D-Cycloserine

Absorption

Rapidly and almost completely absorbed (70 to 90%) from the gastrointestinal tract following oral administration.

Toxicity

Oral LD50 in mouse is 5290 mg/kg, and in rat is over 5000 mg/kg. Symptoms of a cycloserine overdose include drowsiness, confusion, headache, dizziness, irritability, numbness and tingling, difficulty speaking, paralysis, abnormal behavior, seizures, and unconsciousness.

Description

D-Cycloserine (68-41-7) is a partial agonist at the glycine modulatory site of NMDA glutamatergic receptors.1?Blocks kainate-induced seizures2?and displays anticonvulsant effects3?in rat models. D-Cycloserine facilitates synaptic plasticity but impairs glutamatergic neurotransmission in rat hippocampal slices.4?Second-line drug for the treatment of tuberculosis. ?Enhances activity-dependent plasticity in human adults.5

Description

d-Cycloserine is a naturally occurring cyclic amino acid that can be thought of as an oxidatively cyclized version of its namesake d-serine. It is produced by?Streptomyces?bacteria and has been used to treat the tuberculosis pathogen,?Mycobacterium tuberculosis.
d-Cycloserine, also called oxymycin and?D-4-amino-3-isoxazolidone, was the subject of a flurry of articles published in issue 8 of the 1955 volume of?JACS. In succession, Merck researchers reported its?isolation from?Streptomyces garyphalus; scientists at Eli Lilly and Commercial Solvents Corp. reported?similar results from?Streptomyces ocrhidaceus?; and Merck chemists?synthesized racemic cycloserine.
Fast-forward to 2015: Psychologist Robert S. Asarnow and co-workers at UCLA were building on earlier research in lab animals that showed that?N-methyl-D-aspartate receptor (NMDAR) signaling in the brain is involved in strengthening synapses during learning.
They hypothesized that?D-cycloserine, an NMDAR signal booster, might have the same effects in humans. Using electroencephalography (EEG), they found that healthy subjects treated with the compound?exhibited larger “learning spikes”? in their EEG traces than did untreated individuals.
Psychologist Stefan G. Hoffmann at Boston University says that this finding is an indication that?D-cycloserine or other NMDAR signal enhancers might be useful for enhancing forms of cognition that are relevant to psychiatric disorders.

Chemical properties

White to pale yellow cryst. powder

Originator

Oxamycin,Merck Sharp and Dohme,US,1956

The Uses of D-Cycloserine

D-Cycloserine inhibits cell wall biosynthesis (D-Ala peptide bond formation). D-Cycloserine also prevents conversion of D-Ala to L-Ala. D-Cycloserine is an bacteriostatic. D-Cycloserine is an antibiot ic against Gram-negative bacteria.

The Uses of D-Cycloserine

antibacterial (tuberculostatic)

The Uses of D-Cycloserine

D-cycloserine has been used to inhibit serine hydroxymethyltransferase.

Indications

Used in combination with up to 5 other drugs as a treatment for Mycobacterium avium complex (MAC) and is also used to treat tuberculosis (TB).

Background

Antibiotic substance produced by Streptomyces garyphalus.

What are the applications of Application

D-Cycloserine is antibiotic and a partial agonist of NMDA receptors at the glycine modulatory site

Indications

Cycloserine is a broad-spectrum antibiotic produced by Streptomyces orchidaceus. It is structural analogue of Dalanine and acts through a competitive inhibition of the D-alanine that is involved in bacterial cell wall synthesis. Cycloserine is inhibitory to M. tuberculosis and active against Escherichia coli, S. aureus, and Enterococcus, Nocardia, and Chlamydia spp. It is used in the treatment of MDR tuberculosis and is useful in renal tuberculosis, since most of the drug is excreted unchanged in the urine.

