Measurement of intracellular ROS
Oxidation-sensitive dye, DCFDA was employed to measure
the intracellular ROS activity induced by hydrogen peroxide
in human neural cell line (Wang and Joseph, 1999). On entering
the cell, DCFDA is hydrolyzed by cellular esterase enzyme
to a non-fluorescent dichloro-dihydro-fluorescein (DCFH)
which is oxidized to highly fluorescent dichlorofluorescein
(DCF) by the intracellular ROS. The amount of fluorescence
is equal to the amount of intracellular ROS generated inside
the cells (Lebel et al., 1992). Human neural cells were plated
at a density of 1 · 106 cells/well in 12-well plate; after 24 h, cells
were treated with different concentrations of H. rhamnoides
extract and exposed to 250 lM of H2O2 for 6 h. At the end
of treatment 10 lM DCFDA was added to the cells and incubated
for 30 min. The fluorescence was detected in flowcytometer
at an excitation wavelength of 485 nm and an
emission wavelength of 535 nm.