proanthocyanidin

Proanthocyanidins, including the lesser bioactive and bioavailable polymers (four or more catechins), represent a group of condensed flavan-3-ols, such as procyanidins, prodelphinidins and propelargonidins. They can be found in many plants, most notably apples, maritime pine bark and that of most other pine species, cinnamon,{{cite journal | title = New identification of proanthocyanidins in cinnamon (Cinnamomum zeylanicum L.) using MALDI-TOF/TOF mass spectrometry | display-authors=3 |vauthors = Mateos-Martín ML, Fuguet E, Quero C, Pérez-Jiménez J, Torres JL| year = 2012 | journal = Analytical and Bioanalytical Chemistry | volume = 402 | issue = 3 | pages = 1327–1336 | doi = 10.1007/s00216-011-5557-3 | pmid = 22101466| hdl = 10261/88579 | s2cid = 23120410 }} aronia fruit, cocoa beans, grape seed, grape skin (procyanidins and prodelphinidins),{{cite journal |last1=Souquet |first1=J |title=Polymeric proanthocyanidins from grape skins |journal=Phytochemistry |volume=43 |pages=509–512 |year=1996 |doi=10.1016/0031-9422(96)00301-9 |last2=Cheynier |first2=Véronique |last3=Brossaud |first3=Franck |last4=Moutounet |first4=Michel |issue=2|bibcode=1996PChem..43..509S }} and red wines of Vitis vinifera (the European wine grape). However, bilberry, cranberry, black currant, green tea, black tea, and other plants also contain these flavonoids. Cocoa beans contain the highest concentrations. Proanthocyanidins also may be isolated from Quercus petraea and Q. robur heartwood (wine barrel oaks).{{cite journal |last1=Vivas |first1=N |last2=Nonier |first2=M |last3=Pianet |first3=I |last4=Vivasdegaulejac |first4=N |last5=Fouquet |first5=E |title=Proanthocyanidins from Quercus petraea and Q. robur heartwood: quantification and structures |journal=Comptes Rendus Chimie |volume=9 |pages=120–126 |year=2006 |doi=10.1016/j.crci.2005.09.001|url=https://comptes-rendus.academie-sciences.fr/chimie/articles/10.1016/j.crci.2005.09.001/ |url-access=subscription }} Açaí oil, obtained from the fruit of the açaí palm (Euterpe oleracea), is rich in numerous procyanidin oligomers.{{cite journal |journal = J Agric Food Chem |date=Jun 2008 | volume = 56 | issue = 12 | pages = 4631–4636 | title = Chemical composition, antioxidant properties, and thermal stability of a phytochemical enriched oil from Acai (Euterpe oleracea Mart.) |pmid = 18522407| doi = 10.1021/jf800161u |vauthors=Pacheco-Palencia LA, Mertens-Talcott S, Talcott ST }}

Apples contain on average per serving about eight times the amount of proanthocyanidin found in wine, with some of the highest amounts found in the Red Delicious and Granny Smith varieties.{{cite journal |first1=John F. |last1=Hammerstone |first2=Sheryl A. |last2=Lazarus |first3=Harold H. |last3=Schmitz |title=Procyanidin content and variation in some commonly consumed foods |volume=130 |issue=8S Suppl |pages=2086S–2092S |journal=The Journal of Nutrition |date=August 2000 |pmid=10917927 |quote=Figure 5|doi=10.1093/jn/130.8.2086S |doi-access=free }}

An extract of maritime pine bark called Pycnogenol bears 65–75 percent proanthocyanidins (procyanidins).{{cite journal |last1=Rohdewald |first1=P |title=A review of the French maritime pine bark extract (Pycnogenol), a herbal medication with a diverse clinical pharmacology |journal=International Journal of Clinical Pharmacology and Therapeutics |volume=40 |issue=4 |pages=158–168 |year=2002 |pmid=11996210 |doi=10.5414/cpp40158}} Thus a 100 mg serving would contain 65 to 75 mg of proanthocyanidins (procyanidins).

