The effects of tea (Camellia sinensis L.) of three types on excessive free radicals were examined utilizing spin trapping, 1,1-diphenyl-2-picrylhydrazyl radical, lipid peroxidation, and lactate dehydrogenase leakage from cultured cells. Green tea extract presented significant antiradical effects in these four assay systems, whereas oolong tea and black tea extracts showed a rather weak protective effect against free radicals. A more potent scavenger effect using cultured cells was found with a green tea tannin mixture. Similarly to the effects of the green tea tannin mixture, (-)epigallocatechin 3-O-gallate, its main ingredient, had an inhibitory effect on oxidative stress-induced apoptosis. The activities of the antioxidation enzymes in rats after subtotal nephrectomy were increased, suggesting a protective action against oxidative stress. The increased levels of uremic toxins in the blood were also reduced in rats given (-)-epigallocatechin 3-O-gallate. These findings indicate that (-)-epigallocatechin 3-O-gallate helps to inhibit the progression of renal failure by scavenging radicals.

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A b initio LCAO SCF MO calculations were carried out on Fe-porphine, Fe-porphine-pyridine, and Fe-porphine-pyridine-carbonmonoxide which are typical intermediate-, high-, and low-spin complexes, respectively. Mössbauer spectra of ferrous porphyrins were analyzed theoretically by the evaluation of isomer shift (IS), quadrupole splitting (QS), sign and direction of the principal component of electric field gradient tensor, and asymmetry parameter for the complexes. The calculated values have a good agreement with the experimental ones for the low- and high-spin complexes. The ground state of Fe-porphine, which remains undetermined so far, is assigned as the 3Eg state which is described by mixing of the two configurations, (dxy)2 (dxz,dyz)3 (dz2)1 and (dxy)1 (dxz,dyz)3 (dz2)2. A new relation between Mössbauer spectra and electronic structure is found. The field gradient along the perpendicular axis to the porphyrin plane is determined by two factors, the d-electron configuration and a constant term depending on axial ligands.