Lipid peroxidation was
estimated by the level of malondialdehyde (MDA) production
based on the thiobarbituricacid (TBA) method described by Heath
and Packer 11. Fresh leaf (250 mg)samples were homogenized in 5
mL of 0.1% (w/v) trichloroacetic acid (TCA) solution. The
homogenate was centrifuged at 15,000 g for 15 min. Of the
supernatant 1.0 mL was added to 4 mL of 0.5% (w/v) TBA in 20%
TCA (w/v), heated in a boiling water bath for half an hour and
immediately cooled in an ice bath to stop reaction. The absorbance
of the resulting supernatantwas recordedat 532 nm and corrected
for nonspecific turbidity by subtracting the absorbance at 600
nm. MDA concentrations were calculated by means of anextinction
coefficient of 155 mM-1 cm-1