Pyrogallol is a polyphenol compound that generates superoxide anions (O₂•⁻) and induces cell death through oxidative stress mechanisms. [1]

Pyrogallol (PG) is a reducing agent that is frequently employed as a photographic developer and in the hair dye business because it may produce free radicals, particularly superoxide anions (O2•-). Pyrogallol inhibits the development of Calu-6 and A549 lung cancer cells via depleting glutathione (GSH) and inducing apoptosis. Pyrogallol (PG) impacts mitogen-activated protein kinase (MAPK) and causes lung cancer cells to overproduce O2•-, which in turn causes apoptosis [1]. Investigations were conducted on the impact of pyrogallol on necrotic cell death and the survival of human lung fibroblasts (HPF). In these investigations, the level of inhibition or death of cell viability with or without a specific MAPK inhibitor was determined using 0, 50, or 100 µM pyrogallol. After 24 hours, treatment with 50 and 100 µM pyrogallol decreased HPF activity by roughly 40% and 65%, respectively. Treatment with a MEK inhibitor marginally increased, and treatment with a p38 inhibitor somewhat decreased, the suppression of cell viability in HPF cells treated with 50 µM pyrogallol. All MAPK inhibitors to some extent improved the inhibition of vitality in HPF cells treated with 100 µM pyrogallol; treatment with p38 inhibitor alone increased the viability of HPF control cells. Lactate dehydrogenase (LDH) release from cells was used to measure necrotic cell death. While LDH release from HPF cells was not affected by treatment with 50 µM pyrogallol, it was dramatically increased by treatment with 100 µM pyrogallol [1].

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Cell Viability Inhibition: In human pulmonary fibroblast (HPF) cells, treatment with 50 μM and 100 μM pyrogallol for 24 hours decreased cell viability by approximately 40% and 65%, respectively, as measured by MTT assay. [1]
Necrotic Cell Death (LDH Release): Treatment with 100 μM pyrogallol significantly increased LDH release from HPF cells, indicating necrotic cell death. Treatment with 50 μM pyrogallol did not affect LDH release. [1]
Apoptotic Cell Death (Annexin V/PI Staining): Pyrogallol (50 and 100 μM) significantly increased the rate of apoptosis in HPF cells. Treatment with 100 μM pyrogallol also increased the number of necrotic cells. The p38 inhibitor slightly increased apoptotic cells in 50 μM PG-treated cells and significantly increased apoptotic cells in 100 μM PG-treated cells. [1]
PARP Cleavage: PARP protein levels were not altered in 50 μM pyrogallol-treated HPF cells but were decreased in 100 μM pyrogallol-treated cells, indicating caspase activation and apoptosis. [1]
Mitochondrial Membrane Potential (MMP) Loss: Treatment with 50 and 100 μM pyrogallol significantly decreased MMP (ΔΨm) in HPF cells as measured by rhodamine 123 staining. All MAPK inhibitors enhanced the decrease in MMP in pyrogallol-treated cells. [1]
Superoxide Anion (O₂•⁻) Levels: Pyrogallol treatment increased cellular O₂•⁻ levels (measured by DHE fluorescence) and mitochondrial O₂•⁻ levels (measured by MitoSOX Red fluorescence) in HPF cells. All MAPK inhibitors increased O₂•⁻ levels in 100 μM pyrogallol-treated HPF cells. [1]
Total ROS Levels: Total ROS levels (measured by H₂DCFDA fluorescence) were increased by 50 μM pyrogallol but not by 100 μM pyrogallol. MAPK inhibitors decreased ROS levels in pyrogallol-treated cells. [1]
Glutathione (GSH) Depletion: Treatment with 50 or 100 μM pyrogallol significantly increased the number of GSH-depleted HPF cells compared to control, as measured by CMFDA staining. None of the MAPK inhibitors significantly altered GSH depletion in pyrogallol-treated cells. [1]
MAPK Inhibitor Effects: MEK inhibitor (PD98059, 10 μM) enhanced the inhibition of cell viability, cell death, and MMP loss in pyrogallol-treated HPF cells. JNK inhibitor (SP600125, 10 μM) and p38 inhibitor (SB203580, 10 μM) also enhanced these effects, suggesting that all three MAPK pathways may have pro-survival roles in this context. [1]