Proanthocyanidin glycosides can be isolated from cocoa liquor.{{cite journal |last1=Hatano |first1=T |last2=Miyatake |first2=H |last3=Natsume |first3=M |last4=Osakabe |first4=N |last5=Takizawa |first5=T |last6=Ito |first6=H |last7=Yoshida |first7=T |title=Proanthocyanidin glycosides and related polyphenols from cacao liquor and their antioxidant effects |journal=Phytochemistry |volume=59 |issue=7 |year=2002 |pmid=11909632 |doi=10.1016/S0031-9422(02)00051-1 |pages=749–758|bibcode=2002PChem..59..749H }}

The seed testas of field beans (Vicia faba) contain proanthocyanidins{{Cite journal | last1 = Merghem | first1 = R. | last2 = Jay | first2 = M. | last3 = Brun | first3 = N. | last4 = Voirin | first4 = B. | title = Qualitative analysis and HPLC isolation and identification of procyanidins fromvicia faba | doi = 10.1002/pca.731 | journal = Phytochemical Analysis | volume = 15 | issue = 2 | pages = 95–99 | year = 2004 | pmid = 15116939| bibcode = 2004PChAn..15...95M }} that affect the digestibility in piglets{{Cite journal | last1 = Van Der Poel | first1 = A. F. B. | last2 = Dellaert | first2 = L. M. W. | last3 = Van Norel | first3 = A. | last4 = Helsper | first4 = J. P. F. G. | title = The digestibility in piglets of faba bean (Vicia faba L.) as affected by breeding towards the absence of condensed tannins | doi = 10.1079/BJN19920134 | journal = British Journal of Nutrition | volume = 68 | issue = 3 | pages = 793–800 | year = 2007 | pmid = 1493141| doi-access = free }} and could have an inhibitory activity on enzymes.{{Cite journal | last1 = Griffiths | first1 = D. W. | title = The polyphenolic content and enzyme inhibitory activity of testas from bean (Vicia faba) and pea (Pisum spp.) varieties | doi = 10.1002/jsfa.2740320808 | journal = Journal of the Science of Food and Agriculture | volume = 32 | issue = 8 | pages = 797–804 | year = 1981 | bibcode = 1981JSFA...32..797G }} Cistus salviifolius also contains oligomeric proanthocyanidins.{{Cite journal | last1 = Qa’Dan | first1 = F. | last2 = Petereit | first2 = F. | last3 = Mansoor | first3 = K. | last4 = Nahrstedt | first4 = A. | title = Antioxidant oligomeric proanthocyanidins fromCistus salvifolius | doi = 10.1080/14786410600899225 | journal = Natural Product Research | volume = 20 | issue = 13 | pages = 1216–1224 | year = 2006 | pmid = 17127512| s2cid = 254865 }}

Condensed tannins may be characterised by a number of techniques including depolymerisation, asymmetric flow field flow fractionation or small-angle X-ray scattering.

DMACA is a dye that is particularly useful for localization of proanthocyanidin compounds in plant histology. The use of the reagent results in blue staining.{{cite journal |last1=Bogs |first1=J. |last2=Jaffe |first2=F. W. |last3=Takos |first3=A. M. |last4=Walker |first4=A. R. |last5=Robinson |first5=S. P. |title=The Grapevine Transcription Factor VvMYBPA1 Regulates Proanthocyanidin Synthesis during Fruit Development |journal=Plant Physiology |volume=143 |issue=3 |pages=1347–1361 |year=2007 |pmid=17208963 |pmc=1820911 |doi=10.1104/pp.106.093203}} It can also be used to titrate proanthocyanidins.

Proanthocyanidins from field beans (Vicia faba){{Cite journal | last1 = Cabrera | first1 = A. | last2 = Martin | first2 = A. | doi = 10.1017/S0021859600084665 | title = Genetics of tannin content and its relationship with flower and testa colours in Vicia faba | journal = The Journal of Agricultural Science | volume = 113 | pages = 93–98 | year = 2009 | s2cid = 84456901 }} or barley{{Cite journal | last1 = Kristensen | first1 = H. | last2 = Aastrup | first2 = S. | doi = 10.1007/BF02906893 | title = A non-destructive screening method for proanthocyanidin-free barley mutants | journal = Carlsberg Research Communications | volume = 51 | issue = 7 | pages = 509–513 | year = 1986 | doi-access = free }} have been estimated using the vanillin-HCl method, resulting in a red color of the test in the presence of catechins or proanthocyanidins.

