Coluracetam Reference Standard — CAS 135463-81-9, ≥99% by HPLC

1. Substance identity and registry data

Coluracetam is the international nonproprietary name for N-(2,3-dimethyl-5,6,7,8-tetrahydrofuro[2,3-b]quinolin-4-yl)-2-(2-oxopyrrolidin-1-yl)acetamide [1]. The name places it in the racetam family, and the 2-oxopyrrolidin-1-yl-acetamide fragment on the right of the molecule is indeed the shared racetam motif. Everything to the left of it is not: a tricyclic furo[2,3-b]quinoline with a saturated carbocyclic ring, which no other member of the family carries. That asymmetry between the name and the structure is the single most useful thing to understand about this compound, and section 12 explains why.

Every identifier below comes from a public authoritative registry [1][2], so a receiving laboratory can reconcile the material against its own inventory system without ambiguity.

Coluracetam or MKC-231 — what is the difference?

None at the level of the substance. MKC-231 is the development code from the original Mitsubishi programme and is the designation used in essentially the whole primary pharmacological literature [6][7][8][9][10][11][12][13]. Coluracetam is the later INN. A literature search on the INN alone will miss almost everything published about the compound; searching on the code is what finds it. Note also that the code is written with a hyphen — searching MKC231 without one returns nothing in PubChem.

2. Molecular structure

Three regions govern its behaviour in the laboratory.

The furo[2,3-b]quinoline core is a flat, fused, electron-rich heteroaromatic system carrying two methyl groups on the furan ring. It supplies almost all of the molecule's ultraviolet absorbance and almost all of its bulk: at complexity 540 it is by a wide margin the most structurally intricate compound in this catalogue [1]. It is also the reason coluracetam is retained far more strongly on reversed-phase columns than the small polar racetams it is nominally grouped with.

The saturated carbocyclic ring fused at positions 5 to 8 removes aromaticity from one third of the tricycle. That matters for photostability and for the fragmentation pattern, since a saturated ring fragments differently from an aromatic one.

The 2-oxopyrrolidin-1-yl acetamide arm is the racetam motif, and it is the only part of the molecule shared with piracetam, aniracetam or oxiracetam. It carries the single hydrogen-bond donor — the anilide NH — and two of the four acceptors.

Structural neighbours in this catalogue

The comparison that teaches the most is with oxiracetam, a small, strongly polar racetam of computed logP around −2.2 and molecular mass 158. Coluracetam shares its terminal fragment and almost nothing else: nearly 2.2 times the mass, and a computed logP more than four and a half log units higher. Any method built for one will fail on the other, which makes the pair a useful bracket when qualifying a gradient. Aniracetam and noopept sit between them.

3. Computed descriptors and what they predict

What these numbers predict in the laboratory

A computed logP of 2.4 with a polar surface area of 75.4 Ų describes a moderately lipophilic, well-behaved reversed-phase analyte. Expect comfortable retention on C18 with a mid-range organic mobile phase — neither the excessive retention of a strongly lipophilic solid nor the void-volume elution of a polar racetam.

The extended heteroaromatic system is the practical gift. A fused, electron-rich tricycle absorbs strongly in the ultraviolet, so diode-array detection should give good sensitivity and a distinctive spectrum for library matching. For a compound with no deposited ultraviolet spectrum (section 7), acquiring one against an authentic standard is both easy and worth doing.

Only three rotatable bonds for twenty-five heavy atoms means an unusually rigid molecule. Rigid analytes give narrow, symmetrical peaks and reproducible retention, and are less prone to temperature-dependent peak distortion.

No ionisable centre of consequence. The quinoline nitrogen is part of a fused, electron-delocalised system and the anilide NH is not acidic in any usable range; mobile-phase pH is therefore a weak lever on retention. That removes a common source of inter-laboratory drift but also removes a tool for adjusting selectivity, so stationary-phase choice does the work.

4. Stereochemistry: coluracetam is achiral

Coluracetam has no stereocentre. The registry record reports zero defined and zero undefined atom stereocentres, and zero of each for bond stereocentres [1]; the standard InChIKey ends in UHFFFAOYSA, the marker for a structure carrying no stereochemical layer at all.

