Catalase (CAT; U/min/mg protein), superoxide dismutase (SOD; U/min/mg protein), glutathione reductase (GR; mmol/min/mg protein), and glutathione transferase (GST; mmol/min/mg protein) activities in HepG2 cells treated with two concentrations of receptacle, red or white, for 24 h or AAPH (2.5 mM) for 24 h and two concentrations of receptacle, red or white, then stressed with AAPH. Data are expressed as mean values ± SE. Columns with different superscript letters are significantly different (p < 0.05). CTL: cells without treatment; AAPH: cells incubated with AAPH; RR: cells incubated with red receptacle; WR: cells incubated with white receptacle; RR + AAPH: cells preincubated with red receptacle, then stressed with AAPH; WR + AAPH: cells preincubated with white receptacle, then stressed with AAPH; C1: concentration 1 (10 µg/mL); C2: concentration 2 (25 µg/mL).