87-66-1

white crystalline solid

Complexing agent; reducing agent; alkaline solution indicator for gaseous oxygen.

Metal-complexing agent

ChEBI: A benzenetriol carrying hydroxy groups at positions 1, 2 and 3.

Odorless white to gray solid. Sinks and mixes with water.

PYROGALLIC ACID(87-66-1) is a strong reducing agent. Reacts with alkalis, NH3, antipyrine, camphor, phenol, iron and lead salts, iodine, lime water, menthol and KMnO4.

Turns gray on exposure to light or air. Water soluble.

Toxic by ingestion and skin absorption.

Inhalation of dust causes irritation of nose and throat. Ingestion may cause severe gastrointestinal irritation, convulsions, circulatory collapse, and death. Contact with eyes causes irritation. Skin contact can cause local discoloration, irritation, eczema, and death; repeated contact can cause sensitization.

This compound is probably combustible.

Pyrogallol is a natural oxidant that can generate superoxide (O₂^-) in alkaline solutions through autoxidation to a semiquinone radical. Importantly, the semiquinone radical can react with O₂^- in an acidic environment to produce a quinone and H₂O₂. Pyrogallol autoxidation is used in superoxide dismutase activity assays. It can also be used in assays to assess antioxidant capacity. Pyrogallol is used in some biological systems as an O₂^- scavenger. In other biological systems, it is used as an O₂^- generator. Pyrogallol effectively scavenges DPPH radical (Item No. 14805) and ABTS⁺ in vitro. Pyrogallol is a product of tannin degradation to gallic acid (Item No. 11846) by ruminant microbes and has hepatotoxic and nephrotoxic effects in vivo.

Pyrogallol is prepared by heating dried gallic acid at about 200°C with the loss of carbon dioxide or by the chlorination of cyclohexanol to tetrachlorocyclohexanone, followed by hydrolysis.

Pyrogallol also referred to as 1,2,3-trihydroxybenzene inhibits the response to nitric oxide (NO) in the rat anococcygeus muscle.

Pyrogallol was not carcinogenic in mouse and rabbit chronic dermal studies. Mice were treated twice weekly with pyrogallol in acetone (50%) on the shaved flank for life. There was no increase in dermal or systemic tumors. A similar study in rabbits also revealed no skin tumors, although positive controls showed an increase in tumors in both mice and rabbits.
Pyrogallol was considered to be cocarcinogenic when administered dermally three times a week together with the skin carcinogen benzo[a]pyrene for 440 days; pyrogallol administered alone caused no increase in skin tumors.

Due to its oxygen radical generating property, pyrogallol is commonly used as a photographic developing agent, in hair dying industry, as an antiseptic and to calculate the amount of oxygen in the air.

[1] LUC MAGNANI  Jean C H  Emile M Gaydou. Spectrophotometric measurement of antioxidant properties of flavones and flavonols against superoxide anion[J]. Analytica Chimica Acta, 2000, 411 1: Pages 209-216. DOI: 10.1016/s0003-2670(00)00717-0
[2] LI* X. Improved Pyrogallol Autoxidation Method: A Reliable and Cheap Superoxide-Scavenging Assay Suitable for All Antioxidants[J]. Journal of Agricultural and Food Chemistry, 2012, 60 25: 6418-6424. DOI: 10.1021/jf204970r
[3] CHI-SEN CHANG  Guia H L  Chia Lin Chang. Reactive oxygen species scavenging activities in a chemiluminescence model and neuroprotection in rat pheochromocytoma cells by astaxanthin, beta-carotene, and canthaxanthin[J]. Kaohsiung Journal of Medical Sciences, 2013, 29 8: Pages 412-421. DOI: 10.1016/j.kjms.2012.12.002
[4] TINGTING WANG. Fisetin Protects DNA Against Oxidative Damage and Its Possible Mechanism.[J]. Advanced pharmaceutical bulletin, 2016, 6 2: 267-270. DOI: 10.15171/apb.2016.037
[5] AMY L SINDLER. Age and exercise training alter signaling through reactive oxygen species in the endothelium of skeletal muscle arterioles.[J]. Journal of applied physiology, 2013: 681-693. DOI: 10.1152/japplphysiol.00341.2012
[6] V MORENO-MANZANO. Selective involvement of superoxide anion, but not downstream compounds hydrogen peroxide and peroxynitrite, in tumor necrosis factor-alpha-induced apoptosis of rat mesangial cells.[J]. The Journal of Biological Chemistry, 2000, 275 17: 12684-12691. DOI: 10.1074/jbc.275.17.12684
[7] SINDHU MATHEW  Zainul A Z  T Emilia Abraham. Reactivity of phenolic compounds towards free radicals under in vitro conditions[J]. Journal of Food Science and Technology, 2015, 52 9: 5790-5798. DOI: 10.1007/s13197-014-1704-0
[8] REED J D. Nutritional toxicology of tannins and related polyphenols in forage legumes.[J]. Journal of animal science, 1995, 73 5: 1516-1528. DOI: 10.2527/1995.7351516x