JPH0153659B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel diterpene compound, 3-hydroxy-7-oxo-sandarakopimaradiene (3-hydroxy-7-oxo-
The present invention relates to a plant disease control agent characterized by containing (sandaracopimaradiene) and the compound as an active ingredient. Rice cultivation in Japan has been seriously damaged by major diseases, especially rice blast disease, resulting in a decrease in rice yields, and many control methods using pesticides have been adopted. However, in recent years, environmental pollution caused by agricultural chemicals has become a problem, and it is currently difficult to say that an optimal control method has been found. From this point of view, research on plant phytoalexins is attracting attention as a disease control mechanism that inherently exists in the living environment of living things, but the mechanism of action has not yet been clarified. do not have. Previously, in research on phaite alexin, there have been reports that momilactone, which is obtained from rice husks as a plant growth inhibitor, has been recognized as a phaite alexin in rice. It is not isolated and is a different compound from the compounds of the present invention. The present inventors studied the metabolic relationship between host plants and plant pathogens with the aim of isolating new substances involved in the control mechanism of plant diseases and developing new plant disease control agents. We have succeeded in isolating a novel diterpene compound produced in the human body and found that it exhibits a strong inhibitory effect on plant pathogenic bacteria, especially rice blast pathogen. We have now completed a plant disease control agent containing the following ingredients: The compound of the present invention has the following structural formula [ ], is a new substance that has not been described in any known literature in terms of physical properties, and has biological properties such as plant pathogenic bacteria,
In particular, it has the effect of significantly inhibiting germ tube elongation and spore germination of rice blast pathogens, making it useful as a new plant disease control agent. That is, the compound of the present invention itself is biosynthesized in the host plant due to the metabolic relationship between the host plant and plant pathogenic bacteria, and is recognized to be involved in the regulatory action of the plant itself. There is no fear of contamination, and it has the characteristics of an extremely safe and non-polluting pesticide. The compound of the present invention can be obtained by extracting the homogenate of the lesions on leaves of rice affected by rice blast with petroleum ether, subjecting the concentrate to thin layer chromatography, and further applying the extracted concentrate to a gel filtration column. The eluate fraction showing antifungal activity was obtained by chromatography, and this concentrate was subjected to thin layer chromatography.
It is obtained by purifying the antifungal active component based on the R _f value. The physical and chemical properties of the substance thus obtained are as follows. (1) Shape: Oily substance (hydrated crystals in water-containing methanol). (2) Molecular formula: C ₂₀ H ₃₀ O ₂ . (3) Molecular weight: (high resolution mass spectrum). 302.2211 (actual value), 302.2244 (theoretical value). (As shown in Figure 1). (4) Specific rotation: [α]27°D=+20° (C, 0.13, in methanol). (5) Ultraviolet absorption spectrum: λ ^MeOH _nax 250nm (ε=
3730). (As shown in Figure 2). (6) Infrared absorption spectrum: ν ^KBr _nax 1685cm ^-1 (C=
O), 3353cm ^-1 (OH). (As shown in Figure 3). (7) Nuclear magnetic resonance absorption: Attribution of absorption by hydrogen nuclear magnetic resonance method (400MHz, heavy water saturated chloroform) is as shown in Table 1.

