BACKGROUND ART Conventional method of producing valienamine in commercial scale includes the following two methods at large: a method in which valienamine is directly obtained from hydrolysis of validamycin by bacteria, and the other method in which valienamine is synthesized from glucose as a starting material.

The validamycin derivatives basically comprise a valienamine moiety, and selectively bond with validamine or valiolamine. The validamycin derivatives are pseudotrisaccharides in which a series of glucoses are successively bonded.

A validamycin mixture, which is an antibiotic used in a rice cultivation field in East Asia as a bactericide, can be produced from a culture of soil microorganisms such as Streptomyces hygroscopicus, etc. , wherein the validamycin mixture includes a small amount of its intermediate, i. e. valienamine, which can be obtained from a column separation.

Valienamine can be produced by another method which involves a decomposition of validamycin by bacteria such as F. saccharophilum or P. denitrificans specifically, in the method, validamycin is added as a substrate or a medium, to a mixed bacteria solution, and cultured for a certain period of time so that validamycin can be decomposed by bacteria to give valienamine, then the valienamine can be obtained from a column separation.

Both of the methods described above are disadvantageous due to its time-consuming fermentation and a low production yield.

Reaction Scheme 1

Another compound having a valienamine moiety is acarbose, which is used as a therapeutic agent for diabetes, obtained from a secondary metabolite of Actinoplanes sp., a kind of soil microorganisms, and has a function of inhibiting a-amylase. However, a commercial production of acarbose from valienamine has not been developed yet.

One of production methods of valienamine reported in this field is a chemical production method that uses validamycin as a raw material and NBS (N-Bromosuccinimide). However, this method has a low production yield and difficulties in removing side products as well as difficulties in purification process, since it uses DMSO (dimethylsulfoxide) as a solvent. There has been another approach to produce valienamine by using organic or inorganic acid such as sulfuric, hydrochloric and acetic acid, however it is not successful due to insufficient hydrolysis which effects to only one sugar at the end group. Other method of producing valienamine by an organosynthetic method has been attempted, however practical use of this method is at a standstill due to its inefficiency in purification and organosynthetic process.

As a method for producing valienamine recently being in active progress, there is a method involving presynthesis with an enzyme. This method includes a search of

enzymes that are related to the synthesis of valienamine and expressed by bacterial strains, and then makes use of a cost-effective substrate to produce valienamine. However, the production according to the method at present state is difficult owing to some technical problems such as gene expression and the degree of activity of the probed genes.

As described so far, an in vitro production method of valienamine involving purified enzymes or chemical agents has not been commercialized yet, therefore valienamine has been produced heretofore by a biosynthetic method in which validoxylamine and validamycin are hydrolyzed to valienamine, by bacterial strains such as, mainly Pseudomonas denitrificans and Flavobacterium saccharophilum. Japanese Patent No. 57054593 discloses a method of converting validoxylamine and validamycin by using microorganisms, specifically a method of reacting 1-5 wt% of a mixture of validoxylamine and validamycin with Flavobacterium saccharophilum at 20-45°C in pH 5-8 for 24-200 hours to biosynthesize valienamine.

Other compounds having a valienamine moiety include acarbose, validoxylamine, validamycin and the like, and all of these are potential raw materials of valienamine which can be produced through different fermentation processes by each different bacterial strain.

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a method of producing valienamine with significantly high conversion rate, by selectively hydrolyzing acarbose derivatives or validamycin derivatives, using a heterogeneous solid catalyst such as a strong acidic cation exchange resin, an anion exchange resin, or a zeolite-based catalyst, and removing the catalyst and side products such as monosaccharides or disaccharides in a convenient manner.

In order to achieve said object, the method according to the present invention comprises a step of producing valienamine, which is a key precursor of voglibose that is a stronger a-glucosidase inhibitor per se than valienamine, from compounds having a valienamine moiety such as acarbose derivatives which are used as a therapeutic agent for diabetes in the form of a pseudodisaccharide or pseudotrisaccharide and validamycin derivatives, by using a heterogeneous solid catalyst.

The present invention relates to a method of producing valienamine using a solid

catalyst, characterized by reacting at least one compound having a valienamine moiety in the presence of a strong acidic or strong basic solid catalyst.

Further, the present invention relates to a method of producing valienamine, characterized in that the compound having a valienamine moiety is selected from the group consisting of acarbose and its derivates, validamycin and its derivatives, and validoxylamine and its derivatives.

