Talk:Catechin

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Unsigned, undated[edit]

Could yous not use ONLINE STORES as REFERENCE ?

I added the cleanup tag because this page needs a rewrite, and I don't have the requisite knowledge. For instance, the second paragraph is one line, and the third paragraph is unclear in the "several thousand . . . " line. The article vascillates between using EGCg and EGCG to refer to a particular compound. (I don't know which is correct, of if they're interchangeable.) The conclusion discusses what would appear to be antimicrobial properties of catechin. The sole reference for this article also discusses these properties, but provides no reference of its own. Indeed, most of this article appears to have been directly plagiarized from the source. This is inexcusable.

update by my ip in the edit history 5/14/06 reference from a online store! is not a valid reference. so i removed, and replaced with a valid ref. link. and added some text, but someone should find reference for those magical antioxidant properties, im tired right now, and disecting this topic has been very time consuming.

this is a biochemistry subject, please treat it as such.

Cleanup Tag[edit]

This article is poorly organized, and does not provide an adequate description of what a catechin is, or what the current scientific\medical opinion about it's effects is. It is almost entirely lacking in citations, and only one of these appears to be a sufficiently rigorous source. I attempted to find some more reliable information, but I am not familiar enough with the subject to write a better article. 70.162.14.102 05:55, 11 June 2006 (UTC)

Latercomer to this article[edit]

i havent been involved in creating this article or developing its text, but i have started to try to add citations and rewrite as needed. much of the material seems valid, but sourcing will take some time. cheers Covalent 21:01, 12 June 2006 (UTC)


"Dictionary.com: Catechin; A crystalline substance, C15H14O6, derived from catechu and used in tanning and dyeing. Also called catechol."

Catechol: A biologically important organic phenol, having two hydroxyl groups attached to the benzene ring.

Phenol: A caustic, poisonous, white crystalline compound, C6H5OH, derived from benzene and used in resins, plastics, and pharmaceuticals and in dilute form as a disinfectant and antiseptic. Also called carbolic acid. Any of a class of aromatic organic compounds having at least one hydroxyl group attached directly to the benzene ring."

I think this supports the theory that catechins have antimicrobial properties. At least we know it's not a protein, and rather a crystalline substance. But a phenol can also be an "aromatic organic compound." I'm sorry, I don't have much knowledge of the subject as a whole, but is there any way to tell which type of phenol the catechins from Green/White tea are?


In case you are not familiar with organic chemistry, the two definitions of "phenol" are not mutually exclusive--the first is specific and the second is general:
  1. Phenol as a specific compound, is C6H5OH, which is basically a benzene ring with one of the hydrogen atoms replaced by a hydroxyl group, and has the properties listed above.
  2. Phenols as a general class of compounds are structurally similar to phenol-- they must have at least one hydroxyl group attached directly to the benzene ring. Note that "aromatic" means "containing a benzene ring".
With that in mind, I think it's pretty clear that catechins are of the general type of phenol, not the specific compound called phenol.
Structural similarity often implies similar properties, but the fact that phenol is used as an antiseptic does not mean that catechins are antimicrobial just because they are phenols. They might be, but more evidence is needed. You might as well say that wood alcohol is good to drink because it's an alcohol!
Catechins are definitely not proteins. Proteins are made up of amino acids (i.e. containing NH2). However, as far as I can tell, the article (at least the current version) does not claim that catechins are proteins.
--MAzari 02:40, 10 August 2006 (UTC)

I think the retention time under Spectral Data/UV-Vis should be removed. As an analytical chemist I know that retention time varies tremendously under different instrument conditions, even different instruments. This data is too narrow, not useful, and misleading.

--achemist4u 11:00, 12 August 2011

Comment/Question for Authors/Editors:[edit]

The article mentions bacteria as being a type of protein. I'm not an expert but this does not seem right. Bacteria are living entities. Proteins, as such, are not living. --CalumetK.

Bacteria produce toxins. The toxins are proteins. The current wording is confusing, and that sentence should be re-written.
--MAzari 02:44, 10 August 2006 (UTC)

I have no expertise in this area and don't want to mess with the article, but I found catechin as an herbicide produced (in two isomers) by spotted knapweed. It was touted as a candidate for commercial application, but I have found no products. Fairandbalanced 16:53, 15 September 2007 (UTC)

Links to other articles:[edit]

Hi, the first question that occurred to me when reading this article is why is it called "catechin". So I looked it up in the dictionary and found that it is related to the Catechu plant and other substances derived from it, such as pyrocatechol. I think it would be interesting to relate these to catechin, even though tea is more popular.

