Protection by L-ascorbic acid against phototoxicity in tin-protoporphyrin-treated suckling rats.

The protective effect of free radical scavengers against phototoxicity was investigated with tin-protoporphyrin (SnPP)-treated suckling rats. Six kinds of scavengers (L-ascorbic acid, reduced glutathione, alpha-tocopherol, retinol, uric acid and cystine) were intraperitoneally injected to rats treated with SnPP plus photoirradiation. Among them, L-ascorbic acid was found to be most effective in protecting SnPP-treated rats against phototoxicity. The survival period was markedly prolonged, and the frequency of abnormal behaviors was reduced with the treatment. Lipid peroxidation in vitro with the brain membrane fraction was also suppressed. The other five substances gave only a little antioxidant effect both in vivo and in vitro. The present study shows that L-ascorbic acid may be a promising chemical to prevent the phototoxicity of SnPP.