Giardia duodenalis: Effects of an ozonized sunflower oil product (Oleozon®) on in vitro trophozoites

The ozonized sunflower oil product (Oleozon®) was investigated to explore its cytotoxic activity on Giardia duodenalis in vitro cultivated trophozites. Oleozon® produced inactivation of Giardia trophozoites in a dose- and cell density-dependent manner. Thirty microliter of Oleozon® with peroxide index value of 500 equivalent-mmol of activated oxygen per kilogram were used to achieve a 100% inhibition (<−4.00 log unit) of trophozoites from an initial inoculum of 15 × 104 cells. This potent effect was confirmed by transmission electron microscopy where morphological deterioration of superficial structures mainly in the ventral disc, and formation of a great number of micro vesicles in the cytoplasm were found. We concluded that a direct chemical-oxidation attack by the active substances from Oleozon® is one of the causes of the parasitocidal effect of this product. We suggest that the dose and cell density-dependent effect must be taken into account when prescription of this product for giardiasis treatment in humans.