idref="DRAWINGS">FIG. 4 shows the results of ¹³C-NMR analysis of L-serine.

FIG. 5 shows the results of ¹³C-NMR analysis of the magnesium-serinate (AST-011) of the present invention.

FIG. 6 shows the results of ¹³C-NMR analysis of the magnesium-serinate (AST-014) of the present invention.

FIG. 7 shows the results of FT-IR analysis of L-serine.

FIG. 8 shows the results of FT-IR analysis of the magnesium-serinate (AST-011) of the present invention.

FIG. 9 shows the results of FT-IR analysis of the magnesium-serinate (AST-014) of the present invention.

FIG. 10 shows the results of FT-IR analysis of the magnesium-serinate (a compound obtained according to a synthesis method described in Example 3 below; hereinafter referred to as “AST-016”) of the present invention.

FIG. 11 shows the cell viability of mouse hippocampal neuronal HT-22 cells as a function of the treatment concentration of the magnesium-serinate (AST-011) of the present invention. (A) shows cell viability in serine/glycerin-deficient medium, and (B) shows cell viability in complete medium.

FIG. 12 shows the results of analysis performed using a Seahorse extracellular flux (XF) analyzer to examine the effect of the magnesium-serinate (AST-011) of the present invention on the metabolic capacity of the mitochondrial energy production system and respiration system in mouse hippocampal neuronal HT-22 cells.

FIG. 13 shows the cell protective effect of the magnesium-serinate (AST-011) of the present invention on the protection of mouse hippocampal neuronal HT-22 cells, treated with DMNQ (2,3-dimethoxy-1,4-napthoquinone), as a function of the treatment concentration of the magnesium-serinate (AST-011).

FIG. 14 shows the blood-brain barrier permeabilities of drugs, determined by administering the magnesium-serinate (AST-011) of the present invention to ICR mice, quantifying the concentrations of the magnesium-serinate distributed in the blood and brain, and calculating the ratio of the concentration of the magnesium-serinate in the brain to that in the blood.

BEST MODE

Hereinafter, the present invention will be described in detail.

For the purpose of developing a novel compound capable of exhibiting the effect of increasing not only the intracellular uptake of magnesium and L-serine but also the concentrations of magnesium and L-serine in the brains by simultaneously delivering magnesium and L-serine into the human body as needed, the present inventors treated L-serine with a magnesium salt (MgO or MgH₂), thereby producing a magnesium serinate as a metal amino acid chelate in which magnesium is chelated to the amino acid L-serine. It was shown that the produced magnesium serinate was solubilized at a concentration of about 500 mg/ml in water at room temperature at a pH of 6.0 to 10.0, and was maintained in an aqueous solution state without forming a precipitate. In addition, the produced magnesium serinate was also solubilized at a concentration of 500 mg/ml in a saline solution containing sodium chloride (NaCl) and phosphate at room temperature without forming a precipitate.

Therefore, the present invention provides a compound of the following Formula (I) or a pharmaceutically acceptable salt, solvate, hydrate or isomer of the compound:

[Image Omitted]

As shown in the following Structural Formula, the compound of Formula (I) has a structure in which two molecules of serine form an ionic bond and a coordinate bond with one molecule of magnesium:

[Image Omitted]

The compound of Formula (I) may exist as a base-addition salt or an acid-addition salt. The addition salt is included as a part of the present invention. Although the salt is advantageously prepared with a pharmaceutically acceptable acid, for example, salts of other acids useful for purifying or isolating the compound of Formula (I) are also included as a part of the present invention. The acids may be, for example, picric acid, oxalic acid or optically active acids such as tartaric acid, dibenzoyl tartaric acid, mandelic acid or a camphorsulfonic acid, and acids which form physiologically acceptable salts such as hydrochloride, hydrobromide, sulfate, hydrogen sulfate, dihydrogen phosphate, maleate, fumarate, 2-naphthalene sulfonate or para-toluenesulfonate. For physiologically acceptable salts, reference may be made to Handbook of Pharmaceutical Salts: Properties, Selection and Use by Stahl and Wermuth (Wiley-VCH, 2002).

