The protective properties of synthetic porphyrin tin complexes in toxic hyperbilirubinemia

Tin complexes of meso-substituted synthetic porphyrins, namely Sn4+-meso-tetraphenyl- porphyrin (Sn-TPP) and Sn4+-meso-tetrakis(N-methyl-3-pyridyl)porphyrin tetratosylate (Sn-TMe-3-PyP), efficiently decrease the serum bilirubin level when injected subcutaneously at a dose of 100 μM kg−1 body weight into mice. These compounds are active during hyperbilirubinemia, induced by phenylhydrazine, hemin and tetrachloromethane, and also during autoimmune hemolytic anemia. In the latter case a decrease in serum bilirubin content was observed, as well as a decrease in the amount of blood reticulocytes which reflects a milder course of the disease. The Sn complexes under study induce, in vivo, cytochrome P-450, inhibit microsomal heme oxygenase and decrease the intensity of lipid peroxidation. At the same time, in vitro the hepatic and splenic heme oxygenase activity is blocked only when a 0.1 μM concentration of Sn-TMe-3-PyP or Sn-protoporphyrin IX is added to the incubation mixture. Sn-TPP does not affect the activity of this enzyme in vitro.