This section exists because the claim that this substance is a "dextrorotatory stereoisomer" circulates widely in commercial listings. It is not a matter of interpretation. A molecule with no stereogenic atom and no stereogenic bond has no enantiomers, cannot be dextrorotatory or laevorotatory, and cannot exist as a resolved isomer. Every carbon in the tricycle is either aromatic, or a methylene with two hydrogens, or a ring-fusion carbon whose substituents are fixed by the ring system.

5. Solid-state behaviour and solution preparation

What can be said follows from structure. Coluracetam is a neutral, rigid, moderately lipophilic crystalline solid with a single hydrogen-bond donor and a large flat aromatic surface. Flat fused aromatics of this kind tend to pack efficiently and are not usually hygroscopic; there is no ionisable group to complicate handling. Methanol, acetonitrile, acetone and dimethyl sulfoxide are the rational solvents for chromatographic stock solutions. Water is not usable at practically relevant concentrations.

Because no certified solubility figure exists, determine the working concentration gravimetrically for the specific batch rather than inheriting one: weigh, dissolve, confirm complete dissolution, verify against a ultraviolet or mass-spectrometric response, and record the result. For this compound that record has more value than usual, because there is nothing published to compare it with.

6. Use as an analytical reference standard

6.1 The gap this standard fills

Most reference standards exist because a well-studied substance needs routine confirmation. Coluracetam is the opposite case, and it is worth stating plainly because it is the whole argument for stocking it.

The substance is consumed, and it cannot be measured. On the demand side, coluracetam appears as a labelled ingredient in products sold as dietary supplements, and the United States Drug Enforcement Administration has recorded it in the National Forensic Laboratory Information System under the category New Drug since December 2023 [5] — an entry that exists only because forensic laboratories were submitting samples containing it. On the supply side, the published analytical literature for this compound is close to empty: no validated HPLC method, no LC-MS/MS assay, no impurity profile, no crystal structure and no published synthesis could be located for coluracetam specifically.

6.2 What has to be built from scratch, and what helps

Three properties make this compound easier to work with than its literature suggests:

• A strong, distinctive ultraviolet chromophore. The fused, electron-rich furoquinoline tricycle absorbs well, so diode-array detection gives both sensitivity and a spectrum worth putting in a library. No ultraviolet spectrum is deposited anywhere (section 7), so this is the cheapest useful measurement to make first.
• Rigidity. Three rotatable bonds across twenty-five heavy atoms means narrow, reproducible peaks.
• Achirality. No chiral method to develop, no enantiomeric purity to specify, no chiral column screen to fund (section 4).

What has to be established from the standard itself: retention time and relative retention on the laboratory's own column, the ultraviolet spectrum, the product-ion transitions and their ratios, the response factor, the limit of detection actually achieved in the relevant matrix, and the impurity profile of authentic material against which a sample can be judged.

6.3 Distinguishing coluracetam from the rest of the racetam family

The name is misleading and the structure is the reason. Coluracetam shares only the terminal 2-oxopyrrolidin-1-yl acetamide fragment with the classical racetams; the rest of the molecule has no counterpart in the family [14][15].

The row that matters operationally is logP. A gradient that elutes oxiracetam near the void will retain coluracetam strongly; a method built for coluracetam will not see oxiracetam at all. Grouping these substances under one catalogue heading does not make them one chromatographic problem, and a laboratory qualifying a multi-analyte racetam method needs both extremes present to prove it.

6.4 Screening consumer products

Because coluracetam is present in products on sale and absent from the analytical literature, the laboratories most likely to need this material are those screening consumer products for declared or undeclared ingredients. Identification in such work requires an authenticated standard for each substance claimed, and for this compound no pharmacopoeial or certified alternative exists.

7. Reference spectral data

Third-party spectra deposited against the compound record are listed below with attribution. They are the property of the depositors named and are cited so that a laboratory can locate an independent comparison. They are not the spectra of the batch supplied.

8. Batch specification and Certificate of Analysis

The layout of the certificate and the method stated against each parameter can be reviewed on the specimen Certificate of Analysis.