Done. MatthewEHarbowy 18:11, 15 December 2006 (UTC)

Catechin is the proper name for this class of compounds. That said if it relates then it would be nice to see. Jasoninkid 22:59, 31 May 2007 (UTC)

"What is a catechin?"[edit]

I noticed the editor mentioning there is insufficient data to provide an adequate description of what exactly a catechin is.

"Catechins belong to the flavan-3-ol class of flavonoids and these are found in green tea leaves. . There are 4 major catechins in green tea leaves, namely (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epicatechin (EC), all polyphenolic compounds."

Polyphenolic compounds are "any of a large group of plant substances that include the anthocyanins."

Anthocyanins are the various water-soluble pigments that are found in flowers and other plants, ranging from violet, blue, to many shades of red.

There you have it... a catechin is the pigmentation created by the plant, I believe during photosynthesis.... Though why it would be a different pigment than green, perhaps the biosynthesis process, I don't know. I'll edit if I think up of anything else.

I'm fairly sure, as someone else mentioned, that catechins are not proteins. I believe this because simple biology tells us that chlorophyll is a pigment, yet it is not a protein. I believe these catechins are a different kind of pigment, created by the plants, to either hue a certain flower petal, or leaf, to aid in either reproduction or as a self-defense mechanism. (Camouflage)

Sorry, I dont have a MD in biochemistry, but I believe my info is up-to-date :)


The role of a catechin is not known, polyphenolic compounds are compounds that have 2 or more phenol groups (an OH on a benzing ring. Anthocyanins are similar to but not the same as catechins. You are right that it is not a protein, at the most basic level proteins are made of amino acids and catichins are not, it is best described as a small molecule.

Also would people pleases sine their posts! Jasoninkid 22:57, 31 May 2007 (UTC)

Decay after brewing?[edit]

My sister learned in school that catechins in tea decay/deteriorate after 24-48 hours. Can anyone confirm this?

Yes they do and in much less time. Jasoninkid 22:48, 31 May 2007 (UTC)

Catechin Temperature Decomposition[edit]

This Article reads: "Heating catechin past its point of decomposition releases pyrocatechol, which explains the common origin of the names of these compounds."

What is the temperature of decomposition? —The preceding unsigned comment was added by 67.79.200.162 (talk) 14:55, 9 May 2007 (UTC).

Pyrolysis of catechin begins above it's melting point, approx 200 degrees C, and the principal products of pyrolysis are catehin and 4-methylcatechin at 500C (see, e.g., Ohara et al, Structure Elucidation of Condensed Tannins, Holzforshung 57 (2003) 145-149.) MatthewEHarbowy 21:45, 9 May 2007 (UTC)

My experience has suggest that they will discompose at any temp if in solution with the rate being personal to temp. Jasoninkid 22:51, 31 May 2007 (UTC)

Chocolate / Cocoa[edit]

Is Catechin only present in chocolate or also in low fat cocoa? --91.15.72.16 (talk) 12:22, 14 August 2008 (UTC)

Pronunciation?[edit]

I'm not sure what the norm is for articles with titles of scientific origin, but would it be possible to include an IPA pronunciation (or, more likely, a couple of common pronunciations) of "catechin" at the beginning of the article? ----72.207.255.52 (talk) 21:03, 6 January 2010 (UTC)

various problems[edit]

Infobox - LD50: oral? Chemistry - catechin numbered: most of the numbers are missing. It would be better to say it has 4 stereoisomers. "activating the double bond on ring C"? What double bond? Biosynthesis : The shikimate pathway is not involved in converting phenylalanine to hydroxycinnamoyl CoA. The step from hydroxycinnamic acid to hydroxycinnamoyl CoA is not mentioned. Wouldn't E5 be dihydroflavaNOnol 4-reductase? Interactions with human genes - CYP1A1: implied should be implicated. S100B: It isn't an enzyme. This states twice that catechin decreases expression. "oxidative stress, are in agreement": "are" should be deleted. Candidate therapeutic protective for HIV-associated neurocognitive disorders: "and caused by" - delete "and". Suppression heat-induced pain: Suppression of. Ecological effects: should be a ; after behavior. Ref. 5 & 26 are missing a space. Ref. 31: The P of P450 is always upper case. Ref. 52 appears to be truncated. 69.72.92.28 (talk) 04:39, 27 September 2014 (UTC)

