Headgroup interactions with phospholipids lead to a consistent depth distribution for these molecules at around 12-18 Å relative to the membrane center (Fig. ). This is comparable to prior simulation studies for ubiquinone, where the quinone headgroup is frequently found near the membrane surface. Interestingly, we find that the equilibrium position for the quinone headgroups in our compounds are slightly deeper than in these comparison studies, with the distribution peaking near the membrane carbonyl groups in the acyl tails. Ordinarily, we would anticipate that the additional hydroxyl group relative to ubiquinone would draw the headgroup closer to the membrane surface, tempered with the removal of the methoxy group in sorgoleone relative to ubiquinone. Methoxy groups draw the quinone towards the membrane surface, possibly due to water interactions with the methoxy oxygen.