Definition

ChEBI: D-cycloserine is a 4-amino-1,2-oxazolidin-3-one that has R configuration. It is an antibiotic produced by Streptomyces garyphalus or S. orchidaceus and is used as part of a multi-drug regimen for the treatment of tuberculosis when resistance to, or toxicity from, primary drugs has developed. An analogue of D-alanine, it interferes with bacterial cell wall synthesis in the cytoplasm by competitive inhibition of L-alanine racemase (which forms D-alanine from L-alanine) and D-alanine--D-alanine ligase (which incorporates D-alanine into the pentapeptide required for peptidoglycan formation and bacterial cell wall synthesis). It has a role as an antitubercular agent, an antiinfective agent, an antimetabolite, a metabolite and a NMDA receptor agonist. It is an organooxygen heterocyclic antibiotic, an organonitrogen heterocyclic antibiotic and a 4-amino-1,2-oxazolidin-3-one. It is a conjugate base of a D-cycloserine(1+). It is an enantiomer of a L-cycloserine. It is a tautomer of a D-cycloserine zwitterion.

Manufacturing Process

Cycloserine may be made by a fermentation process or by direct synthesis. The fermentation process is described in US Patent 2,773,878. A fermentation medium containing the following proportions of ingredients was prepared:
Parts by Weight
Soybean meal
30.0
Cornstarch
5.0
Corn steep liquor
3.0
Sodium nitrate
3.0
This material was made up with distilled water to provide 41 g per liter, and the mixture was adjusted to pH 7.0 with potassium hydroxide solution. To the mixture were added per liter 5.0 g of calcium carbonate and 7.5 ml of soybean oil. 2,000 ml portions of this medium were then added to fermentation vessels, equipped with stirrers and aeration spargers, and sterilized at 121°C for 60 minutes. After cooling the flasks were inoculated with a suspension of strain No. ATCC 11924 of Streptomyces lavendulae,obtained from the surface of agar slants. The flasks were stirred for 4 days at 28°C at approximately 1,700 rpm. At the end of this period the broth was found to contain cycloserine in the amount of about 250 C.D.U./ml of broth. The mycelium was separated from the broth by filtration. The broth had a pH of about 7.5. Tests showed it to be highly active against a variety of microorganisms.
The direct synthetic process is described in US Patent 2,772,280. A solution of 73.3 g (0.332 mol) of β-aminoxyalanine ethyl ester dihydrochloride in 100 ml of water was stirred in a 500 ml 3-necked round-bottomed flask cooled in an ice-bath. To the above solution was added over a 30-minute period 65.6 g (1.17 mols) of potassium hydroxide dissolved in 100 ml of water, While the pH of the reaction mixture was 7 to 10.5, a red color appeared which disappeared when the pH reached 11 to 11.5. The light yellow solution was allowed to stand at room temperature for ? hour and then added to 1,800 ml of 1:1 ethanol-isopropanol. The reaction flask was washed twice with 10 ml portions of water and the washings added to the alcohol solution. The precipitated salts were filtered out of the alcohol solution and the filtrate cooled to 5°C in a 5 liter 3-necked round-bottomed flask. To the cold, well-stirred solution was added dropwise over a 35-minute period sufficient glacial acetic acid to bring the pH of the alcohol solution to 6.0. When the pH of the solution had reached 7 to 7.5, the solution was seeded and no further acetic acid added until crystallization of the oil already precipitated had definitely begun. The crystalline precipitate was collected on a filter, washed twice with 1:1 ethanolisopropanol and twice with ether. The yield of 4-amino-3-isoxazolidone was 22.7 g.

brand name

Seromycin (Lilly).

Therapeutic Function

Antitubercular

Synthesis Reference(s)

Journal of the American Chemical Society, 79, p. 3236, 1957 DOI: 10.1021/ja01569a065

