<p>This study aimed to screen <i>in vitro</i> antitumour activity of the redox couple avarol/avarone against the human malignant glioma cell line U-251 MG for the first time. Compared both with avarol and positive controls used (temozolomide and doxorubicin), avarone was found to be the most active compound with IC<sub>50</sub> value below 1 μM (IC<sub>50</sub> 0.68 ± 0.04 μM, 96 h). Considerable less DNA damage in the cells treated with avarol and avarone vs. doxorubicin (105 & 123% vs. 299%, respectively; untreated U-251 MG cells were used as a control, 100%), coupled with no sign of cytotoxicity against the normal human foetal lung fibroblast MRC-5 cells (IC<sub>50</sub> > 100 μM), has actually pointed out the importance of this marine sesquiterpenoid quinone structure as a promising lead compound in development of novel brain chemotherapeutics.</p
