A-type proanthocyanidin

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A type proanthocyanidins are a specific type of proanthocyanidins, which are a class of flavanoid. Proanthocyanidins fall under a wide range of names in the nutritional and scientific vernacular, including oligomeric proanthocyanidins, flavanoids, polyphenols, condensed tannins, and OPCs. Proanthocyanidins were first popularized by French scientist Jacques Masquelier.[1]

Distribution in plants[edit]

Schematic chemical structure of an A type proanthocyanidin dimer

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

A-type proanthocyanidin glycosides can be isolated from cocoa liquor.[3]


Other A-type proanthocyanidins can be found in cranberries,[2] in apricots, in cinnamon,[4] in Prunus armeniaca (ent-epiafzelechin-3-O-p-hydroxybenzoate-(4α→8,2α→O→7)-epiafzelechin) and in peanut skins (epicatechin-(2β→O→7, 4β→8)-ent-epicatechin).[5]

Epi-afzelechin-(4β→8, 2β→O→7)-afzelechin (geranin A) and epi-catechin-(4β→8, 2β→O→7)-afzelechin (geranin B) can be found in Geranium niveum.[6]


An A type proanthocyanidins trimer can be found in Lindera aggregata (epicatechin-(4β→8,2β→O→7)-entcatechin-(4β-8)-catechin).[8] This compound shows cytoprotective action against ethanol-induced gastric injury.[9]

In Ecdysanthera utilis (epicatechin-(4β→8,2β→O→7)-epicatechin-(4β→8)-epicatechin and epicatechin-(4β→8)-epicatechin-(4β→8,2β→O→7)-epicatechin-(4β→8)-epicatechin) can be found.[10]


B-type procyanidins (catechin dimers) can be converted to A-type procyanidins by radical oxidation.[11] 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).[12]

No effect on urinary tract infection[edit]

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 units in the small intestine, then cleaved into smaller phenolic acids with no known biological role.[13]

In vitro, A-type proanthocyanidins isolated from cranberry juice cocktail demonstrated anti-adhesion activity against E. coli binding to urinary tract epithelial cells, whereas B-type proanthocyanidins from grape exhibited minor activity.[14] However, in humans, there is no sufficient clinical evidence that cranberry type-A proanthocyanidins are effective in lowering risk of urinary tract infection.[15][16]


