Article · Wikipedia archive · Last revised Jul 5, 2026

1-Trichloromethyl-1,2,3,4-tetrahydro-β-carboline

1-Trichloromethyl-1,2,3,4-tetrahydro-β-carboline (1-TCMTC), also known as tryptamine–chloral (TaClo), is a mammalian alkaloid and potent dopaminergic neurotoxin of the β-carboline family. It can form spontaneously in vivo as a condensation product of endogenous tryptamine (Ta) with chloral hydrate (Clo) or trichloroethylene. The drug shows structural similarity to MPTP. As with MPTP, it acts as an inhibitor of mitochondrial complex I, but shows greater potency in comparison.

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1-Trichloromethyl-1,2,3,4-tetrahydro-β-carboline
Clinical data
Other namesTaClo; 1-Trichloromethyl-THβC; 1-TCMTC
ATC code
  • None
Identifiers
  • 1-(trichloromethyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole
CAS Number
PubChem CID
ChemSpider
CompTox Dashboard (EPA)
Chemical and physical data
FormulaC12H11Cl3N2
Molar mass289.58 g·mol−1
3D model (JSmol)
  • C1CNC(C2=C1C3=CC=CC=C3N2)C(Cl)(Cl)Cl
  • InChI=1S/C12H11Cl3N2/c13-12(14,15)11-10-8(5-6-16-11)7-3-1-2-4-9(7)17-10/h1-4,11,16-17H,5-6H2
  • Key:DPPAKKMPHBZNQA-UHFFFAOYSA-N

1-Trichloromethyl-1,2,3,4-tetrahydro-β-carboline (1-TCMTC), also known as tryptamine–chloral (TaClo), is a mammalian alkaloid and potent dopaminergic neurotoxin of the β-carboline family.1234 It can form spontaneously in vivo as a condensation product of endogenous tryptamine (Ta) with chloral hydrate (Clo) or trichloroethylene.12356748 The drug shows structural similarity to MPTP.2910 As with MPTP, it acts as an inhibitor of mitochondrial complex I, but shows greater potency in comparison.15

TaClo has been found to acutely elevate levels of serotonin and possibly dopamine in the brain in rodents, and elevated serotonin levels may be involved in its dopaminergic neurotoxicity.111 It exclusively enters serotonergic neurons via passive diffusion rather than by the serotonin transporter (SERT).112 TaClo produces long-lasting behavioral changes in rodents, such as parkinsonism, changes in locomotor activity, and altered sensitivity to dopaminergic drugs.19107 While initially characterized as a dopaminergic neurotoxin, TaClo has since been reported to be non-selective, acting as a general strong cytotoxin and without specificity for dopaminergic neurons nor for neurons generally.13

The chemical synthesis of TaClo has been described.1143 The N-methyl derivative of TaClo, N-methyl-TaClo, is a more potent dopaminergic neurotoxin than TaClo.1515 Another analogue, TaBro, is also more potent.115 Other analogues have been described as well.11216

TaClo was first described in the scientific literature in 1990.14 It was subsequently described as a neurotoxin in 1995.23 The compound may be an endogenous or environmental neurotoxin and might be involved in the development of Parkinson's disease in some people.1178

