition according to any one of 〔1〕 to 〔5〕 above, wherein the aflatoxin-producing bacteria are Aspergillus spp. 〔7〕The composition according to any one of 〔1〕 to 〔6〕 above, wherein the content of the extract is 0.01 to 20% by mass in terms of the dry mass of the raw material plant based on the total mass of the composition. 〔8〕A method for suppressing the production of aflatoxin, comprising the step of applying at least one selected from the group consisting of Taiwanese camellia extract, garden huckleberry extract, wallum banksia extract, and Welwitschia mirabilis extract to aflatoxin-producing bacteria. 〔9〕A method for suppressing the growth of aflatoxin-producing bacteria, comprising the step of applying at least one selected from the group consisting of Taiwanese camellia extract, garden huckleberry extract, and wallum banksia extract to the bacteria. 〔10〕A method for suppressing the production of aflatoxin, comprising the step of applying a Gymnema sylvestre extract to aflatoxin-producing bacteria, wherein the Gymnema sylvestre extract is an alcohol extract. 〔11〕A method for suppressing the growth of aflatoxin-producing bacteria, A method comprising the step of applying a Gymnema extract to the aflatoxin-producing bacterium, wherein the Gymnema extract is an alcohol extract.

Advantages of the Invention

[0008] According to the present invention, the production of aflatoxin can be suppressed by a Taiwan camellia extract, a garden huckleberry extract, a Wallum banksia extract, a Welwitschia mirabilis extract, or a Gymnema extract, and the growth of aflatoxin-producing bacteria can be suppressed by a Taiwan camellia extract, a garden huckleberry extract, a Wallum banksia extract, or a Gymnema extract. Since these plant extracts have less concern about persistence and toxicity than general fungicides, it is possible to provide highly safe materials.

Modes for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described in more detail. The present invention relates to a composition for suppressing aflatoxin production by aflatoxin-producing bacteria, and contains an extract of Taiwan camellia, garden huckleberry, Wallum banksia, Welwitschia mirabilis, or Gymnema. None of these plants are known to be toxic to humans. The present invention also relates to an antibacterial composition against aflatoxin-producing bacteria, and contains an extract of Taiwan camellia, garden huckleberry, Wallum banksia, or Gymnema.

[0010] Taiwan Camellia (Gordonia axillaris) is an evergreen tree of the Camellia family, and its leaves or stems may be used as raw materials for the extract. Garden Huckleberry (Solanum nigrum L. var. guineense L.) is a fruit tree, and its leaves or stems may be used as raw materials for the extract. Wallum Banksia (Banksia aemula) is an evergreen tree, and its leaves or stems may be used as raw materials for the extract. Welwitschia mirabilis is a gymnosperm, and its leaves may be used as raw materials for the extract. Myrtle (Myrtus communis) is an evergreen shrub, and its leaves or stems may be used as raw materials for the extract.

[0011] As a method for preparing the extract, those commonly used in the art can be adopted without particular limitation. For example, the leaves or the entire above-ground part of the target plant can be ground, an extraction solvent can be added and stirred to prepare an extract (extract solution) of the plant. While blowing an inert gas into this extract solution, it can be dried, for example, at about 35 to about 45 °C to prepare an extract in the form of a dried product. The extraction solvent is not particularly limited, and for example, it may be an alcohol such as methanol, ethanol, 1-propanol, and isopropanol, or an organic solvent such as acetone, or it may be hot water. In one aspect, the extract may be an alcohol extract or a hot water extract.

[0012] The content of the extract is not particularly limited. For example, it may be about 0.01 to about 20% by mass in terms of the dry mass of the raw material plant relative to the total mass of the composition of the present invention, preferably about 0.1 to about 10% by mass. The "converted dry mass of the raw material plant" described in this specification refers to the mass when the mass of the extract is converted to the dry mass of the plant that is the raw material.

