JP2010248088A - Cyclic diterpene compound, method of producing the same, soil improver, nitrification inhibitor, and fertilizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a novel compound exhibiting a nitrification-inhibitory action which is applicable to a wide area from the tropical zone to the temperate zone and can easily be obtained from a material of a natural origin; a soil improver; a nitrification inhibitor; and a fertilizer each containing the same. <P>SOLUTION: There is provided a cyclic diterpene compound, including a 5-8-5 membered ring as its basic skeleton and further comprising a lactone ring, which is secreted from a root of creeping signal grass, namely grass of the tropical family Gramineae, immersed in an ammonium salt. The cyclic diterpene compound is as powerful as nitrapyrin, and exhibits a sufficient nitrification-inhibitory action at a far lower concentration than dicyandiamide. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel cyclic diterpene compound and a method for producing the same, and a soil conditioner, nitrification inhibitor and fertilizer for soil containing the compound.

  Ammonia nitrogen contained in chemical fertilizers such as ammonia, ammonium salts, urea, etc., and ammonia nitrogen produced by the decomposition of organic fertilizers are nitrate nitrogen under oxidative conditions such as the surface layer of fields and paddy fields. Easy to change. This action called nitrification occurs due to the action of nitrifying bacteria such as nitrite bacteria and nitrate bacteria, and the produced nitrate nitrogen is washed away and released into the groundwater and the atmosphere without being adsorbed by the above-mentioned soil colloids. For this reason, the utilization rate of fertilized nitrogen fertilizers by crops is very low in soil conditions with strong nitrification, and the diffusion of nitric acid produced by nitrification into the environment is a cause of natural environmental pollution.

  In order to suppress nitrification in soil, conventionally, synthetic drugs such as nitrapiline (2-chloro-6-trichloromethylpyridine) and dicyandiamide described in Patent Document 1, for example, have been used. However, since nitrapirine is highly volatile and has little effect under conditions where the ground temperature is 20 ° C. or higher, it is only used under limited conditions in limited areas such as winter crops in North America.

  The dicyandiamide can also be used at a higher temperature than nitrapiline. However, it requires use at a high concentration and is expensive, which greatly affects agricultural production costs. Therefore, the area where dicyandiamide is also used is limited.

  In tropical regions, a phenomenon in which nitrification is suppressed in soil where creeping signal grass (Brachiaria humidicola), which is a tropical grass, grows, is known (Non-Patent Document 1 and Non-Patent Document 2). No effective nitrification inhibition method and nitrification inhibitor have been reported.

JP 11-278973 A Japanese Patent Publication No. 2008-245628

CIAT 1983 ANNUAL REPORT p.224 CIAT 1985 ANNUAL REPORT p.210-211 J. Plant Growth Regntl. 13 39-49, 1994 Iizumi et al. Appl. Environment. Microbiol. Vol. 3656-3662, 1998

  The present invention is a novel compound having a nitrification inhibitory action that can be used in a wide area from the tropics to the temperate zone and is easily obtained from naturally-derived materials, a method for producing the same, and a soil improver and a nitrification inhibitor containing the same Aims to provide fertilizer.

  Based on a report of a nitrification inhibition phenomenon (Non-Patent Document 1 and Non-Patent Document 2) in a soil where creeping signal grass (Brachiaria Humidicola), which is a tropical grass family grass, grows, We have conducted intensive research in anticipation of releasing some nitrification-inhibiting substances. As a result, the nitrification inhibitory substance was isolated and acquired, its chemical structure was determined, and further, the isolated compound was confirmed to have a nitrification inhibitory effect, and the invention was completed.

  That is, the compound of the present invention is a cyclic diterpene compound represented by the chemical formula (I). Hereinafter, the compound of the formula (I) is sometimes referred to as brachialactone.

The present invention is also a fertilizer containing a soil conditioner or nitrification inhibitor containing brachialactone as an active ingredient and brachialactone.
Furthermore, the present invention includes a step of immersing the root of the creeping signal glass in an ammonium salt to obtain a root leaching solution, a step of drying the obtained root leaching solution, extracting the dried product with methanol, and further drying the dried product with dichloromethane. Provided is a method for producing Brachylactone, comprising the steps of extraction and fractionation by reverse phase column chromatography and high performance liquid chromatography.

  Brachialactone is a naturally occurring novel compound having an excellent nitrification-inhibiting action, and is particularly a compound that can be used as a soil conditioner, nitrification inhibitor, and fertilizer in the tropics and temperate zones.

It is a figure showing the electron impact ionization mass spectrum of the brachialactone based on this invention. It is a figure which shows the spectrum analysis regarding the brachylactone which concerns on this invention, A represents the result of an ultraviolet absorption spectrum analysis, and B represents the result of a circular dichroism spectrum. It is a figure which shows the nitrification suppression rate of the brachialactone based on this invention.

