Enhancement of Health Functional Compounds in the Sprouts of Barley (Hordeum vulgare L.) Cultivars by UV-B and Salicylic Acid Treatments

Barley (Hordeum vulgare L.) sprouts are a vegetable commonly used as a functional food material due to its high vitamin C concentration and antioxidant activity. In this experiment, we measured the changes in the antioxidant activity of several barley cultivars as well as in the concentrations of related compounds such as ascorbate and glutathione upon treatment with UV-B or salicylic acid (SA). The six barely cultivars were grown in a plant growth chamber (25/$18^{\circ}C$, 14/10 h, 200 ${\mu}mol{\cdot}m^{-1}{\cdot}s^{-1}$, 70% relative humidity) for 10 days. All barely cultivars showed different 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activities, which were increased by UV-B treatment and not by SA treatment. The changes in ascorbate concentrations were correlated with DPPH scavenging activity in both the treatments, suggesting that the antioxidant activity in barley sprouts was mainly dependent on ascorbate concentration. Furthermore, changes in ascorbate concentration showed similar tendencies to changes in free sugar concentration, especially glucose and sucrose, in both treatments. On the other hand, the concentrations of glutathione and cysteine highly increased by SA treatment, representing different tendencies compared to the DPPH scavenging activity and ascorbate concentration. 'Donghanchal' cultivar showed comparatively higher antioxidant activity, both constitutively and inducingly by UV-B treatment, with its higher concentrations of ascorbate and glutathione. These results suggest that barley sprouts could be used as a health-functional vegetable, contributing to the overall supply of antioxidant and sulfur-containing organic compounds.