Cell‐Type‐Dependent Differential Cytotoxic and Genotoxic Effects: Comprehensive Mechanistic Insights of L‐Ascorbic Acid on Healthy Lymphocytes and HL‐60 Cancer Cells

ABSTRACT l ‐Ascorbic acid exhibits paradoxical behavior as both antioxidant and pro‐oxidant in cancer treatment, with mechanisms and optimal dosing remaining unclear. This in vitro study investigated l ‐ascorbic acid's effects on healthy lymphocytes and HL‐60 leukemia cells using concentrations of 0.5–2 mg/mL for 6 and 24 h. Analyses included cell viability, gene expression, DNA damage, mutagenicity, and oxidative stress markers. The results demonstrated a dose‐dependent increase in the metabolic activity of HL‐60 cells, with a ~ sixfold increase observed at 2 mg/mL ( p ≤ 0.001), and opposing modulation of FAS/catalase gene expression between the two cell types. In healthy lymphocytes, both genes were suppressed with increasing exposure, while HL‐60 cells exhibited significant early induction (29‐fold for FAS and 47‐fold for catalase, p ≤ 0.001). l ‐Ascorbic acid concentrations (0.5–2 mg/mL) exhibited no significant genotoxicity in healthy cells, increased antioxidant status in healthy lymphocytes, and elevated oxidative stress (a 1.4‐fold increase in the oxidative stress index at 24 h, p ≤ 0.001) in HL‐60 cells. Ames testing confirmed non‐mutagenicity, while plasmid analysis revealed bimodal effects, being pro‐oxidant at an intermediate dose and protective at a high dose. These findings suggest that l ‐ascorbic acid requires cell‐type‐specific application in hematological malignancies and may offer a therapeutic window in leukemia treatment protocols, providing a foundation for optimizing combination strategies with conventional chemotherapeutics.