Proanthocyanidins antimicrobial activity

Catechins and Proanthocyanidins Naturally Occurring 0-Heterocycles with Antimicrobial Activity... 

Biological Activity of Catechins and Proanthocyanidins Other than Antimicrobial Activity... 

Additional hypotheses for their mechanism of action have more recently been proposed. It is well known that proanthocyanidins are able to complex metals through their ortho-diphenol groups. This property is often viewed as imparting negative traits (e.g., reduction of the bioavailability of essential mineral micronutrients, especially iron and zinc) [87]. Since iron depletion causes severe limitation to microbial growth, their ability to bind iron has been suggested as one of the possible mechanisms explaining the antimicrobial activity of proanthocyanidins [88] (Table 1). 

Buzzini P, Timchetti B, leri F, Goretti M, Branda E, Mulinacci N, Romani A (2007) Cate-chins and Proanthocyanidins Naturally Occurring 0-Heterocycles with Antimicrobial Activity. 10 239-264... 

De R, Kundu P, Swamakar S, Ramamurthy T, Chowdhury A, Nair GB, Mukhopadhyay AK(2009) Antimicrobial activity of curcumin against Helicobacter pylori isolates from India and during infections in mice. Antimicrob Agents Chemother 53 1592-1597 De Bruyne T, Pieters L, Witvrouw M, De Clercq E, Vanden Berghe D, VUetinck AJ (1999) Biological evaluation of proanthocyanidin dimers and related polyphenols. J Nat Prod 62 954-958... 

Although a few mechanisms have so far been proposed to explain the antimicrobial properties exhibited by proanthocyanidins (e.g., inhibition of extracellular enzymes) [86], Jones et al. [83] postulated that their ability to bind bacterial cell coat polymers and their abihty to inhibit cell-associated proteolysis might be considered responsible for the observed activity (Table 1). Accordingly, despite the formation of complexes with cell coat polymers, proanthocyanidins penetrated to the cell wall in sufficient concentration to react with one or more ultra-structural components and to selectively inhibit cell wall synthesis. Decreased proteolysis in these strains may also reflect a reduction of the export of proteases from the cell in the presence of proanthocyanidins [83]. 

Sivakumaran S, Molan AL, Meagher LP, Kolb B, Foo LY, Lane GA, Attwood GA, Fraser K, Tavendale M (2004) Variation in antimicrobial action of proanthocyanidins from Dorycnium rectum against rumen bacteria. Phytochemistry 65 2485-2497 Skene IK, Brooker JD (1995) Characterization of tannin acylhydrolase activity in the ruminal bacterium Selenomonas ruminantium. Anaerobe 1 321-327 Sly LI, Cahill MM, Osawa R, Fujisawa T (1997) The tannindegrading species Streptococcus gallolyticus and Streptococcus caprinus are subjective synonyms. Int J Syst Bacteriol 47 893-894... 

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