Chemical constituents, cytotoxic and antioxidant activities of extract from the rhizomes of Osmunda japonica Thunb.

Thirty-three compounds (1-33) were isolated from the rhizomes of Osmunda japonica. Their structures were elucidated on the basis of spectral analysis and identified as ent-kaurene terpenoids (1-3), anthraquinones (4-8), flavonoids (9-12), steroids (13-15), and other compounds (16-33). Compound 1-14, 19-27 were isolated from the genus osmunda for the first time. Compound 28-29 were isolated from the plant for the first time. Cytotoxicities of all compounds against Hela, HepG2 and A549 cell lines were measured by MTT assay, and their antioxidant activities were determined by DPPH and ABTS radical scavenging assays. Compound 2 exhibited potent cytotoxicity against Hela, HepG2 cell lines with IC50 values of 9.31 and 9.66 μM, respectively. Compound 9 showed good antioxidant activity. The Trolox-equivalent antioxidant capacity (TEAC) value was 0.95 mM in ABTS assay, and the IC50 value was 18.63 μM in DPPH assay.