Procyanidins are members of the

proanthocyanidin Proanthocyanidins are a class of polyphenols found in many plants, such as cranberry, blueberry, and grape seeds. Chemically, they are oligomeric flavonoids. Many are oligomers of catechin and epicatechin and their gallic acid esters. More complex ...

(or condensed tannins) class of

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s. They are oligomeric compounds, formed from

catechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from ''catechu'', which is the tannic ...

and

epicatechin Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids. The name of the catechin chemical family derives from ''catechu'', which is the tanni ...

molecules. They yield

cyanidin Cyanidin is a natural organic compound. It is a particular type of anthocyanidin (glycoside version called anthocyanins). It is a pigment found in many red berries including grapes, bilberry, blackberry, blueberry, cherry, chokeberry, cranb ...

when depolymerized under oxidative conditions. See the box below entitled "Types of procyanidins" for links to articles on the various types.

Distribution in plants

Procyanidins, including the lesser bioactive / bioavailable polymers (4 or more catechines), represent a group of condensed flavan-3-ols that can be found in many plants, most notably

apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...

maritime pine ''Pinus pinaster'', the maritime pine or cluster pine, is a pine native to the south Atlantic Europe region and parts of the western Mediterranean. It is a hard, fast growing pine bearing small seeds with large wings. Description ''Pinus pinast ...

bark,

cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakfa ...

aronia ''Aronia'' is a genus of deciduous shrubs, the chokeberries, in the family Rosaceae native to eastern North America and most commonly found in wet woods and swamps. The genus Aronia is considered to have 3 species. The most common and wi ...

fruit,

cocoa bean The cocoa bean (technically cocoa seed) or simply cocoa (), also called the cacao bean (technically cacao seed) or cacao (), is the dried and fully fermented seed of ''Theobroma cacao'', from which cocoa solids (a mixture of nonfat substances ...

grape seed A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years ago ...

grape skin A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years ago, ...

, and

red wine Red wine is a type of wine made from dark-colored grape varieties. The color of the wine can range from intense violet, typical of young wines, through to brick red for mature wines and brown for older red wines. The juice from most purple grap ...

s of ''

Vitis vinifera ''Vitis vinifera'', the common grape vine, is a species of flowering plant, native to the Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran. There are curre ...

'' (the common grape). However,

bilberry Bilberries (), or sometimes European blueberries, are a primarily Eurasian species of low-growing shrubs in the genus ''Vaccinium'' (family Ericaceae), bearing edible, dark blue berries. The species most often referred to is ''Vaccinium myrtillus ...

cranberry Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus ''Oxycoccus'' of the genus ''Vaccinium''. In Britain, cranberry may refer to the native species ''Vaccinium oxycoccos'', while in North America, cranberry ...

black currant The blackcurrant (''Ribes nigrum''), also known as black currant or cassis, is a deciduous shrub in the family Grossulariaceae grown for its edible berries. It is native to temperate parts of central and northern Europe and northern Asia, whe ...

green tea Green tea is a type of tea that is made from '' Camellia sinensis'' leaves and buds that have not undergone the same withering and oxidation process which is used to make oolong teas and black teas. Green tea originated in China, and since the ...

black tea Black tea, also translated to red tea in various East Asian languages, is a type of tea that is more oxidized than oolong, yellow, white and green teas. Black tea is generally stronger in flavour than other teas. All five types are made from ...

, and other plants also contain these flavonoids.USDA, August 2004
USDA Database for the Proanthocyanidin Content of Selected Foods
PDF summary accessed from main USDA pag

Page accessed July 31, 2015 Procyanidins can also be isolated from ''

Quercus petraea ''Quercus petraea'', commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emble ...

'' and '' Q. robur'' heartwood (wine barrel oaks).

Açaí oil Açaí oil is obtained from the fruit of ''Euterpe oleracea'' (açaí palm), which grows in the Amazon rainforest. The oil is rich in phenolic compounds similar in profile to the pulp itself, such as vanillic acid, syringic acid, p-hydroxybenzoi ...

, obtained from the fruit of the

açaí palm The açaí palm (, , from Nheengatu ''asai''), '' Euterpe oleracea,'' is a species of palm tree (Arecaceae) cultivated for its fruit (açaí berries, or simply açaí), hearts of palm (a vegetable), leaves, and trunk wood. Global demand for t ...

(''Euterpe oleracea''), is rich in numerous procyanidin

oligomer In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relativ ...

s. Apples contain on average per serving about eight times the amount of procyanidin found in wine, with some of the highest amounts found in the

Red Delicious Red Delicious is a type of apple with a red exterior and sweet taste that was first recognized in Madison County, Iowa, in 1872. Today, the name ''Red Delicious'' comprises more than 50 cultivars. From 1968 to 2018, it was the most produced cu ...

and

Granny Smith The Granny Smith, also known as a green apple or sour apple, is an apple cultivar which originated in Australia in 1868. It is named after Maria Ann Smith, who propagated the cultivar from a chance seedling. The tree is thought to be a hybrid ...

varieties. The seed testas of field beans (''

Vicia faba ''Vicia faba'', commonly known as the broad bean, fava bean, or faba bean, is a species of vetch, a flowering plant in the pea and bean family Fabaceae. It is widely cultivated as a crop for human consumption, and also as a cover crop. Variet ...