Cyclic diterpene derivatives (hereinafter sometimes referred to as 5-8-5 cyclic diterpenes) having a 5-8-5-membered ring structure such as brachialactone are components contained in microorganisms and plants, and have been conventionally known. A group of compounds. Until now, it has been known that 5-8-5 cyclic diterpenes show a hormone-like action such as growth promotion and an action of increasing membrane permeability of various substances by activating H ⁺ -ATPase to plants. ing. On the other hand, it is known that animal cells are promoted to induce differentiation and have functions such as anticancer action (see Patent Document 2 and Non-Patent Document 3).
However, there is no report of a derivative having a lactone ring in the 5-8-5 membered skeleton such as Brachialactone.

  Brachialactone is obtained by immersing the root of creeping signal glass in an aqueous ammonium salt solution to obtain a root exudate, then drying the resulting root exudate, further extracting with methanol, further extracting with dichloromethane, and partition adsorption. It can be obtained by fractionation by column chromatography.

  Brachylactone is secreted by immersing the root of the creeping signal glass in an aqueous ammonium salt solution at room temperature for 1 to 5 days. Brachylactone is derived from inorganic ammonium salts such as ammonium chloride, ammonium sulfate, ammonium bicarbonate, ammonium nitrate. When ammonium chloride is used as the inorganic ammonium salt, the concentration range is preferably 1 to 5 mM. However, it is not limited to this concentration range, and can be induced even at 1 mM or less from a comparison of the amount of activity induction between 1 mM and 5 mM.

  The organic solvent for extracting the leachate of the creeping signal glass is alcohol, acetonitrile, diethyl ether, dichloromethane, chloroform, ethyl acetate, hexane or the like. From the relationship between purity and recovery rate, dichloromethane is the most efficient.

  The obtained organic solvent extract can be fractionated by partition adsorption column chromatography to obtain brachylactone.

  Brachialactone exhibits an excellent nitrification inhibitory action, and can be used as a nitrification inhibitor added to soil improvers, fertilizers and the like. Brachylactone used as a nitrification inhibitor can be easily produced by grass. For this reason, the soil improvement agent containing a nitrification inhibitor can be manufactured at low cost.

Brachialactone can be added to an inorganic material such as lime or fertile soil such as black soil to make a soil conditioner. What is necessary is just to select and determine the addition amount suitably as needed. For example, it is the range of 15-50 microgram per 1g of soil.
Since the soil conditioner containing brachialactone has a nitrification inhibitory action, it can suppress nitrification of nitrogen components and prevent deterioration of the soil environment.

Brachylactone can be blended with a fertilizer to form a fertilizer containing a nitrification inhibitor. As a fertilizer to mix | blend, an inorganic fertilizer and an organic fertilizer are mentioned, These mixed fertilizers may be sufficient. As the inorganic fertilizer, nitrogenous fertilizers such as urea, ammonium sulfate, and ammonium sulfate, phosphate fertilizers such as lime superphosphate, and potassium fertilizers such as potassium sulfate and potassium chloride can be used. Moreover, as an organic fertilizer, bone meal, compost, etc. can be used.
Since the fertilizer containing brachialactone contains a nitrification inhibitor together with the fertilizer component, nitrification of the nitrogen component can be suppressed, and fertilizer saving and soil environment deterioration can be prevented.

  Examples relating to the production of brachialactone from creeping signal glass and examples of measuring the nitrification inhibitory action are described below.

[Production and analysis of Brachylactone]
The root part of the creeping signal glass that was hydroponically cultivated by a known method was washed well with distilled water, immersed in 10 L of 2 mM ammonium chloride aqueous solution and treated at room temperature for 24 hours to obtain a root exudate. The root exudate was dried using a rotary evaporator and the residue was extracted with 100 mL of methanol. The obtained extract was filtered and then dried again, extracted with 20 mL of dichloromethane, and dried. The dried product was dissolved in a small amount of methanol, and diluted by adding an equivalent amount of water. This solution was packed in a reverse phase column (SepPak C18, 1 g solution) that had been equilibrated in advance with 50% methanol, and eluted sequentially with 50 to 90% methanol. The obtained fraction was subjected to high performance liquid chromatography connected to a TSKgel SuperODS column (moving bed: 20 to 40% acetonitrile / water, 10 minutes, then 40 to 43% acetonitrile / water, gradient for 8 minutes, flow rate of 1 mL / min. The nitrification inhibitory activity of each of the obtained fractions was measured by the method described later. A fraction showing nitrification inhibitory activity was selected to obtain 0.7 mg of a colorless pure compound. The chemical structure of this compound was determined by mass spectrometry, ultraviolet absorption spectrum analysis, circular dichroism and nuclear magnetic resonance analysis.