Proanthocyanidins can be titrated using the Procyanidolic Index (also called the Bates-Smith Assay). It is a testing method that measures the change in color when the product is mixed with certain chemicals. The greater the color changes, the higher the PCOs content is. However, the Procyanidolic Index is a relative value that can measure well over 100. Unfortunately, a Procyanidolic Index of 95 was erroneously taken to mean 95% PCO by some and began appearing on the labels of finished products. All current methods of analysis suggest that the actual PCO content of these products is much lower than 95%.[http://www.activin.com/Testing%20White%20paper__.html Grape Seed Extract, White paper, The Grape Seed Method Evaluation Committee, Under the Auspices of NNFA ComPli] {{webarchive|url=https://web.archive.org/web/20021224073156/http://www.activin.com/Testing%20White%20paper__.html |date=2002-12-24 }}{{Unreliable medical source|date=October 2010}}

Gel permeation chromatography (GPC) analysis allows separation of monomers from larger proanthocyanidin molecules.{{Cite journal

| pmid = 21930278

| year = 2011

| last1 = Stringano

| first1 = E

| title = Simple solution for a complex problem: Proanthocyanidins, galloyl glucoses and ellagitannins fit on a single calibration curve in high performance-gel permeation chromatography

| journal = Journal of Chromatography A

| volume = 1218

| issue = 43

| pages = 7804–7812

| last2 = Gea

| first2 = A

| last3 = Salminen

| first3 = J. P.

| last4 = Mueller-Harvey

| first4 = I

| doi = 10.1016/j.chroma.2011.08.082

}}

Monomers of proanthocyanidins can be characterized by analysis with HPLC and mass spectrometry.{{Cite journal

| pmid = 24665824

| year = 2014

| last1 = Engström

| first1 = M. T.

| title = Rapid Qualitative and Quantitative Analyses of Proanthocyanidin Oligomers and Polymers by UPLC-MS/MS

| journal = Journal of Agricultural and Food Chemistry

| volume = 62

| issue = 15

| pages = 3390–3399

| last2 = Pälijärvi

| first2 = M

| last3 = Fryganas

| first3 = C

| last4 = Grabber

| first4 = J. H.

| last5 = Mueller-Harvey

| first5 = I

| last6 = Salminen

| first6 = J. P.

| doi = 10.1021/jf500745y

}} Condensed tannins can undergo acid-catalyzed cleavage in the presence of a nucleophile like phloroglucinol (reaction called phloroglucinolysis), thioglycolic acid (thioglycolysis), benzyl mercaptan or cysteamine (processes called thiolysis{{cite journal |last1=Torres |first1=J. L. |last2=Lozano |first2=C. |title=Chromatographic characterization of proanthocyanidins after thiolysis with cysteamine |journal=Chromatographia |volume=54 |pages=523–526 |year=2001 |doi=10.1007/BF02491211 |issue=7–8|s2cid=95355684 }}) leading to the formation of oligomers that can be further analyzed.{{cite journal |last1=Jorgensen |first1=Emily M. |last2=Marin |first2=Anna B. |last3=Kennedy |first3=James A. |title=Analysis of the Oxidative Degradation of Proanthocyanidins under Basic Conditions |journal=Journal of Agricultural and Food Chemistry |volume=52 |issue=8 |pages=2292–2296 |year=2004 |pmid=15080635 |doi=10.1021/jf035311i}}

Tandem mass spectrometry can be used to sequence proanthocyanidins.{{cite journal | last1 = Li | first1 = Hui-Jing | last2 = Deinzer | first2 = Max L | year = 2007 | title = Tandem mass spectrometry for sequencing proanthocyanidins | journal = Analytical Chemistry | volume = 79 | issue = 4| pages = 1739–1748 | id = {{INIST|18534021}} | doi=10.1021/ac061823v| pmid = 17297981 }}