The present invention also relates to a method of producing valienamine, characterized in that the solid catalyst is a strong acidic cation exchange resin containing a sulfonic acid functional group or a strong basic anion exchange resin containing a quaternary ammonium functional group.

Moreover, the present invention relates to a method of producing valienamine, characterized in that the solid catalyst is at least one selected from the group consisting of acidic zeolite, bentonite and montmorillonite. Preferably selected is a strong acidic synthetic or natural zeolite containing a sulfonic acid functional group, being treated with an inorganic acid having a high Si/Al ratio.

Further, the present invention is characterized in that the amount of the solid catalyst is 5-200 parts by weight, preferably 50-150 parts by weight, per 100 parts by weight of the reaction substrate.

Still further, the present invention is characterized in that the reaction is conducted at 40-150°C for 30 min. -24 hours.

Hereinafter, the method according to the present invention is described in detail.

For the raw materials of the present method, compounds having a valienamine moiety such as acarbose (available from Bayer), validoxylamine and validamycin, etc. may be used.

For the solid catalyst used in the above reaction, although it is not specially limite preference is made to, as a strong acidic cation exchange resin, a copolymer resin of polystyrene containing a functional group of sulfonic acid with divinylbenzene, for example Amberlyst 131 (Registered trademark of Rohm & Haas Co. ) and Diaion SK,<BR> Diaion PK (Registered trademark of Mitsubishi Chemical Industries Co. Ltd. ), and as a strong basic anion exchange resin, a copolymer resin of polystyrene containing a

functional group of quaternary ammonium with divinylbenzene, for example Amberjet <BR> <BR> 4400 OH (Registered trademark of Rohm & Haas Co. ) and Diaion SA, Diaion PA (Registered trademark of Mitsubishi Chemical Industries Co. Ltd.).

Further, a zeolite-, a bentonite-or a montmorillonite-based catalyst can be suitably used as the solid catalyst of the present invention. Among these, preferred is a strong acidic synthetic or natural zeolite-based catalyst containing a functional group of sulfonic acid, with high Si/Al ratio, such as ZSM-5.

The specific condition for the reaction between the compound having a valienamine moiety and the solid acid catalyst may depend on the catalyst species. The reaction temperature is in the range of 30-200°C : particularly when using a cation exchange resin, preferably being 80-120°C ; when using an anion exchange resin, preferably being 40-120°C ; and when using a zeolite catalyst, preferably being 80-150°C.

The reaction time is in the range of 30 min. -24 hours, preferably in the range of 2-24 hours.

The amount of the solid catalyst added is suitably 5-200 parts by weight, preferably 50-150 parts by weight, per 100 parts by weight of the reaction substrate.

In the resulted solution, after completing the reaction with the solid catalyst, the desired compound valienamine is adsorbed to the sulfonic acid group in porous matrix of the catalyst resin or the zeolite. The adsorbed valienamine can be separated by using an aqueous primary or secondary amine solution at a concentration of 0.5-2. 0 wt% or preferably 5-20 wt%.

In purification process for removing undesirable components, the solution is passed through a weak acidic cation exchange resin column, for example where a copolymer resin of polystyrene containing a carboxyl functional group and divinylbenzene <BR> <BR> is packed, such as Amberlite IRC-50 (Registered trademark of Rohm & Haas Co. ) and<BR> Diaion WK (Registered trademark of Mitsubishi Chemical Industries Co. Ltd. ) ; the eluted solution is collected from the column; the column is washed with deionized water; the washing solution is collected from the column ; and the collected solution is concentrated and recrystallized to give crystal of the desired product being almost free of impurities.

BRIEF DESCRIPTION OF DRAWINGS Figure 1 represents a TLC (thin layer chromatography) result of valienamine.

From the left, lane 1: a product from the reaction between acarbose and TFA (trifluoroacetic acid) (before purification), lane 2: valienamine produced by reacting acarbose with TFA, lane 3: Co-Spot of lanes 2 and 4, lane 4: the resulted product of Example 1 (valienamine), lane 5: a product produced by reacting acarbose with a cation exchange resin, Amberlyst 131 (before purification), Figure 2 is a plot representing'H-NMR data of the result of Example 4.

Figure 3 is a plot representing 13C-NMR data of the result of Example 4.

