Absorption, Distribution and Excretion
Glutamate is absorbed from the gut by an active transport system specific for amino acids. This process is saturable, can be competitively inhibited, and is dependent on sodium ion concentration... . During intestinal absorption, a large proportion of glutamic acid is transaminated and consequently alanine levels in portal blood are elevated. If large amounts of glutamate are ingested, portal glutamate levels increase ... . This elevation results in increased hepatic metabolism of glutamate, leading to release of glucose, lactate, glutamine, and other amino acids, into systemic circulation ... . The pharmacokinetics of glutamate depend on whether it is free or incorporated into protein, and on the presence of other food components. Digestion of protein in the intestinal lumen and at the brush border produces a mixture of small peptides and amino acids; di-and tri-peptides may enter the absorptive cells where intracellular hydrolysis may occur, liberating further amino acids. Defects are known in both amino acid and peptide transport ... .. Glutamic acid in dietary protein, together with endogenous protein secreted into the gut, is digested to free amino acids and small peptides, both of which are absorbed into mucosal cells where peptides are hydrolyzed to free amino acids and some of the glutamate is metabolized. Excess glutamate and other amino acids appear in portal blood. As a consequence of the rapid metabolism of glutamate in intestinal mucosal cells and in the liver, systemic plasma levels are low, even after ingestion of large amounts of dietary protein. /Glutamic acid/
... Intestinal and hepatic metabolism results in elevation of levels in systemic circulation only after extremely high doses given by gavage (>30mg/kg body weight). Ingestion of monosodium glutamate (MSG) was not associated with elevated levels in maternal milk, and glutamate did not readily pass the placental barrier. Human infants metabolized glutamate similarly to adults.
Oral administration of pharmacologically high doses of glutamate results in elevated plasma levels. The peak plasma glutamate levels are both dose and concentration dependent ... . When the same dose (1 g/kg b.w.) of monosodium glutamate (MSG) was administered by gavage in aqueous solution to neonatal rats, increasing the concentration from 2% to 10% caused a five-fold increase in the plasma area under curve; similar results were observed in mice ... . Conversely, when MSG (1.5 g/kg b.w.) was administered to 43-day-old mice by gavage at varying concentrations of 2 to 20% w/v, no correlation could be established between plasma levels and concentration ...
Administration of a standard dose of 1 g/kg b.w. MSG by gavage as a 10% w/v solution resulted in a marked increase of plasma glutamate in all species studied. Peak plasma glutamate levels were lowest in adult monkeys (6 times fasting levels) and highest in mice (12-35 times fasting levels). Age-related differences between neonates and adults were observed; in mice and rats, peak plasma levels and area under curve were higher in infants than in adults while in guinea pigs the converse was observed.
For more Absorption, Distribution and Excretion (Complete) data for MONOSODIUM GLUTAMATE (7 total), please visit the HSDB record page.

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Metabolism / Metabolites
Glutamic acid is metabolized in the tissues by oxidative deamination ... or by transamination with pyruvate to yield oxaloacetic acid ... which, via alpha-ketoglutarate, enters the citric acid cycle ... .. Quantitatively minor but physiologically important pathways of glutamate metabolism involve decarboxylation to gamma-aminobutyrate (GABA) and amidation to glutamine ... . Decarboxylation to GABA is dependent on pyridoxal phosphate, a coenzyme of glutamic acid decarboxylase ..., as is glutamate transaminase. Vitamin B6-deficient rats have elevated serum glutamate levels and delayed glutamate clearance ... . /Glutamic acid/
Oral dose of 1 g/kg monosodium glutamate given to rats was followed by only a small rise in plasma pyroglutamate levels. No incr of pyroglutamate or glutamate brain levels was observed under these conditions.

Toxicity Summary
L-Glutamic acid and its ammonium, calcium, monosodium and potassium salts were evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1988. The Committee noted that intestinal and hepatic metabolism results in elevation of levels in systemic circulation only after extremely high doses given by gavage (>30mg/kg body weight). Ingestion of monosodium glutamate (MSG) was not associated with elevated levels in maternal milk, and glutamate did not readily pass the placental barrier. Human infants metabolized glutamate similarly to adults. Conventional toxicity studies using dietary administration of MSG in several species did not reveal any specific toxic or carcinogenic effects nor were there any adverse outcomes in reproduction and teratology studies. Attention was paid to central nervous system lesions produced in several species after parenteral administration of MSG or as a consequence of very high doses by gavage. Comparative studies indicated that the neonatal mouse was most sensitive to neuronal injury; older animals and other species (including primates) were less so. Blood levels of glutamate associated with lesions of the hypothalamus in the neonatal mouse were not approached in humans even after bolus doses of 10 g MSG in drinking water. Because human studies failed to confirm an involvement of MSG in "Chinese Restaurant Syndrome" or other idiosyncratic intolerance, the JECFA allocated an "acceptable daily intake (ADI) not specified" to glutamic acid and its salts. No additional risk to infants was indicated. The Scientific Committee for Food (SCF) of the European Commission reached a similar evaluation in 1991. The conclusions of a subsequent review by the Federation of American Societies for Experimental Biology (FASEB) and the Federal Drug Administration (FDA) did not discount the existence of a sensitive subpopulation but otherwise concurred with the safety evaluation of JECFA and the SCF.