Oligomeric proanthocyanidins (OPC) strictly refer to dimer and trimer polymerizations of catechins. OPCs are found in most plants and thus are common in the human diet. Especially the skin, seeds, and seed coats of purple or red pigmented plants contain large amounts of OPCs. They are dense in grape seeds and skin, and therefore in red wine and grape seed extract, cocoa, nuts and all Prunus fruits (most concentrated in the skin), and in the bark of Cinnamomum (cinnamon) and Pinus pinaster (pine bark; formerly known as Pinus maritima), along with many other pine species. OPCs also can be found in blueberries, cranberries (notably procyanidin A2),{{cite journal|journal= J Sci Food Agric|year=2014|volume=94|issue=13|pages=2738–2745|doi=10.1002/jsfa.6618|pmid=24532348|title=Variation in proanthocyanidin content and composition among commonly grown North American cranberry cultivars (Vaccinium macrocarpon)|vauthors=Carpenter JL, Caruso FL, Tata A, Vorsa N, Neto CC |bibcode=2014JSFA...94.2738C }} aronia,{{cite journal|first1=Rod |last1=Taheri |first2=Bryan A. |last2=Connolly |first3=Mark H. |last3=Brand |first4=Bradley W. |last4=Bolling |title=Underutilized Chokeberry (Aronia melanocarpa, Aronia arbutifolia, Aronia prunifolia) Accessions Are Rich Sources of Anthocyanins, Flavonoids, Hydroxycinnamic Acids, and Proanthocyanidins |journal=Journal of Agricultural and Food Chemistry |volume=61 |issue=36 |pages=8581–8588 |year=2013 |pmid=23941506 |doi=10.1021/jf402449q}} hawthorn, rosehip, and sea buckthorn.{{cite journal |last1=Rösch |first1=Daniel R. |last2=Mügge |first2=Clemens |last3=Fogliano |first3=Vincenzo |last4=Kroh |first4=Lothar W. |title=Antioxidant Oligomeric Proanthocyanidins from Sea Buckthorn (Hippophaë rhamnoides) Pomace |journal=Journal of Agricultural and Food Chemistry |volume=52 |issue=22 |pages=6712–6718 |year=2004 |pmid=15506806 |doi=10.1021/jf040241g}}

Oligomeric proanthocyanidins can be extracted via Vaccinium pahalae from in vitro cell culture.{{cite journal |last1=Kandil |first1=F. E. |last2=Song |first2=L. |last3=Pezzuto |first3=J. M. |last4=Marley |first4=K. |last5=Seigler |first5=D. S. |last6=Smith |first6=M. A. L. |title=Isolation of oligomeric proanthocyanidins from flavonoid-producing cell cultures |journal=In Vitro Cellular & Developmental Biology - Plant |volume=36 |pages=492–500 |year=2000 |doi=10.1007/s11627-000-0088-1 |issue=6|s2cid=25781920 }} The US Department of Agriculture maintains a database of botanical and food sources of proanthocyanidins.{{cite web|title=USDA Database for the Proanthocyanidin Content of Selected Foods – 2004 |publisher=USDA|url=https://www.ars.usda.gov/ARSUserFiles/80400525/Data/PA/PA.pdf|date=2004|access-date=24 April 2014}}

In nature, proanthocyanidins serve among other chemical and induced defense mechanisms against plant pathogens and predators, such as occurs in strawberries.{{Cite journal | doi = 10.1093/pcp/pcr136| pmid = 21984602| title = The Strawberry Plant Defense Mechanism: A Molecular Review| journal = Plant and Cell Physiology| volume = 52| issue = 11| pages = 1873–1903| year = 2011| last1 = Amil-Ruiz | first1 = F.| last2 = Blanco-Portales | first2 = R.| last3 = Munoz-Blanco | first3 = J.| last4 = Caballero | first4 = J. L.| doi-access = free}}

Proanthocyanidin has low bioavailability, with 90% remaining unabsorbed from the intestines until metabolized by gut flora to the more bioavailable metabolites.