Trying to add info about in vitro receptor activity from journal article[edit]

This is the article in question: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2265593/

The portion dealing with catechin is in regard to compounds 12-15 (the four isomers of catechin) and their collective activities as opiate receptor antagonists. The exception is (-)-catechin (compound 13) which had "weak partial agonist activity (Emax = 18% of U69,593)." U69,593 is according to it's own wiki article "a potent and selective" kappa 1 receptor agonist.

I'm having problems editing this on my tablet (keeps crashing Firefox). I will try and revisit this, however if someone else feels like adding the info feel free.

In my opinion the information is relevant here under the bioactivity studies sub heading with it's own sub heading "Interactions with human opiate receptors in vitro". This way it matches the previous sub heading "Interactions with human genes in vitro". Does anyone agree/disagree with this?

Any reasons for or against including this information in the article? I know that my save earlier was incomplete and had issues. I was trying to change modes to fix it, and it was deleted in the interim. Apologies for that.

Thanks and cheers! Dogtoy (talk) 23:25, 20 May 2016 (UTC)

Reading through that article, Dogtoy, I vote that the whole section under Bioactivity be removed. The studies and article content are highly preliminary as early-stage lab research and esoteric for the majority of encyclopedia users. The extensive list under "Detail for all tested genes" should be removed as WP:IINFO. These studies are years/decades from being relevant to human physiology or medicine. The study you wish to add is similar as an early-stage in vitro receptor analysis not yet confirmed by other in vitro or in vivo work, therefore WP:PRIMARY. I suggest this information is not encyclopedic per WP:NOTJOURNAL and WP:NOTCRYSTAL; its inference for relevance to humans is not supportable by WP:MEDRS. --Zefr (talk) 02:11, 21 May 2016 (UTC)
I can understand this point of view, Zefr. I was thinking that the article which I referenced is relevant based upon using the gene interaction section as a model. Would it be acceptable to include something along the lines of, "Preliminary in vitro testing suggests possible interactions with human genes (ref) and opiate receptors (ref)." Just as a short footnote without listing all of the details which would be boring to the average wiki reader? That way people who are interested in that info can read the reference papers for more info and it doesn't clutter the page. What do you think? Dogtoy (talk) 12:07, 21 May 2016 (UTC)
Would this be frowned upon because of WP:PRIMARY? Thanks for the help and input btw. Cheers! Dogtoy (talk) 12:14, 21 May 2016 (UTC)
While I respect the science, I maintain this early-stage information about gene models is not encyclopedic and is at the lowest level of evidence quality. By WP:NOTEVERYTHING, we do not need to write into articles all information about the topic. But that is just my interpretation, so we can wait to see if other editors get into the conversation. Thanks for the reply. --Zefr (talk) 15:52, 21 May 2016 (UTC)

Human Metabolism - References[edit]

I have to admit I am a bit confused by the latest edit by Zefr - the Linus Pauling reference [1] doesn't include the details shown in the text (the details on individual metabolites - for methodological reasons, this is mainly from [2] which is so far the only ADME study that used radio-labelled compounds. I appreciate that primary sources are not welcome, but the reference for metabolism in the jejunum [3] is also primary research (and based on an organ model).

I'm also a bit surprised by the following statement: "As of 2016, clinical research has been insufficient to prove any specific biological effects of catechins in humans.[28]" there are several studies showing an acute effect of (-)-epicatechin, and this is shown in at least 2 meta-analyses by Hooper [4] and Ellinger [5]. Shouldn't this be taken into consideration?

