1-[2-Hydroxy-3-octadecan-1'-oate]propyl-2",2",5",5"-tetramethyl pyrolidine-N-oxyl-3"-carboxylate as a potential spin probe for membrane structure studies

The synthesis of a new minimum steric perturbing proxyl nitroxide, which is a derivative of glycerol and contains a stearic acid moiety, has been carried out. Its localization in model membrane L-alpha-dipalmitoyl phosphatidyl choline (DPPC) was ascertained with the help of ESR, DSC, H-1 and P-31 NMR techniques. The nitroxide was used for detecting the changes in the phase transition temperature of the model membranes in the presence and absence of drugs. The permeation of the vasodilating drug epinephrine has also been studied using this spin label. The results prove the potential applicability of the new spin probe in the spin labeling of biomembranes. (C) 1999 Elsevier Science Ltd. All rights reserved.