[0013] "Aflatoxin" described in this specification is a type of mold toxin, and types such as B1, B2, G1, and G2 are known. It is also known that these aflatoxins are biosynthesized through a common pathway. In addition, it is known that among fungi such as Aspergillus spp., there are fungi that produce the said aflatoxin, namely "aflatoxin-producing fungi". Examples of the Aspergillus spp. that are the said aflatoxin-producing fungi include A. flavus, A. parasiticus, A. nomius, A. pseudotamarii, A. bombycis, and A. parvisclerotigenus, etc.

[0014] The composition of the present invention may further contain any solvent and / or additive, etc. commonly used in the art, as long as the object of the present invention is not impaired, and may further contain other components effective for suppressing aflatoxin production or antibacterial against aflatoxin-producing fungi. As the said solvent, those commonly used in the art can be adopted without particular limitation. For example, it may be water, a buffer solution, or an alcohol such as methanol, ethanol, 1-propanol, and isopropanol, or a mixture thereof, etc.

[0015] The composition of the present invention can be applied and used at a place where aflatoxin-producing fungi are growing or a place where the growth of aflatoxin-producing fungi is suspected. The specific objects of application are not particularly limited. For example, they may be seeds, plants, or harvested agricultural crops, or a field, etc.

[0016] In another aspect, the present invention also relates to a method for suppressing the production of aflatoxin, which includes applying an extract of Camellia japonica var. formosana, Rubus occidentalis, Banksia integrifolia, Welwitschia mirabilis, or Ginkgo biloba to an aflatoxin-producing bacterium. Further, the present invention also relates to a method for suppressing the growth of an aflatoxin-producing bacterium, which includes applying an extract of Camellia japonica var. formosana, Rubus occidentalis, Banksia integrifolia, or Ginkgo biloba to an aflatoxin-producing bacterium. The extract is as described above in relation to the composition of the present invention, and can also be used in the method of the present invention in the form of the composition.

[0017] Hereinafter, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited to these examples.

Examples

[0018] 〔Preparation Example〕 Various plants were collected and dried at 60°C for 24 hours. Specifically, Sisymbrium orientale and Euphorbia sieboldiana were collected within the premises of the Food Research Division of the National Agriculture and Food Research Organization, and the other plants were collected at the Tsukuba Experimental Botanical Garden.

[0019] The leaf parts of the dried plants were finely ground with a Waring blender. However, for Cleome viscosa, since the whole plant body was small, the entire above-ground part was ground together. 2 g of the prepared ground material was placed in a 50 mL tube, 10 mL of 99.5% ethanol was added, and after stirring for 1 minute, ultrasonic treatment was performed for 3 minutes, and then left standing at room temperature for 24 hours to prepare an extract. This was centrifuged at 4400 rpm for 5 minutes to collect the supernatant, and 1 mL of it was taken into a 5 mL test tube and dried at 40°C while blowing nitrogen gas to prepare a plant extract in the form of a dried solid. This plant extract was redissolved in 100 μL of 99.5% ethanol and used in subsequent tests.

[0020] 〔Test Example 1〕 Using a spore suspension of Aspergillus flavus MAFF111229 strain, the bacteria were cultured by the TIP method according to the description in Non-Patent Document 1 (refer to Document 5 cited in Non-Patent Document 1 if necessary). As the medium, YES liquid medium (yeast extract 2 g / 100 mL, sucrose 20 g / 100 mL) was used. 244 μL of the medium packed with quartz wool was added per 1 mL sterilized tip, 5 μL of the spore suspension and 1 μL of the redissolved plant extract (ethanol solution) were added. The final concentration of each plant extract was 8 mg / mL (about 1% by mass) in terms of the dry mass of the raw material plant. In the control group, ethanol was added instead of the plant extract. After culturing, the concentration of aflatoxin B1 (AFB1) in the medium was quantified by a conventional method, and the weight (wet weight) of the bacterial cells accumulated in the tip was measured, and the relative values (%) to the values of the control group were calculated respectively. The AFB1 concentration was quantified by adding trifluoroacetic acid to the above medium and detecting hemiacetal AFB2a converted from AFB1 by HPLC. The results are shown in Table 1.

