Flavan-3-ols and proanthocyanidins from Limonium brasiliense inhibit the adhesion of Porphyromonas gingivalis to epithelial host cells by interaction with gingipains.

Porphyromonas gingivalis is a pathogen strongly involved in chronic and aggressive forms of periodontitis. Natural products, mainly polyphenols, have been described for advanced treatment of periodontitis by inhibition of the bacterial adhesion of P. gingivalis to the epithelial host cells. An acetone:water extract (LBE) from the rhizomes of Limonium brasiliense (Boiss.) Kuntze was tested under in vitro conditions for potential antiadhesive effects against P. gingivalis to human KB cells and for inhibition of the proteolytic activity of gingipains, the main virulence factor of P. gingivalis. LBE≤100µg/mL had no cytotoxicity against the bacteria and did not influence the cell physiology of human epithelial KB cells. At 100µg/mL LBE reduced the adhesion of P. gingivalis to KB cells significantly by about 80%. LBE at 20µg/mL reduced the proteolytic activity of the arginin-specific Rgp gingipain by about 75%. Chemical profiling of LBE indicated the presence of gallic acid, epigallocatechin-3-O-gallate and samarangenins A and B as lead compounds. UHPLC by using MS and UV detection displays a suitable method for quality control of the extract for identification and quantification of the lead compounds.