The Sunlight Experiment

Compound Monograph

Gallic acid

Gallic acid — a hydroxybenzoic (phenolic) acid and the building block of the gallotannins, best characterised as an antioxidant and gastroprotective polyphenol.

Work in progress

Classification

Gallic acid is a hydroxybenzoic acid (phenolic acid), part of the phenolics class. Antioxidant compounds built around one or more phenol rings — the flavonoids, tannins, phenolic acids, coumarins, and pigments behind much of a plant's protective chemistry.

Phenolics Phenolic Acids

Where Does It Come From? (16)

Gallic acid is a naturally occurring hydroxybenzoic acid (phenolic acid), found in Arjuna, Bearberry, Cashew and 13 other sources. It is well tolerated orally (low toxicity).

Acacia Acacia spp. Amaranth Amaranthus blitum Arjuna Terminalia arjuna Bearberry Arctostaphylos uva-ursi Black Ant Polyrhachis spp. Cashew Anacardium occidentale Chanca Piedra Phyllanthus niruri Clove Syzygium aromaticum Guarana Paullinia cupana Many fruits, nuts and red wineOak galls and tannin-rich barks Raspberry Leaf Rubus idaeus Rhubarb Rheum palmatum Tea Camellia sinensis Walnut Juglans nigra Yerba Maté Ilex paraguariensis

Research & Evidence

Gallic acid is a hydroxybenzoic acid — a simple phenolic acid that also forms the core unit of the gallotannins (hydrolysable tannins). It occurs in tannin-rich and polyphenol-rich herbs, where the source monographs generally report it as part of a plant’s phenolic fraction rather than as an isolated drug.

  • Gastroprotective — guarana’s protective effect against gastric lesions is attributed to its polyphenol content, specifically caffeic acid, gallic acid and tannic acid 1Reference 1Basile et al. · 2005Antibacterial and antioxidant activities of ethanol extract from Paullinia cupana Mart.
  • Antimicrobial support — in bearberry (uva-ursi), gallic acid is listed among the constituents thought to support the herb’s urinary-antiseptic action alongside its principal arbutin/hydroquinone chemistry; bearberry leaves are noted to contain gallotannins and gallic acid as part of their polyphenol profile 2Reference 2Bone K · 2013Principles and Practice of Phytotherapy.
  • Tea constituent — gallic acid content varies by tea type, being lowest in green tea and higher in fully-oxidised black tea 3Reference 3Barceloux · 2012Medical Toxicology of Drug Abuse: Synthesized Chemicals and Psychoactive Plants; it is part of the galloylated polyphenol chemistry that underlies tea’s antioxidant activity.
  • Other sources — gallic acid is documented in the constituent profile of cashew (Anacardium occidentale) 4Reference 4Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals, and is also reported in arjuna and yerba maté as part of their phenolic content.

Because the source pages treat gallic acid as one of several co-occurring polyphenols, this page is kept appropriately concise.

Toxicity & Safety

Gallic acid is a common dietary phenolic acid found in tea, fruits and nuts, and is well tolerated; none of the source herb monographs flag it as toxic. As a tannin-related compound it shares the general property of astringency, and any practical cautions attach to the tannin-rich whole herbs (such as bearberry’s recommended short-term use) rather than to gallic acid in isolation. The source material does not describe an isolated-compound overdose or interaction profile.

References

  1. Basile, A., Ferrara, L., Del Pezzo, M., Mele, G., Sorbo, S., Bassi, P., & Montesano, D. (2005). Antibacterial and antioxidant activities of ethanol extract from Paullinia cupana Mart. Journal of Ethnopharmacology, 102(1), 32-36.
  2. Bone K, Mills S. (2013). Principles and Practice of Phytotherapy. Elsevier Health, China.
  3. Barceloux, D. G. (2012). Medical Toxicology of Drug Abuse: Synthesized Chemicals and Psychoactive Plants. John Wiley & Sons.
  4. Taylor, L. (2005). The healing power of rainforest herbs: A guide to understanding and using herbal medicinals. Garden City Park, NY: Square One Publishers.