Talk:Gallic acid

Untitled
The COOH group has a pKa of 4.5, and the phenolic OHs have pKa of 10.

this is wrong a priori, you cannot deprotonate all three phenols at once. I don't know which one deprotonates first so i'm not changing it but my guess is on meta. 24.181.29.106

Synthetic route for Gallic acid -> Mescaline
I don't know how to add a citation to this page, but a synthesis of Mescaline from Gallic acid can be found here :

A New Synthesis of Mescaline, Makepeace U. Tsao, J. Am. Chem. Soc. 5495-5496 (1951) —Preceding unsigned comment added by 212.238.246.56 (talk) 11:35, 9 August 2008 (UTC)

Corrrection - following line removed
Early photographers, including Joseph Bancroft Reade (1801–1870) and William Fox Talbot (1800–1877), used gallic acid for developing latent images in calotypes. It has also been used as a coating agent in zincography.

Claims made on behalf of Joseph Bancroft Reade (1801–1870) were shown by RD Wood to be erroneous he was working with Silver Nitrate; only AgNo3, AgBr, AgI, and  theoretically AgF [ie silver chloride/bromide/iodide] have the potential to develop the latent negative image.[See British Journal of Photography, 28 July 1972, Volume 119, No. 5845, pp.644–646, 643]  — Preceding unsigned comment added by Michael W Gray (talk • contribs) 14:11, 23 October 2013 (UTC)

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chemical properties citation needed
do you think, phytochemicals.info is a site worth a citation??? esp. because half the article is a citation from there -hig- —Preceding unsigned comment added by 77.132.208.48 (talk) 23:12, 25 April 2009 (UTC)

pKa-Value
As I am a German Wikipedia user, I read in the German article that the pKa (or pKs as it is called in german) is not 4.5 but 3.13 wich seems correct according to the literature (e.g. Bykova L.N., Petrov S.I.& Blagodatskava Z.G. (1970). Relative acidity of phenol and its derivatives in a medium of nonaqueous solvents. Zh. Obshch. Khim., 40, 2295-3000. and the citation No 3 from the german article). I also think that a higher acidity could be expected than for benzoic acid. This thought also fits following german article (you SHOULD translate that one too, if possible) http://de.wikipedia.org/wiki/Hydroxybenzoes%C3%A4uren (Hydroxybenzoesäuren). — Preceding unsigned comment added by 134.130.112.64 (talk) 20:04, 2 November 2011 (UTC)

George Washington & his spies
That George Washington's spies used gallic acid as an invisible ink is supposedly mentioned in "Episode 2: Revolution" of the series "America: The Story of Us", which was broadcast by the U.S. cable TV channel, the "History Channel".

However, in "Chapter 4: 711 and the Sympathetic Stain" (pages 101-124) of his book Washington's Spies:  The story of America's first spy ring (New York, New York:  Bantam, 2006), author Alexander Rose states that one of Washington's spies, Abraham Woodhull, used an invisible ink when he wrote to George Washington, who then used a developing solution to read the writing. However, Rose states that the nature of the invisible ink and the developing solution are unknown -- although Rose speculates that the invisible ink was gallic acid and that the developing solution was iron sulfate.

So I think that this claim -- that Washington's spies used gallic acid -- should either be deleted or tagged as "dubious". Cwkmail (talk) 01:13, 5 August 2012 (UTC)

✅ Tomásdearg92 (talk) 23:22, 2 November 2016 (UTC)

Plagiarized content unacceptable
The site "http://www.phytochemicals.info/phytochemicals/gallic-acid.php' reads:

"Gallic acid seems to have anti-fungal and anti-viral properties. Gallic acid acts as a antioxidant and helps to protect our cells against oxidative damage. Gallic acid was found to show cytotoxicity against cancer cells, without harming healthy cells. Gallic acid is used a remote astringent in cases of internal haemorrhage. Gallic acid is also used to treat albuminuria and diabetes. Some ointment to treat psoriasis and external haemorrhoids contain gallic acid."

The wikipedia article reads:

''Gallic acid seems to have anti-fungal and anti-viral properties. Gallic acid acts as an antioxidant and helps to protect human cells against oxidative damage. Gallic acid was found to show cytotoxicity against cancer cells, without harming healthy cells. Gallic acid is used as a remote astringent in cases of internal haemorrhage. Gallic acid is also used to treat albuminuria and diabetes. Some ointments to treat psoriasis and external haemorrhoids contain gallic acid.''

[i.e., without quotation marks to indicate that the content was lifted in entirety from another source].