Condensed tannins can undergo acid-catalyzed cleavage in the presence of (or an excess of) a nucleophile{{Cite journal | last1 = Matthews | first1 = S. | last2 = Mila | first2 = I. | last3 = Scalbert | first3 = A. | last4 = Pollet | first4 = B. | last5 = Lapierre | first5 = C. | last6 = Hervé Du Penhoat | first6 = C. L. M. | last7 = Rolando | first7 = C. | last8 = Donnelly | first8 = D. M. X. | doi = 10.1021/jf9607573 | title = Method for Estimation of Proanthocyanidins Based on Their Acid Depolymerization in the Presence of Nucleophiles | journal = Journal of Agricultural and Food Chemistry | volume = 45 | issue = 4 | pages = 1195–1201 | year = 1997 }} like phloroglucinol (reaction called phloroglucinolysis), benzyl mercaptan (reaction called thiolysis), thioglycolic acid (reaction called thioglycolysis) or cysteamine. Flavan-3-ol compounds used with methanol produce short-chain procyanidin dimers, trimers, or tetramers which are more absorbable.{{Cite journal

| pmid = 23768384

| year = 2013

| last1 = Liu

| first1 = H

| title = Depolymerization of cranberry procyanidins using (+)-catechin, (-)-epicatechin, and (-)-epigallocatechin gallate as chain breakers

| journal = Food Chemistry

| volume = 141

| issue = 1

| pages = 488–494

| last2 = Zou

| first2 = T

| last3 = Gao

| first3 = J. M.

| last4 = Gu

| first4 = L

| doi = 10.1016/j.foodchem.2013.03.003

}}

These techniques are generally called depolymerisation and give information such as average degree of polymerisation or percentage of galloylation. These are SN1 reactions, a type of substitution reaction in organic chemistry, involving a carbocation intermediate under strongly acidic conditions in polar protic solvents like methanol. The reaction leads to the formation of free and derived monomers that can be further analyzed or used to enhance procyanidin absorption and bioavailability. The free monomers correspond to the terminal units of the condensed tannins chains.

In general, reactions are made in methanol, especially thiolysis, as benzyl mercaptan has a low solubility in water. They involve a moderate (50 to 90 °C) heating for a few minutes. Epimerisation may happen.

Phloroglucinolysis can be used for instance for proanthocyanidins characterisation in wine or in grape seeds and skin.{{Cite journal | last1 = Kennedy | first1 = J. A. | last2 = Jones | first2 = G. P. | doi = 10.1021/jf001030o | title = Analysis of Proanthocyanidin Cleavage Products Following Acid-Catalysis in the Presence of Excess Phloroglucinol | journal = Journal of Agricultural and Food Chemistry | volume = 49 | issue = 4 | pages = 1740–1746 | year = 2001 | pmid = 11308320}}

Thioglycolysis can be used to study proanthocyanidins{{Cite journal | last1 = Sears | first1 = K. D. | last2 = Casebier | first2 = R. L. | doi = 10.1039/C19680001437 | title = Cleavage of proanthocyanidins with thioglycollic acid | journal = Chemical Communications | issue = 22 | pages = 1437 | year = 1968 }} or the oxidation of condensed tannins.{{Cite journal

| last1 = Vernhet | first1 = A.

| last2 = Dubascoux | first2 = S. P.

| last3 = Cabane | first3 = B.

| last4 = Fulcrand | first4 = H. L. N.

| last5 = Dubreucq | first5 = E.

| last6 = Poncet-Legrand | first6 = C. L.

| doi = 10.1007/s00216-011-5076-2

| title = Characterization of oxidized tannins: Comparison of depolymerization methods, asymmetric flow field-flow fractionation and small-angle X-ray scattering

| journal = Analytical and Bioanalytical Chemistry

| volume = 401

| issue = 5

| pages = 1559–1569

| year = 2011

| pmid = 21573842

| s2cid = 4645218

}}, {{Cite journal | last1 = Vernhet | first1 = A. | last2 = Dubascoux | first2 = S. P. | last3 = Cabane | first3 = B. | last4 = Fulcrand | first4 = H. L. N. | last5 = Dubreucq | first5 = E. | last6 = Poncet-Legrand | first6 = C. L. | doi = 10.1007/s00216-011-5076-2 | title = Characterization of oxidized tannins: Comparison of depolymerization methods, asymmetric flow field-flow fractionation and small-angle X-ray scattering | journal = Analytical and Bioanalytical Chemistry | volume = 401 | issue = 5 | pages = 1559–1569 | year = 2011 | pmid = 21573842 | s2cid = 4645218 }} It is also used for lignin quantitation.{{Cite journal

| last1 = Lange | first1 = B. M.

