Flavone production in transformed root cultures of Scutellaria baicalensis Georgi

Abstract

A flavone derivative 5,2′-dihydroxy-6,7,8,3′-tetramethoxyflavone identified by 1H-, 13C-NMR, FABMS, together with two known phenolics skullcapflavone I and acteoside ( 3), were isolated from Scutellaria baicalensis transformed roots (clone C) into which the β-glucuronidase gene had been integrated by the infection with Agrobacterium rhizogenes A13. Another clone of transformed roots (clone W) was also induced by infection with A. rhizogenes ATCC 15834 (wild type). Both clones C and W, cultured in phytohormone-free BF liquid medium, produced 3 at a high content (maximum; clone C: 1.81% and clone W: 2.96% of tissue dry weight) under the light and dark conditions. The contents of glucuronide-type flavonoids, such as baicalin and wogonin 7- O-glucuronide in clone W, were almost three times higher than those in clone C. Compound 3, which was not detected in the intact plant roots, also accumulated in leaf (0.23% dry weight) and root (0.68% dry weight) parts of in vitro cultured plantlets.