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5,6-Dihydroxyindole is a melanin precursor. It is one of the toxic compounds in the melanin biosynthetic pathway. 5,6-Dihydroxyindole is an indole derivative that contains two hydroxyl groups attached to the 5th and 6th positions of the indole ring. It is an intermediate in the biosynthesis of melanin, a pigment responsible for the coloration of hair, skin, and eyes in humans and other organisms.

5,6-Dihydroxyindole is the second isomer of dihydroxyindole. Pure 5,6-dihydroxyindole is soluble in hot water, insoluble in petroleum ether, and stable in the crystalline state, but oxidizes rapidly to melanin-like substances in slightly alkaline solutions.

5,6-Dihydroxyindole is an intermediate in melanogenesis, the production of melanin which is found in our skin, eyes, hair, and inner ear.

ChEBI: 5,6-dihydroxyindole is a dihydroxyindole. It has a role as a mouse metabolite.

Synthetic Communications, 15, p. 321, 1985 DOI: 10.1080/00397918508063806

General procedure for the synthesis of 5,6-dihydroxyindole from the compound (CAS: 89762-39-0): sodium chloride was added to the melanin precursor solution (mainly composed of dopachrome) obtained in step 5, adjusting the final concentration to 2.5%. The reaction mixture was allowed to stand at room temperature for 45 min, which significantly accelerated the conversion of dopa pigment to 5,6-dihydroxyindole as compared to the precursor solution without the addition of sodium chloride. If sodium ascorbate solution was added to the reaction system instead of sodium chloride, the yield of 5,6-dihydroxyindole was significantly increased (up to 90% of 5,6-dihydroxyindole in the melanin precursor solution).

Human Endogenous Metabolite

[1] Patent: EP1820491, 2007, A1. Location in patent: Page/Page column 12
[2] Patent: EP1820491, 2007, A1. Location in patent: Page/Page column 12