Proanthocyanidin-enriched extract of Rumex acetosa L. inhibits the in vitro adhesion of Porphyromonas gingivalis to KB cells and decreases the biofilm formation

Porphyromonas gingivalis is a gram-negative periodontal pathogen, which plays a significant role in the progression of chronic periodontitis and may even be involved in the development of other cardiovascular diseases. The first critical step for the initiation of periodontitis is the specific adhesion of bacteria to tissue cells. By forming complex biofilms, anaerobic bacteria as P. gingivalis evade the hosts immune defense. In contrast to conventional antibacterial therapy approaches, an acetone-water extract of Rumex acetosa L. (RA1) [1] was tested for in vitro antiadhesive activity on KB cells by flow cytometrie in order to initiate a development against the first step of the infection.

Bacteria, preincubated with RA1 (100 µg/mL) showed 25% less adhesion to KB cells. By coincubating bacteria, KB cells and RA1 (10 µg/mL) a significant decrease of adhesion of 37% was observed. Structure-activity relationship of relevant polyphenols from RA1 indicated that proanthocyanidins are responsible for these effects. Especially epicatechin-3-O-gallate-(4β-> 8)-epicatechin-3-O-gallate (20µM: 61%; 30µM: 96% inhibition) significantly reduces the adhesion of P. gingivalis to KB cells. Epicatechin-3-O-gallat has a lower antiadhesive activity (20µM: 21%; 30µM: 25% inhibition). Non-galloylated flavan-3-ols had no effect.

Besides the inhibition of bacterial adhesion, the influence of RA1 on the biofilm formation was investigated. We could detect a significant inhibition of biofilm formation, after staining the biofilm with crystal violet (RA1 100 µg/mL, 51% inhibition).

Reference:

[1] Bicker J, Petereit F, Hensel A (2009) Proanthocyanidins and a phloroglucinol derivative from Rumex acetosa L. Fitoterapia. 80(8); 483 – 95.