Electron impact ionization mass spectrum analysis was performed using a QP-2010 mass spectrometer (direct introduction probe use, 70 keV) manufactured by Shimadzu Corporation. The electrospray ionization Fourier transform ion cyclotron resonance mass spectrum was measured using an Apex II 70e mass spectrometer manufactured by Bruker Daltonics. The results are shown below. An electron impact ionization mass spectrum is shown in FIG.
Molecular formula: C ₂₀ H ₃₁ O ₄
Electron impact ionization mass spectrum (see Fig. 1): (m / z,%): 334 (M ⁺ , 17), 291 (9), 273 (5), 245 (5), 227 (5), 199 (11 ), 149 (21), 137 (100), 136 (75), 123 (20), 121 (47), 107 (22)
Electrospray ionization Fourier transform ion cyclotron resonance mass spectrum: m / z 335.2213 ([M + H] ⁺ )

The ultraviolet absorption spectrum analysis was performed using a Shimadzu UV-1600 spectrophotometer. Circular dichroism spectrum analysis was performed using a J-820 optical rotatory dispersometer manufactured by JASCO Corporation.
The results are shown in FIG. A shows the result of ultraviolet absorption spectrum analysis, and B shows the result of circular dichroism spectrum. Each peak has an ultraviolet absorption spectrum of λmax 230 nm (methanol, ε = 2.4 × 103), and a circular dichroism spectrum of λext: 232 nm (methanol, [θ] = + 6500, 0.0274 mmol / dl). )Met.

  Table 1 shows the results of the nuclear magnetic resonance spectrum. Nuclear magnetic resonance was performed using an Avance 800 or Avance 500 nuclear magnetic resonance spectrometer manufactured by Bruker Biospin.

  Since one signal in the one-dimensional proton NMR spectrum overlaps with the solvent peak, the chemical shift value was measured by HSQC.

  From these analysis results, the chemical structure of Brachialactone was identified as follows.

[Measurement of nitrification inhibitory action of brachylactone]
The nitrification inhibitory action was measured using nitrifying bacteria in vitro. First, preparation of a suspension of nitrifying bacteria used for measurement will be described.

Nitrosomonas europaea IFO14298 (see Non-Patent Document 4) into which bacterium-derived luciferase gene (luxAB) is introduced is aerobically cultured at 30 ° C. for 7 to 9 days in a P medium containing 25 mg / 1000 cm ³ of kanamycin. After washing and suspending in fresh P medium, a nitrifying bacterial suspension was prepared. This nitrifying bacterial suspension was left in a dark place for 30 minutes or more before the experiment. The composition of P medium was (NH ₄ ) ₂ SO ₄ 2.5 g, KH ₂ PO ₄ 0.7 g, Na ₂ HPO ₄ 13.5 g, NaHCO ₃ 0.5 g, MgSO ₄ -7H ₂ O 100 mg, CaCl ₂ -2H. ₂ O ₅ mg, Fe-EDTA 1 mg, water 1000 cm ³ , and its pH was 8.0.

Nitrification, the test aqueous solution of nitrifying bacteria suspension consisting of nitrifying bacteria suspension 0.25 cm ³ of water 0.2 cm ³ of the above, a sample solution 0.01 cm ³ of Examples and Comparative Examples, the tube Then, the amount of bioluminescence accompanying the nitrification reaction during the 30-minute incubation at 15 ° C. was evaluated by measuring using a luminometer (Turner Designs, model TD20 / 20). The amount of bioluminescence accompanying the nitrification reaction is reduced if a nitrification inhibitory substance is present in the sample solutions of the examples and comparative examples. Therefore, the amount of luminescence when the sample solution of each example and comparative example is added to the aqueous solution of nitrifying bacteria suspension, the aqueous solution of bacterial cell suspension without adding the sample solution of each example and comparative example The value obtained by dividing by the amount of luminescence in the case of only nitrification was defined as the nitrification inhibition rate. FIG. 3 shows the nitrification inhibition rate of Brachylactone in the examples.

The 80% inhibitory concentration of a conventional nitrification inhibitor composed of a synthetic drug is 6 μM for nitrapirine and 270 μM for dicyandiamide.
The brachialactone has an 80% inhibitory concentration of 11 μM, which is comparable to nitrapirine, and it has been found that a sufficient nitrification inhibitory effect can be obtained even at a much lower concentration than dicyandiamide.

Claims (5)

The cyclic diterpene compound shown by chemical formula (I).

  A soil improver comprising the cyclic diterpene compound according to claim 1 as an active ingredient.   A soil nitrification inhibitor comprising the cyclic diterpene compound according to claim 1 as an active ingredient.   A fertilizer containing the cyclic diterpene compound according to claim 1.   A step of obtaining a root exudate by immersing the root part of the creeping signal glass in an ammonium salt, a step of drying the obtained root exudate and extracting the dried product with methanol, and further extracting the dried product with dichloromethane to distribute the adsorption column The manufacturing method of the cyclic diterpene compound of Claim 1 including the process of fractionating by chromatography.

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