Tryptophol

Natural occurrences

Tryptophol can be found in Pinus sylvestris needles or seeds. It is produced by the trypanosomal parasite (Trypanosoma brucei) in sleeping sickness (African trypanosomiasis). Tryptophol is found in wine and beer as a secondary product of ethanol fermentation (a product also known as congener) by Saccharomyces cerevisiae. It is also an autoantibiotic produced by the fungus Candida albicans. It can also be isolated from the marine sponge Ircinia spiculosa.

Metabolism

Biosynthesis

It was first described by Felix Ehrlich in 1912. Ehrlich demonstrated that yeast attacks the natural amino acids essentially by splitting off carbon dioxide and replacing the amino group with hydroxyl. By this reaction, tryptophan gives rise to tryptophol. Tryptophan is first deaminated to 3-indolepyruvate. It is then decarboxylated to indole acetaldehyde by indolepyruvate decarboxylase. This latter compound is transformed to tryptophol by alcohol dehydrogenase.

It is formed from tryptophan, along with indole-3-acetic acid in rats infected by Trypanosoma brucei gambiense.

An efficient conversion of tryptophan to indole-3-acetic acid and/or tryptophol can be achieved by some species of fungi in the genus Rhizoctonia.

Biodegradation

In Cucumis sativus (cucumber), the enzymes indole-3-acetaldehyde reductase (NADH) and indole-3-acetaldehyde reductase (NADPH) use tryptophol to form (indol-3-yl)acetaldehyde.

Glycosides

The unicellular alga Euglena gracilis converts exogenous tryptophol to two major metabolites: tryptophol galactoside and an unknown compound (a tryptophol ester), and to minor amounts of indole-3-acetic acid, tryptophol acetate, and tryptophol glucoside.

Biological effects

Tryptophol and its derivatives 5-hydroxytryptophol and 5-methoxytryptophol, induce sleep in mice. It induces a sleep-like state that lasts less than an hour at the 250 mg/kg dose. It may be a functional analog of serotonin or melatonin, compounds involved in sleep regulation.

Tryptophol shows genotoxicity in vitro.

Tryptophol is a quorum sensing molecule for the yeast Saccharomyces cerevisiae. It is also found in the bloodstream of patients with chronic trypanosomiasis. For that reason, it may be a quorum sensing molecule for the trypanosome parasite.

In the case of trypanosome infection, tryptophol decreases the immune response of the host.

As it is formed in the liver after ethanol ingestion or disulfiram treatment, it is also associated with the study of alcoholism. Pyrazole and ethanol have been shown to inhibit the conversion of exogenous tryptophol to indole-3-acetic acid and to potentiate the sleep-inducing hypothermic effects of tryptophol in mice.

It is a growth promoter of cucumber hypocotyl segments. The auxinic action in terms of embryo formation is even better for tryptophol arabinoside on Cucurbita pepo hypocotyl fragments.

References

References

1. GHS: [https://www.sigmaaldrich.com/GB/en/product/aldrich/t90301 Sigma-Aldrich 115460 ]
2. (1979). "Rapid distribution of tryptophol (3-indole ethanol) to the brain and other tissues". Journal of Clinical Investigation.
3. (1984). "Biosynthesis and metabolism of indole-3-ethanol and indole-3-acetic acid by Pinus sylvestris L. Needles". Planta.
4. (1987). "Dynamics of indole-3-acetic acid and indole-3-ethanol during development and germination of Pinus sylvestris seeds". Physiologia Plantarum.
5. (1978). "The biological effects of tryptophol (indole-3-ethanol): Hemolytic, biochemical and behavior modifying activity". Comparative Biochemistry and Physiology C.
6. (1986). "Tryptophol content of young wines made from Tempranillo, Garnacha, Viura and Airén grapes". Food Chemistry.
7. (1965). "On the presence in wine of tyrosol, tryptophol, phenylethyl alcohol and gamma-butyrolactone, secondary products of alcoholic fermentation". Comptes Rendus de l'Académie des Sciences, Série D.
8. (1969). "Phenethyl alcohol and tryptophol: Autoantibiotics produced by the fungus Candida albicans". Science.
9. (2000). "Tryptophol, a plant auxin isolated from the marine sponge Ircinia spinulosa". Biochemical Systematics and Ecology.
10. Richard W. Jackson (1930). "A synthesis of tryptophol". Journal of Biological Chemistry.
11. (2003). "The catabolism of amino acids to long chain and complex alcohols in Saccharomyces cerevisiae". The Journal of Biological Chemistry.
12. [http://biocyc.org/YEAST/NEW-IMAGE?type=PATHWAY&object=PWY-5081 Pathway: tryptophan degradation VIII (to tryptophol) at BioCyc.org]
13. (1975). "Short-Term Metabolism of \14C]Tryptophan in Rats Infected with Trypanosoma brucei gambiense". Journal of Infectious Diseases.
14. Toshiko Furukawa, Jinichiro Koga, Takashi Adachi, Kunihei Kishi and Kunihiko Syono. (1996). "Efficient Conversion of L-Tryptophan to Indole-3-Acetic Acid and/or Tryptophol by Some Species of Rhizoctonia". Plant Cell Physiol..
15. (1976). "Isolation and characterization of indole-3-acetaldehyde reductases from ''Cucumis sativus''". J. Biol. Chem..
16. (1984). "Formation of Tryptophol Galactoside and an Unknown Tryptophol Ester in Euglena gracilis". Plant Physiology.
17. (1970). "Tryptophol, 5-hydroxytryptophol and 5-methoxytryptophol induced sleep in mice". Life Sciences.
18. (2011). "Assessment of Tryptophol Genotoxicity in Four Cell Lines in Vitro: A Pilot Study with Alkaline Comet Assay". Archives of Industrial Hygiene and Toxicology.
19. (2010). "Transcriptional control of the quorum sensing response in yeast". Molecular BioSystems.
20. (1976). "The effects of tryptophol on immune responses and its implications toward trypanosome-induced immunosuppression". Experientia.
21. (1977). "Tryptophol levels in mice injected with pharmacological doses of tryptophol, and the effect of pyrazole and ethanol on these levels". Life Sciences.
22. (1967). "Isolation and Identification of Indole-3-Ethanol (Tryptophol) from Cucumber Seedlings". Plant Physiology.
23. (1985). "Induction of embryogenic callus in Cucurbita pepo hypocotyl explants by indole-3-ethanol and its sugar conjugates". Physiologia Plantarum.