Gentisic Acid (Hydroxybenzoic Acid · Anti-inflammatory · Uricosuric)

Compound	Gentisic Acid
Chemical class	Polyphenol — Hydroxybenzoic Acid (2,5-Dihydroxybenzoic Acid)
CAS	490-79-9
Primary source	Salix spp. (willow bark), Gentiana spp. (gentian root), Olea europaea (olive)
Key applications	Anti-inflammatory, antioxidant, analgesic support
Claim strength	Moderate
Typical form	White willow bark extract co-constituent; gentisic acid isolate
Buy from Herbuno	White Willow (Salix Alba) Extract Powder → White Willow Bark Liquid Extract (Water Soluble) - Salix alba →

Name origin: From Gentiana (gentian genus), where it was first isolated. The 2,5-dihydroxybenzoic acid structure places the two hydroxyl groups at ortho and para positions relative to the carboxyl group — a different substitution pattern from PCA (3,4-dihydroxy). Traditional use: Willow bark (Salix alba) has been used since ancient times for fever, pain, and inflammation — the original source of salicylic acid from which aspirin was derived. Gentisic acid is a secondary metabolite in willow bark (alongside salicin, salicortin, and salicylic acid) that contributes to its anti-inflammatory profile. Research trajectory: Gentisic acid has a more limited research base than other hydroxybenzoic acids, but documented anti-inflammatory, antioxidant, and uricosuric (uric acid-lowering) activities make it relevant to gout and arthritis formulations. It is also an in vivo metabolite of aspirin (salicylate). Commercial source: Commercially available as a co-constituent of white willow bark extract. See sourcing options below.

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Evidence for Gentisic Acid Applications

Anti-inflammatory: Gentisic acid inhibits prostaglandin synthesis and NF-κB in cell-based models. In vivo anti-inflammatory activity in rodent carrageenan paw oedema models is documented at 10–50 mg/kg oral doses. Mechanism partially overlaps with salicylates (COX modulation) but is distinct from aspirin’s irreversible acetylation mechanism. Claim strength: Moderate.

Uricosuric activity: Gentisic acid promotes uric acid excretion in animal models, relevant to gout and hyperuricaemia management. This mechanism parallels that of probenecid (a uricosuric drug) but at far lower potency. Relevant as a supporting co-active in gout management botanical formulations alongside tart cherry and celery seed extracts. Claim strength: Moderate (preclinical; no human trials for isolated gentisic acid).

Antioxidant: The 2,5-dihydroxy substitution pattern confers radical-scavenging activity, though somewhat lower than the catechol (3,4-dihydroxy) pattern of PCA due to the non-adjacent hydroxyl arrangement. Metal chelation is documented. Contributes to the antioxidant profile of willow bark preparations. Claim strength: Moderate.

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Dosage & Formulator Specification

No established isolated human supplement dose for gentisic acid. White willow bark extract for anti-inflammatory and analgesic applications: 120–240 mg/day standardised to 15% total salicin, which co-delivers gentisic acid as a minor phenolic constituent. For gout support formulations, willow bark extract at the above dose provides gentisic acid alongside salicin for complementary uricosuric and anti-inflammatory activity.

Gentisic acid is water-soluble and well-absorbed orally. It is also produced endogenously as a minor aspirin metabolite (salicylate → gentisic acid via cytochrome P450 hydroxylation). This endogenous production route means individuals taking aspirin already have some systemic gentisic acid exposure. Isolated gentisic acid is available as a research-grade material (≥98% HPLC) from specialist suppliers.

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Frequently Asked Questions — Gentisic Acid

Is gentisic acid related to aspirin?
Yes — gentisic acid is a metabolite of salicylate (the core aspirin pharmacophore) formed by cytochrome P450-mediated hydroxylation in vivo. After aspirin ingestion, a small fraction is converted to gentisic acid. Additionally, white willow bark — the botanical origin of salicin (aspirin’s precursor) — contains gentisic acid as a natural constituent alongside salicin. The relationship is metabolic and botanical but not structural; aspirin (acetylsalicylic acid) and gentisic acid are chemically distinct.

What distinguishes white willow bark from aspirin pharmacologically?
White willow bark extract provides a complex phytochemical matrix including salicin (prodrug to salicylic acid), polyphenols (gentisic acid, catechins, flavonoids), and other phenolics that provide anti-inflammatory mechanisms beyond COX inhibition alone. Clinical trials show willow bark extract is effective for lower back pain and osteoarthritis but with slower onset than aspirin (due to the prodrug conversion step for salicin). The polyphenol fraction — including gentisic acid — is considered to contribute synergistically to the overall anti-inflammatory effect.

Can gentisic acid-containing willow bark extract be used in gout formulations?
Yes. White willow extract combines uricosuric activity (gentisic acid) with anti-inflammatory activity (salicin/salicylate + polyphenols), providing dual-mechanism relevance for gout management support. Co-formulation with tart cherry extract (anti-inflammatory + uric acid reduction) and celery seed extract provides complementary multi-mechanism gout support positioning.

Is there a salicylate allergy concern with willow bark/gentisic acid?
Individuals with aspirin or salicylate hypersensitivity should avoid white willow bark preparations. Gentisic acid itself is structurally distinct from acetylsalicylic acid, but cross-reactivity is possible in salicylate-sensitive individuals. Standard advisory language for aspirin/NSAID-sensitive populations is appropriate for willow bark-containing products.

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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