I fully agree with the comment above and I also do not understand edits by Zefr. Regarding the above statement: "As of 2016, clinical research has been insufficient to prove any specific biological effects of catechins in humans.[28]" this is not just outdated based on the 2 meta-analyses mentioned above, but the current use ref 28, which references the Linus Pauling Institute, Oregon State University, Corvallis. 2016. Retrieved 24 July 2016, is out of date in that the reference materials have been updated. The Linus Pauling Institute currently states on their web-based information that: "Accumulating evidence from randomized controlled trials suggests that consumption of flavan-3-ols and anthocyanidins can be beneficial for metabolic and cardiovascular health.", a fact that contradicts the current use of this reference in the current version of this text as the term flavan-3-ol is just another term for catechins PolyphenolNet (talk) 23:35, 24 July 2016 (UTC).

I'm happy to contribute more, but I don't want to write some paragraphs which then disappear quickly.

[1] http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids [2] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4929566/ [3] http://www.sciencedirect.com/science/article/pii/S0006291X0093701X [4] http://www.ncbi.nlm.nih.gov/pubmed/22301923 [5] http://www.ncbi.nlm.nih.gov/pubmed/22552030 Ggux (talk) 22:40, 24 July 2016 (UTC)

The LPI review of flavonoids does display catechin metabolites under "Chemical structure of flavonoids". Neither of the meta-analysis references you offer (#4,5) are compliant with WP:MEDRS sourcing to substantiate any biological effect in humans. Also, current regulatory and scientific expert opinion on catechins and other flavonoids is that there is no proof of cause-and-effect to indicate their role in human physiology. --Zefr (talk) 22:50, 24 July 2016 (UTC);
I'm not sure why #4 and #5 are not compliant - these are both systematic reviews which are well conducted. And as PolyphenolNet (talk writes, there is evidence for a physiological effect elsewhere, not only the EFSA health claim, but also a number of other studies, e.g. [1]. The LPI reference does not include the metabolites currently cited in the text (as I have added them based on the removed reference) - as you have included the study with 14C-epicatechin that I added in the animal section, I don't understand why it can't be referred to there as well. In general, I'm a bit confused by the adherence to the primary source rule as many references in this article are clearly primary sources, including some added by Zefr. There are considerably more studies on in vivo metabolism in humans than cited here which are comparable to those cited elsewhere.
I fail to see why the EFSA health claim cited by PolyphenolNet does not comply with WP:MEDRS whereas the EFSA statement currently added to the text is. Perhaps it would be helpful to give some more information regarding the acceptable sources as there does not seem to be a consistent approach within this article.


[1] http://www.pnas.org/content/103/4/1024.full

Ggux (talk) 07:27, 25 July 2016 (UTC)

This last statement by Zefr is incomplete, i.e. the general breath of its validity is unjustified, as it does not consider "Scientific Opinion on the modification of the authorisation of a health claim related to cocoa flavanols and maintenance of normal endothelium-dependent vasodilation pursuant to Article 13(5) of Regulation (EC) No 1924/2006 following a request in accordance with Article 19 of Regulation (EC) No 1924/2006" EFSA Journal: EFSA Journal 2014;12(5):3654 [13 pp.. DOI: 10.2903/j.efsa.2014.3654" PolyphenolNet (talk) 23:35, 24 July 2016 (UTC).

There is no WP:MEDRS source linking cocoa flavanols in intervention studies affecting the course of diseases that would enable a health claim; see this critique from the FDA for green tea (updated to July 2015). If you find an appropriate source, please draft the content supported by it. The relevant part of MEDRS for sourcing is here. --Zefr (talk) 23:52, 24 July 2016 (UTC)

Human gene research in vitro[edit]

I moved the section below from the article because it is WP:PRIMARY in vitro research alluding to a possibility for in vivo effect. As we are writing an encyclopedia, not a textbook WP:NOTTEXTBOOK, this type of highly preliminary detail does not add substance to the article, but rather is a tangential highly speculative discussion far from proof of human relevance, and so is WP:UNDUE. We can discuss it here. --Zefr (talk) 14:17, 25 July 2016 (UTC)

- Removed text follows - In vitro, catechin interacts the most with the PTGS2, IL1B, CAT, CYP1A1, SOD, BAX, CASP3, MAPK1, MAPK3 and S100B human genes.catechin on Comparative Toxicogenomics Database