[0021]

Table 1

[0022] Among the plant extracts used in the test, each of the Ginbajika extract, Wallum Banksia extract, Garden Huckleberry extract, Welwitschia mirabilis extract, and Taiwan Camellia extract significantly suppressed the production of AFB1 by A. flavus and also suppressed the growth of A. flavus (Table 1). In particular, the inhibitory effect of these extracts on the production of AFB1 was relatively higher than the inhibitory effect on the growth of A. flavus. That is, the above extracts acted specifically on the production of aflatoxin rather than on the growth of A. flavus. For components with a low impact on the growth of A. flavus, it is expected that resistant bacteria are less likely to occur.

[0023] Although resveratrol is contained in the Welwitschia mirabilis extract (Non-Patent Document 3), the concentration of resveratrol in the plant extract used in the test was estimated to be at most about 3.3 μg / mL by comparison (peak height) with the data of the standard substance based on the HPLC chromatogram. It is unlikely that such a low concentration of resveratrol inhibits the production of AFB1 by A. flavus or the growth of A. flavus. In addition, as a result of HPLC analysis, many components that brought about higher peaks were detected. Therefore, it is considered that any one or combination of these components contributes to the inhibition of the production of AFB1 by A. flavus and the growth of A. flavus.

[0024] 〔Test Example 2〕 A. parasiticus was cultured in a medium containing a Wallum banksia extract, a Welwitschia mirabilis extract, a Taiwan camellia extract, or ethanol (control group) in the same manner as in Test Example 1, except that A. parasiticus NRRL2999 strain was used instead of A. flavus MAFF111229 strain. The concentrations of various aflatoxins in the culture solution were quantified by a conventional method (fluorescence detection by HPLC after derivatization with trifluoroacetic acid), and the weight (wet weight) of the bacterial cells accumulated on the chip was measured, and the relative value (%) with respect to the value of the control group was calculated. The results are shown in Tables 2 and 3.

[0025]

Table 2

Table 3

[0026] The plant extract that inhibited the production of AFB1 by A. flavus also inhibited the production of various aflatoxins by A. parasiticus (Table 2). The growth of A. parasiticus was not inhibited by the Welwitschia mirabilis extract, but was inhibited by the Wallum banksia extract or the Taiwan camellia extract (Table 3).

[0027] From the above, it has been found that the production of aflatoxin can be suppressed by extracts of Taiwan camellia, garden huckleberry, waratah, welwitschia mirabilis, or Gymnema sylvestre, and the growth of aflatoxin-producing bacteria can be suppressed by extracts of Taiwan camellia, garden huckleberry, waratah, or Gymnema sylvestre. Therefore, it is possible to provide a highly safe material, namely a plant extract, which has less concern about persistence and toxicity than general fungicides.

Claims

1. A composition for inhibiting aflatoxin production by aflatoxin-producing bacteria, comprising at least one selected from the group consisting of Taiwan tubaki extract, garden hackberry extract, waratah banksia extract, and welwitschia mirabilis extract.

2. An antibacterial composition against aflatoxin-producing bacteria, comprising at least one selected from the group consisting of Taiwan tubaki extract, garden hackberry extract, and waratah banksia extract.

3. The composition according to claim 1 or 2, wherein the extract is an alcohol extract.

4. A composition for inhibiting aflatoxin production, comprising a gimbai ka extract, wherein the gimbai ka extract is an alcohol extract, and the composition is for inhibiting aflatoxin production by aflatoxin-producing bacteria.

5. A method for inhibiting the production of aflatoxin, comprising the step of applying at least one selected from the group consisting of Taiwan tubaki extract, garden hackberry extract, waratah banksia extract, and welwitschia mirabilis extract to aflatoxin-producing bacteria.

6. A method for inhibiting the growth of aflatoxin-producing bacteria, comprising the step of applying at least one selected from the group consisting of Taiwan tubaki extract, garden hackberry extract, and waratah banksia extract to the bacteria.

7. A method for inhibiting the production of aflatoxin, comprising the step of applying a gimbai ka extract to aflatoxin-producing bacteria, wherein the gimbai ka extract is an alcohol extract.

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