Changes of antioxidative systems in various color leaves of Japanese spindle (Euonymus japonicus Thunb.)

Some physiological parameters and antioxidant responses were investigated in different color leaves of the evergreen shrub Japanese spindle (Euonymus japonica Thunb.). The shrub has leaves with three colors including dark green, light green, and yellow. Oxidative stress markers (hydrogen peroxide concentration, cell membrane stability, and lipids peroxidation), activity of peroxidase and some antioxidant molecules (phenolic compounds, proline, and free amino acids) were studied. Significant differences were found in hydrogen peroxide content, cell membrane stability, and membrane lipids peroxidation among leaves. In yellow leaves, the total content of proline and free amino acids were higher than those of the dark green and light green leaves. The highest and lowest free phenolic compounds contents were found in the dark green and yellow leaves, respectively. The POD activity increased significantly with changing leaf color from dark green to light green and to yellow. As a result, despite the activity of the antioxidant systems, the color change from dark green to yellow caused a gradual increase in the oxidative damage.