Abstract
[I] Synthesis and vitamin C activity of L-threo-hexo-2-enaro-1,4-lactone (S-AsA) have been studied. (i) S-AsA was almost quantitatively obtained by the hydrolysis of 6-carboxyascorbic acid-2-sulfate (S-AsS) for 10 min at 100℃, which, in turn, was prepared by the selective oxidation of ascorbate-2-sulfate (AsS) over platinum black. (ii) The oxidative cleavage of S-AsS with bromine formed 6-carboxydehydroascorbic acid, of which intermediate gave S-AsA by the reduction with hydrogensulfide in a 65% yield. [II] The antiscorbutic activity of sodium salt of S-AsA (S-AsA・Na) was examined by the three methods in Hartley guinea pigs fed on a vitamin C deficient diet. (i) The antiscorbutic activity of S-AsA・Na was compared with that of equimolar AsA orally administered. (ii) Hartley guinea pigs, which had been fed on a vitamin C deficient diet and resulted in scurvy, were divided two groups. Each group was orally administered with AsA and equimolar S-AsA・Na, respectively. Recovery tests from the scurvy of these two groups were carried out. (iii) Because the guinea pig receiving S-AsA・Na suffured from scurvy, treatment effects of the double dose of S-AsA・Na orally administered and intraperitoneally injected were compared with those of AsA. The results of this investigation indicate that the close relationship may exist between structure of C-6 position of ascorbic acid analogues and the development of vitamin C activity, although S-AsA・Na does not prevent and cures scurvy in the guinea pig.
