A specialized flavone biosynthetic pathway has evolved in the medicinal plant, Scutellaria baicalensis
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Author(s)
Zhao, Q.
Zhang, Y.
Wang, G.
Hill, L.
Chen, X.-Y.
Xue, H.
Martin, C.
Weng, Jing-Ke
Date Issued
May 2016
Journal
Science Advances
Publisher
American Association for the Advancement of Science (AAAS)
Citation
Zhao, Q. et al. “A Specialized Flavone Biosynthetic Pathway Has Evolved in the Medicinal Plant, Scutellaria Baicalensis.” Science Advances 2.4 (2016): e1501780–e1501780.
Version
Final published version
Abstract
Wogonin and baicalein are bioactive flavones in the popular Chinese herbal remedy Huang-Qin (Scutellaria baicalensis Georgi). These specialized flavones lack a 4′-hydroxyl group on the B ring (4′-deoxyflavones) and induce apoptosis in a wide spectrum of human tumor cells in vitro and inhibit tumor growth in vivo in different mouse tumor models. Root-specific flavones (RSFs) from Scutellaria have a variety of reported additional beneficial effects including antioxidant and antiviral properties. We describe the characterization of a new pathway for the synthesis of these compounds, in which pinocembrin (a 4′-deoxyflavanone) serves as a key intermediate. Although two genes encoding flavone synthase II (FNSII) are expressed in the roots of S. baicalensis, FNSII-1 has broad specificity for flavanones as substrates, whereas FNSII-2 is specific for pinocembrin. FNSII-2 is responsible for the synthesis of 4′-deoxyRSFs, such as chrysin and wogonin, wogonoside, baicalein, and baicalin, which are synthesized from chrysin. A gene encoding a cinnamic acid–specific coenzyme A ligase (SbCLL-7), which is highly expressed in roots, is required for the synthesis of RSFs by FNSII-2, as demonstrated by gene silencing. A specific isoform of chalcone synthase (SbCHS-2) that is highly expressed in roots producing RSFs is also required for the synthesis of chrysin. Our studies reveal a recently evolved pathway for biosynthesis of specific, bioactive 4′-deoxyflavones in the roots of S. baicalensis.
MIT Department
Massachusetts Institute of Technology. Department of Biology
Whitehead Institute for Biomedical Research
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Creative Commons Attribution-NonCommercial 4.0 International
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DOI of Published Version
https://doi.org/10.1126/sciadv.1501780
