Tropolone is a tropone analogue with a hydroxyl group at the 2-position, and is the precursor of many Azulene analogues, like 2-methylazulene-1-carboxylate. Tropolone is a potent inhibitor of mushroom tyrosinase with IC50 of 0.4 μM. Its inhibitory activity can be reversed by dialysis or excess CU2+.

Physicochemical Properties

Molecular Formula	C7H6O2
Molecular Weight	122.12
Exact Mass	122.036
CAS #	533-75-5
PubChem CID	10789
Appearance	Light yellow to brown solid powder
Density	1.3±0.1 g/cm3
Boiling Point	290.1±33.0 °C at 760 mmHg
Melting Point	50-52 °C(lit.)
Flash Point	122.0±18.0 °C
Vapour Pressure	0.0±1.4 mmHg at 25°C
Index of Refraction	1.603
LogP	0.42
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	2
Rotatable Bond Count	0
Heavy Atom Count	9
Complexity	209
Defined Atom Stereocenter Count	0
InChi Key	MDYOLVRUBBJPFM-UHFFFAOYSA-N
InChi Code	InChI=1S/C7H6O2/c8-6-4-2-1-3-5-7(6)9/h1-5H,(H,8,9)
Chemical Name	2-hydroxycyclohepta-2,4,6-trien-1-one
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
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

References

[1]. In vitro evaluation of tropolone absorption, metabolism, and clearance. Antiviral Res. 2023 Dec;220:105762. [2]. Investigation of the activity of a novel tropolone in osteosarcoma. Drug Dev Res. 2024 Feb;85(1):e22129. [3]. Synthesis of bicyclo[5.3.0]azulene derivatives. Nat Protoc. 2009; 4(8): 1113–1117. [4]. Inhibition of mushroom tyrosinase by tropolone Phytochemistry. Volume 24, Issue 5, 1985, Pages 905-908.

Additional Infomation

Tropolone is a cyclic ketone that is cyclohepta-2,4,6-trien-1-one substituted by a hydroxy group at position 2. It is a toxin produced by the agricultural pathogen Burkholderia plantarii. It has a role as a bacterial metabolite, a toxin and a fungicide. It is a cyclic ketone, an enol and an alpha-hydroxy ketone. It derives from a hydride of a cyclohepta-1,3,5-triene. A seven-membered aromatic ring compound. It is structurally related to a number of naturally occurring antifungal compounds (ANTIFUNGAL AGENTS).

Solubility Data

Solubility (In Vitro)

DMSO : ≥ 100 mg/mL (~818.87 mM) H2O : ~25 mg/mL (~204.72 mM)

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.5 mg/mL (20.47 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 25.0 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: ≥ 2.5 mg/mL (20.47 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 25.0 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: ≥ 2.5 mg/mL (20.47 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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. Solubility in Formulation 4: 20 mg/mL (163.77 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	8.1887 mL	40.9433 mL	81.8867 mL
	5 mM	1.6377 mL	8.1887 mL	16.3773 mL
	10 mM	0.8189 mL	4.0943 mL	8.1887 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.