Pyrocatechuic acid is a metabolite of benzoic acid present in plasma and its levels are increased when aspirin is ingested.

Physicochemical Properties

Molecular Formula	C7H6O4
Molecular Weight	154.12014
Exact Mass	154.026
CAS #	303-38-8
Related CAS #	875-28-5 (hydrochloride salt)
PubChem CID	19
Appearance	Off-white to light brown solid powder
Density	1.6±0.1 g/cm3
Boiling Point	362.5±32.0 °C at 760 mmHg
Melting Point	204-206 °C(lit.)
Flash Point	187.2±21.6 °C
Vapour Pressure	0.0±0.9 mmHg at 25°C
Index of Refraction	1.671
LogP	1.8
Hydrogen Bond Donor Count	3
Hydrogen Bond Acceptor Count	4
Rotatable Bond Count	1
Heavy Atom Count	11
Complexity	157
Defined Atom Stereocenter Count	0
InChi Key	GLDQAMYCGOIJDV-UHFFFAOYSA-N
InChi Code	InChI=1S/C7H6O4/c8-5-3-1-2-4(6(5)9)7(10)11/h1-3,8-9H,(H,10,11)
Chemical Name	2,3-dihydroxybenzoic acid
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

ln Vitro	Aspirin consumption raises the levels of pyrocatechuic acid (2,3-dihydroxybenzoic acid), a typical human benzoic acid metabolite that is present in plasma [1].
Enzyme Assay	For detection of Pyrocatechuic acid in human urine and plasma: Collect urine and plasma samples from subjects after oral aspirin administration; acidify samples with dilute acid to stabilize Pyrocatechuic acid; extract the compound using organic solvent; separate the extract via high-performance liquid chromatography (HPLC) with a reverse-phase column; detect and quantify Pyrocatechuic acid via ultraviolet (UV) detection at a wavelength of 290 nm; confirm the identity of the compound by comparing retention time with a standard reference[1]
ADME/Pharmacokinetics	Pyrocatechuic acid (also known as 2,3-dihydroxybenzoic acid) is an endogenous metabolite of aspirin in humans; it is formed by the oxidative metabolism of aspirin's primary metabolite, salicylic acid[1] Pyrocatechuic acid is primarily excreted in human urine; after oral administration of aspirin, it accounts for approximately 1-3% of the total urinary metabolites of aspirin[1] The formation of Pyrocatechuic acid involves hydroxylative metabolism of salicylic acid in the liver, with no significant accumulation in systemic circulation[1]
References	[1]. 2,3-Dihydroxybenzoic acid is a product of human aspirin metabolism. Biochem Pharmacol. 1988 Jan 15;37(2):271-80.
Additional Infomation	2,3-dihydroxybenzoic acid is a dihydroxybenzoic acid that is benzoic acid substituted by hydroxy groups at positions 2 and 3. It occurs naturally in Phyllanthus acidus and in the aquatic fern Salvinia molesta. It has a role as a human xenobiotic metabolite and a plant metabolite. It is functionally related to a benzoic acid. It is a conjugate acid of a 2,3-dihydroxybenzoate. 2-Pyrocatechuic acid is a metabolite found in or produced by Escherichia coli (strain K12, MG1655). 2,3-Dihydroxybenzoic acid is a metabolite found in or produced by Escherichia coli (strain K12, MG1655). 2,3-Dihydroxybenzoic acid has been reported in Grosmannia huntii, Streptomyces, and other organisms with data available. See also: 2,3-Dihydroxybenzoate (annotation moved to). Pyrocatechuic acid is the chemical synonym of 2,3-dihydroxybenzoic acid, a monohydroxybenzoic acid derivative[1] It is a minor but significant metabolite of aspirin, distinguishing itself from other major metabolites (e.g., salicyluric acid, glucuronide conjugates) by its dihydroxy substitution pattern[1] The metabolic pathway leading to Pyrocatechuic acid reflects the oxidative biotransformation capacity of the human liver for aromatic compounds[1]

Solubility Data

Solubility (In Vitro)

DMSO : ~100 mg/mL (~648.85 mM) H2O : < 0.1 mg/mL

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.5 mg/mL (16.22 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 (16.22 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.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	6.4885 mL	32.4423 mL	64.8845 mL
	5 mM	1.2977 mL	6.4885 mL	12.9769 mL
	10 mM	0.6488 mL	3.2442 mL	6.4885 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.