Abstract
The protective effects of mucin and chondroitin sulfate (Ch-S) on the oxidation of ascorbic acid (AsA) were studied. The results obtained are summarized as follows:
(1) AsA in 0.1M phosphate buffer (pH 6.4 and 7.4) was protected from oxidation by the addition of more than 0.05% of Ch-S and 0.01% of mucin at 37°C, but not in 0.1M veronal buffer (pH 8.6).
(2) Similar results were also observed in the presence of 500γ% of Fe+++ and 50γ % of Cu++ in the AsA solutions containing mucin and Ch-S, and mucin was more effective than Ch-S.
(3) Iron chondroitin sulfate and copper chondroitin sulfate prepared by the reaction of Ch-S with FeSO4 and CuSO4 did not show the protective effect.
(4) At 60° and 80°, the AsA oxidation was slightly protected by the addition of 0.1-1.0% of mucin and Ch-S at pH 6.4, but not at pH 7.4.
(5) d-Glucuronic acid and sulfuric acid, the constituents of mucin and Ch-S, showed a slight protective effect on the AsA oxidation, whereas N-acetylglucosamine and N-acetylgalactosamine didn't.
A mechanism of protective action shown by means of mucin and Ch-S on the oxidation of AsA was also discussed.