  1. ^ Fine, AM (2000). "Oligomeric proanthocyanidin complexes: history, structure, and phytopharmaceutical applications" (PDF). Alternative medicine review 5 (2): 144–51. PMID 10767669. 
  2. ^ a b Neto, CC (2007). "Cranberry and its phytochemicals: a review of in vitro anticancer studies". The Journal of nutrition 137 (1 Suppl): 186S–193S. PMID 17182824. 
  3. ^ Hatano, T; Miyatake, H; Natsume, M; Osakabe, N; Takizawa, T; Ito, H; Yoshida, T (2002). "Proanthocyanidin glycosides and related polyphenols from cacao liquor and their antioxidant effects". Phytochemistry 59 (7): 749–58. doi:10.1016/S0031-9422(02)00051-1. PMID 11909632. 
  4. ^ María Luisa Mateos-Martín, Elisabet Fuguet, Carmen Quero, Jara Pérez-Jiménez, Josep Lluís Torres. (2012). "New identification of proanthocyanidins in cinnamon (Cinnamomum zeylanicum L.) using MALDI-TOF/TOF mass spectrometry". Analytical and Bioanalytical Chemistry 402 (3): 1327–1336. doi:10.1007/s00216-011-5557-3. PMID 22101466. 
  5. ^ Hongxiang Lou; Yamazaku Y.; Sasaku T.; Uchida M.; Tanaka H.; Oka S. (1999). "A-type proanthocyanidins from peanut skins". Phytochemistry 51 (2): 297–308. doi:10.1016/S0031-9422(98)00736-5. 
  6. ^ Calzada, F; Cerda-García-Rojas, CM; Meckes, M; Cedillo-Rivera, R; Bye, R; Mata, R (1999). "Geranins a and B, new antiprotozoal A-type proanthocyanidins from Geranium niveum". Journal of Natural Products 62 (5): 705–9. doi:10.1021/np980467b. PMID 10346950. 
  7. ^ Baek Nam-In; Kennelly E.J.; Kardono L.B.S.; Tsauri S.; Padmawinata K.; Soejarto D.D.; Kinghorn A.D. (1994). "Flavonoids and a proanthrocyanidin from rhizomes of Selliguea feei". Phytochemistry 36 (2): 513–518. doi:10.1016/S0031-9422(00)97105-X. 
  8. ^ Feng, Zhang Chao; Shi, Sun Qi; Tao, Wang Zheng; Hattori, Masao (2003). "One New A-type Proanthocyanidin Trimer from Lindera aggregata (Sims) Kosterm" (PDF). Chinese Chemical Letters 14 (10): 1033–1036. 
  9. ^ M. Zhu; C. T. Luk; T. H. Lew (1998). "Cytoprotective Effect of Lindera aggregata Roots Against Ethanol-Induced Acute Gastric Injury". Pharmaceutical Biology 36 (3): 222–226. doi:10.1076/phbi. 
  10. ^ Lin, Lie-Chwen; Kuo, Yuh-Chi; Chou, Cheng-Jen (2002). "Immunomodulatory Proanthocyanidins fromEcdysantherautilis". Journal of Natural Products 65 (4): 505–8. doi:10.1021/np010414l. PMID 11975489. 
  11. ^ Kondo, Kazunari; Kurihara, Masaaki; Fukuhara, Kiyoshi; Tanaka, Takashi; Suzuki, Takashi; Miyata, Naoki; Toyoda, Masatake (2000). "Conversion of procyanidin B-type (catechin dimer) to A-type: Evidence for abstraction of C-2 hydrogen in catechin during radical oxidation". Tetrahedron Letters 41 (4): 485. doi:10.1016/S0040-4039(99)02097-3. 
  12. ^ Li, Hui-Jing; Deinzer, Max L. (2008). "The mass spectral analysis of isolated hops A-type proanthocyanidins by electrospray ionization tandem mass spectrometry". Journal of Mass Spectrometry 43 (10): 1353–63. doi:10.1002/jms.1411. PMID 18416438. 
  13. ^ María Luisa Mateos-Martín, Jara Pérez-Jiménez, Elisabet Fuguet and Josep Lluís Torres. (2012). "Profile of urinary and fecal proanthocyanidin metabolites from common cinnamon (Cinnamomum zeylanicum L.) in rats". Mol. Nutr. Food Res. 56 (4): 671–675. doi:10.1002/mnfr.201100672. PMID 22383303. 
  14. ^ Howell AB, Reed JD, Krueger CG, Winterbottom R, Cunningham DG, Leahy M (2005). "A-type cranberry proanthocyanidins and uropathogenic bacterial anti-adhesion activity". Phytochemistry 66 (18): 2281–91. doi:10.1016/j.phytochem.2005.05.022. PMID 16055161. 
  15. ^ "Scientific Opinion on the substantiation of a health claim related to CranMax® and reduction of the risk of urinary tract infection by inhibiting the adhesion of certain bacteria in the urinary tract pursuant to Article 14 of Regulation (EC) No 1924/20061" (PDF). EFSA Journal (European Food Safety Authority) 12 (5): 3657. 2014. Retrieved 22 May 2014. 
  16. ^ Jepson, RG; Williams, G; Craig, JC (Oct 17, 2012). Jepson, Ruth G, ed. "Cranberries for preventing urinary tract infections". Cochrane database of systematic reviews (Online) 10: CD001321. doi:10.1002/14651858.CD001321.pub5. PMID 23076891.