General Description

Chemical structure: amino acid derivatives

Pharmaceutical Applications

A fermentation product of Strep. orchidaceus and other related organisms now produced synthetically. Aqueous solutions are stable at pH 7.8 but the agent is rapidly destroyed in acid conditions. It is active against a wide range of Gram-negative and Grampositive bacteria, including Staphylococcus aureus, streptococci, including Enterococcus faecalis, various enterobacteria, Nocardia and Chlamydia spp. M. tuberculosis is inhibited by 8–16 mg/L. Some environmental mycobacteria, including M. avium, are also susceptible. Its action is specifically antagonized by d-alanine, from which media for in-vitro tests should be free. Its use is limited by neurological and psychiatric side effects. Primary resistance in M. tuberculosis is rare and develops only slowly in patients treated with cycloserine alone. Its inclusion in combinations deters the development of resistance to other drugs. There is no cross-resistance with other therapeutic antibiotics.
It is well absorbed when given orally, achieving a concentration of c. 10 mg/L 3–4 h after a 250 mg dose. Doubling the dose approximately doubles the plasma level. Some accumulation occurs over the first 3 or 4 days of treatment. In children receiving 20 mg/kg orally, plasma levels of 20–35 mg/L have been found. It is widely distributed throughout the body fluids, including the CSF. About 50% is excreted unchanged in the glomerular filtrate over 24 h and 65–70% over the subsequent 2 days. The remainder is metabolized. There is no tubular secretion and no effect of probenecid. Cycloserine accumulates in renal failure, reaching toxic levels if dosage is uncontrolled. It can be removed by hemodialysis.
Evidence of central nervous system toxicity, including headache, somnolence, vertigo, visual disturbances, confusion, depression, acute psychotic reactions and tremors, may develop over the first 2 weeks of treatment. The effects may be exacerbated by alcohol and can be reduced, to some extent, by administering pyridoxine. Treatment should be stopped promptly if any mental or neurological signs develop. Convulsions are said to occur in about 50% of patients when the plasma concentration exceeds 20–25 mg/L, but the relationship to dose is not particularly close. No permanent damage appears to be caused. Cycloserine inhibits mammalian transaminases and this and the convulsant effects of the drug have been attributed to a metabolite, amino-oxyalanine. Use of the drug should be avoided in patients with previous fits or other neurological or psychiatric abnormalities. Rare side effects include rashes, cardiac arrhythmia and deficiency in folate and vitamin B₁₂ leading to peripheral neuritis.
It is occasionally used in MDR tuberculosis (with other antituberculosis drugs) and other mycobacterioses (with appropriate additional drugs).

Biochem/physiol Actions

Mode of Action: Inhibits cell wall biosynthesis (D-Ala peptide bond formation). Also prevents conversion of D-Ala to L-Ala. Bacteriostatic.Partial agonist at the glycine modulatory site of NMDA glutamatergic receptors; antibiotic against Gram-negative bacteria.Mode of Resistance: D-Ala transport interference.

Mechanism of action

D-Cycloserine is considered to be the active form of the drug, having its action associated with the ability to inhibit two key enzymes, D-alanine racemase and D-alanine ligase. D-Alanine is an important component of the peptidoglycan portion of the mycobacterial cell wall. Mycobacterium are capable of utilizing natural occurring L-alanine and converting the L-alanine to D-alanine via the enzyme D-alanine racemase. The resulting D-alanine is coupled with itself to form a D-alanine–D-alanine complex under the influence of D-alanine ligase, and this complex is incorporated into the peptidoglycan of the mycobacterial cell wall . D-Cycloserine is a rigid analogue of D-alanine; therefore, it competitively inhibits the binding of D-alanine to both of these enzymes and its incorporation into the peptidoglycan. Resistance is associated with an over expression of D-alanine racemase.

Pharmacokinetics

Cycloserine, a broad-spectrum antibiotic, may be bactericidal or bacteriostatic, depending on its concentration at the site of infection and the susceptibility of the organism. Cycloserine works by blocking the formation of these peptidoglycans. By doing this the walls of the bacteria become weak and it results in the death of the bacteria

Pharmacology

Cycloserine is readily absorbed orally and distributes throughout body fluids including the cerebrospinal fluid. The concentrations of cycloserine in tissues, body fluids, and the cerebrospinal fluid are approximately equal to the plasma level. Cycloserine is partially metabolized, and 60 to 80% is excreted unchanged by the kidney.

