In SH-SY5Y cells exposed to THA, we detected significant decreases in dehydrogenase activity (p < 0.001) and ATP levels (p < 0.001) only in cells treated with the highest concentration of 100 µM THA after 48 h, compared to controls. After the treatment with 100 µM 7-PhO-THA, the significant impairment of SH-SY5Y cells progressed between 6 and 48h of incubation according to the measurements of dehydrogenase activity, GSH, and ATP levels. However, the extent of cellular damage was lower than in the cases of 5i and 5m. We did not detect any morphological changes in SH-SY5Y cells after incubation with 25 µM THA and 25 µM 7-PhO-THA of 24 h. The data are presented as mean ± SEM (n = 3-6; three independent experiments). Statistical significance was analyzed using ANOVA followed by Tukey´s test to compare results with negative controls at significance level p = 0.05 (*, p < 0.05; **, p < 0.01; ***, p < 0.001, vs. untreated cells at appropriate time interval).