The solvates or hydrates may be obtained directly from the synthetic process, and the compound (I) may be isolated in the form of a hydrate, for example a mono- or hemi-hydrate or a solvate of a reaction or purification solvent.

In addition, the compound of Formula (I) may exist as an isomer, for example, as a rotational isomer. Rotational isomers of the compound of Formula (I) are included as a part of the present invention.

The compound of Formula (I) according to the present invention may be synthesized with high yield and purity by a production method as described below.

Therefore, the present invention provides a method of producing the compound of Formula (I) by reacting MgO with L-serine.

The compound of Formula (I) is synthesized according to the following reaction formula, and the synthetic reaction is preferably performed at a temperature of 70 to 80° C.:

2L-serine+MgO→Serine-Mg-Serine+H₂O

Specifically, the compound of Formula (I) may be obtained by adding and dissolving L-serine in a reactor containing distilled water, and adding powdered MgO at once thereto, and allowing the mixture to react with stirring for about 2 hours. A process of recovering and purifying the compound of Formula (I) in the reactor may be performed according to a general isolation and purification method after an organic synthetic reaction.

The present invention also provides a method of producing the compound of Formula (I) by reacting MgH₂with L-serine.

The compound of Formula (I) is synthesized according to the following reaction formula, and the synthetic reaction is preferably performed at a temperature of 70 to 80° C.:

2L-Serine+MgH₂→Serine-Mg-Serine+2H₂

Specifically, the compound of Formula (I) may be obtained by adding L-serine to a reactor containing distilled water, adding MgH₂thereto in small portions at room temperature (for room temperature reaction) or an elevated temperature of 70 to 80° C. (elevated-temperature reaction), and allowing the mixture to react stirring for about 14 hours (room temperature reaction) or about 6 hours (elevated-temperature reaction) until H₂gas is not generated. A process of recovering and purifying the compound of Formula (I) in the reactor may be performed according to a general isolation and purification method after an organic synthetic reaction.

The magnesium-serinate compound of the present invention may improve the blood-brain barrier permeability of magnesium and L-serine by simultaneously delivering magnesium and L-serine into the human body as needed, and may exhibit effects against diseases related to the central nervous system, such as congenital neurological diseases and degenerative neurological diseases. Thus, the magnesium-serinate compound may be used as a pharmaceutical drug against these diseases.

Therefore, the present invention provides a pharmaceutical composition for preventing or treating central nervous system diseases, the pharmaceutical composition containing the compound of Formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient.

The active ingredient of the present invention may be applied as a pharmaceutical drug against central nervous system diseases, wherein the central nervous system diseases are preferably selected from the group consisting of cognitive disorder, intellectual disability, microcephaly, epilepsy, neurodevelopmental disorder, dementia, autism spectrum disorder, Down's syndrome, Rett's syndrome, fragile X syndrome, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis.

The active ingredient preferably induces activation of neuronal cell proliferation. The term “activation of neuronal cell proliferation” may be understood to include both an action of promoting neuronal cell division and an action of inhibiting neuronal apoptosis or necrosis.

The activation of neuronal cell proliferation is preferably an effect obtained by increasing the oxygen consumption rate of mitochondria.

The active ingredient preferably has neuronal cell protection activity. The term “neuronal cell protection” refers to an action of inhibiting neuronal apoptosis or necrosis from being caused by external factors or cellular internal factors.

The neuronal cell protection is preferably protection from oxidative stress. The term “oxidative stress” means that cells are in an abnormal state due to reactive oxygen species.

The protection from oxidative stress is preferably achieved by inhibition of cell death caused by mitochondrial membrane potential damage.

The protection from oxidative stress is preferably achieved by inhibition of cell death caused by endoplasmic reticulum stress.

The active ingredient preferably has the ability to permeate the blood-brain barrier. The active ingredient of the present invention significantly improves the blood-brain barrier permeability of L-serine, and can be effectively delivered into the brain when administered to a patient with L-serine biosynthesis defects.

