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 carr ied out. Its localization in model membrane L-alpha-dipalmitoyl phosphatidy l choline (DPPC) was ascertained with the help of ESR, DSC, H-1 and P-31 NM R 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 applicabili ty of the new spin probe in the spin labeling of biomembranes. (C) 1999 Els evier Science Ltd. All rights reserved.