JPS6332781B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a novel neutral L-arginine L-
Concerning malate crystals and their production method. L-arginine is a compound that has a very wide range of uses as a fortifying additive and as a pharmaceutical, but it is extremely difficult to isolate in crystalline form as the free base. Even if it is isolated, it is usually used in the form of hydrochloride because it easily absorbs carbon dioxide gas in the air, has poor moisture resistance, and is extremely prone to compositional changes. However, in cases where oral nutritional intake is difficult and parenteral nutrition must be relied upon, administering L-arginine in the form of hydrochloride may cause acidosis symptoms due to the influence of chloride ions. Furthermore, it is undesirable to inject infusions containing a large amount of hydrochloride ions into renal disease patients, and therefore there has been a particularly strong demand for amino acid infusions that do not contain chloride ions. On the other hand, even when amino acid-containing preparations are taken orally, amino acid mixtures containing amino acids in the form of hydrochloride have a strong bitter taste and are unpleasant to taste.
This is particularly noticeable in preparations containing amino acids as the main ingredient. In chemical diets that use amino acid mixtures as the sole nitrogen source, various flavors are added to change the taste and make them easier to eat and drink, but the bitterness derived from the hydrochloride of basic L-amino acids A fundamental solution has not yet been found. As a result of various studies to obtain a crystalline L-arginine salt that does not contain chloride ions, the present inventors discovered that L-malic acid, which is easily metabolized in the body and has medicinal effects, has been synthesized from L-arginine. is reacted in an aqueous solvent, the L-malic acid is converted into this L-malic acid.
By forming a neutral salt with arginine in a molar ratio of 1:2, and by growing and crystallizing the crystals of these salts, the crystalline state is stable against moisture and has a very high solvity with respect to water. The present inventors have discovered that they can be harvested as large, highly pure crystals, and have completed the present invention. Examples of the neutral salt of the present invention consisting of 2 moles of L-arginine and 1 mole of L-malic acid (hereinafter simply referred to as neutral salt) include neutral L-arginine/L-malate/anhydride crystals. It will be done. This neutral salt crystal is a new substance and is a very useful substance in preparing crystalline amino acid infusions, especially infusions with reduced or no chloride ion content. There have also been reports of cases of hyperammonemia caused by intravenous infusion of amino acids, but it is known that L-malic acid has the effect of improving liver function and is effective in preventing ammonia poisoning. Therefore, in terms of preventing hyperammonemia, the neutral salt crystals of the present invention not only replenish L-arginine, but also have the property of being able to utilize the efficacy of L-malic acid. It is extremely useful medically. Furthermore, the neutral salt of the present invention is almost tasteless and odorless, making it ideal for oral administration. The neutral salt crystal of the present invention contains L-arginine and L-arginine.
Neutralize malic acid in an aqueous solvent to generate a neutral salt consisting of 2 moles of L-arginine and 1 mole of L-malic acid, and concentrate the reaction solution until the concentration of the neutral salt in the concentrated solution is 30%. By adjusting the water content to ~80% and then adding a hydrophilic organic solvent to adjust the water content of the solvent in the crystallization system to about 10 to 50%, crystals can be precipitated. To form the neutral salt in an aqueous medium, add about 0.8 mol of L-malic acid to 2 moles of L-arginine in an aqueous solution containing free L-arginine (e.g., an aqueous solution). It is preferable to dissolve up to 1.2 mol, preferably 1 mol, and adjust the pH to about 6.0 to 8.5, particularly around 6.5 to 7.5. Incidentally, if L-malic acid is used in excess, an acid salt in which 1 mol of L-arginine and 1 mol of L-malic acid are combined is also produced, which is not preferable. In order to precipitate the neutral salt crystals from the neutral salt-containing aqueous solution obtained above, there are methods such as adding a hydrophilic organic solvent to the solution, adding the solution to a hydrophilic organic solvent, and seeding. A method of inoculating crystals, or a method combining these methods (for example, adding a hydrophilic organic solvent to the solution to precipitate some crystals, and then adding this crystal-containing mixture to the hydrophilic organic solvent) method) etc. can be adopted. However, simply concentrating the reaction-completed solution tends to produce an amorphous, grease-like product because the neutral salt itself is extremely soluble in water, and the viscosity of the mother liquor is also high, making solid-liquid separation difficult. This makes it difficult to obtain crystals of good quality. The concentration of the neutral salt-containing aqueous solution used in the precipitation operation is not particularly limited, but is about 30 to
80%, especially about 50 to 70% is preferable. At concentrations lower than this, the precipitated crystals tend to form blocks. Examples of the hydrophilic organic solvent used in the precipitation operation include lower alkanols such as methanol, ethanol, and isopropanol, ketones such as acetone, and N,N'-dimethylformamide. Further, in this operation, these may be used alone or in combination of two or more. Furthermore, the amount of these hydrophilic organic solvents to be used is generally determined because if the water content of the solvent in the crystallization system is high, the crystallization rate will be low, and the precipitated crystals may dissolve again during solid-liquid separation. The water content of the solvent in the system is preferably adjusted to approximately 50% or less, particularly 30% or less. Although the crystallization operation can be carried out at room temperature and is not particularly limited, it is generally preferable to carry out the crystallization operation under cooling, as this often improves the yield of the neutral salt. The above crystallization operation will be explained in more detail as follows. That is, first, a neutralization reaction solution of L-arginine and L-malic acid is concentrated so that the concentration of the neutral salt contained in the reaction solution is about 30 to 80%,
Then, it is preferable to add an appropriate amount of a hydrophilic organic solvent to this concentrated solution and then inoculate with seed crystals, or to inoculate seed crystals and then add an appropriate amount of the organic solvent to precipitate the neutral salt. For example, when methanol is used as a hydrophilic organic solvent, methanol is preferably added so that the water content of the solvent in the crystallization system is approximately 10 to 50%, and the amount of seed crystals used is The more the content, the better, but about 0.05% of the neutral salt normally contained is sufficient. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Free L-arginine aqueous solution (L-arginine
3.35 g of L-malic acid crystals (containing 0.05 mol)
0.5 molar ratio to arginine) to perform a neutralization reaction (PH of reaction solution: 0.7). The reaction solution was concentrated under reduced pressure to a total volume of 15.2 g (this concentrated aqueous solution was allowed to stand overnight at room temperature, but no crystals were deposited at all). 4 ml of methanol is added to this solution, and 20 mg of neutral L-arginine/DL-malate crystals are inoculated as seed crystals, and the mixture is left overnight. The precipitated crystals were collected by filtration, washed with 80% methanol aqueous solution, and then heated at 60°C.
By drying with ventilation overnight, 8.6 g of neutral L-arginine/L-malate/anhydride crystals were obtained as colorless granular to columnar crystals. Yield: 71.3% Melting point 219°C (decomposed) Specific optical rotation [α] ²⁰ _D : +20・94° (C=8, 6N-HCl) Infrared absorption spectrum (KBr method) As shown in Figure 1, L-arginine and L -Malic acid content as shown in Table 1

