Anti-Helicobacter pylori activities of Eucalyptus grandis: Effects on susceptibility, urease activity and cell surface hydrophobicity

Helicobacter pylori is the primary etiologic agent of peptic ulcer, duodenal ulcer, chronic gastritis, gastric adenocarcinoma and related gastroduodenal disorders. Current triple therapy, including antibiotics and proton-pump inhibitors, has been successful; however, adverse events, non-patient compliance and consequent relapse of Helicobacter pylori infections are common. Crude methanol extracts of Eucalyptus grandis Hill ex. Maiden (Myrtaceae) stem bark were screened against a standard strain ATCC 43504 and ten clinical strains of H. pylori using the agar diffusion method on Mueller-Hinton agar supplemented with defibrinated horse blood and grown in a microaerophilic incubator. All the strains except UCH 97002 and UCH 98020 were inhibited by the extract to varying degrees. The minimum inhibitory concentration (MIC) against the susceptible strains tested ranged from 0.39 and 1.56 mu g/mL. The urease activity of the three H. pylori strains tested decreased with increasing concentrations of the extract. The greatest inhibition of urease activity was observed in clinical strain UCH 97009. In addition, methanol extracts of the E grandis enhanced cell aggregation of seven of the R pylori strains leading to a decrease in the cell surface hydrophobicity. The salt aggregation test titer decreased from >3 to <1.5 for five of the strains and to <3 for two of the strains. Phytochemical screening of the plant revealed the presence of tannins, essential oils and saponins, while alkaloids were not detected. The anti-Helicobacter pylori activity observed in this study correlates well with the traditional use of this plant in Nigeria.