  • PTGS2 (aka COX-2 for cyclooxygenase-2) is a dioxygenase. The presence of catechin seems to increase its expression.
  • IL1B induces the formation of cyclooxygenase-2 (PTGS2/COX2). Catechin increases its expression.
  • CAT is a catalase. Catechin decreases its expression.
  • CYP1A1 (Cytochrome P450, family 1, member A1) is an enzyme implied in the metabolism of xenobiotics. Catechin decreases its expression.
  • SOD (Superoxide dismutase) is an enzyme that catalyzes the dismutation of superoxide into oxygen and hydrogen peroxide. Catechin increases its expression.
  • BAX (Bcl-2–associated X protein) is a protein of the Bcl-2 gene family. It promotes apoptosis by competing with Bcl-2 proper. Catechin increases its expression.
  • CASP3 (Caspase 3) is a protein that plays a central role in the execution-phase of cell apoptosis. Catechin increases its expression.
  • MAPK1 (Mitogen-activated protein kinase 1) and MAPK3 (Mitogen-activated protein kinase 3) are enzymes that are extracellular signal-regulated kinases (ERKs) and act as an integration point for multiple biochemical signals, involved in a wide variety of cellular processes such as proliferation, differentiation, transcription regulation, and development. Catechin seems to increase their expression.
  • S100B (S100 calcium binding protein B) is a pro-inflammatory enzyme specific of mature astrocytes that ensheath the blood vessels. Catechin decreases the expression of the gene and could regulate S100B-activated oxidant stress-sensitive pathways through blocking p47phox protein expression. Treatment with catechin could eliminate reactive oxygen species (ROS) to reduce oxidative stress stimulated by S100B. Catechin decreases its expression.

Experiments on human Caco-2 cells show changes in the expression of genes like STAT1, MAPKK1, MRP1 and FTH1 genes, which are involved in the cellular response to oxidative stress, are in agreement with the antioxidant properties of catechin. In addition, the changes in the expression of genes like C/EBPG, topoisomerase 1, MLF2 and XRCC1 suggest novel mechanisms of action at the molecular level.[1]

Detail for all tested genes :
(dec : decreased expression, inc : increased expression, = : does not affect the activity, expression assayed in human if not specified otherwise)Catechin interactions with genes
ABCG2 : (-)-catechin decreases the expression of ABCG2
ACE (in Rattus norvegicus) : (+)-catechin or (-)-epicatechin do not affect the activity of the angiotensin-converting enzyme
ACTB (in Rattus norvegicus) decrease
AKT1 decrease
ANXA2 increase
ARHGAP4 decrease
ATF4 increase
BAT2 increase
BAX (rattus norvegicus) increase
BCL2 decrease
BRCC3 decrease
BTG1 increase
CASP3 increase
CAT (mus musculus) decrease
CCL2 increase
CCND1 decrease
CD81 increase
CD9 increase
CEBPG increase
CXCL10 increase
CYP19A1 (rattus norvegicus) increase
CYP1A1 decrease
CYP1A2 =
DEK decrease
DFFA (mus musculus) decrease
DNMT1 decrease
EWSR1 increase
FLT3LG decrease
FTH1 increase
GRN increase
HCFC1 increase
HEAB decrease
HMOX1 increase
HOXD3 increase
HSPD1 decrease
ICAM1 increase
IL10 increase
IL1B increase
IL2RA decrease
IL32 decrease
IRF4 decrease
ITGAL increase
ITGB2 increase
LYN decrease
MAP2K1 decrease ?
MAPK1 increase ?
MAPK3 increase ?
MIF decrease
NCF1 ?
NFE2L2 increase
NFKBIA decrease
NOS2 (mus musculus) increase
NOTCH1 increase
NPM1 decrease
PARP1 (mus musculus) increase
PECAM1 increase
PLAT increase
PLAU increase
PON1 =
PTGS2 increase?
RAC1 decrease
RARB decrease
RELA decrease
RPL6 increase
S100B decrease
SERPINE1 decrease
SF1 decrease
SLC20A1 increase
SOD (Drosophila melanogaster) increase
SOD2 (Drosophila melanogaster) increase
STAT1 decrease
STAT5B increase
STAT6 increase
SULT1A1 increase : sulfation of catechin
TCF7 increase
TK1 decrease
TNF increase
TNFRSF8 decrease
TOP1 decrease
TOP2A decrease
TRP53 increase
XCR1 decrease
ZNF593 increase

