Extractives from Guttiferae. Part XXVI. Isolation and structure of six xanthones, a biflavanoid, and triterpenes from the heartwood of Pentaphalangium solomonse Warb
Two new naturally occurring xanthones, 6,11-dihydroxy-3,3-dimethylpyrano[2,3-c]xanthen-7(3H)-one (1) and its probable biogenetic precursor, 1,3,5-trihydroxy-4-(3-methylbut-2-enyl)xanthene-9-one, have been isolated from Pentaphalangium solomonse Warb. Other xanthones found were 1,3,7-trihydroxy-2-(3-methylbut-2-enyl)-,1,3,6,7-tetrahydroxy-, and 5-hydroxy-1-methoxy-xanthen-9-one. The isolation of a 3–8 linked biflavanone, GB-1a, and of a sterol mixture is reported.