9. Handling, storage and stability

• Storage. Sealed, cool, dry, protected from light. The extended heteroaromatic chromophore that makes ultraviolet detection easy also makes photodegradation a plausible route; amber glass costs nothing.
• Hydrolysis. The molecule contains two amide linkages, the anilide and the lactam. Amides are robust at neutral pH but both are potential sites under strongly acidic or basic conditions at elevated temperature. Avoid such conditions in sample preparation unless the effect has been characterised.
• Hygroscopicity. Not expected, on structural grounds — one donor, a large flat non-polar surface. No measured data exist either way.
• Solution stability. Prepare stocks in methanol, acetonitrile or dimethyl sulfoxide, store refrigerated and protected from light, and re-verify rather than assume stability. No published stability study for coluracetam solutions was located.
• Personal protection. Gloves, eye protection, dust containment under local exhaust. See section 10: this recommendation rests on the absence of data, not on its presence.

10. Hazard classification — and its absence

In the absence of any classification the defensible approach is to treat coluracetam as a biologically active organic solid of unknown hazard: gloves, eye protection, containment of dust under local exhaust, no eating or drinking in the handling area, and a workplace risk assessment that records the absence of data as a finding in its own right. The Safety Data Sheet shipped with the batch is the controlling document.

11. Discovery and development history

Coluracetam was developed in Japan under the code MKC-231 in a programme at Mitsubishi, and the whole of its primary pharmacological literature carries that designation. The compound was designed around a specific and unusual pharmacological hypothesis — enhancement of high-affinity choline uptake — rather than around structural analogy to piracetam, which is why its structure departs so far from the rest of the family it is named after.

The literature falls into three clear phases. The first, in the mid-1990s, established the behavioural effect: Murai and colleagues reported in 1994 that MKC-231 ameliorated working-memory deficits and decreased hippocampal acetylcholine in rats treated with the cholinergic neurotoxin AF64A [6], and Bessho and colleagues reported effects on water-maze learning deficits in 1996 [7].

The second, at the turn of the century, probed the boundaries: Akaike and colleagues examined a protective effect against glutamate cytotoxicity in cultured cortical neurons [8], and Uemura and colleagues reported central hyperglycaemic effects [9].

The third and most informative is a coordinated three-part series published together in the Journal of Neural Transmission in 2008, which set out to establish the mechanism directly [11][12][13]. Between the second and third phases, Shirayama and colleagues examined the compound against phencyclidine-induced behavioural deficits [10].

Development did not continue to an authorised medicine in any jurisdiction. What followed instead was appearance on the consumer market, and the regulatory footprint described in section 14 — a forensic reporting entry rather than an approval.

12. Preclinical pharmacology: the HACU mechanism

Coluracetam is one of the few compounds in this catalogue for which a specific proposed mechanism exists in the primary literature, and it is not the mechanism its family name suggests.

The proposal is enhancement of high-affinity choline uptake (HACU), the rate-limiting step in acetylcholine synthesis at cholinergic nerve terminals. The 2008 three-part series in the Journal of Neural Transmission examined it systematically in rats treated with AF64A, a neurotoxin that selectively damages cholinergic terminals. Part 1 reported long-lasting cognitive improvement after repeated administration [11]; part 2 examined effects on the synthesis and release of acetylcholine [12]; part 3 addressed the mode of action of the enhancement of high-affinity choline uptake itself [13].

That the third paper exists at all is what distinguishes this compound. Most of the substances catalogued as racetams have no established single target — a point made in the standard reviews of the class [14][15]. Coluracetam has a named, specific, mechanistically framed hypothesis with a dedicated study behind it.

13. Clinical research literature

What can be said without qualification is that the substance is not, and has never been, an authorised medicine, and that nothing on this page offers it as one.

14. Regulatory status

15. Permitted use and terms of supply

16. Frequently asked questions

What is coluracetam used for in a laboratory?

