Postharvest UV-A radiation affects flavonoid content, composition, and bioactivity of Scutellaria baicalensis root

Abstract

Ultraviolet A (UV-A) radiation is the main component of solar radiation and can elicit a wide range of biochemical responses in plants. In this study, the effects of UV-A radiation on the flavonoid content, composition, and bioactivity in postharvest Scutellaria baicalensis roots were investigated. The total flavonoid content in S. baicalensis roots under postharvest UV-A radiation increased in a time-dependent manner and reached its maximum value (183.64 g kg−1) on the fifth day. Compared with the control group, the contents of four main flavonoids—baicalin, baicalein, wogonoside, and wogonin increased by 1.68 times, 3.00 times, 2.07 times, and 1.57 times, respectively; and new chemicals including pectolinarigenin, puerarin, isokaempferide, and jaceosidin were detected after 5 d of UV-A radiation. In addition, extracts of S. baicalensis roots exposed to postharvest UV-A radiation showed stronger antioxidant and antibacterial activities than control root extracts. Further correlation analysis revealed that baicalin and baicalein contents in the roots of S. baicalensis after postharvest UV-A radiation were positively correlated with antioxidant activity, while the main flavonoids showed different correlations with various bacteria. These results suggest that the appropriate duration of postharvest UV-A radiation is an effective way to enhance bioactive compound contents and their bioactivities in S. baicalensis roots.