5,6-Dihydroxyindole is a melanin precursor with broad spectrum (a wide range) antibacterial, antifungal, antiviral, and antiparasitic activities. 5,6-Dihydroxyindole has cytotoxicities and is highly toxic to a variety of pathogens.

Physicochemical Properties

Molecular Formula	C₈H₇NO₂
Molecular Weight	149.15
Exact Mass	149.047
CAS #	3131-52-0
Related CAS #	25656-67-1
PubChem CID	114683
Appearance	Off-white to light brown solid powder
Density	1.5±0.1 g/cm3
Boiling Point	411.2±25.0 °C at 760 mmHg
Flash Point	202.5±23.2 °C
Vapour Pressure	0.0±1.0 mmHg at 25°C
Index of Refraction	1.802
LogP	0.37
Hydrogen Bond Donor Count	3
Hydrogen Bond Acceptor Count	2
Rotatable Bond Count	0
Heavy Atom Count	11
Complexity	151
Defined Atom Stereocenter Count	0
InChi Key	SGNZYJXNUURYCH-UHFFFAOYSA-N
InChi Code	InChI=1S/C8H7NO2/c10-7-3-5-1-2-9-6(5)4-8(7)11/h1-4,9-11H
Chemical Name	1H-indole-5,6-diol
Synonyms	5,6Dihydroxyindole; 5,6 Dihydroxyindole
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: (1). This product requires protection from light (avoid light exposure) during transportation and storage.(2). Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	5,6-Dihydroxyindole (1, 10, 20, 50, 100 μM; for 4 hours) decreased OD492 readings in a dose-dependent manner. For four hours, 1.0 mM 5,6-dihydroxyindole was used as a pretreatment on Sf9 cells. 97% of the population died. The LC50 values in the culture medium were 131.8 μM and 20.3 μM, respectively, in the buffer [1]. The baculovirus stock produced nearly no recombinant protein after three hours of preincubation with 1.25 mM 5,6-dihydroxyindole. Eggs of the wasp Microplitis demolitor and the lambda phage have LC50 values of 111.0 μM and 5.6 μM, respectively [1]. Additionally effective against viruses and parasitic wasps are 5,6-dihydroxyindole and its spontaneous oxidation products [1].
ADME/Pharmacokinetics	Metabolism / Metabolites Dihyroxy-1H-indole has known human metabolites that include Dihyroxy-1H-indole glucuronide I.
References	[1]. Antiviral, anti-parasitic, and cytotoxic effects of 5,6-dihydroxyindole (DHI), a reactive compound generated by phenoloxidase during insect immune response. Insect Biochem Mol Biol. 2011 Sep;41(9):645-52. [2]. Melanin precursor 5,6-dihydroxyindol: protective effects and cytotoxicity on retinal cells in vitroand in vivo. Toxicol Pathol. 2007 Dec;35(7):1030-8.
Additional Infomation	5,6-dihydroxyindole is a dihydroxyindole. It has a role as a mouse metabolite. 5,6-Dihydroxyindole has been reported in Homo sapiens and Trypanosoma brucei with data available.

Solubility Data

Solubility (In Vitro)

DMSO : ~50 mg/mL (~335.23 mM) H2O : < 0.1 mg/mL

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 1.25 mg/mL (8.38 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 1.25 mg/mL (8.38 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 3: ≥ 1.25 mg/mL (8.38 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 12.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	6.7047 mL	33.5233 mL	67.0466 mL
	5 mM	1.3409 mL	6.7047 mL	13.4093 mL
	10 mM	0.6705 mL	3.3523 mL	6.7047 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.