Liposome Modified with Mn−Porphyrin Complex Can Simultaneously Induce Antioxidative Enzyme-like Activity of Both Superoxide Dismutase and Peroxidase

An antioxidative liposome catalysis that mimics both superoxide dismutase (SOD) and peroxidase (POD) activities has been developed by using the liposomes modified with lipophilic Mn−(5,10,15,20-tetrakis[1-hexadecylpyridium-4-yl]-21H,23H-porphyrin) (Mn−HPyP). The SOD- and POD-like activities of the Mn−HPyP-modified liposome were first investigated by varying the type of phospholipid, such as 1,2-distearyl-sn-glycero-3-phosphocholine (DSPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC). Higher SOD-like activity was obtained in the case of DLPC and DMPC liposomes, in which the ligands were well-dispersed on the membrane in the liquid crystalline phase. The POD-like activity was maximal in the case of DMPC liposome, in which the Mn−HPyP complex was appropriately clustered on the membrane in the gel phase. On the basis of the above results, the co-induction of the SOD and POD activities to eliminate the superoxide and also hydrogen peroxide as a one-pot reaction was finally performed by using the Mn−HPyP-modified DMPC liposome, resulting in an increase in the efficiency of the elimination of both superoxide and hydrogen peroxide.