The effect of blueberry extracts on Giardia duodenalis viability and spontaneous excystation of Cryptosporidium parvum oocysts, in vitro

• Published in: Methods (San Diego, Calif.) Vol. 42; no. 4; pp. 339 - 348
• Main Authors: Anthony, J.-P., Fyfe, L., Stewart, D., McDougall, G.J., Smith, H.V.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2007
• Subjects: Animals; Antiparasitic Agents - chemistry; Antiparasitic Agents - pharmacology; Blueberry extracts; Blueberry Plants - chemistry; Cells, Cultured; Cryptosporidium parvum; Cryptosporidium parvum - drug effects; Cryptosporidium parvum - growth & development; Flavonoids - pharmacology; Giardia - drug effects; Giardia duodenalis; In vitro; Oocysts; Oocysts - cytology; Oocysts - growth & development; Phenols - pharmacology; Plant Extracts - chemistry; Plant Extracts - pharmacology; Plants, Medicinal - chemistry; Polyphenols; Solvents - chemistry; Spontaneous excystation; Trophozoites - cytology; Trophozoites - growth & development; Viability; Water - chemistry; Cryptosporidium parvum; Spontaneous excystation; Giardia duodenalis; Blueberry extracts; Viability; In vitro; Oocysts
• ISSN: 1046-2023; 1095-9130
• DOI: 10.1016/j.ymeth.2007.02.011

The protozoan parasites Giardia duodenalis and Cryptosporidium parvum are common causes of diarrhoea, worldwide. Effective drug treatment is available for G. duodenalis, but with anecdotal evidence of resistance or reduced compliance. There is no effective specific chemotherapeutic intervention for Cryptosporidium. Recently, there has been renewed interest in the antimicrobial properties of berries and their phenolic compounds but little work has been done on their antiparasitic actions. The effect of various preparations of blueberry (Vaccinium myrtillus) extract on G. duodenalis trophozoites and C. parvum oocysts were investigated. Pressed blueberry extract, a polyphenolic-rich blueberry extract, and a commercially produced blueberry drink (Bouvrage) all demonstrated antigiardial activity. The polyphenol-rich blueberry extract reduced trophozoite viability in a dose dependent manner. At 167μgml−1, this extract performed as well as all dilutions of pressed blueberry extract and the Bouvrage beverage (9.6±2.8% live trophozoites remaining after 24h incubation). The lowest dilution of blueberry extract tested (12.5% v/v) contained >167μgml−1 of polyphenolic compounds suggesting that polyphenols are responsible for the reduced survival of G. duodenalis trophozoites. The pressed blueberry extract, Bouvrage beverage and the polyphenolic-rich blueberry extract increased the spontaneous excystation of C. parvum oocysts at 37°C, compared to controls, but only at a dilution of 50% Bouvrage beverage, equivalent to 213μgml−1 gallic acid equivalents in the polyphenolic-rich blueberry extract. Above this level, spontaneous excystation is decreased. We conclude that water soluble extracts of blueberries can kill G. duodenalis trophozoites and modify the morphology of G. duodenalis and C. parvum.