New prenylated bi- and tricyclic phloroglucinol derivatives from Hypericum papuanum

Five new prenylated tricyclic and three new bicyclic acylphloroglucinol derivatives have been isolated by bioactivity-guided fractionation of the petroleum ether extract of the dried aerial parts of Hypericum papuanum. The tricyclic compounds (1-5) were named papuaforins A-E. The bicyclic compounds were isolated together with their corresponding tautomers and were named hyperguinones A and B (6/6a, 7/7a) and hyperpapuanone (8/8a), respectively. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments, as well as mass spectrometry. Furthermore, the cytotoxicity toward KB nasopharyngeal carcinoma cells and the antibacterial activity of the isolated compounds were determined.