EFFECT OF ELEVATED COPPER ON PHENOLIC COMPOUNDS OF SPINACH LEAF TISSUES

ABSTRACT The effect of copper [Cu(II)] on the phenolic compounds of spinach (Spinacea oleracea L.) leaf tissues was investigated. Leaf disks (7 mm) were exposed to CuSO4·5H2O concentrations from 50 μM (12.5 ppm) to 2.5 mM (625 ppm) at pHs from 4.0 to 9.0 for 24 hr in both the light and dark. Acidified, aqueous methanol (flavonoid-rich fraction) extracts were analyzed by high performance liquid chromatography. Cu(II) altered the levels of the phenolic compounds, increasing the levels of some compounds at low Cu(II) concentrations and decreasing the levels of all the phenolic compounds at higher Cu(II) levels. In most cases, the magnitude of the Cu(II)-induced changes in spinach phenolics was independent of treatment pH. These Cu(II)-induced changes in phenolic compounds may modify plant responses to environmental or biotic stresses and alter the nutritional values of certain vegetable crops.