Probucol: Antioxidant Lipid-Lowering Agent for Research

Probucol is a bisphenol-derived small molecule widely used in biomedical research for its dual capacity to lower plasma cholesterol and potently inhibit the oxidative modification of low-density lipoprotein (LDL).

CAS Number

23288-49-5

Molecular Formula

C₃₁H₄₈O₂S₂

Molecular Weight

516.84 g/mol

Primary Mechanism

Antioxidant inhibition of LDL oxidation and plasma cholesterol reduction

Solubility

Soluble in DMSO and ethanol; poorly soluble in water

Storage Condition

Store at –20 °C, protected from light and moisture

Aladdin SKU

P129365

Background and Mechanism of Action

Probucol (CAS 23288-49-5) is a lipophilic bisphenol compound originally developed as a cholesterol-lowering drug and subsequently recognized as a powerful chain-breaking antioxidant. Its sulfide-linked di-tert-butylphenol scaffold enables it to scavenge free radicals and interrupt lipid peroxidation chain reactions, making it one of the most studied small molecules in oxidative stress and cardiovascular research.

The compound exerts its lipid-lowering effect primarily by accelerating LDL catabolism through pathways that are partially independent of LDL receptor upregulation. Importantly, probucol also reduces plasma HDL cholesterol levels, a property that has been leveraged in research models to dissect HDL function independently of cholesterol efflux capacity.

As an antioxidant, probucol directly intercepts reactive oxygen species (ROS) and inhibits the oxidative modification of LDL particles. Oxidized LDL (oxLDL) is a key driver of foam cell formation and atherosclerotic plaque development; by suppressing oxLDL generation, probucol has become a standard pharmacological tool in atherosclerosis research. The molecule also activates antioxidant response pathways and may modulate inflammatory signaling, although these secondary mechanisms are still under active investigation.

Physicochemical Properties and Handling

Probucol is a white to off-white crystalline powder with a molecular weight of 516.84 g/mol and molecular formula C₃₁H₄₈O₂S₂. Its high lipophilicity (log P > 7) renders it practically insoluble in aqueous buffers, requiring organic co-solvents for stock preparation.

Recommended solvents: Probucol dissolves readily in dimethyl sulfoxide (DMSO) and absolute ethanol at concentrations typically up to 10–20 mM. When diluting into aqueous cell culture media or physiological buffers, prepare a concentrated stock in DMSO and add dropwise to pre-warmed media with vigorous mixing to minimize precipitation; final DMSO concentration should not exceed 0.1% (v/v) for most cell-based assays.

Storage: Store the neat compound at –20 °C in a tightly sealed, desiccated container protected from light. Prepared stock solutions in DMSO are stable for up to 6 months when stored at –20 °C and protected from repeated freeze-thaw cycles; aliquot before storage.

Safety: Handle according to standard laboratory safety practices. Consult the Safety Data Sheet (SDS) for complete hazard information. Avoid inhalation of dust and contact with skin or eyes.

Research Applications

Probucol is employed across a broad spectrum of research areas, primarily centered on cardiovascular biology, lipid metabolism, and oxidative stress:

• Atherosclerosis models: Probucol is administered to apoE-knockout or LDL receptor-knockout mice fed high-fat diets to assess the contribution of LDL oxidation to plaque formation. It is one of the benchmark compounds for validating antioxidant interventions in vascular biology.
• Oxidative stress assays: At low micromolar concentrations, probucol is used in cell-based assays to suppress ROS accumulation induced by hydrogen peroxide, menadione, or oxidized lipids. It serves as a positive control for antioxidant capacity experiments.
• HDL metabolism studies: Because probucol substantially lowers HDL cholesterol without affecting reverse cholesterol transport equally, researchers use it to create animal models with selectively reduced HDL to probe HDL function.
• Neuroprotection research: Emerging studies have explored probucol's capacity to attenuate oxidative neuronal damage in models of Parkinson's disease and amyloid-beta toxicity, where ROS play a central pathogenic role.
• Diabetes and metabolic syndrome: Probucol has been investigated for its ability to reduce oxidative stress in pancreatic beta cells and improve insulin sensitivity in rodent models of metabolic syndrome.

Researchers should include appropriate vehicle controls (DMSO or ethanol at matched concentrations) and validate compound activity in each experimental system before use.

Experimental Protocols and Dosing Guidance

The following guidance reflects commonly reported practices in the literature; researchers should optimize conditions for their specific experimental systems.

In vitro (cell-based assays): Typical working concentrations range from 1 µM to 100 µM depending on the cell type and endpoint. For ROS inhibition assays, concentrations of 10–50 µM are frequently reported. Pre-treat cells with probucol for 1–2 hours before oxidative challenge. Solubilize in DMSO (stock: 10–20 mM) and dilute to final concentration in complete medium; final DMSO ≤ 0.1% (v/v).