History[edit]

Zefr - I disagree with the removal of the history section. The sources are readily available in any library, and as far as I understand, Wikipedia does not require English language sources. In my opinion, it is very relevant that catechin-containing preparations have been used for a considerable amount of time and that research into the purported beneficial effect are nothing new (e.g. the claim that they might be even Vitamins). The use as drug 'catergen' is also relevant - after all, "catergen" was a licensed drug at least in Switzerland and Germany, and the side effects included fatalities. This information might be appropriate in a different section - but as the drugs are not currently in use (they are available as slimming drugs though), I think it is best suited for the "history" section. Ggux (talk) 20:04, 25 July 2016 (UTC)

The content and references you provided do not impress as having significance to the current interests about catechins, leading to over-emphasis as WP:UNDUE. The emphasis you wish to make is not readily verifiable for English users of the encyclopedia. It's possible other editors may agree with you, but to reinstate the History section as you wrote it, WP:CON is needed per WP:ONUS. --Zefr (talk) 21:27, 25 July 2016 (UTC)
I think the historic use of a compound (or class thereof) such as catechins is very relevant for an encyclopedia, especially as it is not really something that is disputed. The current interest focuses on potentially beneficial effects, but this does not mean that adverse effects should be ignored - those drugs might not have been available in other countries, but there is a considerable amount of literature showing the effect (and potential mechanisms). What is the process to achieve WP:CON?Ggux (talk) 22:18, 25 July 2016 (UTC)
Editors wishing to engage in this discussion about catechins will come here for comments. You can invite editors who have been part of the article's history, or can initiate dispute resolution per WP:DR. --Zefr (talk) 22:47, 25 July 2016 (UTC)
Why do you object to historical data - it was part of the article before I made my edits, although the information was very limited. If I understood the reason for your decision, it would be easier to find a solution. Ggux (talk) 23:03, 25 July 2016 (UTC)
I don't object to relevant historical information that affects why catechins are of interest today. The response I gave in the 2nd paragraph above summarizes my view about the content and sources you chose to add. --Zefr (talk) 23:12, 25 July 2016 (UTC)
I respectfully disagree. The historic (pre 1940s) references are mainly in German/Latin due to the nature of research - but I still believe that a brief paragraph on historical uses is appropriate for an encyclopaedia article, especially for a compound that does have such a long history of medicinal use. The information could of course also be included in other sections regarding the physiological effects - but I'm not sure whether this would be much better. Ggux (talk) 23:21, 25 July 2016 (UTC)

Proposed section on medicinal use[edit]

The section below is neither mainstream for history nor for medicinal use; WP:UNDUE. Stronger references are needed if this is to be included. Also, a search within the source for "catechin" produced no content, so the information is not WP:V. The page cited, 371, was not viewable. If available by another source, a quote should be provided, but that may not be sufficient to prove that this history is significant as a foundation of current uses for catechins.

Lastly, the paragraph was poorly written with punctuation and spelling errors. Since this has been a problem with your other edits, creating work for other editors to correct your entries, perhaps you should post a draft on the Talk page first, so you can get help with prose and reference formatting. The content leading to catechin immune function where you made an edit created an error in reference formatting that was visible in bold red in the preview screen. --Zefr (talk) 14:23, 26 July 2016 (UTC)

- Removed from article - (+)-catechin has been used to treat acute viral hepatitis (Assessment and Management of Hepatobiliary Disease, p 371) and was marketed under the name Catergen by Zyma (now Novartis). Severe side effects (see Catechin#Immune function) lead to the withdrawal of the drug.

There are a number of different names for Catechin (as outlined on this page) - the drug was not referred to as 'Catechin' but Cyanidanol; the immunogenic effects are very well documented. Most of the literature of the 70s, 80s and early 90s refers to catechin by different names, especially cyanidanol - you can't really blame me for that. I have selected deliberately a non-primary reference (i.e. a textbook on the treatment of liver diseases) - but this makes it of course more difficult to access.
I also fail to see how this paragraph is "poorly written with punctuation (...) errors" (yes - I see the lead).
But lastly, I really don't understand the resistance against including historical information. If they are so irrelevant, why does the article mention the extraction from green tea and cocoa beans?Ggux (talk) 14:52, 26 July 2016 (UTC)

