Synthesis of Pegylated Manganese Protoporphyrin as a Catalase Mimic and Its Therapeutic Application to Acetaminophen-Induced Acute Liver Failure.

Abstract

Metalloporphyrin derivatives have been investigated for their therapeutic potential for oxidative stress-related diseases because of their scavenging of reactive oxygen species (ROS). Here, we describe the synthesis, physicochemical properties, and ROS-scavenging activities of one such derivative-polyethylene glycol (PEG)-conjugated manganese protoporphyrin (PEG-MnPP). Carboxyl groups of the protoporphyrin ring at the C6 and C7 positions were first conjugated with ethylenediamine to introduce amino groups into the protoporphyrin structure. The amino groups were then reacted with succinimidyl PEG, with an average molecular weight of 2000, to obtain pegylated protoporphyrin (PEG-PP). Manganese was chelated to the protoporphyrin ring by incubating PEG-PP and manganese acetate in methanol. Dynamic light scattering and fluorescent spectrometry analyses revealed that PEG-MnPP self-assembled into nanoparticles in aqueous media with an apparent diameter of 70 nm. PEG-MnPP effectively eliminated hydrogen peroxide from cell culture media and protected cultured mammalian cells from toxic insults induced by hydrogen peroxide exposure or by 6-hydroxydopamine treatment. Intravenous administration of PEG-MnPP to mice significantly suppressed acute liver failure that had been induced by acetaminophen overdose. These data warrant additional investigation to study the therapeutic potential of PEG-MnPP as a water-soluble metalloporphyrin-based catalase mimic for oxidative stress-associated diseases.