2.3. Sample extracts
Fresh leaves were pulverised with liquid nitrogen, using a mortar. The aqueous extract was obtained using Milli Q water, accurately degassed, containing 5 mM diethyldithiocarbamic acid and 5 mM Na2EDTA. After centrifugation at 12,100g for 15 min, the pellet was discarded and the supernatant was used for determination of the total antioxidant activity of the aqueous phase and phenolic acid composition. Lipid extraction was performed in the dark and under a continuous flux of nitrogen, using chloroform/methanol (2:1, v/v). The extract was washed three times with KCl 0.88% (w/v) in order to eliminate salts. Chloroform phases were taken to dryness with a rotary evaporator and resuspended in chloroform/ethanol (1:5, v/v). Soon after resuspension, the lipid extract was used for determination of antioxidant activity of total lipid phase and tocopherol composition.