In vivo (rodent models): Probucol is commonly incorporated into a high-fat or atherogenic diet at concentrations of 0.5–1% (w/w) for chronic atherosclerosis studies, or administered by oral gavage. Due to its high lipophilicity, dietary administration in fat-containing feed is generally preferred for consistent bioavailability. Exact dosing should be determined based on the animal model and study objectives; consult published protocols for apoE-KO or LDLR-KO mouse models.

Preparation tips: Always prepare fresh working solutions from –20 °C aliquots. Warm DMSO stock to room temperature before opening to prevent moisture condensation. Filter-sterilize aqueous dilutions (0.2 µm) for cell culture use. Verify dissolution visually; do not use if precipitate is observed in the working solution.

Regulatory Status and Research Context

Probucol was approved as a pharmaceutical agent in several countries for the treatment of hypercholesterolemia but was withdrawn from clinical use in the United States and some other markets due to concerns about QT interval prolongation at therapeutic doses. It remains commercially available and widely used as a research reagent and pharmacological tool compound.

Its established safety profile at sub-therapeutic concentrations, combined with well-characterized mechanisms of action, makes probucol valuable as a benchmark antioxidant in mechanistic studies. Researchers should note that all Aladdin Scientific reagents, including P129365, are supplied for research use only and are not intended for human or veterinary therapeutic use, clinical diagnostics, or food applications.

When publishing results obtained with probucol, authors are encouraged to report the source, purity, lot number, solvent vehicle, and exact concentrations used to ensure reproducibility across laboratories.

Frequently asked questions

What solvents are recommended for dissolving probucol for cell culture experiments?

Probucol is best dissolved in DMSO or absolute ethanol to prepare concentrated stock solutions (typically 10–20 mM). For cell culture, dilute the DMSO stock into pre-warmed complete medium immediately before use, keeping the final DMSO concentration at or below 0.1% (v/v) to avoid cytotoxic effects. Probucol is not directly soluble in aqueous buffers due to its high lipophilicity.

What concentration range of probucol is typically used in in vitro oxidative stress studies?

In cell-based oxidative stress assays, probucol is most commonly used at concentrations between 10 µM and 50 µM, though the optimal concentration depends on cell type, the oxidative stimulus used, and the assay endpoint. Researchers should perform a dose-response experiment to determine the minimum effective concentration for their specific system, as excessive concentrations may introduce cytotoxicity independent of antioxidant effects.

How should probucol stock solutions be stored to maintain stability?

Probucol stock solutions prepared in DMSO should be stored in single-use aliquots at –20 °C, protected from light and moisture. Avoid repeated freeze-thaw cycles, which can degrade compound integrity. Under these conditions, DMSO stocks are generally stable for up to 6 months. The neat powder should also be stored at –20 °C in a sealed, desiccated container away from light.

Is probucol suitable for use as a positive control in antioxidant assays?

Yes, probucol is widely used as a positive control in antioxidant assays due to its well-characterized, potent free radical-scavenging and LDL oxidation-inhibiting activity. Its defined mechanism and extensive literature precedent make it suitable for benchmarking novel antioxidant compounds or pathway interventions in both cell-based and cell-free systems.

Can probucol be used in animal diet studies, and if so, how is it typically administered?

Yes, probucol is routinely incorporated into high-fat atherogenic diets at concentrations of 0.5–1% (w/w) for chronic rodent studies, particularly in apoE-knockout and LDL receptor-knockout mouse models of atherosclerosis. Dietary administration in fat-containing feed is preferred over aqueous gavage due to probucol's high lipophilicity, which improves oral bioavailability when co-administered with dietary fats.

References

1. Parthasarathy S, Young SG, Witztum JL, Pittman RC, Steinberg D. Probucol inhibits oxidative modification of low density lipoprotein. J Clin Invest. 1986;77(2):641–644.
2. Steinberg D, Parthasarathy S, Carew TE, Khoo JC, Witztum JL. Beyond cholesterol: modifications of low-density lipoprotein that increase its atherogenicity. N Engl J Med. 1989;320(14):915–924.
3. Tardif JC, Grégoire J, Schwartz L, et al. Effects of AGI-1067 and probucol after percutaneous coronary interventions. Circulation. 2003;107(4):552–558.
4. Yamashita S, Matsuzawa Y. Re-evaluation of cholesterol-lowering therapy due to adverse effects: lessons from clinical trials of probucol. J Atheroscler Thromb. 2009;16(5):532–543.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.