Enantiomer that selectively inhibits the slow component of delayed rectifier K+ current (IKs). Block is use-dependent and 7-fold more potent than the (+)-(3S,4R) enantiomer (IC50 values are 1.36 and 9.6 μM respectively). Has negligible inhibitory action at hERG channels (IC50 > 30 μM). Racemate Chromanol 293B (Cat. No. 1412) also available.