Enhancement of radical intensity and cytotoxic activity of ascorbate by hyperthermia.

ESR spectroscopy revealed that the radical intensity of sodium ascorbate and ascorbic acid was significantly higher under hyperthermic conditions. The enhancement of ascorbyl radical intensity was coupled with the accelerated degradation of ascorbate and cytotoxicity induction against human leukemic and glioblastoma cell lines. Sodium ascorbate produced higher ascorbyl radical intensity and more potent cytotoxicity, as compared with ascorbic acid. These data demonstrate that ascorbic acid does not inhibit, but rather stimulates the cytotoxic action of hyperthermia. The combination of hyperthermia and ascorbate treatment might produce higher antitumor activity.