Synthesis of Nanovesicular Glutathione Peroxidase Mimics with a Selenenylsulfide-Bearing Lipid

In this article, we describe the development of a nanosized-glutathione peroxidase (GPx) mimic based on liposomes of which the amphiphilic selenenylsulfide derivative (R−Se−S−R′) was incorporated into a lipid membrane. A lipid membrane-compatible selenenylsulfide derivative, 1-oxoheadecyl- seleno-L-cysteine-methyl-Se-yl-S-L-penicillamine methyl ester (OHSeP), was synthesized. X-ray photoelectron spectroscopy revealed that the sulfur and selenium atoms of the OHSeP molecule formed a selenenylsulfide linkage. The use of OHSeP easily allowed the introduction of the seleno-Lcysteine (SeCys) moiety into the liposomal membranes by mixing with the phosphatidylcholines (PCs), which gave rise to the GPx-like catalytic activity because of the selenium atom in the SeCys moiety. The penicillamine moiety of the OHSeP molecule incorporated into the OHSeP/PC liposomes was thought to orient toward the outer water phase. The OHSeP/PC liposomes generated the GPx-like catalytic activity, which was ascribed to the SeCys moiety that was introduced into the PC-based liposomes. Consequently, the lipid/water interface of the liposomal membranes could possibly provide an effective colloidal platform for the development of water-soluble nanosized GPx mimics.