Determination of the absolute configuration and evaluation of the in vitro antitumor activity of dilospirane B

► The absolute configuration of dilospirane B was determined. ► Its experimental and theoretically calculated ECD spectra were compared. ► Dilospirane B exhibited growth inhibitory activity with a mean IC50 value of 66 μM. ► Dilospirane B initially displays cytostatic effects which later become cytotoxic.