As an analytical reference standard: to establish retention time and an ultraviolet spectrum in a laboratory's own method, to determine product-ion transitions for mass spectrometry, to measure a real limit of detection by spiking blank matrix, to prepare quality-control samples, and to identify the substance in consumer products that declare or contain it. Because no validated public method exists for this compound, almost every parameter has to be established from the standard itself.

Is this product intended for human consumption?

No. It is a chemical reagent and analytical reference material supplied for in-vitro laboratory use only. It is not a medicinal product, supplement or food, it holds no marketing authorisation anywhere, and it must not be ingested or administered to any human or animal.

What is the molecular weight of coluracetam?

341.4 grams per mole, for the molecular formula C19H23N3O3, with a monoisotopic mass of 341.17394 daltons. Listings quoting a mass near 168 grams per mole are wrong by a factor of two and should be disregarded; the registry value is the one above.

Is coluracetam chiral, or a dextrorotatory isomer?

Neither. Coluracetam has no stereocentre at all: the registry record reports zero defined and zero undefined atom stereocentres and zero of each for bond stereocentres, and its standard InChIKey carries no stereochemical layer. A molecule with no stereogenic atom cannot be dextrorotatory or laevorotatory and has no enantiomers. Descriptions of this substance as an isolated optical isomer are structurally impossible and indicate a datasheet that has not been checked.

Is coluracetam the same as MKC-231?

Yes. MKC-231 is the development code from the original Japanese programme and coluracetam is the later international nonproprietary name. Almost the entire primary pharmacological literature uses the code rather than the name, so a search on the name alone will miss most of it. Note that the code must be searched with its hyphen; without it, database searches return nothing useful.

What is the melting point of coluracetam?

No validated experimental value is published, and this page prints none. The same applies to density, boiling point and solubility: the compound record contains no experimental properties section at all. Values circulating in commercial listings, including a density below that of water, are not traceable to any measurement. Use the values determined for the batch supplied.

What chromatographic conditions suit this compound?

Its computed logP of 2.4 and polar surface area of 75.4 square angstroms describe a moderately lipophilic, well-behaved reversed-phase analyte, comfortably retained on C18 with a mid-range organic mobile phase. The fused heteroaromatic core absorbs strongly in the ultraviolet, so diode-array detection is both sensitive and informative. There is no ionisable centre of consequence, so mobile-phase pH is a weak lever on retention and stationary-phase choice does the work of adjusting selectivity.

How does coluracetam differ from other racetams?

Far more than the shared name suggests. It shares only the terminal 2-oxopyrrolidinyl acetamide fragment; the rest of the molecule is a tricyclic furoquinoline that no other member of the family carries. In practical terms it is 2.2 times the mass of oxiracetam and more than four and a half log units more lipophilic, so a chromatographic method built for one will not work for the other. It is also the only member of the family with a specific named mechanistic hypothesis in the primary literature, namely enhancement of high-affinity choline uptake.

What does the published research actually say about coluracetam?

That it was studied as an enhancer of high-affinity choline uptake, the rate-limiting step in acetylcholine synthesis, mainly in rats with chemically induced cholinergic lesions. A coordinated three-part series published in 2008 addressed cognitive effects after repeated administration, effects on acetylcholine synthesis and release, and the mode of action of the uptake enhancement itself. The important qualification is that essentially all of this work comes from one research group within a single development programme, uses one lesion model, is between seventeen and thirty years old, and has no independent replication that could be located. It is a well-specified hypothesis with narrow supporting evidence, not an established mechanism.

Is coluracetam banned in sport?

It is not on the World Anti-Doping Agency 2026 Prohibited List. Of the racetam family only fonturacetam, also called 4-phenylpiracetam or carphedon, is named there, in class S6.A; piracetam itself is not listed. Absence from the list is a statement about that document on the date checked and nothing more, and athletes should verify the current list themselves rather than relying on this page.

Is coluracetam legal in Poland or the United States?

In Poland it does not appear in the consolidated list of narcotic drugs, psychotropic substances and new psychoactive substances, and it is not a registered medicine. In the United States it is not a controlled substance under the Controlled Substances Act; the only federal entry is a Drug Enforcement Administration forensic reporting category, added in December 2023, which records how laboratory results are tabulated rather than imposing any control. Not being scheduled is not the same as being approved for any human use, and nothing on this page offers it for one. Status differs between countries and must be verified locally.