BEST MODE OR EMBODIMENTS FOR CARRYING OUT THE INVENTION The following examples illustrate the present invention more specifically. They are, however, by no means limiting the scope of the right of the present invention.

Example 1 : Method of Producing Valienamine Using Cation Exchange Resin A high pressure reactor with a volume of 100 ml was charged with 1 g of pure acarbose derivative (disaccharide and/or trisaccharide) (Zhejiang Dongli, China), thereto successively added were 20 ml of water for dissolving the acarbose derivative and 2 g of a strong acidic cation exchange resin, Amberlyst 131 (Registered trademark of Rohm & Hass <BR> <BR> Co. ), and then the mixture was reacted at 80 °C for 12 hours or more and filtrated to remove the reaction solution. To the filtered cation exchange resin, 100 ml of 0. 5N <BR> <BR> ammonia water was added and stirred for 30 min. , then the mixture was filtered, and the filtrate was purified through a weak acidic cation exchange resin to give 0.23 g of valienamine.

Example 2: Method of Producing Valienamine Using Zeolite A high pressure reactor with a volume of 100 ml was charged with 1 g of pure acarbose derivative (disaccharide and/or trisaccharide) (Zhejiang Dongli, China), thereto

successively added were 20 ml of water for dissolving the acarbose derivative and 2 g of a strong acidic zeolite-based catalyst, ZSM-5 (manufactured by Union Carbide), and then the mixture was reacted at 120°C for 12 hours or more and filtrated to remove the reaction solution. To the filtered zeolite-based catalyst, 100 ml of 0. 5N ammonia water was added <BR> <BR> and stirred for 30 min. , then the mixture was filtered, and the filtrate was purified through a weak acidic cation exchange resin to give 0.19 g of valienamine.

Example 3: Method of Producing Valienamine Using Cation Exchange Resin A high pressure reactor with a volume of 100 ml was charged with 1 g of validamycin A and its derivative (Zhejiang Dongli, China), thereto successively added were 20 ml of water for dissolving the validamycin A and its derivative and 2 g of a strong acidic cation exchange resin, Amberlyst 131 (Registered trademark of Rohm & Hass Co.), and then the mixture was reacted at 80 °C for 12 hours or more and filtrated to remove the reaction solution. To the filtered cation exchange resin, 100 ml of 0. 5N ammonia water <BR> <BR> was added and stirred for 30 min. , then the mixture was filtered, and the filtrate was purified through a weak acidic cation exchange resin to give 0.29 g of valienamine.

Example 4: Method of Producing Valienamine Using Anion Exchange Resin A high pressure reactor with a volume of 100 ml was charged with 1 g of pure acarbose derivative (disaccharide and trisaccharide), thereto successively added were 20 ml of water for dissolving the acarbose derivative and 2 g of a strong basic anion exchange <BR> <BR> resin, Amberjet 4400 OH (Registered trademark of Rohm & Haas Co. ), and then the mixture was reacted at 100°C for 12 hours or more and filtrated to remove the reaction solution. To the filtered anion exchange resin, 100 ml of 0. 5N ammonia water was added and stirred for 30 min. , then the mixture was filtered, and the filtrate was purified through a weak acidic cation exchange resin to give 0.22 g of valienamine.

The spectrum of hydrogen and carbon nuclear magnetic resonance of the results from above Examples 1,2, 3 and 4 are presented below.

'H-NMR (D20) 6 : 3.42 (1H, br s, H-1), 3.54 (2H, ABq, J=13.6Hz, H-7),

3.94 (1H, d, J=6.79Hz), 3.97 (1H), 4.05 (1H), 5.64 (1H, d, J=4.6) 13C-NMR (D20) 6 : 48.9 (C-1), 61.2 (C-7), 69.7 (C-2), 71.7 (C-4), 72.0 (C-3), 123.4 (C-6), 139.9 (C-5) It was confirmed that the product obtained from Examples is valienamine from the result of NMR (Figures 2 and 3) and TLC (thin layer chromatography) (Figure 1).

INDUSTRIAL APPLICABILITY By the method of the present invention, the valienamine can be produced with a high production yield of 75-90% which has not been possible in prior art, with few side products such as pseudosaccharide or pseudodisaccharide, since only a-bond is hydrolyzed, thereby causing much less cost for waste water/liquid treatment. Further, the method provides simpler processes for producing and purifying valienamine while inhibiting the generation of side products, thereby it is possible to obtain valienamine having high purity with less cost.