ANTI-GIARDIAL ACTIVITY OF Tasmannia lanceolata (Tasmanian pepper berry)

Abstract

Introduction: Giardia duodenalis is a protozoan parasite of the small intestine that causes extensive morbidity worldwide. Some strains of G. duodenalis have developed immunity to the gold standard drug, metronidazole. The search is on for new anti-Giardial agents from plant sources, as well as by the synthesis of novel agents. Tasmannia lanceolata (TL) is an endemic Australian plant, long used as a food and a medicine by Indigenous Australians. The medicinal bioactivities of this plant are poorly studied and are the focus of this report. Methods: TL was extracted with various solvents, dried and then re-suspended in deionised water. The extracts were tested in vitro for anti-Giardial activity by exposing the protozoan to different concentration of the extracts and noting parasite viability and death. Toxicity was determined using the Artemia nauplii bioassay. Results: All extracts demonstrated inhibition of Giardial growth in the parasite viability assay. The ethyl acetate, hexane and chloroform extracts proved to have greater anti-Giardial activity in comparison to the other extracts. The methanol and water extract had low Giardial inhibitory activity, although at 24 hours all Giardia were dead following exposure to this extract. The non-polar extracts proved more effective anti-Giardial agents than the polar solvent extracts, suggesting that the non-polar phytochemical components are effective in penetrating the parasite. The water, hexane and ethyl acetate extracts were non-toxic, with no significant increase in mortality induction. The chloroform extract displayed low toxicity in the Artemia nauplii bioassay. Conclusions: Tasmannia lanceolata extracts show promise in the treatment of G. duodenalis, yet have low toxicity, validating traditional Aboriginal usage and indicating its medicinal potential.