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Antioxidant capacity and in vitro prevention of dental plaque formation by extracts and condensed tannins of Paullinia cupana.

The researchers first quantified the antioxidants present in different types of guarana extracts. They found the following phytochemicals: caffeine, catechin, epicatechin, ent-epicatechin (chiral form of epicatechin) and different procyanidins. The antioxidant capacity was determined with the diphenylpicrylhydrazyl (DPPH) reduction test by measuring the RAC (relative antioxidant capacity) and IC50 (quantity of antioxidant needed to decrease the concentration of DPPH radical by 50%). The following guarana extracts were tested: water extract, crude extract (with acetone-water) and semi-purified extract.

The guarana seeds contained about 5% tannins and 6% methylxanthines (mainly caffeine). All extracts showed antioxidant activity, proportional to the polyphenol content. The free-radical scavenging capacities of the antioxidants were related to number of their hydroxyl groups.



Previous in-vivo studies have already demonstrated the antibacterial properties of guaran extracts. Nnew in vitro-tests with Streptococcus mutans, bacteria commonly found in the human oral cavity and significant contributor to tooth decay. All tested guarana extracts inhibited the adherence of Streptococcus mutans to a glass surface. The crude extract showed the strongest inhibitory action of up to 80%. The growth of Streptococcus mutans was not much influenced by the extracts. The researchers also noticed that the pH was decreased significantly, which may result in less demineralisation. The study concluded that the guarana extracts could be used to prevent bacterial dental plaque.


Source: Yamaguti-Sasaki E, Ito LA, Canteli VC, Ushirobira TM, Ueda-Nakamura T, Dias Filho BP, Nakamura CV and de Mello JC . Antioxidant capacity and in vitro prevention of dental plaque formation by extracts and condensed tannins of Paullinia cupana.. Molecules 2007; 12(8):1950-63


 
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