3,4-Dihydroxyphenylacetic acid
[CAS# 102-32-9]

Identification

• Classification: Chemical reagent >> Organic reagent >> Aromatic acid
• Name: 3,4-Dihydroxyphenylacetic acid
• Synonyms: Homoprotocatechuic acid; DOPAC
• Molecular Formula: C₈H₈O₄
• Molecular Weight: 168.15
• CAS Registry Number: 102-32-9
• EC Number: 203-024-1
• SMILES: C1=CC(=C(C=C1CC(=O)O)O)O

Properties

• Density: 1.5±0.1 g/cm³, Calc.^*
• Melting point: 127-130 ºC (Expl.)
• Index of Refraction: 1.643, Calc.^*
• Boiling Point: 418.4±30.0 ºC (760 mmHg), Calc.^*
• Flash Point: 221.0±21.1 ºC, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H315-H319-H335
• Precautionary Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319
Eye irritation	Eye Irrit.	2A	H319

Discovory and Applicatios

3,4-Dihydroxyphenylacetic acid, commonly referred to as DOPAC, is a catechol derivative and a key metabolite in the degradation pathway of dopamine. This compound features a phenylacetic acid backbone with two hydroxyl groups at the 3- and 4-positions, which confer its characteristic catechol properties. DOPAC plays a significant role in neurochemical processes and has found diverse applications in biochemical research and clinical studies.

The discovery of DOPAC is linked to early investigations into dopamine metabolism. Researchers identified it as a major product formed during the oxidative deamination of dopamine, catalyzed by monoamine oxidase (MAO). Subsequent studies revealed that DOPAC undergoes further metabolism, ultimately contributing to the excretion of homovanillic acid (HVA), a principal end-product of dopamine catabolism. This understanding has been instrumental in exploring the dynamics of neurotransmitter turnover and function.

DOPAC has been widely used as a biomarker in neuroscience and clinical research. Its presence and concentration in biological fluids, such as cerebrospinal fluid and urine, serve as indicators of dopamine metabolism. These measurements are critical for diagnosing and monitoring neurological disorders, including Parkinson’s disease, schizophrenia, and certain mood disorders. Elevated or diminished levels of DOPAC can provide insights into dopaminergic activity, enabling more precise assessments of disease progression and therapeutic efficacy.

In addition to its role as a biomarker, DOPAC has garnered interest for its antioxidant properties. As a catechol compound, it has the ability to scavenge reactive oxygen species and protect cells from oxidative stress. These characteristics make it a valuable tool in studying oxidative damage and its implications for neurodegenerative diseases. Researchers have explored its effects in in vitro and in vivo models, highlighting its potential as a neuroprotective agent.

DOPAC also serves as a precursor in the synthesis of dopamine derivatives and other biologically active compounds. Its well-defined chemical structure allows for modifications that produce a variety of functional molecules. These derivatives have applications in pharmacology, particularly in the design of drugs targeting dopaminergic systems.

Despite its benefits, DOPAC’s reactivity as a catechol poses challenges in storage and handling, requiring specific conditions to prevent oxidation. Advances in analytical techniques, such as high-performance liquid chromatography (HPLC), have enhanced the accuracy and efficiency of DOPAC quantification in biological samples, further expanding its utility in research and diagnostics.

The continued investigation of 3,4-dihydroxyphenylacetic acid underscores its significance in understanding dopamine metabolism and its broader implications for human health. Its roles as a biomarker, antioxidant, and chemical precursor ensure its ongoing relevance in both basic and applied sciences.

References

1979. Striatal DOPAC elevation predicts antipsychotic efficacy of metoclopramide. Life Sciences, 24(20).
DOI: 10.1016/0024-3205(79)90243-1

1979. Further studies on the sequence of dopamine metabolism in the rat brain. European Journal of Pharmacology, 56(4).
DOI: 10.1016/0014-2999(79)90261-9

1979. Baclofen and muscimol: Behavioural and neurochemical sequelae of unilateral intranigral administration and effects on 3H-GABA receptor binding. Naunyn-Schmiedeberg's Archives of Pharmacology, 307(1).
DOI: 10.1007/bf00507114