Neobraclactones A-C, three unprecedented chaise longue-shaped xanthones from Garcinia bracteata.

Neobraclactones A-C (1-3), featuring an unprecedented further rearranged prenylxanthone skeleton with a unique octahydro-2H-1,3-dioxacyclopenta[c,d]inden-2-one scaffold, along with their biosynthesis-related known compound neobractatin (4), were isolated from the leaves of Garcinia bracteata. Their structures with absolute configurations were determined by extensive analyses of spectroscopic data and ECD calculations. Compounds 1 and 2 showed significant growth inhibition activities against the human leukaemia HL-60 and K562 cell lines with GI50 values from 0.40 to 0.86 μM.