[Table] Elemental analysis value (C ₆ H ₁₄ N ₄ O ₂ ) ₂・C ₄ H ₆ O ₅ Calculated value: C, 39.83; H, 7.10; 23.23 Actual value: C, 29.85; H, 7.12; N, 23.21 Differential thermal analysis As shown in Figure 2 (temperature increase 1℃/min, nitrogen flow) Solubility in water (10℃) 139.2 (g/100g water) PH of 10% aqueous solution 7.0 Critical humidity (40℃) 85%RH Note 3.35 g of DL-malic acid crystals (0.025 mol of DL-malic acid, pH 7.0 of the solution) was added to a free L-arginine aqueous solution (containing 0.05 mol) to perform a neutralization reaction. Concentrate this solution under reduced pressure to reduce the amount of remaining liquid to 15.2g.
And so. When this concentrated solution was left overnight, crystals precipitated. When the precipitated crystals were separated and chemically analyzed, they were found to be neutral L-arginine/DL-malate crystals. Yield: 6.7g. Melting point: 220°C (decomposition) Example 2 22g of L-arginine hydrochloride (18.2g as L-arginine) was dissolved in 800ml of water, and this was added to the strongly acidic ion exchange resin Amberlite IR-120 (H type).
Connect to a column packed with 150 ml. After washing this column with 300% water, 1N ammonia water
Elute in 500ml. The eluate is concentrated under reduced pressure to about 40 ml and then decolorized and filtered. This aqueous solution (containing 0.0998 mol of L-arginine) contains 6.62 g of L-malic acid crystals.
and adjust the pH of the reaction solution to 7.0. The reaction solution was concentrated under reduced pressure to a total volume of 34.7 g, and 0.1 g of neutral L-arginine/L-malate crystals were inoculated thereto as seed crystals. 20 ml of methanol is gradually added to this solution while stirring, and the mixture is cooled to 10°C. The precipitated crystals were collected by filtration, washed with 80% methanol aqueous solution,
By drying with ventilation overnight at 60° C., 23 g of neutral L-arginine/L-malate/anhydride crystals are obtained as colorless granular to columnar crystals. Yield: 95.5% The physicochemical properties of this product matched those of the crystals obtained in Example 1.

[Brief explanation of the drawing]

Figure 1 is an infrared absorption spectrum of neutral L-arginine/L-malate/anhydride crystals, and Figure 2 is a differential thermal analysis diagram of neutral L-arginine/L-malate/anhydride crystals. It is.

Claims (1)

[Claims] 1. A neutral salt crystal consisting of 2 moles of L-arginine and 1 mole of L-malic acid. 2. The crystal according to claim 1, wherein the neutral salt crystal is a neutral L-arginine L-malate anhydride. 3. Neutralize L-arginine and L-malic acid in an aqueous solvent to generate a neutral salt consisting of 2 moles of L-arginine and 1 mole of L-malic acid, and concentrate the reaction solution to form a concentrated solution. The neutral salt concentration is adjusted to 30 to 80%, and then a hydrophilic organic solvent is added to adjust the water content of the solvent in the crystallization system to be approximately 10 to 50%. L-Arginine 2 characterized by precipitating a neutral salt as crystals
1 mole of L-malic acid.