For use, the pharmaceutical composition of the present invention may be formulated in oral dosage forms such as pills, granules, tablets, capsules, suspensions, emulsions, syrups or aerosols, or other various forms such as sterile injectable solutions, depending on the intended use thereof according to conventional methods. The pharmaceutical composition may be administered orally or may be administered through various routes including intravenous, intraperitoneal, subcutaneous, rectal and topical routes.

This pharmaceutical composition may further contain carriers, excipients or diluents, and examples of suitable carriers, excipients or diluents that may be contained in the composition include lactose, dextrose, sucrose, sorbitol, mannitol, xylitol, erythritol, maltitol, starch, acacia gum, alginate, gelatin, calcium phosphate, calcium silicate, cellulose, methyl cellulose, amorphous cellulose, polyvinyl pyrrolidone, water, methylhydroxybenzoate, propylhydroxybenzoate, talc, magnesium stearate, and mineral oil.

In addition, the pharmaceutical composition of the present invention may further contain a filler, an anti-aggregating agent, a lubricant, a wetting agent, a fragrance, an emulsifier, a preservative, and the like.

The pharmaceutical composition of the present invention may be administered in a pharmaceutically effective amount. As used herein, the term “pharmaceutically effective amount” refers to an amount sufficient to treat diseases, at a reasonable benefit/risk ratio applicable to any medical treatment. The effective dosage level of the composition may be determined depending on factors, including the kind and severity of the disease of a patient, the activity of the drug, sensitivity to the drug, the time of administration, the route of administration, excretion rate, the duration of treatment, drugs used in combination with the composition, and other factors known in the medical field.

The pharmaceutical composition of the present invention may be administered individually or in combination with other therapeutic agents, and may be administered sequentially or simultaneously with conventional therapeutic agents. The pharmaceutical composition may be administered in a single or multiple dosage form. It is important to administer the composition in the minimum amount that can exhibit the maximum effect without causing side effects, in view of all the above-described factors, and this amount can be easily determined by a person skilled in the art.

In a preferred embodiment, the effective amount of the active ingredient in the pharmaceutical composition of the present invention may vary depending on the patient's age, sex and bodyweight. In general, the active ingredient may be administered at a dose of 1 to 5,000 mg/kg bodyweight/day, preferably 100 to 3,000 mg/kg bodyweight/day, daily or every other day, or may be administered one to three times a day. However, since the dose may increase or decrease depending on the route of administration, the severity of the disease, the patient's sex, bodyweight and age, etc., the dose is not intended to limit the scope of the present disclosure in any way.

The pharmaceutical composition of the present invention may be administered to a subject through various routes. All modes of administration can be contemplated. For example, the composition may be administered orally, intrarectally, or by intravenous, intramuscular, subcutaneous, intrauterine, intrathecal or intracerebroventricular injection.

In the present invention, “administration” means providing a given substance to a patient by any suitable method. The pharmaceutical composition of the present invention may be administered orally or parenterally through all general routes as long as it can reach the target tissue. In addition, the composition of the present invention may also be administered using any device capable of delivering the active ingredient to target cells.

In the present invention, the term “subject” is not particularly limited, but includes, for example, humans, monkeys, cattle, horses, sheep, pigs, chicken, turkeys, quails, cats, dogs, mice, rats, rabbits or guinea pigs, and preferably refers to mammals, more preferably humans.

In addition to being used as a pharmaceutical drug as described above, the magnesium-serinate compound of the present invention may be used as a health functional food.

Therefore, the present invention provides a health functional food for preventing or alleviating central nervous system diseases, the health functional food containing the compound of Formula (I) or a pharmaceutically acceptable salt thereof as an active ingredient.

The central nervous system diseases are preferably selected from the group consisting of cognitive disorder, intellectual disability, microcephaly, epilepsy, neurodevelopmental disorder, dementia, autism spectrum disorder, Down's syndrome, Rett's syndrome, fragile X syndrome, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis.

The health functional food of the present invention may be variously used in foods and beverages effective in preventing and improving diseases related to the central nervous system.

