Investigations into the antibacterial activities of herbal medicines against Helicobacter pylori and Campylobacter jejuni

Abstract

Prevalence of gastric diseases in the Australian population is increasing with H. pylori, the causative agent of acute and chronic gastritis, being a major predisposing factor for peptic ulcer disease and gastric carcinoma. C. jejuni is the most common cause of enteric infections, particularly among children, resulting in severe diarrhoea. Increasing drug resistance of these bacteria against standard antibiotics, and the more widespread use of herbal medicines, favours investigations into additional anti-Helicobacter and anti-Campylobacter effects of phytotherapeutics that are already used for their beneficial effects on bowel and digestive functions [1,2]. Dilutions (1:25 and 1:100) of 21 ethanolic herbal extracts were screened for antibacterial activity using a modification of a previously described micro-dilution assay [3] and compared to the inhibitory effects of antibiotics. Thirteen herbal extracts inhibited the growth of C. jejuni, 7 to almost 100% for a 1:100 dilution. Similarly, 11 herbal extracts inhibited the growth of H. pylori, but in contrast to C. jejuni only 1 extract (sage) caused 100% inhibition at a 1:100 dilution. The herbal extracts showing the highest antibacterial activity against C. jejuni were calendula, chamomile, fennel, ginger, licorice, sage and St Mary's thistle. Agrimony (Agrimonia eupatoria), golden seal (Hydrastis canadensis), meadowsweet (Ulmaria filipendula) and sage (Salvia officinalis) were the most active herbal extracts against H. pylori. This study provides evidence for additional beneficial effects of marketed phytotherapeutics in gastrointestinal disorders. Further research may identify i) synergistic effects of different herbal extracts, ii) antibacterial potential of as yet unknown compounds or iii) the antibacterial potential of known herbal constituents.