Impact of Blue Light on Plant Growth, Flowering and Accumulation of Medicinal Flavones in Scutellaria baicalensis and S. lateriflora

Scutellaria baicalensis Georgi (Baikal skullcap) and S. lateriflora (American skullcap) are two ethnobotanical medicinal plants used to treat gastrointestinal, respiratory, and inflammatory disorders, in addition to demonstrated anti-cancer properties. The predominant bioactive compounds produced in these species are unique 4′-deoxyflavones, in roots of S. baicalensis and leaves of S. lateriflora, making these two species suitable to study the effects of light quality on flavone accumulation in aerial and underground tissues. Light emitting diodes were used to study the impact of blue-dominated spectrum on the accumulation of bioactive flavones. Eight major flavones, including 4′-deoxyflavones baicalein, wogonin, baicalin, wogonoside and chrysin, along with 4′-hydroxyflavones scutellarein, scutellarin and apigenin, were quantified using HPLC in high flavone accumulating tissues. Aerial tissues directly exposed to blue light in S. lateriflora showed an increase in the concentrations of scutellarein by 18.7%, scutellarin by 296%, and baicalin by 31.6%. While the roots in S. baicalensis also had significant increases in baicalein by 154% and wogonin by 76% in response to blue light, there was a slight reduction in their respective glycosides baicalin and wogonoside as well as a decrease in total flavone content. Blue light resulted in compact skullcap plants with early flowering and modified flavone profiles.