Effect of Selenium-Rich Green Tea Extract on the Course of Sporulation of Eimeria Oocysts

The effect of green tea extracts on the sporulation of oocysts of 3 species of Eimeria was investigated. The unsporulated oocysts were exposed to 0%, 5% and 10% of green tea extracts (1 and 2% strengths, w/v). A new sporulation inhibition bioassay was designed to evaluate the anticocccidial activity of the tea extracts. The results showed for the first time that water-soluble extracts from green tea have anticoccidial activity as evidenced by their ability to significantly decrease (P< 0.0001) the sporulatuion of the oocysts of three species of Eimeria, namely Eimeria tenella, E. maxima and E. acervulina under laboratory conditions. Incubation of unsporulated oocysts of these parasites in water containing 10% and 25% of tea extract resulted in inhibition of sporulation of these oocysts by about 28-84% relative to the oocysts in the control incubations (no tea extract added). In addition, the sporocysts in about 5-30% of the sporulated oocysts of the three species of Eimeria recovered from incubations containing the tea extract were abnormal in their shapes and sizes. In conclusion, water-soluble extracts of selenium-rich green tea demonstrated anticocidial activity as evidenced by their ability to decrease the sporulation process and via interference with the development of the sporocysts.