Studies On Flavonoids Of Scorzonera Austriaca Willd.(Ⅱ)

Background:The Scorzonera austriaca Willd is a perennial herb of Scorzonera genus in Compositae. The resource of Scorzonera is abundant and is widely distributed in the northeast, northwest and north region of China. As a traditional chinese herb, Scorzonera austriaca Willd was widely used for relieving swelling, detoxication, carbuncle and mastitis. The modern pharmacological studies found the total flavonoids of Scorzonera austriaca Willd can obviously induce acute chemical and autoimmune liver injury in animal experiments. And they can significantly inhibit transcription and replication of HBV-DNA in Hep G2.2.15 cell experiment, therefore Scorzonera austriaca Willd has good value for medicinal purposes. Objective:Based on the related reports, the sesquiterpenoids, triterpenoids, coumarins and flavonoids have been isolated from Scorzonera. Among the isolated compounds, the sesquiterpenoid and triterpenoid has been researched clearly. However, the number of flavonoids were only 8, which is so few that the reason why the total flavonoids of Scorzonera can protect liver and inhibit virus can not be explained clearly.Therefore, in order to develop and make full of medicinal values of Scorzonera, it is very necessary to make further research on flavonoids of Scorzonera.This report is mainly about the isolation and the structural identification of the flavonoids. Methods:1: Extract of the total flavonoids of Scorzonera: Scorzonera austriaca Willd was soaked with 70% ethanol three times, and the whole extract was concentrated, dissolved in water, and subjected to D-101 macroporous resin column,60% ethanol elution part of which was concentrated and then collected the total flavonoids.2: Isolation of monomeric flavonoids: The total flavonoids of Scorzonera were isolated with macroporous resin columns, silica gel columns, ODS columns, and were purified with semi-preparing liquid chromatography.3. The structural identification: By physico-chemical property and spectral analysis methods, the structures of the flavonoids were identified. Results:With the above methods, the follow six flavonoids were isolated from Scorzonera austriaca Willd, and the structures were identified.(I): Isovitexin 2′′-O-β-D-glucopyranoside(II): Isovitexin(III): Rutin(IV): Isoscoparin.(V): Quercetin 3-O-β-D-glucopyranoside(VI): Apigenin 8-C-(6″-O- trans-caffeoyl-β-D-glucopyranoside) Conclusion:Comp. VI is a new C-glycosylflavone, Comp. Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ all are first isolated from Scorzonera austriaca Willd.