Inhibiting effect of ascorbic acid on the growth of human mammary tumor xenografts.

The effect of ascorbic acid on the growth of a human mammary tumor in mice has been investigated using the 6-d subrenal capsule assay method. The results indicated that ascorbic acid administered in the drinking water significantly inhibited the growth of the tumor fragments implanted beneath the renal capsule of mice. Administration of a mixture of ascorbic acid and cupric sulfate orally or intraperitoneally significantly inhibited tumor growth in these mice, whereas neither alone was effective. These results support the hypothesis that certain oxidation or degradation products of ascorbic acid were active antineoplastic agents for the human mammary tumor studied. The activity of D-isoascorbic acid, an isomer of ascorbic acid, was similar to that of ascorbic acid. This suggests that the antitumor activity of ascorbic acid was not due to the metabolism of ascorbic acid as a vitamin, but due to its chemical properties.