A type proanthocyanidins are a specific type of

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 compl ...

s, which are a class of flavonoid. Proanthocyanidins fall under a wide range of names in the nutritional and scientific vernacular, including oligomeric proanthocyanidins, flavonoids,

polyphenol Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some o ...

s, condensed tannins, and OPCs. Proanthocyanidins were first popularized by French scientist Jacques Masquelier.

Distribution in plants

A-type linkage is a less common feature in proanthocyanidins with both 4β→8 ( B-type) and 2β→O→7 interflavanoid bonds. A-type proanthocyanidin

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycoside ...

s can be isolated from

cocoa liquor Chocolate liquor (cocoa liquor) is pure cocoa mass (cocoa paste) in solid or semi-solid form. Like the cocoa beans (nibs) from which it is produced, it contains both cocoa solids and cocoa butter in roughly equal proportion. It is produced f ...

Dimers

Procyanidin A1 Procyanidin A1 is an A type proanthocyanidin dimer. It is an epicatechin-(2β→7,4β→8)-catechin dimer found in '' Rhododendron spiciferum'', in peanut skins and in ''Ecdysanthera utilis''. Procyanidin B1 can be converted into procyanidin A1 ...

is an epicatechin-(2β→7,4β→8)-catechin dimer. * Procyanidin A2 is a dimeric (-)epicatechin. Other A-type proanthocyanidins can be found in

cranberries 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 ...

, cinnamon, peanut skins and ''

Geranium niveum ''Geranium niveum'' is a plant species in the genus '' Geranium''. It is a medicinal herb widely used by the Tarahumara Indians of Mexico. Geranin A (epi-afzelechin-(4β→8, 2β→O→7)-afzelechin), geranin B (epi-catechin-(4β→8, 2β→ ...

''.

Chemistry

B-type procyanidins (

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 tanni ...

dimers) can be converted to A-type procyanidins by radical oxidation. Fragmentation patterns for A-type proanthocyanidins include heterocyclic ring fission (HRF), retro-Diels-Alder (RDA) fission, benzofuran-forming fission (BFF) and quinone methide fission (QM).

Metabolism

The metabolism of type-A proanthocyanidins is significant since a large number of metabolites are detected in urine and feces soon after ingestion of foods rich in polymers, indicating rapid elimination and absence of physiological effect. Polymeric type-A proanthocyanidins are depolymerized into

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 ...

units in the small intestine, then cleaved into smaller

phenolic acids Phenolic acids or phenolcarboxylic acids are types of aromatic acid compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important naturally occurring types of ...

with no known biological role.

Research

''In vitro'', A-type proanthocyanidins isolated from

cranberry juice Cranberry juice is the liquid juice of the cranberry, typically manufactured to contain sugar, water, and other fruit juices. Cranberry – a fruit native to North America – is recognized for its bright red color, tart taste, and versat ...

cocktail demonstrated anti-adhesion activity against '' E. coli'' binding to

urinary tract The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, c ...

epithelial cells Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercell ...

, whereas B-type proanthocyanidins from grape exhibited minor activity. However, in humans, there is no sufficient clinical evidence that cranberry type-A proanthocyanidins are effective in lowering risk of

urinary tract infection A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidne ...

References

{{DEFAULTSORT:A Type Proanthocyanidin Condensed tannins