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Interactions
Monosodium glutamate (MSG) administered intraperitoneally /for 10 days/ at a dose of 4 mg/g bw markedly increase malondialdehyde (MDA) formation in the liver, the kidney and brain of rats. Simultaneous administration of VIT C, VIT E and quercetin to MSG-treated rats significantly reduced this increase in MDA induced by MSG. VIT E reduced lipid peroxidation mostly in the liver followed by VIT C and then quercetin, while VIT C and quercetin showed a greater ability to protect the brain from membrane damage than VIT E. The decreased glutathione (GSH) level elicited by MSG in the three organs corresponded with marked increase in the activity of glutathione-S-transferase (GST). While MSG increased (p < 0.001) the activities of superoxide dismutase and catalase in the liver, it decreased significantly the activities of these enzymes in the kidney and the brain. The three antioxidants were effective at ameliorating the effects of MSG on GSH levels and the enzymes in the three organs examined. While MSG increased the activity of glucose-6-phosphatase in the liver and kidneys of rats (p < 0.001), the activity of the enzyme was abysmally low in the brain. There were marked increases in the activities of alanine aminotransferase, aspartate aminotransferase and gamma-glutamyl transferase in rats treated with MSG. The antioxidants tested protected against MSG-induced liver toxicity significantly. MSG at a dose of 4 mg/g significantly (p < 0.01) induced the formation of micronucleated polychromatic erythrocytes (MNPCEs). Co-treatment of rats with VIT C and quercetin inhibited the induction of MNPCEs by MSG (p < 0.001) ...

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Non-Human Toxicity Values
LD50 Rat female oral 15800 mg/kg bw
LD50 Rat male oral 17300 mg/kg/day
LD50 Mouse male oral 17700 mg/kg bw
LD50 Mouse female oral 16400 mg/kg bw
For more Non-Human Toxicity Values (Complete) data for MONOSODIUM GLUTAMATE (24 total), please visit the HSDB record page.

[1]. Permissive role for mglu1 metabotropic glutamate receptors in excitotoxic retinal degeneration. Neuroscience. 2017 Sep 14. pii: S0306-4522(17)30640-1.

[2]. Presynaptic effect of L-glutamic acid on the release of dopamine in rat striatal slices. Neurosci Lett. 1977 Oct;6(1):73-7.

[3]. L-Glutamic acid monosodium salt reduces the harmful effect of lithium on the development of Xenopus laevis embryos. Environ Sci Pollut Res Int. 2020 Nov;27(33):42124-42132.

[4]. Hydrochloric acid alters the effect of L-glutamic acid on cell viability in human neuroblastoma cell cultures. J Neurosci Methods. 2013 Jul 15;217(1-2):26-30.

[5]. Protective role of l-glutamic acid and l-cysteine in mitigation the chlorpyrifos-induced oxidative stress in rats. Environ Toxicol Pharmacol. 2018 Dec;64:155-163.

Monosodium glutamate appears as white or off-white crystalline powder with a slight peptone-like odor. pH (0.2% solution)7.0. (NTP, 1992)
One of the FLAVORING AGENTS used to impart a meat-like flavor.
See also: Glutamic Acid (has active moiety) ... View More ...

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Mechanism of Action
L-Glutamate and GABA supposedly act as excitatory and inhibitory transmitters, respectively, in the central nervous system. Glutamate is also involved in the synthesis of proteins. /Glutamate/

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Therapeutic Uses
One of the FLAVORING AGENTS used to impart a meat-like flavor. Medically it has been used to reduce blood ammonia levels in ammoniacal azotemia, therapy of hepatic coma, in psychosis, and mental retardation.

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Drug Warnings
The large doses of sodium glutamate required for the treatment of hepatic encephalopathy may result in dangerous alkalosis and hypokalemia ... important to keep close control on the electrolyte balance during therapy.
Injections of sodium glutamate should be given with caution to patients with hepatic cirrhosis, impaired renal function, or liver disease not associated with hyperammonemia.
Food and Environmental Agents: Effect on Breast-Feeding: Monosodium glutamate: None. /from Table 7/

C5H8NNAO4

169.11

169.035

142-47-2

L-Glutamic acid;56-86-0

23672308

White to off-white solid powder

333.8ºC at 760 mmHg

232°C

155.7ºC

2.55E-05mmHg at 25°C

25 ° (C=10, 2mol/L HCl)

2

5

4

11

149

1

C(CC(=O)O)[C@@H](C(=O)[O-])N.[Na+]

LPUQAYUQRXPFSQ-DFWYDOINSA-M

InChI=1S/C5H9NO4.Na/c6-3(5(9)10)1-2-4(7)8;/h3H,1-2,6H2,(H,7,8)(H,9,10);/q;+1/p-1/t3-;/m0./s1

sodium;(2S)-2-amino-5-hydroxy-5-oxopentanoate

MSG; Sodium glutamate; Monosodium glutamate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~7.14 mg/mL (~42.22 mM)
DMSO :< 1 mg/mL

Solubility in Formulation 1: 100 mg/mL (591.33 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)