Combination Studies of Eucalyptus torelliana F. Muell. Leaf Extracts and Clarithromycin on Helicobacter pylori

Abstract

Helicobacter pylori is a Gram-negative bacillus that is associated with the development of gastritis and peptic ulcer disease (PUD). In Nigeria, leaf extracts of Eucalyptus torelliana F. Muell. are used in traditional medicine to treat PUD and other gastrointestinal ailments. The additive and synergistic effects of E. torelliana leaf extracts, in combination with clarithromycin, were investigated using two types of H. pylori strains (ATCC 43629, ATCC 43579) and four clinical isolates of H. pylori (Ed, A2, G1-1, 5514) in the checkerboard assay and the fractional inhibitory concentration (FIC) index. A time-kill study was also performed on the strain ATCC 43579. The results showed that the E. torelliana extract inhibited the growth of all H. pylori strains, and the addition of one of the isolated active compounds, namely compound 2 (a substituted pyrenyl ester) enhanced the activity of clarithromycin. The minimum inhibitory concentration values of clarithromycin and the botanical compound were reduced twofold (from 0.125 to 0.0625 µg/mL and > 100 to 50 µg/mL respectively). A 100% reduction in CFU/mL of H. pylori ATCC 43579 was observed with the combination of 0.25 µg/mL clarithromycin and 100 µg/mL and 200 µg/mL compound 2 after 3 h of exposure. The results of the investigation showed that the combination of botanical compounds and antibiotics may be beneficial in the treatment of H. pylori infections.