determine the IC50 for C. longa and curcumin (used as a standard), cells were treated with different concentrations of either extract for 72 h and then cell viability was assessed. The IC50 for aqueous extract of C. longa was 45 μg/mL, compared with 36.5 μmol/L for curcumin (data not shown). Using curcumin as a standard, hepatocytes were pretreated with C. longa extract (45 μg/mL) for 24 h and then exposed to a single dose of g-radiation (3.2 Gy), which demonstrated the radioprotective properties of the extract (p < 0.05) (Fig. 1b).