Takaneones A–C, prenylated butylphloroglucinol derivatives from Hypericum sikokumontanum

Three new prenylated butylphloroglucinol derivatives, takaneones A–C (1–3), were isolated from the MeOH extracts of the aerial parts of Hypericum sikokumontanum together with two new prenylated phloroglucinol derivatives, takaneols A and B (4 and 5). The structures of the isolated compounds were elucidated by exhaustive spectroscopic analysis. The cytotoxicities of the isolated compounds against human cancer cell lines were evaluated. Compounds 2–4 showed cytotoxicities against K562/Adr multi-drug resistant (MDR) cancer cells with IC50 values ranging from 4.7 to 10.0 μg/mL, which were slightly more potent than doxorubicin. Their potency of cytotoxicities against MDR cancer cell lines (KB-C2 and K562/Adr) were similar to those against sensitive cell lines (KB and K562).