Cell Culture: Human pulmonary fibroblast (HPF) cells were obtained from PromoCell GmbH and cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum and 1% penicillin-streptomycin in a humidified incubator with 5% CO₂ at 37°C. Cells between passages four and eight were used. [1]
Cell Viability Assay (MTT): HPF cells (5 × 10³ cells/well) were seeded in 96-well plates and treated with 0, 50, or 100 μM pyrogallol with or without MAPK inhibitors (10 μM) for 24 hours at 37°C. MTT solution was added, and absorbance was measured to determine cell viability. [1]
LDH Release Assay (Necrosis): HPF cells (1 × 10⁶ cells) in 60 mm culture plates were treated with pyrogallol and/or MAPK inhibitors for 24 hours. LDH release was measured using an LDH assay kit according to the manufacturer's protocol. LDH release was expressed as percentage of extracellular LDH activity compared to control cells. [1]
Apoptosis Detection (Annexin V/PI Staining): HPF cells (1 × 10⁶ cells) were treated with pyrogallol and/or MAPK inhibitors for 24 hours. Cells were stained with Annexin V-FITC and propidium iodide (PI) and analyzed by flow cytometry. [1]
Mitochondrial Membrane Potential (MMP) Assay: HPF cells (1 × 10⁶ cells) were treated with pyrogallol and/or MAPK inhibitors for 24 hours. Cells were stained with rhodamine 123 fluorescent dye and analyzed by flow cytometry. Loss of MMP was indicated by absence of rhodamine 123 staining. [1]
Western Blot Analysis: HPF cells (1 × 10⁶ cells) were treated with pyrogallol and/or MAPK inhibitors for 24 hours. Cells were lysed in lysis buffer (20 mM HEPES, pH 7.9, 20% glycerol, 200 mM KCl, 0.5 mM EDTA, 0.5% NP40, 0.5 mM DTT, 1% protease inhibitor cocktail). Proteins (30 μg) were separated by 12.5% SDS-PAGE, transferred to PVDF membranes, and probed with anti-PARP and anti-GAPDH antibodies. [1]
ROS Detection (H₂DCFDA): HPF cells (1 × 10⁶ cells) were treated with pyrogallol and/or MAPK inhibitors for 24 hours. Cells were stained with 2',7'-dichlorodihydrofluorescein diacetate (H₂DCFDA) and analyzed by flow cytometry. ROS levels were expressed as mean fluorescence intensity. [1]
Superoxide Anion Detection (DHE and MitoSOX Red): HPF cells (1 × 10⁶ cells) were treated with pyrogallol and/or MAPK inhibitors for 24 hours. Cells were stained with dihydroethidium (DHE) for cellular O₂•⁻ or MitoSOX Red for mitochondrial O₂•⁻ and analyzed by flow cytometry. Fluorescence levels were expressed as mean fluorescence intensity. [1]
Glutathione Detection (CMFDA): HPF cells (1 × 10⁶ cells) were treated with pyrogallol and/or MAPK inhibitors for 24 hours. Cells were stained with 5-chloromethylfluorescein diacetate (CMFDA) and analyzed by flow cytometry. GSH-depleted cells were expressed as percentage of cells negative for CMF staining. [1]

Absorption, Distribution and Excretion
This substance can be absorbed by the human body via oral administration. It is readily absorbed through the skin. …It is readily absorbed from the gastrointestinal tract and injection site. Small amounts can be absorbed through intact skin. …It readily conjugates with hexuronic acid, sulfuric acid, or other acids and is excreted by the kidneys within 24 hours. Some are excreted unchanged. Metabolisms/Metabolites …Pyrogallol is a metabolite of tannic acid… Pyrogallol derivatives…The intermediate phenolic hydroxyl group is methylated. Methylation of catechol derivatives may be meta- or para-methylated, depending on the presence of other substituents. Pyrogallol is methylated by catechol O-methyltransferase to produce 2-methylpyrogallol. Pyrogallol produces 3-methoxycatechol and 2-methoxyresorcinol in rats. In grass, it produces 2-methoxyresorcinol. (From a table) Pyrogallol produces purpuric gallic acid in beef. Purple-red gallic acid is produced in tea leaves. (From table)
For more complete data on the metabolism/metabolites of pyrogallol (7 metabolites in total), please visit the HSDB record page.

