*2.1. Reagents and Equipment*

Salts and other basic chemicals were bought from Sigma (Munich, FRG, analytical grade). The phospholipids were purchased as follows: palmitoyl-oleoyl-phosphatidylcholine (POPC) from Avanti Polar Lipids, (Alabaster, AL, USA); dioleoyl-phosphatidylserine (DOPS); dioleoyl-phosphatidylethanolamine (DOPE); Cholesterol (Ch) from Sigma (Munich, FRG), resveratrol was from Farmalabor® S.r.l. (Canosa of Puglia, Italy). Figure 2 reports the molecular structures of the lipids used in this study. The volumes (Vl) of phospholipids are similar (Vl = 1231.2/1228/1254 Å<sup>3</sup> POPC/DOPE/DOPS, respectively) [39–41], while their shapes are different. Indeed, POPC and DOPS are classified as cylindrical lipids, and DOPE as a conical lipid [42].

Single-channel measurements: the membrane current was monitored with an oscilloscope and recorded on a chart recorder for further analysis by hand. A Teflon chamber made up of two aqueous compartments connected by a small circular hole with a diameter of 300 µm was used. The *cis* and *trans* chambers were connected to the amplifier head stage by Ag/AgCl electrodes in series with a voltage source and a highly sensitive current amplifier (OPA 129). The single-channel instrumentation had a time resolution of 1–10 ms depending on the magnitude of the single-channel conductance. Figure 3 reports the experimental set-up used to study the interaction of resveratrol with PLMs. The polarity of the voltage was defined according to the side where resveratrol was added (the *cis* side). A trans-negative potential (indicated by a minus sign) means that a negative potential was applied to the *trans* side, the compartment opposite the one where resveratrol was added. These experiments are considered to be a sensitive tool for the study of channel-forming substances [43,44].

**Figure 2.** Molecular structures of (**a**) palmitoyl-oleoyl-phosphatidylcholine (POPC), (**b**) dioleoyl-phosphatidylethanolamine (DOPE), (**c**) dioleoyl-phosphatidylserine (DOPS), (**d**) and Cholesterol (Ch).

**Figure 3.** Experimental set-up during investigations into resveratrol channel-like incorporation.

−
