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Free radicals have been known to be involved in the pathogenesis of various diseases such as ischemia, arteriosclerosis, diabetes, rheumatoid arthritis, inflammation and in the initiation of cancer. [1][2][3] Freeradical scavengers are considered to be protective agents against these diseases and thus, the demand for antioxidants having free-radical scavenging effect is gradually growing.Mushrooms are ubiquitous in nature and are a good source of food with high nutritional attributes, as well as they produce various classes of structurally unique secondary metabolites with valuable biological activities. During the screening for natural antioxidants from the Korean native ascomycetes, 4 we found that the fruiting body of ascomycete Daldinia concentrica, belonging to family Xylariaceae, exhibited significant free-radical scavenging activity. D. concentrica is known to produce diverse bioactive entities including azaphilone derivatives daldinins, 5 diaporthin, 6 an anti-HIV agent concentricolide, 7 squalene-type triterpenoids concentriols, 8 aromatic steroids, 9 daldinones 10 and neuroprotective lignans. 11 In this study, we isolated and characterized a novel isoindolinone derivative (daldinan A, Figure 1) responsible for free-radical scavenging effect from the methanolic extract of the fruiting body of D. concentrica.The fruiting body of D. concentrica (B320 g) collected near Muju county, Jeonbuk province, Korea, was ground and extracted with methanol at room temperature. This methanolic extract was concentrated under reduced pressure, and the aqueous resultant was partitioned consecutively between hexane, chloroform, ethyl acetate and butanol and water. The ethyl acetate-soluble portion, exhibiting potent radical-scavenging activity, was concentrated under reduced pressure, subjected to silica gel column chromatography, and eluted stepwise with chloroform:methanol (100:1-1:1, v/v). An antioxidant fraction was further separated by the second silica gel column chromatography eluted with chloroform:methanol (20:1, v/v). Active fractions were combined, concentrated in vacuo and chromatographed on a column of Sephadex LH-20 (Pharmacia, Uppsala, Sweden) eluted with methanol. Active fractions were combined and subjected to a reversed phase (C 18 ) Sep-pak cartridge eluted with 70% aqueous methanol, followed by preparative HPLC equipped with reversed phase column (150Â10 mm i.d.; Cosmosil, Nacalai tesque, Japan) and eluted with 35% aqueous methanol/0.04% trifluoroacetic acid to afford daldinan A (20 mg).The molecular weight of daldinan A was determined to be 415 by EI-mass measurement and its molecular formula was established to be C 22 H 25 NO 7 by high-resolution EI-mass measurement (m/z 415.1634 [M + ], D+3.0 m.m.u.) in combination with 1 H and 13 C NMR data. This molecular formula requires 11 degrees of unsaturation. The UV absorption maxima at 293 and 258 nm suggested the presence of aromatic functions in its structure. The 1 H and 13 C NMR peaks of daldinan A measured at room temperature was very broad and thus, t...

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Diverse p-terphenyl compounds, named curtisians, have been isolated from the fungus Paxillus curtisii, and degradation of wood by this fungus is thought to be progressed by iron chelation of p-terphenyl curtisians. In this study, the iron chelation ability of p-terphenyls has been proved by chrome azurol S (CAS) assay, reducing power, and UV-visible spectroscopic analyses. The catechol moiety of p-terphenyl is an essential factor for the potent iron chelation ability, and thus deacylated curtisian with a tetrahydroxyl moiety in the central ring of p-terphenyl is more effective than acylated curtisians.