See also

See also

References

References

  1. Riederer P, Foley P, Bringmann G, Feineis D, Brückner R, Gerlach M (May 2002). "Biochemical and pharmacological characterization of 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline: a biologically relevant neurotoxin?". European Journal of Pharmacology. 442 (1–2): 1–16. doi:10.1016/s0014-2999(02)01308-0. PMID 12020676.
  2. Bringmann G, God R, Feineis D, Wesemann W, Riederer P, Rausch WD, et al. (1995). "The TaClo concept: 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo), a new toxin for dopaminergic neurons". Journal of Neural Transmission. Supplementum. 46: 235–244. PMID 8821060.
  3. Bringmann G, God R, Feineis D, Janetzky B, Reichmann H (1995). "TaClo as a neurotoxic lead: improved synthesis, stereochemical analysis, and inhibition of the mitochondrial respiratory chain". Journal of Neural Transmission. Supplementum. 46: 245–254. PMID 8821061.
  4. Bringmann G, Feineis D, God R, Peters K, Peters EM, Scholz J, et al. (July 2002). "1-Trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) and related derivatives: chemistry and biochemical effects on catecholamine biosynthesis". Bioorganic & Medicinal Chemistry. 10 (7): 2207–2214. doi:10.1016/s0968-0896(02)00060-3. PMID 11983518.
  5. Janetzky B, God R, Bringmann G, Reichmann H (1995). "1-Trichloromethyl-1,2,3,4-tetrahydro-beta-carboline, a new inhibitor of complex I". Journal of Neural Transmission. Supplementum. 46: 265–273. PMID 8821063.
  6. Bringmann G, God R, Fähr S, Feineis D, Fornadi K, Fornadi F (May 1999). "Identification of the dopaminergic neurotoxin 1-trichloromethyl-1,2, 3,4-tetrahydro-beta-carboline in human blood after intake of the hypnotic chloral hydrate". Analytical Biochemistry. 270 (1): 167–175. doi:10.1006/abio.1999.4088. PMID 10328779.
  7. Leuschner J, Beuscher N, Zimmermann T, Schürer M, Schulz HU, Jeromin J, et al. (January 1998). "Untersuchungen zu Plasmaspiegeln des Neurotoxins 1-Trichlormethyl-1,2,3,4-tetrahydro-beta-carbolin (TaClo) beim Menschen nach oraler Verabreichung von Chloralhydrat" [The plasma level of the neurotoxin 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) in man after oral administration of chloral hydrate]. Arzneimittelforschung (in German). 48 (1): 1–5. PMID 9522023.
  8. Liu M, Shin EJ, Dang DK, Jin CH, Lee PH, Jeong JH, et al. (July 2018). "Trichloroethylene and Parkinson's Disease: Risk Assessment". Molecular Neurobiology. 55 (7): 6201–6214. doi:10.1007/s12035-017-0830-x. PMID 29270919.
  9. Sontag KH, Heim C, Sontag TA, God R, Reichmann H, Wesemann W, et al. (1995). "Long-term behavioural effects of TaClo (1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline) after subchronic treatment in rats". Journal of Neural Transmission. Supplementum. 46: 283–289. PMID 8821065.
  10. Heim C, Sontag KH (1997). "The halogenated tetrahydro-beta-carboline "TaClo": a progressively-acting neurotoxin". Journal of Neural Transmission. Supplementum. Journal of Neural Transmission. Supplementa. 50: 107–111. doi:10.1007/978-3-7091-6842-4_11. ISBN 978-3-211-82898-4. PMID 9120411.
  11. Gerlach M, Xiao AY, Heim C, Lan J, God R, Feineis D, et al. (November 1998). "1-Trichloromethyl-1,2,3,4-tetrahydro-beta-carboline increases extracellular serotonin and stimulates hydroxyl radical production in rats". Neuroscience Letters. 257 (1): 17–20. doi:10.1016/s0304-3940(98)00791-5. PMID 9857955.
  12. Bringmann G, Brückner R, Mössner R, Feineis D, Heils A, Lesch KP (June 2000). "Effect of 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) on human serotonergic cells". Neurochemical Research. 25 (6): 837–843. doi:10.1023/a:1007521625088. PMID 10944002.
  13. Storch A, Hwang YI, Bringmann G, Feineis D, Ott S, Brückner R, et al. (December 2006). "Cytotoxicity of chloral-derived beta-carbolines is not specific towards neuronal nor dopaminergic cells". Journal of Neural Transmission. 113 (12): 1895–1901. doi:10.1007/s00702-006-0495-5. PMID 16868795.
  14. Bringmann G, Hille A (September 1990). "Endogenous alkaloids in man, VII: 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline--a potential chloral-derived indol alkaloid in man". Archiv der Pharmazie. 323 (9): 567–569. doi:10.1002/ardp.19903230903. PMID 2288478.
  15. Grote C, Clement HW, Wesemann W, Bringmann G, Feineis D, Riederer P, et al. (1995). "Biochemical lesions of the nigrostriatal system by TaClo (1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline) and derivatives". Journal of Neural Transmission. Supplementum. 46: 275–281. PMID 8821064.
  16. Bringmann G, Münchbach M, Feineis D, Faulhaber K, Ihmels H (May 2001). "Studies on single-strand scissions to cell-free plasmid DNA by the dopaminergic neurotoxin 'TaClo' (1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline)". Neuroscience Letters. 304 (1–2): 41–44. doi:10.1016/s0304-3940(01)01731-1. PMID 11335050.
  17. Kochen W, Kohlmüller D, De Biasi P, Ramsay R (2003). "The Endogeneous Formation of Highly Chlorinated Tetrahydro-ß-Carbolines as a Possible Causative Mechanism in Idiopathic Parkinson's Disease". The endogeneous formation of highly chlorinated tetrahydro-beta-carbolines as a possible causative mechanism in idiopathic Parkinson's disease. Advances in Experimental Medicine and Biology. Vol. 527. pp. 253–263. doi:10.1007/978-1-4615-0135-0_29. ISBN 978-1-4613-4939-6. PMID 15206739.