Flavonoids from the capitula of Eriocaulon australe.

A flavan, eriocaulin A (1), and three flavone acyl glucosides, eriocaulosides A-C (2-4) were isolated from the capitula of Eriocaulon australe R. Br. (Eriocaulaceae), a Chinese medicine and an herb for health care beverages, together with seven known flavones and three isoflavones (5-14). The new flavonoids were elucidated as (2S)-3',4'-methylenedioxy-5-methoxy-7-hydroxyflavan (1), hispidulin 7-O-β-D-(6-O-cinnamoyl)glucopyranoside (2), jaceosidin 7-O-β-D-(6-O-p-coumaroyl)glucopyranoside (3), jaceosidin 7-O-β-D-(6-O-p-hydroxybenzoyl)glucopyranoside (4) based on their spectroscopic data. All the 14 flavonoids were obtained from this species for the first time. The in vitro cytotoxicity of compounds 1-14 against human lung adenocarcinoma A549, human breast adenocarcinoma MCF-7, and human cervical carcinoma HeLa cell lines was evaluated using the MTT colourimetric assay. Compounds 1, 7, and 9 were cytotoxic to A549, compounds 1, 2, 7, 9, 12, and 14 to MCF-7, and compounds 7, 9, and 14 to HeLa cells, with IC50 values ranging from 7.17 to 29.57 μg/ml, while the others were inactive (IC50>50 μg/ml).