Immune function[edit]

Zefr - why did you remove the reference to immune function? This is very well documented and the reference used is not a primary source but a review article. It is relevant and the information is used for example in the toxicological assessment of phenolic compounds. I appreciate that we disagree about the inclusion of historic data - but the ability of catechin to cause haemolytic anaemia via auto-antibodies is neither a historic remark nor irrelevant. I'm happy to provide more details about this if necessary - but a paragraph on catechin-bioactivity should include these effects as well. Ggux (talk) 22:28, 26 July 2016 (UTC)

The reference has to comply with source quality described in WP:MEDRS. Please read this, as it will clarify your choice of sources in the future when pertaining to human health or disease. --Zefr (talk) 22:37, 26 July 2016 (UTC)
Having read WP:MEDRS, I fail to see how "Martinez SE; Davies NM; Reynolds JK (2013). "Toxicology and Safety of Flavonoids". Methods of Analysis, Preclinical and Clinical Pharmacokinetics, Safety, and Toxicology. John Wiley & Son. p. 257. ISBN 978-0-470-57871-1." could not be seen as a reliable source. It is a medical textbook and includes numerous references to primary sources. Ggux (talk) 22:59, 26 July 2016 (UTC)
For this type of content you wanted to add: "Catechin and its metabolites can bind tightly to red blood cells and thereby induce the development of Autoantibody, resulting in haemolytic anaemia and renal failure", you would need a systematic review of high-quality controlled trials to support statement of an effect on immune functions. No such work has been done. --Zefr (talk) 23:58, 26 July 2016 (UTC)
That is not possible as there are no systematic reviews - but a sufficient number of case reports, primary studies etc. systematic reviews are not conducted for all biomedical questions - and applying this criterion correctly, you would probably have to remove 2/3 of the catechin article. A book chapter is in general a reasonably good review, and this one includes numerous references to primary sources. I will revise the statement to refer to the hepatoprotective drug and it's side effect - it is, in my opinion, extremely relevant.Ggux (talk) 06:48, 27 July 2016 (UTC)

Systematic review[edit]

Zefr - if I were to write and publish a systematic review on catechin, would this be a sufficient source to include here?Ggux (talk) 11:16, 27 July 2016 (UTC)

WP:SELFPUBLISH; WP:MEDINDY. --Zefr (talk) 13:46, 27 July 2016 (UTC)
Zefr Ggux (talk) 14:03, 27 July 2016 (UTC)Should I then take out all references of which I am an author?Ggux (talk) 14:24, 27 July 2016 (UTC)
It is likely there are independent secondary sources adequate to represent the facts other than your own studies, so you should use them. Using your own research potentially leads to WP:SYNTH and WP:OR which are discouraged. As WP is an encyclopedia, not a textbook for writing your own research results, WP:5P1 applies, and for topics like catechin which partly fall under human health, medical references should comply with WP:MEDREV. --Zefr (talk) 14:38, 27 July 2016 (UTC)
I understand the concept of focusing on secondary sources, but there simply aren't many for catechin. What makes for example the Linus-Pauling-Institute Website more reliable than a textbook on the safety of flavonoids? Based on this discussion, I think there is really the need for a proper review of catechins. But if I were to write such a review (and obviously publish it in an appropriate journal), wouldn't this be a very suitable source of information? After all, it would have been peer reviewed. — Preceding unsigned comment added by Ggux (talkcontribs) 14:47, 27 July 2016 (UTC) Ggux (talk) 14:52, 27 July 2016 (UTC)

RfC:Is historical overview appropriate?[edit]

The consensus is that the proposed statement is appropriate with a suggested modification by Roches to make the statement more specific by using specific years. Cunard (talk) 03:19, 15 August 2016 (UTC)

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

I believe a brief overview of the historical use of catechin is appropriate in an encyclopaedic article and belief the following statement is appropriate

"Catechin-containing extracts have a long been used for the treatment of heart diseases,[1][2] and an effect on the permeability of capillaries has been shown 1936.[3]" It does not give overdue importance to historical data, but it puts current research into context.