Clinical Use

D-(+)-4-Amino-3-isoxazolidinone (Seromycin) is an antibioticthat has been isolated from the fermentation beer of threedifferent Streptomyces species: S. orchidaceus, S. garyphalus,and S. lavendulus. It occurs as a white to pale yellow crystallinematerial that is very soluble in water. It is stable in alkaline,but unstable in acidic, solutions. The compoundslowly dimerizes to 2,5-bis(aminoxymethyl)-3,6-diketopiperazinein solution or standing.
The structure of cycloserine was reported simultaneouslyby Kuehl et al. and Hidy et al.81 to be D-( +)-4-amino-3-isoxazolidinone. It has been synthesized byStammer et al. and by Smart et al.83 Cycloserine is stereochemicallyrelated to D-serine. However, the L-form hassimilar antibiotic activity.
Although cycloserine exhibits antibiotic activity invitro against a wide spectrum of both Gram-negative andGram-positive organisms, its relatively weak potency andfrequent toxic reactions limit its use to the treatment of tuberculosis.It is recommended for patients who fail to respondto other tuberculostatic drugs or who are known tobe infected with organisms resistant to other agents. It isusually administered orally in combination with otherdrugs, commonly isoniazid.

Clinical Use

Neurological symptoms, which tend to appear in the first week of therapy, consist of dizziness, confusion, irritability, psychotic behavioral changes, and even suicidal ideation. Cycloserine is contraindicated in patients with underlying psychiatric and seizure disorders.Other side effects include occasional peripheral neuropathy and low magnesium levels.

Side Effects

Cycloserine is readily absorbed after oral administration and is widely distributed, including the CNS. Unfortunately, D-cycloserine binds to neuronal N-methylasparate receptors and, in addition, affects synthesis and metabolism of γ-aminobutyric acid, leading to complex series of CNS effects. As a second-line agent, cycloserine should only be used when retreatment is necessary or when the organism is resistant to other drugs. Cycloserine should not be used as a single drug; it must be used in combination.

Synthesis

Cycloserine, 4-amino-3-isoxalidinone (34.1.19), can be synthesized both biosynthetically from the actinomycetes Streptomyces garyphalus, Streptomyces orchidaceus, and Streptomyces lavenduale as well as synthetically from the methyl ester of D-serine, the hydroxyl group of which is replaced with a chlorine atom when reacted with phosphorous pentachloride, and subsequent reaction of the resulting product (34.1.19) with hydroxylamine results in heterocyclization to the desired cycloserine (34.1.20).

Drug interactions

Potentially hazardous interactions with other drugs
Alcohol: Increased risk of seizures.

Metabolism

Not Available

Metabolism

Cycloserine is excreted largely unchanged by glomerular filtration. About 50% of a single 250 mg dose is excreted unchanged in the urine within 12 hours and about 70% is excreted within 72 hours. As negligible amounts of cycloserine appear in the faeces, it is assumed that the remainder of a dose is metabolised to unidentified metabolites.

Purification Methods

Purify cycloserine by recrystallisation from aqueous EtOH or MeOH or aqueous NH3/EtOH or isoPrOH. Also recrystallise it from aqueous ammoniacal solution at pH 10.5 (100mg/mL) by diluting with 5 volumes of isopropanol and then adjusting to pH 6 with acetic acid. An aqueous solution, buffered to pH 10 with Na2CO3, can be stored in a refrigerator for 1week without decomposition. UV: max at 226nm (A1cm 1% 4.02). The tartrate salt has m 165-166o (dec), 166-168o (dec), and [] D 24 -41o (c 0.7, H2O). [Stammer et al. J Am Chem Soc 79 3236 1959, UV: Kuehl J Am Chem Soc 77 2344 1955, Beilstein 27 III/IV 5549.]

References

1) Watson?et al. (1990),?D-cycloserine acts as a partial agonist at the glycine modulatory site of the NMDA receptor expressed in Xenopus oocytes; Brain Res.,?510?158 2) Baran?et al. (1994),?The glycine/NMDA receptor partial agonist D-cycloserine blocks kainite-induced seizures in rats. Comparison with MK-801 and diazepam; Brain Res.,?652?195 3) L?scher?et al. (1994),?Anticonvulsant effects of the glycine/NMDA receptor ligands D-cycloserine and D-serine but not R(+)-HA-966 in amygdala-kindled rats; Br. J. Pharmacol., 112?97 4) Rouaud and Billard (2003),?D-cycloserine facilitates synaptic plasticity but impairs glutamatergic neurotransmission in rat hippocampal slices; Br. J. Pharmacol.,?140?1051 5) Forsyth?et al. (2015),?Augmenting NMDA receptor signaling boosts experience-dependent neuroplasticity in the adult human brain; Proc. Natl. Acad. Sci. USA,?112?15331