'') contain procyanidins that affect the

digestibility Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...

in piglets and could have an inhibitory activity on

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

s. ''

Cistus salviifolius ''Cistus salviifolius'', common names sage-leaved rock-rose, salvia cistus or Gallipoli rose, is a shrub of the family Cistaceae. Etymology The genus name ''Cistus'' derives from the Ancient Greek words ''κίσθος'' (''kisthos'') meaning bas ...

'' also contains oligomeric procyanidins.

Analysis

Condensed tannins can be characterised by a number of techniques including depolymerisation, asymmetric flow field flow fractionation or small-angle

X-ray scattering X-ray scattering techniques are a family of non-destructive analytical techniques which reveal information about the crystal structure, chemical composition, and physical properties of materials and thin films. These techniques are based on observ ...

. DMACA is a dye used for localization of procyanidin compounds in plant histology. The use of the reagent results in blue staining. It can also be used to titrate procyanidins. Total phenols (or antioxidant effect) can be measured using the Folin-Ciocalteu reaction. Results are typically expressed as

gallic acid Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. It i ...

equivalents (GAE). Procyanidins from field beans (''

'') or

barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...

have been estimated using the vanillin-HCl method, resulting in a red color of the test in the presence of catechin or proanthocyanidins. Procyanidins 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%. An improved colorimetric test, called the ''Porter Assay'' or ''butanol-HCl-iron method'', is the most common PCO assay currently in use. The unit of measurement of the Porter Assay is the PVU (Porter Value Unit). The Porter Assay is a chemical test to help determine the potency of procyanidin containing compounds, such as grape seed extract. It is an acid hydrolysis, which splits larger chain units (dimers and trimers) into single unit monomers and oxidizes them. This leads to a colour change, which can be measured using a spectrophotometer. The greater the absorbance at a certain wavelength of light, the greater the potency. Ranges for grape seed extract are from 25 PVU for low grade material to over 300 for premium grape seed extracts.

Gel permeation chromatography Gel permeation chromatography (GPC) is a type of size-exclusion chromatography (SEC), that separates analytes on the basis of size, typically in organic solvents. The technique is often used for the analysis of polymers. As a technique, SEC was fi ...

(GPC) analysis allows to separate monomers from larger PCO molecules. Monomers of procyanidins can be characterized by

HPLC High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...

analysis. Condensed tannins can undergo acid-catalyzed cleavage in the presence of a

nucleophile In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are ...

phloroglucinol Phloroglucinol is an organic compound with the formula C6H3(OH)3. It is a colorless solid. It is used in the synthesis of pharmaceuticals and explosives. Phloroglucinol is one of three isomeric benzenetriols. The other two isomers are hydroxyqu ...

(reaction called phloroglucinolysis),

thioglycolic acid Thioglycolic acid (TGA) is the organic compound HSCH2CO2H. TGA is often called mercaptoacetic acid (MAA). It contains both a thiol ( mercaptan) and carboxylic acid functional groups. It is a colorless liquid with a strongly unpleasant odor. TGA i ...

(thioglycolysis), benzyl mercaptan or cysteamine (processes called

thiolysis Thiolysis is a reaction with a thiol (R-SH) that cleaves one compound into two. Thiolysis involves the addition of coenzyme A to one of the products. This reaction is similar to hydrolysis, which involves water instead of a thiol. This reaction is s ...

) leading to the formation of oligomers that can be further analyzed. Phloroglucinolysis can be used for instance for procyanidins characterisation in wine or in the grape seed and skin tissues. Thioglycolysis can be used to study procyanidins or the oxidation of condensed tannins. It is also used for

lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...

quantitation In mathematics and empirical science, quantification (or quantitation) is the act of counting and measuring that maps human sense observations and experiences into quantities. Quantification in this sense is fundamental to the scientific method. ...

. Reaction on condensed tannins from

Douglas fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

bark produces

and

thioglycolate Thioglycolic acid (TGA) is the organic compound HSCH2CO2H. TGA is often called mercaptoacetic acid (MAA). It contains both a thiol (mercaptan) and carboxylic acid functional groups. It is a colorless liquid with a strongly unpleasant odor. TGA is ...

s.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
/ref> Condensed tannins from ''

Lithocarpus glaber ''Lithocarpus glaber'', the Japanese oak, is a tree species in the genus '' Lithocarpus'' found in Japan, China and Taiwan. Mitami Shrine, a Shinto shrine in Sakai, Osaka Prefecture, Japan, is famous locally for its comparatively large populati ...

'' leaves have been analysed through acid-catalyzed degradation in the presence of cysteamine.

Research

Procyanidin content in

dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...

s has not been well documented. Pycnogenol is a dietary supplement derived from

extract An extract is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol, oil or water. Extracts may be sold as tinctures, absolutes or in powder form. The aromatic principles of many spices, nuts, h ...

s from

bark that contains 70% procyanidins, and is marketed with claims it can treat many conditions. The medical evidence is insufficient to support its use for the treatment of seven different chronic disorders.

References

External links

"Pycnogenol: MedlinePlus Supplements"
{{Procyanidin Food chemistry Flavonoid antioxidants de:Oligomere Proanthocyanidine nl:Proanthocyanidine zh:原花色素

Distribution in plants

Analysis

Research

See also

References

External links