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.