Large molecules as antiadhesive compounds against pathogens

Within development of alternative treatment regimes against bacterial infections the use of antiadhesive compounds as prophylactic tools is increasingly under discussion. Because bacterial adhesion is commonly mediated by carbohydrate-protein interactions between surface adhesins of the microorganism and the host cell the use of exogenous polyvalent, high-molecular carbohydrates and tannin-like plant-derived compounds should antagonize the adhesive interaction. Within a broad screening carbohydrates, carbohydrate- and proanthocyanidin-enriched plant extracts were screened on potential antiadhesive effects against Helicobacter pylori, Campylobacter jejuni, Porphyromonas gingivalis and Candida albicans in different in situ assays on primary tissue; thereby the adhesion of fluorescent-labelled microorganisms on the intact tissue was quantified by cell-counting and imaging systems [1].

The adhesion of H. pylori on human stomach tissue was effectively blocked by polysaccharides from immature okra fruits (Abelmoschus esculentus (L.) MOENCH). These extracts additionally had strong in vitro effects against C. jejuni, but failed to be effective within an in vivo study in infected chicken broilers when feeded at 5 and 10%. Polysaccharides from Glycyrrhiza glabra L. showed strong antiadhesive properties against H. pylori and P. gingivalis at 0.1mg/ml. Pelargonium sidoides DC extract, containing mainly polymeric proanthocyanidins was dose-dependently effective against H. pylori. Due to the multifunctional adhesive strategy of C. albicans no effective compounds could be detected against this yeast. Structure-activity relations are presented and the potential in vivo use of carbohydrate-based antiadhesives are discussed critically.

References: [1] Lengsfeld C, Faller G, Hensel A (2007) Okra polysaccharides inhibit adhesion of Campylobacter jejuni to mucosa isolated from poultry in vitro but not in vivo. Animal Feed Science and Technology, 135, 113–125.