Effect of pretreatment with rotenone, EGCG and rotenone plus EGCG on intracellular superoxide anion production in SH-SY5Y cells. The cells, seeded on a 96-well plate, were incubated with rotenone (10 μM), EGCG (25 μM), or rotenone (10 μM) plus EGCG (25 μM) for 20 h prior to the addition of hydroethidine (5 μM). The increase in fluorescence measured at excitation wavelength of 510 nm and emission wavelength of 590 nm was followed over a 4-h period. The data are expressed as means ± S.E. of 4 experiments.