This is plagiarized content, even with citation, and is wholely unacceptable. Please correct immediately. LeProf — Preceding unsigned comment added by 71.201.123.248 (talk) 20:22, 3 March 2013 (UTC)

External links modified
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 * Link is good. --Zefr (talk) 15:52, 7 January 2017 (UTC)

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Please update with: "The gut microbiome switches mutant p53 from tumour-suppressive to oncogenic"
Please add info on this paper to the article to section "Research". It's currently included in 2020 in science like so:

Scientists report that gut microbiomes that produce high levels of gallic acid and gallic acid itself, which can be found in many antioxidant-rich foods considered healthy and earlier reported to induce cell death in prostate and breast cancer cells, can switch mutated p53 proteins from being tumour-suppressive to accelerate the growth of bowel cancers in mice.

I already added this, mostly as is, to the section but it was reverted by User:Zefr with the following rationale: Reverting good faith edits; content is misleading and source is not a reliable medical reference; see WP:MEDRS.


 * Why is the content misleading (and what would be required for it to not be misleading)?
 * Why did you not edit it instead (to make it not misleading)?
 * WP:MEDRS doesn't seem to apply here (referring to this article / its research section / the added content): the content wasn't really "medical content".
 * The study was published in the journal Nature and other papers informed about in that section are of less or at least only equal quality.

Please answer these 4 questions, thank you. --Prototyperspective (talk) 15:04, 1 September 2020 (UTC)


 * 1) The "antioxidant-rich foods" comment is misleading, as there is no proof gallic acid or any polyphenol has biological effects in vivo. A WP:MEDRS review would be needed for such content, but no such review exists. Medicalexpress.com is not a reliable source for the encyclopedia. Chocolate and tea are not "antioxidant-rich". The only relevant biological antioxidants are vitamins A-C-E, which are not present in chocolate and tea.
 * 2) The article in Nature is lab research (in mice), too preliminary to support any encyclopedic content. See WP:MEDREV: lab animal research is often non-replicable, and therefore not useful for the encyclopedia. Wikipedia is not a journal reporting new results from the lab, WP:NOTJOURNAL #6-8. The "2020 in science" article has numerous citation errors and misleading statements, two of which I removed. It's filled with cherry-picking and primary sources, and is not a good Wikipedia article, imo. Zefr (talk) 15:57, 1 September 2020 (UTC)


 * Thanks for answering!
 * Assuming that such proof does not exist: there doesn't need to be "proof gallic acid or any polyphenol has biological effects in vivo" for the statement to be true and relevant even though it should have said "often" considered healthy (as already implied by the study's findings): a) it does not require all antioxidant-rich foods or all foods containing antioxidant-rich substances to be considered healthy b) many gallic acid rich foods are considered to be antioxidant-rich and c) these are typically considered healthy in terms of reasonable whole-food consumption (note: e.g. not referring to chocolate but cocoa). But it may indeed be somewhat misleading as at least "antioxidant-rich" doesn't seem to be the defining characteristic here and is mentioned not even once in the study itself, thanks for pointing it out! Here's the content with the relevant part removed:
 * "Scientists report that gut microbiomes that produce high levels of gallic acid and gallic acid itself can switch mutated p53 proteins from being tumour-suppressive to accelerate the growth of bowel cancers in mice."
 * It would be too preliminary to support the content in an article about a specific therapy or illness or in any other section than "Research" in that article. I disagree with that it's not useful anywhere only because it's animal research which is clarified in the content. I don't think that animal research of this type and published in Nature is "often non-replicable" – do you have any reference to back up this claim? (Even if you consider that paper misleading it's out and excluding it from Wikipedia wouldn't help in correcting it if it was indeed misleading which could be highlighted in other reliable sources.)
 * This is a high-grade paper that is highly relevant and should have some short content about in the article. It's not reporting "new results from the lab" but a high-quality paper published in Nature and news reports about it.
 * Would it be okay for you if I readd it like above? You could edit it or add a tag like for example if you think that this would be appropriate. --Prototyperspective (talk) 17:23, 1 September 2020 (UTC)
 * The report in question is primary research, which is typically excluded from articles per WP:NOTJOURNAL. The 'non-replicable' statement is from WP:MEDREV; it's not a blanket disqualifier, but it acknowledges the research as lab level. The talk page is for consensus-building among several editors, WP:CON, so if others were to agree with you, then a well-qualified statement might be added. My opinion is that - if the finding is important - it will be quickly and thoroughly confirmed by additional quality publications, resulting eventually in a WP:MEDRS review, when we likely all would agree it should be included. MEDRS isn't only about clinical outcomes - it addresses and supports content on human biology, which is the subject of this discussion. Zefr (talk) 20:54, 1 September 2020 (UTC)

Benzene ring
Does this compound contain the benzene ring? 173.88.246.138 (talk) 22:58, 3 October 2021 (UTC)

Contained in buckwheat?
Is this compound contained in buckwheat? 173.88.246.138 (talk) 22:59, 3 October 2021 (UTC)

Polyphenol
Shouldn't the term "polyphenol" be mentioned at least once in the text of this article? 173.88.246.138 (talk) 22:59, 3 October 2021 (UTC)