In Fig. 2, the antioxidant activity, detected by EPR, is expressed as the ability to reduce radicals by 1 g (DW) of basil leaves. Antioxidant potential of aqueous extract was 40.3% higher in plants grown in hydroponics for 20 days (20H) than in those grown for 35 days (35H). A significant decrease, by 14.0%, was also observed in the antioxidant activity of aqueous extract from plants grown in soil for 35 days (35S) in comparison with plants of the same age grown in hydroponics (35H, Fig. 2A). The same trend was shown by spectrophotometric measurements of ABTS+ radical cation scavenged by aqueous extract (Fig. 3A). The two rate constants which characterise the decay kinetics of DPPH are indicative of the presence of antioxidants in the lipid extract distinguishable for a fast or a slow action. For this reason, we can calculate (by EPR kinetics) a fast (Fig. 2B) or slow (Fig. 2C) antioxidant activity of the lipid extract. The fast and slow antioxidant activities were of the same magnitude, even if they showed different trends, depending on age and on the type of cultivation (Fig. 2B and C). Substantial decreases (about 60%) in the fast antioxidant activity of lipid extract were observed in 35H compared to 20H and in 35S compared to 35H (Fig. 2B), whereas the trend of slow antioxidant activity reflected that of antioxidant activity detected spectrophotometrically (Figs. 2C and 3B).