EP-3431488-B1 - METHOD FOR PRODUCING CRYSTAL OF REDUCED GLUTATHIONE

Inventors

• FUKUMOTO, KAZUNARI
• IGUCHI, Maya
• NAGANO, HIROSHI

Dates

Publication Date

20260506

Application Date

20170310

Claims (2)

1. A method for producing a crystal of reduced glutathione in which in an HPLC analysis, the peak area of L-cysteinyl-L-glycine is 0.02 or less with respect to the peak area of reduced glutathione which is taken as 100, wherein the method comprising passing an aqueous solution containing reduced glutathione, wherein the concentration of reduced glutathione is 100 g/L or more, through a cation exchange resin with a high crosslinking degree of 12% or more, recovering the aqueous solution, precipitating a crystal of reduced glutathione in the aqueous solution, and collecting the crystal of reduced glutathione from the aqueous solution, wherein the crosslinking degree refers to the weight ratio of a crosslinking agent relative to the entire raw materials constituting an ion exchange resin in the resin.
2. The production method according to claim 1, wherein the cation exchange resin with a high crosslinking degree is a cation exchange resin having a sulfone group as a cation exchange group.

Description

Technical Field The present invention relates to a method for producing a crystal of reduced glutathione having a reduced content of impurities, particularly L-cysteinyl-L-glycine. Background Art Glutathione (y-L-glutamyl-L-cysteinyl-L-glycine) is a reducing compound widely existing in organisms and is known to have a detoxification effect in the liver. Therefore, glutathione has been widely used as a product such as a pharmaceutical product, a health food, and a cosmetic product, or a raw material or an intermediate thereof. As a method for producing glutathione, a fermentation method using a microorganism such as yeast, an enzymatic method (Non-Patent Document 1), etc. are known, however, there is a problem that an analog impurity having a similar structure is produced as a by-product. As a method for purifying glutathione, a method in which copper suboxide and a copper salt are formed and a method in which glutathione is adsorbed onto a strongly acidic ion exchange resin and glutathione is eluted with an acid or a base (Patent Documents 1 to 3), and a method in which glutathione is passed through a weakly basic anion exchange resin (Patent Document 4) are known, however, glutathione is easily reacted or decomposed by heating, oxidation, pH change, or the like to produce a lot of impurities. Among these impurities, particularly, L-cysteinyl-L-glycine is known to generate free radicals causing various diseases (Non-Patent Documents 2 and 3). Further, in the Guideline for Impurities in Pharmaceutical Drug Substances issued by Ministry of Health, Labour and Welfare, each impurity contained in glutathione needs to be reduced to 0.05% or less at minimum depending on the maximum daily dose of a drug substance. In this manner, in glutathione as a raw material of a pharmaceutical product or a food, reduction in impurities is strongly demanded from the viewpoint of safety. As a method for purifying glutathione, Patent Document 5 discloses a method in which a specific impurity such as cysteine or γ-glutamylcysteine is removed. However, there has been no report so far on a method for removing L-cysteinyl-L-glycine. Patent Document 6 describes a certain method for purifying glutathione, characterized by passing a crude glutathione solution containing impurities through a strongly acidic cation exchange resin (proton type), adsorbing glutathione and impurities, then washing with a 0.05 to 0.5 N concentration of an alkaline hydroxide solution, and recovering a fraction containing high-purity glutathione. Patent Document 7 relates to a method for purifying glutathione, characterized by processing a glutathione-containing solution with a strongly acidic cation exchange resin having a divinylbenzene content of 12% or more, then passing the treated solution through a strongly acidic cation exchange resin with a divinylbenzene content of 6% or less, adsorbing glutathione, eluting it with an aqueous solution of an organic acid salt or a phosphate salt, and recovering glutathione from the eluate. Patent Document 8 concerns a method for separating glutathione and cysteinylglycine, characterized by bringing a coexistence solution of glutathione and cysteinylglycine into contact with a strongly acidic cation exchange resin having a crosslinking degree of 8% or more, thereby adsorbing and removing cysteinylglycine. Patent Document 9 relates to a method for producing reduced glutathione, characterized by electrolytically reducing oxidized glutathione in an acidic solution using a membrane electrolysis cell, wherein a dilute acid solution is used as the anolyte and an alkaline solution is used as the catholyte, with an insoluble electrode having a hydrogen overvoltage higher than carbon serving as the cathode. Patent Document 10 discloses a glutathione crystal having an average width of 7 to 40 µm and an average particle diameter of 10 to 60 µm. Patent Document 11 concern a method for extended storage of reduced glutathione in solution, comprising the steps of: a) dissolving a predetermined quantity of reduced glutathione in an aqueous medium having a pH of between 5.0 and 8.0 to produce a reduced glutathione solution having a predetermined initial concentration [A]0, wherein, when the ratio [A]/[A]0, where [A] is the actual glutathione concentration at time t, is plotted as a function of time t, the concentration of reduced glutathione decreases over time in a linear fashion with a temperature-dependent slope; and b) storing the reduced glutathione solution at a predetermined temperature which is above the freezing point of the solution and below 15°C, so as to maintain the rate of reduced glutathione decay at between 0% and 5% of the predetermined initial concentration per month, where the initial concentration of reduced glutathione is between 10 mg/ml and 400 mg/ml. Related Art Patent Documents Patent Document 1: JP-B-44-239Patent Document 2: JP-B-45-4755Patent Document 3: JP-B-46-2838Patent Document 4: JP-B-45-27797Patent Docu