Cibotium barometz J. Smith (Dicksoniaceae), a traditional Asian herbal medicine, was reported to have several biological activities including neuronal regeneration and an anti-inflammatory effect for the bones. Phytochemical screening of this plant revealed the presence of several compounds such as protocatechuic acid, caffeic acid and shinbarometin (2-O-(9Z,12Z-octadecadienoyl)-3-O-[α-D-galactopyranosyl-(1′′→6')-O-β-D-galactopyranosyl]glycerol). Cell damage by reactive oxygen species such as superoxide anion are generally recognized to cause many kinds of disease and promote aging to living organisms. Free radical scavenging activity is regarded as playing an important role in the prevention of various chronic diseases and the aging process. To search for antioxidant constituents from C. barometz, its rhizomes were extracted with 80% methanol and partitioned into five fractions based on their polarity. Fractionations and subfractionations were performed by bioassay-guided isolation, and bioactive compounds were separated from chloroform and n-butanol fractions showing significant antioxidant effect. Evaluation of antioxidant activity was carried out using the 1,1-diphenyl-2-picrylhydrazyl radical in methanol, and L-ascorbic acid and BHA and BHT were used as positive controls in the assay. Structures of the active compounds were elucidated by spectroscopic techniques inclusive of 2D-NMR (HMBC, HSQC), IR, UV and mass spectrometry