Is it? Ggux (talk) 14:24, 27 July 2016 (UTC)

  • Yes, it seems to me relevant. (I have moved the refs up to appear in this section.) Maproom (talk) 06:25, 5 August 2016 (UTC)
    • Thank you.Ggux (talk) 09:11, 5 August 2016 (UTC)
  1. ^ Schroeder, Johann (1655). Pharmacopoeia medico-chymica: sive thesaurus pharmacologeus. Ulmae Suevorum: Johannis Gerlini. 
  2. ^ Berends, KAW (1829). Handbuch der praktischen Arzneiwissenschaft oder der speziellen Pathologie und Therapie. Berlin: Enslin. 
  3. ^ Armentano, L; Bentsáth, A; Béres, T; Rusznyák, St; Szent-Györgyi, A (1936). "Über den Einfluß von Substanzen der Flavongruppe auf die Permeabilität der Kapillaren. Vitamin P". Deutsche Medizinische Wochenschrift. Thieme. 62 (33): 1325–1328. doi:10.1055/s-0028-1141260. 
      • Zefr - I assumed that after discussion with other editors (such as Maproom here) it is appropriate to reinstate the text. I have asked you before why you consider these references to be weak, however haven't received a reply. The references are readily available in libraries and it is easy to confirm the statement. I have therefore re-instated the previous version.Ggux (talk) 23:11, 5 August 2016 (UTC)
  • Yes but avoid vague statements like "long." For example: "Catechin-containing extracts were recommended for the treatment of heart disease as long ago as 1655. In 1936, catechin was observed to affect the permeability of capillaries." Roches (talk) 01:30, 7 August 2016 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

RfC:Relevance of statement?[edit]

The consensus is that the proposed statement is relevant and should be rewritten slightly as suggested by Maproom. Cunard (talk) 03:19, 15 August 2016 (UTC)

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Catechin has been used as a drug in the 1970s and 1980s (under the name 'Catergen'), but the drug has been withdrawn after it was discovered that catechin can result in the formation of auto-antibodies - which resulted in severe side effects including fatalities. In my opinion, the effect of catechin on the immune system is therefore relevant and the following paragraph should be included: "Catechin and its metabolites can bind tightly to red blood cells and thereby induce the development of Autoantibody, resulting in haemolytic anaemia and renal failure. [1] This has resulted in the withdrawal of the catechin-containing drug Catergen, used to treat viral hepatitis [2], from market in 1985. [3]" Ggux (talk) 14:24, 27 July 2016 (UTC)

  • Agree. I would rewrite the statement slightly: "Catechin and its metabolites can bind tightly to red blood cells and thereby induce the development of autoantibodies, resulting in haemolytic anaemia and renal failure.[4] This resulted in the withdrawal of the catechin-containing drug Catergen, used to treat viral hepatitis[5], from market in 1985.[6]" Maproom (talk) 06:22, 6 August 2016 (UTC)
    • Thank you.Ggux (talk) 15:24, 6 August 2016 (UTC)
  • Agree with the relevance of the statement and the wording above. Roches (talk) 01:32, 7 August 2016 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
  1. ^ Martinez SE; Davies NM; Reynolds JK (2013). "Toxicology and Safety of Flavonoids". Methods of Analysis, Preclinical and Clinical Pharmacokinetics, Safety, and Toxicology. John Wiley & Son. p. 257. ISBN 978-0-470-57871-1. 
  2. ^ Bode, JC (1987). Assessment and Management of Hepatobiliary Disease. Berlin: Springer-Verlag. p. 371. doi:10.1007/978-3-642-72631-6. ISBN 978-3-642-72631-6. 
  3. ^ "Ruhen der Zulassung für Catergen" (PDF). Deutsches Ärzteblatt. 82 (38): 2706. 
  4. ^ Martinez SE; Davies NM; Reynolds JK (2013). "Toxicology and Safety of Flavonoids". Methods of Analysis, Preclinical and Clinical Pharmacokinetics, Safety, and Toxicology. John Wiley & Son. p. 257. ISBN 978-0-470-57871-1. 
  5. ^ Bode, JC (1987). Assessment and Management of Hepatobiliary Disease. Berlin: Springer-Verlag. p. 371. doi:10.1007/978-3-642-72631-6. ISBN 978-3-642-72631-6. 
  6. ^ "Ruhen der Zulassung für Catergen" (PDF). Deutsches Ärzteblatt. 82 (38): 2706.