Variations of Saponarin Content in Young Barley Leaves Illuminated with Different Light-Emitting Diodes (LEDs)

In this study, the effect of light on the regulation of flavonoid production in young barley leaves (YBLs) was investigated. YBLs following germination were illuminated with different light-emitting diode (LED) lights, i.e. blue, red, far-red light, along with fluorescence and dark conditions as controls, and as the main flavonoid, saponarin content of YBLs was analyzed quantitatively with HPLC. In addition, the antioxidant activities of the crude ethanoic extracts of YBLs were analyzed by several antioxidant assays. The content of saponarin in blue light-illuminated barley leaves is two or three times higher than those in barley leaves with other lighting conditions, i.e. red, far-red, and the content with fluorescence and even dark conditions as controls. However, the levels of saponarin among the leaves illuminated with other lighting systems show no significant difference. And, the antioxidant potentials of the extracts of YBLs demonstrated same tendency shown in saponarin levels. Our results suggested that blue lighting conditions might evoke the photoprotection changes in YBLs, leading elevated level of saponarin, consequently increasing their antioxidant potentials.