What are the hazards?

No hazard classification exists. There is no GHS classification for coluracetam and no notifications to the ECHA Classification and Labelling Inventory, so no signal word, no hazard statements and no precautionary statements have been assigned by anyone, and this page prints no pictogram or H-phrase. The cause is traceable: the substance has no EC number, so it never entered the European chemicals inventory and no REACH dossier exists. An absent classification is not a safety claim. Handle the material as a biologically active organic solid of unknown hazard, with gloves, eye protection and dust containment, and treat the absence of data as a finding in the workplace risk assessment.

What pack sizes are available?

Three: 1 g, 5 g and 10 g, each supplied as crystalline powder with a batch Certificate of Analysis. Catalogue numbers follow the CAS-based scheme NSA-135463-81-9 with the pack size appended, for example NSA-135463-81-9-5G.

17. How this page is sourced and verified

Limitations named directly

1. The bibliography is short because the literature is short. Sixteen sources are cited where other pages in this catalogue carry thirty or forty. The primary record for coluracetam is a handful of papers from one programme; padding the list would misrepresent the state of knowledge.
2. There is no experimental physicochemistry and no analytical methodology specific to this compound. Every number in section 3 is computed. The one analytical reference cited [16] concerns piracetam, not coluracetam, and is included only to show what a developed method for a member of this family looks like — it is labelled as a different substance wherever it appears.
3. There is no hazard classification at all, and no mechanism by which one could have been produced. Section 10 explains why that is a reason for more caution rather than less.
4. The pharmacology comes from essentially one group, one lesion model and one era, with no independent replication located. Section 12 says so in place.
5. One clinical-status question is unresolved between two public sources and is reported as unresolved in section 13 rather than decided.

Not yet on this page

This page does not currently carry a named author with stated professional qualifications, a named technical reviewer, or laboratory data generated in-house for a specific batch — no chromatogram, no spectrum, no measured retention or melting data of our own. For a substance with this little public data those gaps matter more than usual: in-house measurements here would be additions to the public record, not merely confirmations of it.

18. References

Citations follow the Chicago author–date convention. All external links carry rel="nofollow". Access to full texts is governed by the policies of the respective publishers.

Registry and regulatory sources

1. National Center for Biotechnology Information. 2026. "PubChem Compound Summary for CID 214346, Coluracetam." PubChem. Accessed August 22, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/214346.
2. U.S. Food and Drug Administration. 2026. "Global Substance Registration System: UNII V6FL6O5GR7, Coluracetam." Accessed August 22, 2026. https://gsrs.ncats.nih.gov/ginas/app/beta/substances/V6FL6O5GR7.
3. World Anti-Doping Agency. 2025. World Anti-Doping Code International Standard: Prohibited List 2026. Effective 1 January 2026. https://www.wada-ama.org/en/prohibited-list.
4. Minister Zdrowia. 2024. Obwieszczenie Ministra Zdrowia z dnia 17 czerwca 2024 r. w sprawie ogłoszenia jednolitego tekstu rozporządzenia Ministra Zdrowia w sprawie wykazu substancji psychotropowych, środków odurzających oraz nowych substancji psychoaktywnych. Dziennik Ustaw 2024, poz. 1139. https://eli.gov.pl/eli/DU/2024/1139.
5. U.S. Drug Enforcement Administration. 2023. "National Forensic Laboratory Information System: Coluracetam, drug category New Drug, added December 2023." Annotation reproduced in the PubChem record for CID 214346. https://www.nflis.deadiversion.usdoj.gov/.

