The first stereoselective total synthesis of the naturally occurring flavan myristinin A has been accomplished, as well as its biochemical evaluation. This synthesis verified the structural assignment and allowed for the determination of the absolute stereochemistry. Myristinin A exhibits biochemical activity both as a potent DNA-damaging agent and DNA polymerase beta inhibitor. Relaxation of supercoiled plasmid DNA was observed at picomolar concentrations, in addition to inhibition of polymerase beta at low micromolar concentrations.