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Interactions
…By comparing the differential mRNA transcriptomes in the livers of control and pyrophenol-treated mice, we elucidated the various molecular events involved in pyrophenol-mediated hepatotoxicity. We also investigated the regulatory role of silymarin on pyrophenol-induced differentially expressed transcripts. Swiss albino mice received either pyrophenol treatment or not. In some experiments, mice were also treated with silymarin 2 hours prior to pyrophenol treatment. Total RNA was isolated from the liver, and polyadenylated RNA was reverse transcribed into cDNA labeled with Cye 3 or Cye 5. Equal amounts of labeled cDNA from both groups of mice were mixed and hybridized to a mouse 15k microarray. The hybridized microarray was scanned, analyzed, and the expression level of each transcript was calculated. Differential expression was validated using quantitative real-time polymerase chain reaction. Comparative transcriptomic analysis revealed altered expression of 183 transcripts related to oxidative stress, cell cycle, cytoskeleton network, intercellular adhesion, extracellular matrix, inflammation, apoptosis, cell signaling, and intermediate metabolism in the liver exposed to pyrophenol (150 upregulated, 33 downregulated), with silymarin pretreatment regulating the expression of many of these transcripts. These results indicate that pyrophenol induces multiple molecular events leading to hepatotoxicity, while silymarin effectively counteracts pyrophenol-mediated alterations. This study aimed to evaluate the effects of resveratrol on pyrophenol-induced changes in liver injury markers, exogenous metabolic enzymes, and oxidative stress. Swiss albino mice were intraperitoneally injected daily with pyrophenol (40 mg/kg) for 1 to 4 weeks, with corresponding control groups. In some experiments, animals were pretreated with resveratrol (10 mg/kg) 2 hours prior to pyrophenol treatment, with corresponding control groups. The levels of alanine aminotransferase, aspartate aminotransferase, and bilirubin in plasma were measured, and the mRNA expression levels of cytochrome P-450 (CYP) 1A1, CYP1A2, CYP2E1, glutathione S-transferase (GST)-ya and GST-yc in the liver were also measured. Furthermore, the catalytic activities of CYP1A1, CYP1A2, CYP2E1, GST, glutathione reductase, and glutathione peroxidase, as well as lipid peroxidation and reduced glutathione (GSH) levels, were also assessed. Resveratrol reduced the increases in alanine aminotransferase, aspartate aminotransferase, bilirubin, lipid peroxidation, and CYP2E1 and CYP1A2 mRNA expression and catalytic activity mediated by pyrogallol. The decreases in GST-ya and GST-yc expression, GST, glutathione peroxidase and glutathione reductase activities, and GSH levels mediated by pyrogallol were significantly attenuated in animals treated with resveratrol. CYP1A1 expression and catalytic activity remained largely unchanged in all treatment groups. These results indicate that resveratrol modulates changes in pyrogallol-induced hepatotoxicity markers, exogenous metabolic enzymes, and oxidative stress. This study also investigated the effects of the free radical generator pyrogallol on gastric emptying in rats. Intraperitoneal injection of pyrogallol at doses of 25, 50, 100, and 150 mg/kg inhibited gastric emptying in a dose-dependent manner. Pre-oral administration of vitamin C (100 and 500 mg/kg) and vitamin E (100 and 500 mg/kg) significantly reversed the gastric emptying inhibition induced by 100 mg/kg pyrogallol. However, the combined administration of vitamin C and vitamin E (100 mg/kg) had a synergistic effect. Pretreatment with intravenous glutathione (100 mg/kg) for 5 minutes also reversed the gastric emptying inhibition induced by 100 mg/kg pyrogallic acid. Oral administration of ondansetron (3 mg/kg) significantly reversed the effects of pyrogallic acid. Furthermore, the effects of pyrogallic acid on malondialdehyde (MDA) and serotonin (5-HT) levels in gastric tissue were investigated. Intraperitoneal injection of 100 mg/kg pyrogallic acid significantly increased the levels of MDA and 5-HT in gastric tissue. Pre-oral administration of vitamin C and vitamin E (100 mg/kg) and intravenous glutathione (100 mg/kg) significantly reduced the increase in MDA in gastric tissue induced by pyrogallic acid, but had no significant effect on the increase in 5-HT levels induced by pyrogallic acid. This study also explored the effects of different doses of 5-HT on gastric emptying. The effects of 5-HT on gastric emptying varied. Low and high doses (0.1, 0.3, and 30 mg/kg, intraperitoneal injection) significantly inhibited gastric emptying, while doses in the 1–10 mg/kg range had no significant effect. Pre-administration of antioxidants, including vitamin C and vitamin E (100 mg/kg each, orally) and glutathione (100 mg/kg, intravenously), had no effect on serotonin (5-HT, 0.3 mg/kg, intraperitoneal injection)-induced gastric emptying delay. These results suggest that free radicals play a role in gastric emptying, and antioxidants may have potential therapeutic value for diseases known to release free radicals and whose gastrointestinal effects manifest as symptoms or side effects of drug treatment. This study aimed to: (i) verify the hypothesis that endothelial-derived hyperpolarizing factor (EDHF) components are impaired upon exposure to superoxide anions during acetylcholine (ACh)-induced vasodilation and vascular smooth muscle cell (SMC) hyperpolarization; and (ii) further investigate whether luteolin and apigenin have vasoprotective effects on rat mesenteric arteries at vasoactive concentrations. In this study, rat mesenteric artery rings were isolated for isometric contractile force recording and electrophysiological studies. Perfusion pressure of the mesenteric artery bed was measured, and superoxide production was detected using fluorescent dyes. 300 μM pyrogallol significantly reduced acetylcholine (ACh)-induced vasodilation and hyperpolarization. Both luteolin and apigenin protected blood vessels from damage to endothelial-derived hyperpolarizing factor (EDHF) components during ACh-induced vasodilation and alleviated ACh-induced hyperpolarization impairment. Oxidative fluorescence micromorphology analysis showed that both luteolin and apigenin significantly reduced superoxide levels. Results showed that superoxide anions impaired ACh-induced relaxation and hyperpolarization of resistance artery smooth muscle cells (SMCs) by inhibiting EDHF-mediated responses. Luteolin and apigenin protected resistance arteries from damage, suggesting their potential efficacy in treating vascular diseases associated with oxidative stress.
For more complete data on interactions of pyrogallic acids (8 in total), please visit the HSDB record page.
Non-human toxicity values