Foods containing the active ingredient of the present invention include various foods, for example, beverages, gums, teas, vitamin complexes, health supplement foods and the like, and may be used in the form of powders, granules, tablets, capsules or beverages.

The active ingredient of the present invention may generally be added in an amount of 0.01 to 15 wt % based on the total food weight. For a health beverage composition, the active ingredient may be added in an amount of 0.02 to 10 g, preferably 0.3 to 1 g, based on 100 ml of the health beverage composition.

The health functional food of the present invention may additionally contain food-acceptable additives, for example, natural carbohydrates and various flavoring agents, in addition to containing the compound as an essential component at the indicated percentage.

Examples of the natural carbohydrates include conventional sugars, such as monosaccharides (e.g., glucose, fructose, etc.), disaccharides (e.g., maltose, sucrose, etc.), polysaccharides (e.g., dextrin, cyclodextrin, etc.), and sugar alcohols such as xylitol, sorbitol, erythritol or the like.

Examples of the flavoring agents that may be used in the present invention include thaumatin, rebaudioside A, glycyrrhizin, saccharin, aspartame, etc. The flavoring agent is used in an amount of about 1 to 20 g, preferably about 5 to 12 g, based on 100 mL of the health functional food of the present invention.

In addition, the health functional food of the present invention may contain various nutrients, vitamins, minerals, flavoring agents such as synthetic flavoring agents and natural flavoring agents, colorants, extenders, pectic acid and its salt, alginic acid and its salt, organic acids, protective colloidal thickeners, pH adjusting agents, stabilizers, preservatives, glycerin, alcohol, carbonizing agents as used in carbonated beverages, etc.

Additionally, the health functional food of the present invention may contain fruit flesh that is used for the preparation of natural fruit juice, fruit juice beverages or vegetable beverages. These components may be used individually or in combination. The content of these additives is generally selected in the range of 0.01 to about 20 parts by weight based on 100 parts by weight of the health functional food.

Since the magnesium-serinate compound of the present invention may effectively supply magnesium and serine into a living body, it may be applied to feed.

Therefore, the present invention provides a feed additive composition containing the compound of Formula (I) or a pharmaceutically acceptable salt thereof.

The feed additive composition may be for animals. The “animals” refers to a group of organisms corresponding to plants, which consumes organic matter as nutrients and in which digestive, excretory and respiratory organs are differentiated. Specifically, the animals may be echinoderms, crustaceans, mollusks, fish, amphibians, reptiles, birds, or mammals. Preferably, the animals are echinoderms such as sea urchins or sea cucumbers; arthropods including crustaceans such as crab, shrimp, and Chinese white shrimp; mollusks such as cephalopods, gastropods, or bivalve; fish such as red bream, sea bream, cod, or halibut or flatfish; birds including poultry such as pheasant or chicken; or mammals such as pigs, cattle, sheep, horses, goats, dogs, or cats.

The feed additive composition may further contain grains, vegetable protein feed, animal protein feed, sugar or a dairy product, in addition to the active ingredient of the present invention. The grains may specifically be ground or crushed wheat, oats, barley, corn and rice; the vegetable protein feed may specifically be based on rapeseed, soybean and sunflower; the animal protein feed may specifically be blood meal, meat meal, bone meal and fish meal; and the sugar or dairy product may specifically be a dry component consisting of various milk powders and whey powders.

The food additive composition may further contain components such as nutritional supplements, digestion and absorption enhancers, growth promoters or disease preventive agents.

The feed additive composition of the present invention may vary depending on the purpose of use and conditions of use of feed. For example, the feed additive composition may be contained in an amount of 0.1 to 100 g based on 1 kg of finally produced feed.

In addition, the feed additive composition may be prepared into consistent viscous coarse or granular materials according to the degree of pulverization of the components thereof. The composition may be supplied as a mesh or may be formed into a desired separate shape for further processing and packaging, and may be subjected to pelletization, expansion or extrusion processes for storage. For the easiness of storage, an excess amount of water may preferably be removed from the composition by drying.

