Gallic Acid (Hydroxybenzoic Acid · Antioxidant · Antimicrobial)
| Compound | Gallic Acid |
| Chemical class | Polyphenol — Hydroxybenzoic Acid (3,4,5-Trihydroxybenzoic Acid) |
| CAS | 149-91-7 |
| Primary source | Terminalia chebula (haritaki), Punica granatum (pomegranate), Quercus infectoria (oak galls), Uncaria gambir |
| Key applications | Antioxidant, antimicrobial, antiviral, anti-inflammatory |
| Claim strength | Moderate |
| Typical form | Tannin-standardised extract; gallic acid isolate; hydrolysable tannin hydrolysis product |
| Buy from Herbuno | Contact Herbuno for sourcing enquiries → |
Name origin: From Latin galla (oak gall) — reflecting its early isolation from oak gall tannins, where it occurs as the monomeric phenolic acid component of hydrolysable tannins (gallotannins). Gallic acid is the structural unit of gallotannins (multiple gallic acid units esterified to glucose) and ellagitannins (gallic acid dimers esterified to glucose). Traditional use: Oak gall preparations have been used since antiquity for wound healing, antidiarrhoeal, and astringent applications. Haritaki (Terminalia chebula), one of the three fruits in Triphala, is used extensively in Ayurveda as a digestive, hepatoprotective, and general tonic herb — with gallic acid as a key bioactive constituent. Research trajectory: Gallic acid has a well-characterised preclinical evidence base for antioxidant, antimicrobial (including anti-MRSA), antiviral, anti-inflammatory, and antiproliferative mechanisms. Clinical evidence for isolated gallic acid is limited; most human data derive from tannin-rich botanical preparations. Commercial source: Available as a hydrolysis product of tannin-rich botanical extracts and as an isolated phenolic acid. See sourcing options below.
Evidence for Gallic Acid Applications
Antioxidant capacity: Gallic acid’s trihydroxybenzoic acid structure confers exceptionally high radical-scavenging and metal-chelating activity — among the highest of simple phenolic acids. It activates Nrf2/HO-1 antioxidant pathway and reduces lipid peroxidation in cell and animal models. Human plasma antioxidant capacity increases with haritaki and pomegranate extract supplementation, partly attributable to gallic acid. Claim strength: Moderate.
Antimicrobial and anti-MRSA: Gallic acid demonstrates inhibitory activity against MRSA, E. coli, Candida albicans, and multiple food-borne pathogens at MIC values of 0.5–4 mg/mL. Mechanism involves disruption of bacterial cell membrane integrity and inhibition of DNA gyrase. Gallic acid esters (gallates — propyl gallate, octyl gallate) have enhanced antimicrobial activity due to improved membrane penetration. Claim strength: Moderate.
Anti-inflammatory and antiproliferative: Gallic acid inhibits NF-κB, COX-2, and multiple inflammatory kinases. Antiproliferative activity across cancer cell lines is documented via induction of apoptosis and cell cycle arrest. These preclinical findings position gallic acid as a broad anti-inflammatory and chemopreventive agent pending clinical substantiation. Claim strength: Moderate.
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Dosage & Formulator Specification
No established isolated human supplement dose for gallic acid. Dietary exposure from tea, wine, berries, and tannin-rich botanicals: 10–50 mg/day. For gallic acid-targeted supplement applications, tannin-standardised haritaki (Terminalia chebula) extract at 50% tannins is the most practical commercial source, delivering gallic acid as a primary tannin hydrolysis product. Dose: 200–500 mg/day haritaki extract.
Gallic acid has good aqueous solubility. Absorbed intact in the small intestine and also generated by colonic microbial hydrolysis of gallotannins. Stable at acidic pH; susceptible to oxidative degradation (trihydroxy structure). Antioxidant co-formulation and nitrogen packaging advised. Request HPLC gallic acid content on CoA for tannin extracts.
Propyl gallate (gallic acid n-propyl ester) is a widely used synthetic antioxidant food additive (E310). Natural gallic acid and propyl gallate have different regulatory classifications; formulators using gallic acid from botanical tannin extraction should ensure clear labelling as a natural botanical extract constituent rather than as the synthetic food additive E310.
Frequently Asked Questions — Gallic Acid
What is the relationship between gallic acid and tannins?
Hydrolysable tannins (gallotannins and ellagitannins) are polymeric esters of gallic acid or its dimer (hexahydroxydiphenic acid / HHDP) with glucose. Acid or enzymatic hydrolysis of gallotannins releases gallic acid as the monomeric product. Ellagitannin hydrolysis releases ellagic acid (from HHDP lactonisation). Gallic acid is thus the structural unit and hydrolysis product of gallotannins — distinct from condensed tannins (proanthocyanidins/OPCs) which do not yield gallic acid on hydrolysis.
Is gallic acid from haritaki the same as from pomegranate?
Chemically identical — gallic acid is gallic acid regardless of botanical source. The botanical context affects co-constituents: haritaki provides gallic acid alongside chebulic acid, ellagic acid, and other Terminalia tannins; pomegranate provides gallic acid alongside punicalagins and ellagic acid. The bioactivity delivered depends on the full extract composition, not just the gallic acid fraction.
Does gallic acid have topical skin benefits?
Yes. Gallic acid has antioxidant, anti-inflammatory, and tyrosinase-inhibiting activity relevant to skin health and brightening. It has been incorporated into cosmetic formulations for anti-ageing and skin tone applications. The trihydroxy structure provides both radical scavenging and metal chelation activity relevant to skin oxidative stress management.
Is there a difference between gallic acid and ellagic acid as tannic acid hydrolysis products?
Yes — ellagic acid is formed from the hexahydroxydiphenic acid (HHDP) portion of ellagitannins on hydrolysis and lactonisation. Gallic acid is the monomer from gallotannin hydrolysis. Both are hydroxybenzoic acid derivatives, but ellagic acid is a larger, more complex molecule (dibenzo-fused dilactone) with distinct bioactivity including urolithin production. Both can be co-present in tannin-rich botanical extracts.
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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