Oxidation of ascorbic acid by terramycin

Abstract

1. 1. Six crystalline antibiotics, penicillin G, dihydrostreptomycin sulphate, aureomycin hydrochloride, chloramphenicol, neomycin sulphate and terramycin hydrochloride were tested for their oxidation on ascorbic acid. Only terramycin was found to catalyse the reaction. 2. 2. Terramycin has been shown to be free from traces of metals. The catalytic activity is thermostable. The antibiotic activity and fluorescent property of terramycin are not altered by its catalysis of ascorbic acid oxidation. 3. 3. Terramycin oxidizes ascorbic to dehydroascorbic acid without liberating any carbon dioxide. pH optimum of the reaction is around 8. Michaelis' constant of the reaction is 0.0103 M whereas the catalyst substrate dissociation constant is 5.10^-6. 4. 4. Sodium cyanide, boric acid, glutathione, cysteine, yeast nucleic acid, purines, pyrimidines, amino acids, vitamins of B complex, menadione and dicumarol do not inhibit the oxidation of ascorbic acid by terramycin, whereas 8-hydroxyquinoline and penicillin G exert 30% inhibition. 5. 5. Significance of the present observations on the mode of action of terramycin is briefly discussed.