Meanwhile, since the magnesium-serinate of the present invention effectively inhibits neuronal cell death, it may be applied as a reagent for inducing cell death in cells, preferably neuronal cells.

Therefore, the present invention provides a reagent composition for research, preferably a reagent composition for inhibiting neuronal cell death, the reagent composition containing the compound of Formula (I) or a pharmaceutically acceptable salt thereof.

The neuronal cells may be primary neuronal cells, transformed neuronal cells, or neuronal cell lines.

The reagent may be used for activation of neuronal cells, activation of neuronal cell proliferation by increased oxygen consumption rate of mitochondria, protection of neuronal cells, inhibition of neuronal cell damage caused by oxidative stress, inhibition of neuronal cell death resulting from mitochondrial membrane potential damage caused by oxidative stress, or inhibition of neuronal cell death resulting from endoplasmic reticulum stress caused by oxidative stress.

The present invention also provides a method for inhibiting neuronal cell death, the method comprising treating neuronal cells with the reagent of the present invention, which contains the compound of Formula (I) or a pharmaceutically acceptable salt thereof.

According to the above method, it is possible to obtain effects of activation of neuronal cells, activation of neuronal cell proliferation by increased oxygen consumption rate of mitochondria, protection of neuronal cells, inhibition of neuronal cell damage caused by oxidative stress, inhibition of neuronal cell death resulting from mitochondrial membrane potential damage caused by oxidative stress, or inhibition of neuronal cell death resulting from endoplasmic reticulum stress caused by oxidative stress.

In the above method, a method for cell culture method, a method for treatment with the reagent, etc. are matters that are obvious to those of ordinary skill in the art. In particular, the treatment concentration of the reagent, etc., may be appropriately modified within the range of matters described in the present specification or within a range in which the effect of the reagent does not change.

The method is preferably performed in vitro.

MODE FOR INVENTION

Hereafter, the present invention will be described in more detail with reference to specific examples. The following examples describe one preferred embodiment of the present invention, and it is to be understood that the scope of the present invention is not limited by the contents described in the following examples.

Examples

1. Production of Mg-Serinate

1.1. Production of Mg-Serinate (AST-011)

100 ml of distilled water was placed in a 500-ml Erlenmeyer flask, and heated to a temperature of 70 to 80° C., and then 50 g (about 0.48 moles) of L-serine (MW: 105.1) was weighed and dissolved in the distilled water with stirring with a magnetic stirrer. MgO (MW: 40.3) was pulverized into small particles in a mortar, and then 9.7 g (about 0.24 moles) of the MgO particles were added in small portions to the aqueous solution of L-serine with stirring at a temperature of 70 to 80° C. Then, the mixture was allowed to react in an Erlenmeyer flask equipped with a reflux condenser for 2 hours under the same conditions.

The reaction solution in a non-cooled state was immediately centrifuged at 6,000 rpm for 10 minutes, and 130 ml of the supernatant was collected. Ethanol was added to the supernatant to a final concentration of 75 v/v %, and the mixture was stirred with a magnetic stirrer at room temperature for 14 hours to form a precipitate. The supernatant was removed by decantation, and only the precipitate was recovered and freeze-dried to obtain a magnesium-serinate solid.

The magnesium-serinate solid recovered by freeze-drying was pulverized into small particles in a mortar to finally obtain magnesium-serinate powder (AST-011). The obtained magnesium-serinate powder was weighed 53.1 g and the yield thereof was about 89%.

1.2. Production of Mg-Serinate (AST-014) by Room-Temperature Reaction

500 ml of distilled water was placed in an Erlenmeyer flask (2,000 ml), and 75 g (about 0.71 moles) of L-serine (MW: 105.1) was weighed and dissolved in the distilled water with stirring at room temperature. 9.5 g (about 0.36 moles) of MgH₂(MW: 26.3) was weighed and added in small portions to the aqueous solution of L-serine with stirring at room temperature. The mixture was allowed to react with stirring with a magnetic stirrer at room temperature for 14 hours until H₂gas was not generated.

