Investigations into the antiadhesive activity of herbal extracts against Campylobacter jejuni

Campylobacter jejuni is one of the most common bacterial causes of diarrhoea in the industrialized world, being associated with the occurrence of Guillain-Barré Syndrome, and inducing diseases partially through intestinal adherence. With increasing reports of C. jejuni drug resistance against standard antibiotics, investigations into antiadhesive agents for the prevention of bacterial infection are highly significant. Given the consumer-driven development towards holistic and integrative healthcare, research into additional anti-Campylobacter effects of herbal medicines that are already used for their beneficial effects on bowel and digestive functions is important. Twenty-one herbal extracts were screened for antiadhesive activity against C. jejuni using modifications of previously published antiadhesion assays. Antiadhesion effects with IC(50) values <3 mg/mL were obtained for seven ethanol plant extracts, with Zingiber officinale (ginger), Capsicum annum (cayenne) and Glycyrrhiza glabra (licorice) displaying the highest antiadhesion activity against C. jejuni (IC(50) : <0.1 mg/mL, 0.29 mg/mL and 0.65 mg/mL, respectively). Differences in antiadhesion activity were found for two different Echinacea species, with E. purpurea displaying significantly higher and dose dependent antiadhesion activity than E. angustifolia. No significant antiadhesion activity (IC(50) values >35 mg/mL) was found for Agrimonia eupatoria (agrimony), Andrographis paniculata (andrographis), Matricaria recutita (chamomile), Foeniculum vulgare (fennel), Filipendula ulmaria (meadowsweet) and Artemisia absinthium (wormwood) extracts. This study provides evidence for additional beneficial effects of marketed herbal medicines in gastrointestinal disorders.