Hepatic and Intrahepatic Targeting of Hydrogen Sulfide Prodrug by Bioconjugation.

Hydrogen sulfide (H2S) is an endogenous gaseous transmitter known to play an important role in biological functions. For the hepatic and intrahepatic targeting of H2S prodrug at the cellular level, we developed two types of sulfo-albumins, in which five sulfide groups (source of H2S) were covalently bound to succinylated (Suc) or galactosylated (Gal) bovine serum albumin (BSA). Sulfo-BSA-Suc and polyethylene glycol (PEG)-Sulfo-BSA-Gal, both released H2S in the 5 mM glutathione solution, but not in the plasma. Sulfo-BSA-Suc and PEG-Sulfo-BSA-Gal were taken up by RAW264.7 cells (mouse macrophage-like cells) and Hep G2 cells (human hepatocellular carcinoma cells), respectively, and H2S was released. These results indicate that Sulfo-BSA-Suc and PEG -Sulfo-BSA-Gal selectively released H2S intracellularly. In a biodistribution study, up to 80% of 111In-labeled Sulfo-BSA-Suc and PEG-Sulfo-BSA-Gal rapidly accumulated in the liver, 30 min after intravenous injection in mice. Furthermore, 111In-labeled Sulfo-BSA-Suc and PEG-Sulfo-BSA-Gal predominantly accumulated in liver nonparenchymal (endothelial cells and Kupffer cells) and parenchymal cells (hepatocytes), respectively. These findings suggest that targeted delivery of H2S prodrug to a specific type of liver cells was successfully achieved by bioconjugation.

Pharmacokinetics and Preventive Effects of Sulfo-Albumin as a Novel Macromolecular Hydrogen Sulfide Prodrug on Carbon Tetrachloride-Induced Hepatic Injury.

Hydrogen sulfide (H2S) has been recently recognized as a gaseous signaling molecule that controls various biological activities. In the present study, we developed sulfo-albumin as a macromolecular H2S prodrug for therapeutic use, in which multisulfide groups (source of H2S) were conjugated with bovine serum albumin through a covalent linkage. In an in vitro study on H2S release in phosphate buffered saline solution, we found that H2S was released from sulfo-albumin in the presence of 5-mM glutathione but not in its absence. Furthermore, sulfo-albumin was taken up by RAW 264.7 cells, and it released H2S in cells but not in plasma. These results indicate that H2S can be selectively released from sulfo-albumin in cells. 111In-labeled sulfo-albumin predominantly accumulated in the liver, dependent upon the number of sulfide groups, after intravenous injection in mice. In a carbon tetrachloride-induced acute liver injury mouse model, sulfo-albumin significantly suppressed the increase in plasma aspartate aminotransferase and alanine aminotransferase activities, which are indicators of hepatocyte injury, after intravenous injection. These findings indicate that sulfo-albumin is a promising compound for the treatment of hepatic injuries.