A New Xanthone from an Endophytic Fungus of Anoectochilus roxburghii

A 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.