The effects of ascorbic acid and sodium ascorbate on doxorubicin-induced H9c2 cell damage

INTRODUCTION: Doxorubicin causes high superoxide levels in the mitochondria contributing to cardiotoxicity. Ascorbic acid (AA) and sodium ascorbate (SA) are antioxidants and may mitigate doxorubicin-induced heart cell damage. OBJECTIVE: This study determined the effects of AA and SA on doxorubicin-induced cell damage. METHODS: AA or SA (10-4000 uM) were tested alone or cotreated with doxorubicin (40 uM) on H9c2 cells. Some cells were pretreated with AA and SA for 24 hours before doxorubicin. Cell viability and superoxides were evaluated using a cell counting kit and Mitosox assay, respectively. RESULTS: AA and SA (10-2000 uM) alone increased cell viability by 17-31% (n=3), accompanied by decreased mitochondrial superoxides by 6-29% (n=2) when compared to the non-treated control. However, higher doses of AA and SA (4000 uM, n=2) decreased cell viability and tripled mitochondrial superoxide levels relative to the non-treated control. Furthermore, when compared to doxorubicin-treated cells, cotreatment of SA or AA (100 uM, n=3) showed a maximum increase of cell viability by 21± 6% and 29± 18%, respectively; and pretreatment of SA or AA (100 uM, n=5) showed a maximum increase of cell viability by 46± 2% and 57± 3%, respectively. Pretreatment of AA also reduced mitochondrial superoxide by 47± 4% (n=2) compared to doxorubicin-treated cells. CONCLUSION: Preliminary data suggest that pretreatment of AA and SA exerted better cardiac protection against doxorubicin than cotreatment in H9c2 cells. The effects of pretreatment may be related to the reduction of mitochondrial superoxide. However, high levels of AA and SA showed pro-oxidant properties