| last2 = Lapierre | first2 = C.

| last3 = Sandermann Jr | first3 = H.

| title = Elicitor-Induced Spruce Stress Lignin (Structural Similarity to Early Developmental Lignins)

| journal = Plant Physiology

| volume = 108

| issue = 3

| pages = 1277–1287

| year = 1995

| pmid = 12228544

| pmc = 157483

| doi = 10.1104/pp.108.3.1277

}} Reaction on condensed tannins from Douglas fir bark produces epicatechin and catechin thioglycolates.[http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/16902/SongHongKeun1985.pdf?sequence=1 Douglas-Fir Bark: Characterization of a Condensed Tannin Extract, by Hong-Keun Song, A thesis submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science, December 13, 1984]

Condensed tannins from Lithocarpus glaber leaves have been analysed through acid-catalyzed degradation in the presence of cysteamine.{{Cite journal | last1 = Zhang | first1 = L. L. | last2 = Lin | first2 = Y. M. | doi = 10.3390/molecules13122986 | title = HPLC, NMR and MALDI-TOF MS Analysis of Condensed Tannins from Lithocarpus glaber Leaves with Potent Free Radical Scavenging Activity | journal = Molecules | volume = 13 | issue = 12 | pages = 2986–2997 | year = 2008 | pmid = 19052523| pmc = 6245341| doi-access = free }}

Cranberries have A2-type proanthocyanidins (PACs) which may be important for the ability of PACs to bind to proteins, such as the adhesins present on E. coli fimbriae and were thought to inhibit bacterial infections, such as urinary tract infections (UTIs).{{cite journal|last1=Howell|first1=AB|title=Bioactive compounds in cranberries and their role in prevention or urinary tract infections|journal=Mol Nutr Food Res|date=2007|volume=51|issue=6|pages=732–737|pmid=17487930|doi=10.1002/mnfr.200700038}} Clinical trials have produced mixed results when asking the question to confirm that PACs, particularly from cranberries, were an alternative to antibiotic prophylaxis for UTIs: 1) a 2014 scientific opinion by the European Food Safety Authority rejected physiological evidence that cranberry PACs have a role in inhibiting bacterial pathogens involved in UTIs; 2) an updated 2023 Cochrane Collaboration review supported the use of cranberry products for the prevention of UTIs for certain groups.

A 2017 systematic review concluded that cranberry products significantly reduced the incidence of UTIs, indicating that cranberry products may be effective particularly for individuals with recurrent infections.{{cite journal|last1=Luís|first1=Â|last2=Domingues|first2=F|last3=Pereira|first3=L|title=Can Cranberries Contribute to Reduce the Incidence of Urinary Tract Infections? A Systematic Review with Meta-Analysis and Trial Sequential Analysis of Clinical Trials.|journal=Journal of Urology|volume=198|issue=3|pages=614–621|date=10 March 2017|doi=10.1016/j.juro.2017.03.078|pmid=28288837|s2cid=206632675}} In 2019, the American Urological Association released guidelines stating that a moderate level of evidence supports the use of cranberry products containing PACs for possible prevention from recurrent UTIs.{{Cite web|url=https://www.auanet.org/guidelines/recurrent-uti|title=Recurrent Uncomplicated Urinary Tract Infections in Women: AUA/CUA/SUFU Guideline (2019)|date=2019|publisher=American Urological Association|website=www.auanet.org|access-date=2019-11-11}}

Proanthocyanidins are the principal polyphenols in red wine that are under research to assess risk of coronary heart disease and lower overall mortality.{{cite journal |last1=Corder |first1=R. |last2=Mullen |first2=W. |last3=Khan |first3=N. Q. |last4=Marks |first4=S. C. |last5=Wood |first5=E. G. |last6=Carrier |first6=M. J. |last7=Crozier |first7=A. |title=Oenology: Red wine procyanidins and vascular health |journal=Nature |volume=444 |issue=7119 |page=566 |year=2006 |pmid=17136085 |doi=10.1038/444566a|bibcode=2006Natur.444..566C |s2cid=4303406 |doi-access=free }} With tannins, they also influence the aroma, flavor, mouth-feel and astringency of red wines.{{Cite journal