The reaction solution was filtered through filter paper (Whatman 3MM Filter Paper, GE Healthcare, Life Sciences, USA), and the filtrate was concentrated to a volume of about 200 ml using a vacuum concentrator (Heidolph LR 4000, Germany). 600 ml of ethanol was added to the concentrate (about 200 ml) to a final concentration of 75 v/v % and stirred with a magnetic stirrer for 14 hours to form a precipitate. Then, the supernatant was removed by decantation, and the precipitate was recovered as magnesium-serinate and freeze-dried.

The magnesium-serinate solid recovered by freeze-drying was pulverized into small particles in a mortar to finally obtain magnesium-serinate powder (AST-014). The obtained magnesium-serinate powder was weighed 48.3 g and the yield thereof was about 57.3%.

1.3. Production of Mg-Serinate (AST-016) by Elevated-Temperature Reaction

200 ml of distilled water was placed in an Erlenmeyer flask (1,000 ml) and pre-heated to 70 to 80° C. 60 g (about 0.57 moles) of L-serine (MW: 105.1) was weighed and dissolved in the heated distilled water with stirring. 7.5 g (about 0.285 moles) of MgH₂(MW: 26.3) was weighed and added in small portions to the aqueous solution of L-serine with stirring with a magnetic stirrer. Then, the mixture was allowed to react in an Erlenmeyer flask equipped with a reflux condenser while it was stirred with a magnetic stirrer at the same temperature of 70 to 80° C. for 6 hours until H₂gas was not generated.

The reaction solution was filtered through filter paper (Whatman 3MM Filter Paper, GE Healthcare, Life Sciences, USA), and about 220 ml of the filtrate was concentrated to a volume of about 100 ml using a vacuum concentrator (Heidolph LR 4000, Germany). Ethanol was added to the concentrate (about 100 ml) to a final concentration of 75 v/v % and stirred with a magnetic stirrer for 14 hours to form a precipitate. Then, the supernatant was removed by decantation, and the precipitate was washed by immersion in 300 ml of 75 v/v % ethanol for 8 hours, and then freeze-dried to obtain magnesium-serinate.

The magnesium-serinate solid recovered by freeze-drying was pulverized into small particles in a mortar to finally obtain magnesium-serinate powder (AST-016). The obtained magnesium-serinate powder was weighed 62.6 g and the yield thereof was about 92.8%.

2. Instrumental Analysis of Synthesized Magnesium-Serinate

2.1. Analysis of Magnesium Content in Magnesium-Serinate

The magnesium content of each chelate compound was analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES) (Optima 7300DV, PerkinElmer, USA). As experimental conditions, a frequency of 40 MHz was used, and a wavelength of 285.213 nm was used for inorganic analysis.

(1) About 0.1 to 0.2 g of each sample was taken and weighed accurately, and then 25 to 30 g of nitric acid was added thereto.

(2) The mixture was treated using an UltraWAVE (Milestone, Italy) device at 220° C. for 25 minutes, and then diluted with 2% nitric acid and analyzed.

The average values of the analysis are shown in Table 1 below.

TABLE 1

Magnesium contents of magnesium-serinate AST-011, AST-014 and AST-016

Weight

Weight

(g) of
Weight of
(g) of 2%
Concentration
MG content
Average

nitric acid
smaple taken
nitric acid
(%) of
(%)
Mg

Sample
solution
off after
solution
magnesium in
excluding
content

Samples
weight (g)
added
pretreatment
added
sample
water
(%)

AST-011
0.17
30.55
1.11
24.98
8.15
9.62
9.63

0.10
29.77
1.11
29.77
8.16
9.63

AST-014
0.15
27.90
1.12
48.53
8.68
10.21
10.06

0.12
30.75
1.11
48.41
8.28
9.90

AST-016
0.21
25.85
1.10
49.09
8.95
10.59
10.77

0.12
27.40
1.04
49.96
9.26
10.95

2.2. Analysis of Contents of Constituent Amino Acids in Magnesium-Serinate

The contents of constituent amino acids in each magnesium-serinate were analyzed using an automatic amino acid analyzer (L-8900, Hitachi, Japan).

