Harrisotones A-E, five novel prenylated polyketides with a rare spirocyclic skeleton from Harrisonia perforata

Five novel prenylated polyketides, harrisotones A-E (1-5) representing a rare spirocyclic skeleton, along with a new hydroperoxypolyketide harrisonol A (6), were isolated from the stems and leaves of Harrisonia perforata. The structures of harrisotones A-E (1-5) were extensively elucidated on the basis of spectroscopic analysis, especially 2D NMR and CD spectra. A plausible origin of compounds 1-5 was rationalized biogenetically, and traced back to harrisonol A (6). Harrisotones A-C (1-3) and harrisonol A (6) exhibited significant cytotoxicity against P-388 and/or A-549 tumor cell lines.