Primary pharmacology of MKC-231

6. Murai, S., H. Saito, E. Abe, Y. Masuda, J. Odashima, and T. Itoh. 1994. "MKC-231, a Choline Uptake Enhancer, Ameliorates Working Memory Deficits and Decreased Hippocampal Acetylcholine Induced by Ethylcholine Aziridinium Ion in Mice." Journal of Neural Transmission, General Section 98 (1): 1–13. https://doi.org/10.1007/BF01277590.
7. Bessho, T., K. Takashina, R. Tabata, C. Ohshima, H. Chaki, H. Yamabe, M. Egawa, A. Tobe, and K. Saito. 1996. "Effect of the Novel High Affinity Choline Uptake Enhancer 2-(2-Oxopyrrolidin-1-yl)-N-(2,3-dimethyl-5,6,7,8-tetrahydrofuro[2,3-b]quinolin-4-yl)acetoamide on Deficits of Water Maze Learning in Rats." Arzneimittelforschung 46 (4): 369–373. https://pubmed.ncbi.nlm.nih.gov/8740080/.
8. Akaike, A., T. Maeda, S. Kaneko, and Y. Tamura. 1998. "Protective Effect of MKC-231, a Novel High Affinity Choline Uptake Enhancer, on Glutamate Cytotoxicity in Cultured Cortical Neurons." Japanese Journal of Pharmacology 76 (2): 219–222. https://doi.org/10.1254/jjp.76.219.
9. Uemura, K., S. Yoshioka, D. M. Surina-Baumgartner, T. Tamagawa, H. Miura, M. Ueda, N. Tamaya, A. Iguchi, and N. Hotta. 1999. "Central Nervous System-Mediated Hyperglycemic Effects of NIK-247, a Cholinesterase Inhibitor, and MKC-231, a Choline Uptake Enhancer, in Rats." Japanese Journal of Pharmacology 79 (1): 113–115. https://doi.org/10.1254/jjp.79.113.
10. Shirayama, Y., A. Yamamoto, T. Nishimura, S. Katayama, and R. Kawahara. 2007. "Subsequent Exposure to the Choline Uptake Enhancer MKC-231 Antagonizes Phencyclidine-Induced Behavioral Deficits and Reduction in Septal Cholinergic Neurons in Rats." European Neuropsychopharmacology 17 (9): 616–626. https://doi.org/10.1016/j.euroneuro.2007.02.011.
11. Bessho, T., K. Takashina, J. Eguchi, T. Komatsu, and K.-I. Saito. 2008. "MKC-231, a Choline-Uptake Enhancer: (1) Long-Lasting Cognitive Improvement after Repeated Administration in AF64A-Treated Rats." Journal of Neural Transmission 115 (7): 1019–1025. https://doi.org/10.1007/s00702-008-0053-4.
12. Takashina, K., T. Bessho, R. Mori, J. Eguchi, and K.-I. Saito. 2008. "MKC-231, a Choline Uptake Enhancer: (2) Effect on Synthesis and Release of Acetylcholine in AF64A-Treated Rats." Journal of Neural Transmission 115 (7): 1027–1035. https://doi.org/10.1007/s00702-008-0048-1.
13. Takashina, K., T. Bessho, R. Mori, K. Kawai, J. Eguchi, and K.-I. Saito. 2008. "MKC-231, a Choline Uptake Enhancer: (3) Mode of Action of MKC-231 in the Enhancement of High-Affinity Choline Uptake." Journal of Neural Transmission 115 (7): 1037–1046. https://doi.org/10.1007/s00702-008-0049-0.

The racetam class, and analytical methodology for a related compound

14. Gouliaev, A. H., and A. Senning. 1994. "Piracetam and Other Structurally Related Nootropics." Brain Research Reviews 19 (2): 180–222. https://doi.org/10.1016/0165-0173(94)90011-6.
15. Malykh, A. G., and M. R. Sadaie. 2010. "Piracetam and Piracetam-Like Drugs: From Basic Science to Novel Clinical Applications to CNS Disorders." Drugs 70 (3): 287–312. https://doi.org/10.2165/11319230-000000000-00000.
16. Ovalles, J. F., J. N. A. Tettey, J. H. McB. Miller, and G. G. Skellern. 2000. "Determination of Piracetam and Its Impurities by TLC." Journal of Pharmaceutical and Biomedical Analysis 23 (4): 757–761. https://doi.org/10.1016/s0731-7085(00)00355-1. (Concerns piracetam, not coluracetam; cited as an example of a developed method for the family.)