A specialized flavone biosynthetic pathway has evolved in the medicinal plant, Scutellaria baicalensis.
A specialized flavone biosynthetic pathway has evolved in the medicinal plant, Scutellaria baicalensis.
复制标题
DOI：
10.1126/sciadv.1501780
复制
发表时间：
2016-04
期刊：
影响因子：
13.6
通讯作者：
Martin C
中科院分区：
文献类型：
--
作者：
Zhao Q;Zhang Y;Wang G;Hill L;Weng JK;Chen XY;Xue H;Martin C
黄芩通过一条新的代谢途径产生具有生物活性的4′-脱氧黄酮。汉黄芩素和黄芩素是广受欢迎的中草药黄芩中的生物活性黄酮。这些专门的黄酮在B环上缺少4′-羟基（4′-脱氧黄酮），并在体外诱导广谱人类肿瘤细胞凋亡，并在不同小鼠肿瘤模型中抑制体内肿瘤生长。来自紫藤属的根特异性黄酮（RSFs）具有多种报道的额外有益作用，包括抗氧化和抗病毒特性。我们描述了一个新的途径，为这些化合物的合成，其中松属素（4′-脱氧黄烷酮）作为一个关键中间体的表征。虽然两个编码黄酮合成酶II（FNSII）的基因在S. FNSII-1对作为底物的黄烷酮具有广泛的特异性，而FNSII-2对松属素具有特异性。FNSII-2负责合成4′-脱氧RSFs，如白杨素和汉黄芩素、汉黄芩苷、黄芩素和黄芩苷，它们是由白杨素合成的。如基因沉默所证明的，编码肉桂酸特异性辅酶A连接酶（SbCLL-7）的基因是FNSII-2合成RSFs所必需的，该酶在根中高度表达。在产生RSFs的根中高度表达的查耳酮合酶（SbCHS-2）的特定同种型也是白杨素合成所需的。我们的研究揭示了一个最近进化的途径，生物活性的特异性，4′-脱氧黄酮的根中的生物合成。黄芩
Scutellaria baicalensis (Huang-Qin in Chinese medicine) produces bioactive 4′-deoxyflavones by a newly evolved metabolic pathway. 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.