(1) 0.05 g of each sample was added to 2 ml of 6N HCl and hydrolyzed at 110° C. for 24 hours under a nitrogen atmosphere.

(2) After acid hydrolysis, the solution was dried by heating at 80° C. for about 24 hours.

(3) The acid-hydrolyzed solution was diluted 1,000-fold with 0.02N HCl, and then analyzed by an automatic amino acid analyzer.

The results of the analysis are shown in Table 2 below.

TABLE 2

Serine contents of magnesium-serinate

AST-011, AST-014 and AST-016

AST-011
AST-014
AST-016

Amino acid
(mg/g)
(mg/g)
(mg/g)

Aspartic acid
ND
ND
ND

Threonine
ND
ND
ND

Serine
890.1
890.5
895.1

Glutamic acid
ND
ND
ND

Glycine
ND
ND
ND

Alanine
ND
ND
ND

Cystine
ND
ND
ND

Valine
ND
ND
ND

Methionine
ND
ND
ND

Isoleucine
ND
ND
ND

Leucine
ND
ND
ND

Tyrosine
ND
ND
ND

Phenylalanine
ND
ND
ND

Lysine
ND
ND
ND

Ammonia
ND
ND
ND

Histi,line
ND
ND
ND

Arginine
ND
ND
ND

Proline
ND
ND
ND

ND: Non-detect

2.3. Analysis of Magnesium-Serinate by Nuclear Magnetic Resonance (NMR)

Each of the magnesium-serinate samples (AST-011, AST-014 and AST-016) and authentic L-serine (ICN Biomedicals, OH, USA) was analyzed by ¹H NMR and ¹³C NMR. 100 mg of each sample was dissolved in 0.7 ml of D₂O and analyzed using NMR spectroscopy (Bruker Avance II 500 MHz with CyroBBO probe, Bruker, Germany) at 24.85° C. (298 K).

2.3.1. ¹H NMR Analysis

As shown in FIGS. 1 to 3 showing the results of ¹H NMR analysis, in the case of authentic L-serine, the peak considered as α-carbon having a carboxyl group and an amino group appeared at 3.7 to 3.8 ppm, and the peak considered as β-carbon having a hydroxyl group appeared at 3.6 to 3.7 ppm. In the case of AST-011, the peak considered as α-carbon having a carboxyl group and an amino group appeared at 3.5 to 3.6 ppm, and the peak considered as β-carbon having a hydroxyl group appeared at 3.2 ppm, and in the case of AST-014, the peak considered as α-carbon having a carboxyl group and an amino group appeared at 3.5 to 3.6 ppm, and the peak considered as β-carbon having a hydroxyl group appeared at 3.2 ppm.

In conclusion, ¹H NMR peaks having a chemical shift similar to that of authentic L-serine were found commonly in the two samples (AST-011 and AST-014). Unlike the ¹H NMR peaks of authentic L-serine, in the case of AST-011 and AST-014, the CH₂peak of ethanol was found at 3.4 to 3.5 ppm, and the CH₃peak of ethanol was found at 1.00 ppm. This is believed to be because the ethanol used in the ethanol precipitation step during the production process of each of AST-011 and AST-014 remained in a small amount in the solid sample even after freeze-drying.

2.3.2. ¹³C NMR Analysis

As shown in FIGS. 4 to 6 showing the results of ¹³C NMR analysis, in the case of AST-011, the C═O peak considered as the carboxyl group of α-carbon in authentic L-serine appeared at 177.885 ppm, the C—O peak of the hydroxyl group of β-carbon appeared at 62.607 ppm, and the C—C peak of α-carbon and β-carbon appeared at 56.151 ppm. In addition, in the case of AST-014, it was confirmed that the C═O peak considered as the carboxyl group of α-carbon appeared at 179.838 ppm, the C—O peak of the hydroxyl group of β-carbon appeared at 63.784 ppm, and the C—C peak of α-carbon and β-carbon appeared at 56.892 ppm.