Zinc compounds combined with cyclodextrin inhibit growth of Helicobacter pylori in-vitro

Zinc compounds have anti-gastric ulcer activity in animal models and in man. Since Helicobacter pylori is a major aetiologic agent in peptic ulcer disease this raised the possibility that part of the anti-ulcer activity of zinc could be due to its effects on the growth of H. pylori. We therefore investigated the in-vitro effects of zinc sulphate and a slow-release zinc compound, zinc monoglycerolate (ZMG), on the growth of H. pylori cultured in either solid agar or liquid phase media (in microtiter plates). Growth media comprised buffered peptone adjusted to pH 5.1 and pH 7.2; the lower pH mimicks that in the stomach without unduly affecting the growth of H. pylori. A total of 26 strains comprising clinical isolates and standards were cultured with the zinc compounds for one to three days. The results showed that Zn²⁺ and ZMG alone had little effect on the growth of H. pylori in solid or liquid phase media at either pH. However, incorporating β-cyclodextrin (β-CyD, 1 mg mL^-1) with both zinc compounds produced marked inhibition of growth in all strains at concentrations of 22.0-77.5 μg mL^-1, with more pronounced inhibition at the lower pH. Zinc compounds inhibit growth of H. pylori when combined with β-CyD; the latter may aid penetrance of zinc compounds into the bacteria.