RESUMEN
Castanea sativa Mill. leaves infusion/decoction has been traditionally used in the northern region of Portugal to treat cough in children, diarrhoea, infertility and hypertension. However, no information exists about its possible toxic effects. This study aims to investigate the toxicity of C. sativa Mill. extract by the determination of population growth impairment, generation time, LC50, morphometric changes in Tetrahymena pyriformis and MTT test. Generation time, growth and MTT assay are affected by chestnut tree leaves extract and these effects are dosage dependent. The morphometry of the Tetrahymena pyriformis cells was also affected. According to the obtained LC50 value, the extract may be considered as mildly toxic. The usage of C. sativa leaves extract must be exercised with caution especially when it comes to children.