| pmid = 21573848

| year = 2011

| last1 = Absalon

| first1 = C

| title = New strategies to study the chemical nature of wine oligomeric procyanidins

| journal = Analytical and Bioanalytical Chemistry

| volume = 401

| issue = 5

| pages = 1485–1495

| last2 = Fabre

| first2 = S

| last3 = Tarascou

| first3 = I

| last4 = Fouquet

| first4 = E

| last5 = Pianet

| first5 = I

| doi = 10.1007/s00216-011-4988-1

| s2cid = 8145537

}}{{Cite journal

| pmid = 23889258

| year = 2013

| last1 = Gonzalo-Diago

| first1 = A

| title = Taste and mouthfeel properties of red wines proanthocyanidins and their relation to the chemical composition

| journal = Journal of Agricultural and Food Chemistry

| volume = 61

| issue = 37

| pages = 8861–8870

| last2 = Dizy

| first2 = M

| last3 = Fernández-Zurbano

| first3 = P

| doi = 10.1021/jf401041q

| hdl = 10261/144130

}}

In red wines, total OPC content, including flavan-3-ols (catechins), was substantially higher (177  mg/L) than that in white wines (9  mg/L).{{cite journal |last1=Sánchez-Moreno |first1=Concepción |last2=Cao |first2=Guohua |last3=Ou |first3=Boxin |last4=Prior |first4=Ronald L. |title=Anthocyanin and Proanthocyanidin Content in Selected White and Red Wines. Oxygen Radical Absorbance Capacity Comparison with Nontraditional Wines Obtained from Highbush Blueberry |journal=Journal of Agricultural and Food Chemistry |volume=51 |issue=17 |pages=4889–4896 |year=2003 |pmid=12903941 |doi=10.1021/jf030081t}}

Proanthocyanidins found in the proprietary extract of maritime pine bark called Pycnogenol were not found (in 2012) to be effective as a treatment for any disease:

:"Current evidence is insufficient to support Pycnogenol(®) use for the treatment of any chronic disorder. Well-designed, adequately powered trials are needed to establish the value of this treatment."{{Cite journal|last1=Robertson|first1=Nina U.|last2=Schoonees|first2=Anel|last3=Brand|first3=Amanda|last4=Visser|first4=Janicke|date=29 September 2020|title=Pine bark (Pinus spp.) extract for treating chronic disorders|journal=The Cochrane Database of Systematic Reviews|volume=2020|issue=9|pages=CD008294|doi=10.1002/14651858.CD008294.pub5|issn=1469-493X|pmid=32990945|pmc=8094515}}

Proanthocyanidins are present in fresh grapes, juice, red wine, and other darkly pigmented fruits such as cranberry, blackcurrant, elderberry, and aronia.{{cite journal|vauthors=Wu X, Gu L, Prior RL, McKay S |year=2004|title=Characterization of anthocyanins and proanthocyanidins in some cultivars of Ribes, Aronia, and Sambucus and their antioxidant capacity|journal=Journal of Agricultural and Food Chemistry|volume=52|issue=26|pages=7846–7856|pmid=15612766|doi=10.1021/jf0486850}} Although red wine may contain more proanthocyanidins by mass per unit of volume than does red grape juice, red grape juice contains more proanthocyanidins per average serving size. An {{convert|8|USoz|ml|spell=in}} serving of grape juice averages 124 milligrams proanthocyanidins, whereas a {{convert|5|USoz|ml|spell=in}} serving of red wine averages 91 milligrams (i.e., 145.6 milligrams per 8 fl. oz. or 240 mL). Many other foods and beverages may also contain proanthocyanidins, but few attain the levels found in red grape seeds and skins, with a notable exception being aronia, which has the highest recorded level of proanthocyanidins among fruits assessed to date (664 milligrams per 100 g).

• A type proanthocyanidin
• B type proanthocyanidin
• Tannin
• Polyphenol
• Phenolic compounds in wine

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• [http://nccam.nih.gov/health/grapeseed/ataglance.htm Grape seed extract, US National Institutes of Health, Office of Dietary Supplements, The National Center for Complementary and Alternative Medicine, 2014]

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Category:Food chemistry

Category:Flavonoid antioxidants

Category:Condensed tannins