Oral LD50 in mice: 300 mg/kg
Intraperitoneal LD50 in mice: 400 mg/kg
Subcutaneous LD50 in mice: 566 mg/kg
Oral LD50 in rabbits: 1600 mg/kg

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[1]. MAPK inhibitors enhance cell death in pyrogallol-treated human pulmonary fibroblast cells via increasing O2•- levels. Oncol Lett. 2017 Jul;14(1):1179-1185.

Therapeutic Uses
/Experimental Treatment/...Pyrogallic acid (PGA) exhibits high cytotoxicity against human lung cancer cell lines, but has a relatively small effect on human bronchial epithelial cell lines. This study aimed to investigate the therapeutic effects of PGA on human lung cancer cell lines H441 (lung adenocarcinoma) and H520 (lung squamous cell carcinoma). MTT (cytotoxicity test) results showed that the growth of lung cancer cells was inhibited after PGA treatment. Flow cytometry analysis showed that the cell cycle of lung cancer cells was arrested in the G2/M phase. Western blot analysis showed that after 4 hours of PGA treatment, the expression of cell cycle-related proteins cyclin B1 and Cdc25c decreased in a time-dependent manner, while the expression of phosphorylated Cdc2 (Thr14) increased. Furthermore, the level of poly(ADP)ribose polymerase (PARP) cleavage was increased, Bax protein expression was increased, and Bcl-2 protein expression was decreased, indicating that PGA treatment can induce apoptosis in lung cancer cells. Annexin V-FITC and TUNEL staining also directly confirmed apoptosis. Furthermore, the antitumor effect of pyrophenol was evaluated using a nude mouse xenograft tumor model. Tumor regression was observed after 5 weeks of pyrophenol treatment. The combined results of in vitro and in vivo studies suggest that pyrophenol holds promise as a potent anti-lung cancer drug for the treatment of non-small cell lung cancer (NSCLC).

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Background: Pyrogallol (benzene-1,2,3-triol) is a polyphenol compound commonly found in hardwood plants. It has anti-fungal and anti-psoriatic properties. It is a reductant that generates free radicals, particularly superoxide anions (O₂•⁻), and has been used as a photographic developing agent and in the hair dyeing industry. [1]
Mechanism of Action: Pyrogallol induces cell death primarily through the overproduction of superoxide anions (O₂•⁻), leading to oxidative stress, mitochondrial membrane potential loss, and glutathione depletion. It induces both apoptosis and necrosis depending on concentration. [1]
Toxicological Concerns: Despite its useful effects, pyrogallol toxicity remains a concern. It has been shown to induce mutagenesis, carcinogenesis, and impair the immune system in other studies. [1]
MAPK Signaling: The study demonstrates that MAPK inhibitors (MEK, JNK, and p38 inhibitors) enhance pyrogallol-induced cell death in HPF cells, suggesting that all three MAPK pathways may play pro-survival roles in normal lung fibroblasts under oxidative stress. This contrasts with findings in some cancer cells where MAPK inhibitors have different effects. [1]
Cell Type Specificity: The effects of pyrogallol and MAPK inhibitors vary depending on cell type. For example, in Calu-6 lung cancer cells, MEK inhibitors (but not JNK or p38 inhibitors) slightly attenuated the effects of pyrogallol, whereas in HPF cells, all three inhibitors enhanced cell death. [1]

C6H6O3

126.111

126.031

87-66-1

30813-84-4

1057

White to off-white solid powder

1.453

309 ºC

131-135 ºC

164.3±16.9 °C

0.0±0.6 mmHg at 25°C

1.677

0.29

3

3

0

9

84.3

0

OC1C(O)=C(O)C=CC=1

WQGWDDDVZFFDIG-UHFFFAOYSA-N

InChI=1S/C6H6O3/c7-4-2-1-3-5(8)6(4)9/h1-3,7-9H

benzene-1,2,3-triol

2,3-Dihydroxyphenol Benzene-1,2,3-triolPyrogallol C.I. 76515 NSC 5035Fouramine Brown AP

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ≥ 100 mg/mL (~792.96 mM)
H2O : ~50 mg/mL (~396.48 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (19.82 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (19.82 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (19.82 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 130 mg/mL (1030.85 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)