5,6-Dihydroxyindole

5,6-Dihydroxyindole is a chemical compound with the molecular formula C₈H₇NO₂. It is an intermediate in the production of the biological pigment eumelanin.^[2] 5,6-Dihydroxyindole is biosynthesized from L-dopachrome in a reaction catalyzed by a tyrosinase enzyme and is further converted into indole-5,6-quinone.^[3] In humans, 5,6-dihydroxyindole is involved in the metabolic disorder hawkinsinuria.^[3]

5,6-Dihydroxyindole

Names
IUPAC name 1H-Indole-5,6-diol
Other names Dopamine lutine Aminochrome DHI
Identifiers
CAS Number	3131-52-0 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:27404
ChEMBL	ChEMBL92636
ChemSpider	102690
DrugBank	DB01811
ECHA InfoCard	100.101.149
EC Number	412-130-9
KEGG	C05578
PubChem CID	114683
UNII	Z3OC8499KG
CompTox Dashboard (EPA)	DTXSID20185242
InChI InChI=1S/C8H7NO2/c10-7-3-5-1-2-9-6(5)4-8(7)11/h1-4,9-11H Key: SGNZYJXNUURYCH-UHFFFAOYSA-N
SMILES C1=CNC2=CC(=C(C=C21)O)O
Properties
Chemical formula	C8H7NO2
Molar mass	149.149 g·mol−1
Hazards
GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H302, H318, H411
Precautionary statements	P264, P264+P265, P270, P273, P280, P301+P317, P305+P354+P338, P317, P330, P391, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

In some insects, 5,6-dihydroxyindole is a reactive compound that is produced as a component of defense responses and has antibacterial and antifungal activity.^[4]

A laboratory synthesis of 5,6-dihydroxyindole can be accomplished starting from 3,4-dibenzyloxybenzaldehyde.^[5] This compound is condensed with nitromethane in a Henry reaction, followed by nitration, reduction of the nitro groups, and hydrogenolysis of the benzyl protecting groups.

References

1. "5,6-Dihydroxyindole". pubchem.ncbi.nlm.nih.gov.
2. d'Ischia, Marco; Napolitano, Alessandra; Pezzella, Alessandro (2011). "5,6-Dihydroxyindole Chemistry: Unexplored Opportunities Beyond Eumelanin". European Journal of Organic Chemistry. 2011 (28): 5501–5516. doi:10.1002/ejoc.201100796.
3. "5,6-Dihydroxyindole". Human Metabolome Database.
4. Zhao, Picheng; Lu, Zhiqiang; Strand, Michael R.; Jiang, Haobo (2011). "Antiviral, anti-parasitic, and cytotoxic effects of 5,6-dihydroxyindole (DHI), a reactive compound generated by phenoloxidase during insect immune response". Insect Biochemistry and Molecular Biology. 41 (9): 645–652. doi:10.1016/j.ibmb.2011.04.006. PMC 3129360. PMID 21554953.
5. Crane, Stuart W.; Ghafur, Omair; Cowie, Thomas Y.; Lindsay, Anita G.; Thompson, James O. F.; Greenwood, Jason B.; Bebbington, Magnus W. P.; Townsend, Dave (2019). "Dynamics of electronically excited states in the eumelanin building block 5,6-dihydroxyindole" (PDF). Physical Chemistry Chemical Physics. 21 (15): 8152–8160. Bibcode:2019PCCP...21.8152C. doi:10.1039/C9CP00620F. PMID 30933211. S2CID 89621632.