Anti-adhesive Activity of Herbal Extracts Against Campylobacter jejuni

Abstract

Campylobacter jejuni is one of the most common bacterial causes of diarrhoea in the industrialised world [1], being associated with the occurrence of Guillain-Barr頓yndrome (GBS) [2] and induces diseases partially through intestinal adherence [3]. With increasing reports of C. jejuni drug resistance against standard antibiotics [4], investigations into anti-adhesive agents for the prevention of bacterial infection [5] are highly significant. Given the consumer-driven development towards holistic and integrative healthcare [6], research into additional anti-Campylobacter effects of phytotherapeutics that are already used for their beneficial effects on bowel and digestive functions is crucial. Dilutions of 21 herbal extracts were screened for anti-adhesive activity against C. jejuni using modifications of previously published anti-adhesion assays [7, 8]. Anti-adhesion effects with IC50 values <3mg/mL were obtained for 7 ethanolic plant extracts, with ginger, cayenne and licorice displaying the highest anti-adhesion activity against C. jejuni (IC50: <0.1mg/mL, 0.29mg/mL and 0.65mg/mL, respectively). Such marked activities could well be clinically relevant. In addition, differences in anti-adhesion activity were found for two different Echinacea species with E. purpurea displaying significantly higher and dose dependent anti-adhesion activity than E. pallida var. angustifolia. No significant anti-adhesion activity (IC50 values >35mg/mL) was found for agrimony, andrographis, chamomile, fennel, meadowsweet and wormwood extracts. This study provides evidence for additional beneficial effects of marketed phytotherapeutics in gastrointestinal disorders. Further research is required to identify i) synergistic effects of different herbal extracts, ii) anti-adhesive potential of as yet unknown compounds and iii) anti-adhesive activities of known herbal constituents.