[Table] Shows protons. 〓
As a result, the positions of the hydroxyl and exovinyl groups are determined by the hydrogen nucleus Overhauser effect between 18-methyl and H ₃ -methine and between 17-methyl and olefinic H15, respectively, and the relative stereochemistry It was confirmed that it was 3-hydroxy-7-oxo-sandaracopimaradiene represented by the following structural formula []. As a result of examining the above properties, this substance exhibited specific physical and chemical properties, and no substance that could be identified as this substance was found among known substances, so it was recognized as a new compound. Next, the method for producing the compound of the present invention will be specifically explained using Examples. Example 1 1.51 kg of diseased leaf spots obtained from 50 kg of rice affected by rice blast disease in paddy fields were boiled for 3 minutes in 70% methanol and pulverized using an ultra homogenizer.
This homogenate was centrifuged (3900x) for 10 minutes.
g) and concentrate the supernatant under reduced pressure. The concentrated supernatant was extracted four times with petroleum ether, the extract was concentrated under reduced pressure, and then subjected to preparative thin layer chromatography [silica gel, 0.5 mm, 20 × 20 cm, benzene:ethyl acetate (10:1, v /v)]. The developed thin layer is scraped off between R _f values of 0.15 and 0.4 and eluted four times with methanol. Concentrate the mixed eluate and
Subjected to column chromatography on Sephadex LH-20 (2.1 x 58.5 cm, methanol). The eluted fractions showing antifungal activity were collected, concentrated under reduced pressure, and further separated using a preparative thin layer plate [silica gel, PLK5F, Watmann, 1 mm, 20 x 20 cm, benzene:ethyl acetate (10:1, v/v)]. refine. Antifungal activity was determined by thin layer chromatography R _f values of 0.22, 0.28,
observed at 0.36 and 0.61, respectively. The main component with an R _f value of 0.22 is further purified using methanol using a Sephadex LH-20 column (2.2 x 92.5 cm). The active eluate is concentrated under reduced pressure and further purified by thin layer chromatography (PLK5F) in the same manner as above. This eluate was subjected to gel permeation column chromatography (Toyopearl HW-
40 columns, 1.4 x 27.0 cm) to yield 1.5 mg of material. As a result of examining the physical and chemical properties of this substance, 3
-Hydroxy-7-oxo-sandaracopimaradiene was confirmed. When the compounds of the present invention are used as plant disease control agents, the above-mentioned active ingredients may be applied alone or, alternatively, they are usually carried in a suitable solid carrier similar to agrochemical formulations known in the art. , a liquid carrier, an emulsifying dispersant, etc., and may be formulated into any dosage form such as granules, powders, emulsions, wettable powders, tablets, oils, sprays, and fumes. These carriers include clay, kaolin, bentonite, acid clay, diatomaceous earth, calcium carbonate, solid carriers include nitrocellulose, starch, gum arabic, etc., and liquid carriers include water, methanol, ethanol, acetone, etc. , dimethylformamide, ethylene glycol and the like. In addition, adjuvants commonly used in formulations, such as sulfuric esters of higher alcohols, polyoxyethylene, alkyl allyl ether, alkyl allyl polyethylene glycol ether, alkyl allyl sorbitan monolaurate, alkyl allyl - Sulfonates, alkyl sulfonates, alkyl allyl sulfonates, quaternary ammonium salts, polyalkylene oxides, etc. can be blended as appropriate. The appropriate blending ratio of the active ingredient is approximately 10 to 90% for emulsions, wettable powders, etc., and approximately 0.1 to 10% for powders, oils, etc., but these may vary depending on the purpose of use. You may increase or decrease the concentration as appropriate. Furthermore, the drug of the present invention can be used with other fungicides, herbicides,
It is also possible to use it by appropriately mixing it with insecticides, fertilizers, soil conditioners, etc. Next, Examples of the plant disease control agent of the present invention will be shown. (Parts indicate parts by weight.) Example 1 (Wettable powder) 10 parts of 3-hydroxy-7-oxo-sandarakopimaradiene, 5 parts of sodium lauryl sulfate, 2 parts of dinaphthylmethane disulfonic acid soda formalin condensate, and Mix and crush 82 parts of clay to make a wettable powder.
Get 100 copies. Example 2 (Powder) 0.2 part of 3-hydroxy-7-oxo-sandarakopimaradiene, 0.5 part of calcium stearate,
Mix and crush 50 parts of talc and 49.3 parts of clay to make a powder.
Get 100 copies. Example 3 (Emulsion) 8 parts of 3-hydroxy-7-oxo-sandarakopimaradiene, 10 parts of ethylene glycol, 20 parts of dimethylformamide, 10 parts of alkyl dimethylbenzyl ammonium chloride, and methanol.
Mix and dissolve 52 parts to obtain 100 parts of emulsion. Example 4 (Granules) 10 parts of 3-hydroxy-7-oxo-sandaracopimaradiene, 15 parts of starch, 72 parts of bentonite, and 3 parts of sodium salt of lauryl alcohol sulfate were mixed and ground to obtain 100 parts of granules. . Next, the anti-plant pathogen activity of the plant disease control agent of the present invention will be specifically explained using test examples. Test example (anti-rice blast pathogen activity test) (1) Effect on spore germination A spore suspension of rice blast pathogen (Pyricularia oryzae) (x200 magnification, prepared to have 10 to 20 per field of view) was injected with the test sample. Add the drug to an alcohol solution to a specified concentration, drop 20μ onto a glass slide, culture in a humid room at 28℃, and measure the number of germinated spores using a microscope after 24 hours. The germination rate was determined. The results are shown in Table 2.

[Consideration]

The compound of the present invention completely inhibited spore germination at a concentration of 200 ppm and exhibited excellent antibacterial activity. (2) Effect on germ tube elongation YS medium (yeast extract 0.5%, glucose 2%
Pre-culture (containing) from spores of rice blast pathogen (28
1 ml of the culture solution (shaking culture at 28° C. for 24 hours) is transferred to 100 ml of YS medium supplemented with a predetermined concentration of the test drug, and cultured with shaking at 28° C. for 2 days. After culturing, germ tube elongation was measured by microscopy on a glass slide, and the inhibition rate was determined. The results are shown in Table 3.

[Table] (Note) The suppression rate was calculated using the following formula.
〓 Germination of spores 〓

Claims (1)

[Claims] 1 Structural formula: 3-hydroxy-7-oxo-sandarakopimaradiene (3-hydroxy-7-oxo-
sandaracopimaradiene). 2 3-hydroxy-7-oxo-sandaracopimaradiene (3-hydroxy-7-oxo-
A plant disease control agent characterized by containing a plant disease control agent (sandaracopimaradiene) as an active ingredient.