SUPEROXIDE-DISMUTASE (SOD) ACTIVITY WITH FE-CHLORIN E6-NA AND SUPPRESSION OF MALIGNANT-TUMOR GROWTH IN RATS

Derivatives of porphyrin, specifically Fe-chlorin e6-Na (FeCNa), mimic superoxide dismutase (SOD). This SOD activity was determined by decre ase in electron spin resonance (ESR) signals and increase in hydrogen peroxide (H2O2) as the intermediate of O-2(<radical anion>) by the col oration using 4-aminoantipyrin. Chlorin e6-Na used for cancer photodyn amic therapy (PDT)(1) does not show SOD mimicking activity. The specif ic activity of FeCNa, comparing with bovine RBC-SOD, was 1/7.5 las det ermined by ESR analysis. The iron element of Fe-chlorin e6-Na, being t ightly encased in the molecule did not participate in the Fenton react ion. The SOD mimetic activity of FeCNa was stable against physico-chem ical treatment such as pH shock heat and digestion by pronase. For can cer bearing rats with oxidative stress (OS), immediate relief of OS wa s possible by a single intraperitoneal injection of FeCNa and relief c ontinued for 24 hours. The subsequent administration of FeCNa suppress ed cancer growth in vivo.