A New Xanthone from an Endophytic Fungus of Anoectochilus roxburghii

new xanthone, 2,8-dihydroxy-9-oxo-9H-xanthene-6-carboxylic acid ( 1 ), together with six known compounds, 2,8-dihydroxy-1-methoxycarbonyl-9-oxo-9H-xanthene-6-carboxylic acid ( 2 ), 8-hydroxy-3-methyl-9-oxo-9Hxanthene-1-carboxylic acid methyl ether ( 3 ), 1,3,6-trihydroxy-8-methylxanthone ( 4 ), 1,6-dihydroxy-3-methoxy-8-methylxanthone ( 5 ), decarboxycitrinone ( 6 ), and formoic acid A ( 7 ), were isolated from an endophytic fungus Arthrinium arundinis of Anoectochilus roxburghii . Compounds 2 , 3 , 5–7 were also isolated from this genus for the first time.