Agricultural or horticultural preparation with light stability

Plant protecting and regulating compositions – Plant growth regulating compositions – Plural active ingredients

Reexamination Certificate

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Details

C504S142000, C514S025000, C514S510000, C514S557000

Reexamination Certificate

active

06242383

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition comprising MK8383 substance and cyclodextrins, and, more particularly, to an agricultural/horticultural preparation having improved photostability.
2. Background Art
MK8383 substance which is produced by Phoma sp. T2526 strain shows high antimicrobial activity against fungi, and is also effective against fungicide resistant fungi (Japanese Patent Laid-Open Publication No. 126211/1995). MK8383substance is therefore expected as an excellent agricultural/horticultural agent.
On the other hand, Japanese Patent Laid-Open Publications No. 71135/1974, No. 149202/1980, No. 149203/1980, No. 79802/1988 and No. 291803/1995 disclose methods for improving the photostability of active components of agricultural chemicals by adding ultraviolet absorbers or forming inclusion compounds.
SUMMARY OF THE INVENTION
We have now found that MK8383 substance is poor in photostability and that it shows greatly improved photostability when it is mixed with cyclodextrins. The present invention has been accomplished based on these findings.
An object of the present invention is therefore to improve the photostability of MK8383 substance. Another object of the present invention is to provide an agricultural/horticultural preparation having improved photostability, comprising MK8383 substance.
A composition according to the present invention comprises a compound represented by the following formula (I):
wherein R
1
represents hydrogen atom, or a lower alkyl or alkyl carbonyl group, and R
2
represents hydroxyl group or a lower alkoxy group,
or its salt, and cyclodextrins.
Deposition of Microorganism
Phoma sp. T2526 strain was deposited in National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology (1-3, Higashi 1-chome, Tsukuba-shi, Ibaragi-ken, Japan) on Oct. 28, 1993. The accession number is FERM BP-6461.
DETAILED DESCRIPTION OF THE INVENTION
Compound of Formula (I)
The compound of formula (I) according to the present invention can be obtained, for example, by cultivating a fungus belonging to the genus Phoma, and isolating the compound from the culture. There is no particular limitation on the production fungi as long as it belongs to the genus Phoma and has the ability to produce MK8383 substance. Specific examples of such fungi include Phoma sp. T2526strain (strain T2526) isolated from fallen leaves.
Strain T2526 readily changes in its property like other fungi. Not only this strain itself but also mutants (either spontaneous or induced), plasmacyte conjugants or gene recombinants derived from this strain can also be used as the production fungi as long as they can produce MK 8383 substance. MK 8383 substance can be obtained by cultivating MK8383-producing fungi on a culture medium containing nutrients that can be utilized by ordinary microorganisms. Known nutrient sources that have conventionally been used for the cultivation of fungi can be employed in the present invention. For instance, rice, glucose, malt syrup, dextrin, starch, sugar syrup, animal or vegetable oils, and the like can be used as carbon sources. Soybean powder, wheat germ, corn steep liquor, cottonseed cake, meat extract, peptone, yeast extract, ammonium sulfate, sodium nitrate, urea and the like can be used as nitrogen sources. It is also effective to add, when necessary, inorganic salts capable of liberating such ions as sodium, potassium, calcium, magnesium, cobalt, chlorine and phosphoric or sulfuric acid ions. Further, it is also possible to properly add organic substances and/or inorganic substances capable of promoting the growth of the fungus to accelerate the production of MK 8383 substance.
Cultivation under aerobic conditions, especially solid culture or deep culture is suitable as the method of cultivation for use in the present invention. The proper cultivation temperature is from 15° C. to 35° C., and the cultivation is usually conducted at a temperature around 20° C. to 30° C. In any of solid culture, shake culture and tank culture, the accumulation amount of MK 8383 substance produced generally reaches a maximum within 2 to 14 days depending on the culture medium and conditions used. When the accumulation amount of MK 8383 substance under cultivation has reached a maximum, the cultivation is terminated, and the desired substance is isolated from the medium and purified.
To isolate MK 8383 substance from the medium after cultivation, conventional separation means such as solvent extraction, ion exchange using ion exchange resin, adsorption or partition column chromatography, gel filtration, dialysis and precipitation can be used either singly or in combination depending upon the state of the substance produced. For example, MK 8383 substance produced can be extracted from the culture with acetone-water, methanol-water, ethyl acetate, or the like. Further, MK 8383 substance accumulated in the medium can be extracted into an organic solvent layer by conducting extraction using an organic solvent immiscible with water such as butanol or ethyl acetate. MK 8383 substance thus extracted may further be purified by means of column chromatography using such an adsorbent as silica gel (e.g., “Wako Gel C-300” manufactured by Wako Pure Chemical Industries, Ltd., Japan) or alumina, or using “Sephadex LH-20” manufactured by Pharmacia AB, high performance liquid chromatography (HPLC), centrifugal separation, or the like.
Functional groups present in MK 8383 substance may be modified. For example, hydroxyl group may be etherified or acylated (e.g., acetylized); and carboxyl group may be esterified. These modifications may be conducted by conventional methods.
The term “lower alkyl” or “lower alkoxy” used in the definition of formula (I) as a group or part of a group means a linear or branched alkyl or alkoxy group having 1 to 6, preferably 1 to 4 carbon atoms.
The compound of formula (I) can form salts. Examples of these salts include alkaline metal salts such as lithium, sodium and potassium salts; alkaline earth metal salts such as magnesium and calcium salts; ammonium salts such as ammonium, methyl ammonium, dimethyl ammonium, trimethyl ammonium and dicyclohexyl ammonium salts; organic amine salts such as triethylamine, trimethylamine, diethylamine, pyridine, ethanolamine, triethanolamine, dicyclohexylamine, procaine, benzylamine, N-methylpiperidine, N-methyl morpholine and diethylaniline; and basic amino acid salts such as lysine, arginine and histidine.
Stereoisomers of the compound of formula (I) can exist, and the present invention encompasses all of these stereoisomers and mixtures thereof.
Agricultural/Horticultural Preparation
A composition according to the present invention can be obtained by mixing the compound of formula (I) with cyclodextrins. To obtain an agricultural/horticultural preparation, the compound of formula (I) may be mixed with cyclodextrins upon the formulation of the preparation. Alternatively, the compound of formula (I) can be mixed with cyclodextrins just before spraying.
Examples of cyclodextrins that can be used in the present invention include &agr;-cyclodextrin, &bgr;-cyclodextrin, &ggr;-cyclodextrin, methylcyclodextrin, ethylcyclodextrin, dimethylcyclodextrin and hydroxypropylcyclodextrin. Of these, &ggr;-cyclodextrin is preferred. Any mixture of these cyclodextrins may also be used.
The composition according to the present invention may contain the cyclodextrins in an amount of 0.10 to 20 moles, preferably 0.5 to 2 moles per 1 mole of the compound of formula (I) used in the composition.
In the case where &ggr;-cyclodextrin is used as the cyclodextrins, the composition according to the present invention may contain it in an amount of 0.10 to 5 moles, preferably 0.5 to 2 moles per 1 mole of the compound of formula (I) used in the composition.
The compound of formula (I) has strong antimicrobial activity against phytopathogenic filamentous fungi. The compound of formula (I) is particularly efficacious against gray mold, rice blast, rice sheath blight, rice ba

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