Eucalyptus spp. outer bark extracts inhibit Helicobacter pylori growth: in vitro studies

Helicobacter pylori is the etiologic agent of several gastric disorders. The growing rates of unsuccessfulness of available antibiotics-based therapy led to the need for non-antibiotic compounds for H. pylori treatment. The antibacterial activity of Eucalyptus nitens and Eucalyptus globulus outer bark lipophilic extracts were evaluated against a panel of H. pylori strains, as well as the role of pure triterpenic acids and synthetic mixtures mimicking the natural extracts. Best results were obtained with E. nitens outer bark extract (MIC = 64 μg/mL) and it was demonstrated that after 6 h of exposure to the MIC, there was a significant decrease (>50%) in H. pylori growth. Moreover, it was determined that the antibacterial effect of Eucalyptus spp. outer bark extracts was due to the synergetic effect of four triterpenic acids, namely betulinic, betulonic, ursolic and oleanolic acids. Our findings open new perspectives for development of anti-H. pylori therapies based on the use of these plant extracts.