Antiadhesive effects of natural extracts out of Myrothamnus flabellifolia Welw. and Rumex acetosa L. against Porphyromonas gingivalis

Porphyromonas gingivalis (ATCC 33277), a Gram-negative anaerobic bacterium, is strongly associated with adult periodontitis, one of the major public health problems. The bacterium expresses a number of well-characterized virulence factors, including lipopolysaccharides, fimbriae and cysteine proteinases, designated gingipains, which contribute to an ultimately loss of tooth. One of the first steps in initiation of this inflammatory disease is the adhesion process of the bacterium to epithelium pocket and therefore it represents one possible aspect of therapy by blocking the adhesion. Basically, the bacterial adhesion is mediated by fimbriae, proteolytic activity and hemagglutinins. Toxicity of the extracts on P. gingivalis (1mg/mL) and KB cells (0.1mg/mL) were tested using MTT assay and did not show any toxic effects.

Polyphenol-enriched extracts from M. flabellifolia Welw. and R. acetosa L. showed strong inhibition (two titer steps) of hemagglutinating activity against P. gingivalis.

The adhesion of P. gingivalis on epithelial buccal cells (KB cells, ATCC CCL 17) was investigated and quantified by flow cytometric analysis (FACS). Preincubation of P. gingivalis with 1mg/mL, resp. 0.1mg/mL extract of M. flabellifolia Welw. reduced adhesion by 40%, resp. 20%. Incubation with 1mg/mL, resp. 0.1mg/mL extract of R. acetosa L. reduced adhesion by 35%, resp. 15%. Preincubation of KB cells with the extracts showed no significant inhibition of adhesion, supporting the thesis that adhesion factors on P. gingivalis are affected by the extracts. Real-time PCR analysis revealed that 10µg/mL extract of M. flabellifolia Welw. did not influence the expression of Lys- or Arg-Gingipains, but enhanced the expression of FimA gene in P. gingivalis threefold compared to an untreated control.