Tomoeones A–H, cytotoxic phloroglucinol derivatives from Hypericum ascyron

Abstract

Phloroglucinol derivatives tomoeones A–H (1–8) and three known compounds were isolated from leaves of Hypericum ascyron. Their structures were established based on spectroscopic analyses. They are all acylphloroglucinol derivatives possessing a spiro skeleton with geminal isoprenyl groups and a monoterpene moiety, and they are stereoisomers to each other at C-4 and C-13. They appear to be a class of phloroglucinol derivatives. Cytotoxicities of the isolated phloroglucinol derivatives against human tumor cell lines, including multidrug-resistant (MDR) cancer cell lines, were evaluated. Tomoeone F (6) demonstrated significant cytotoxicity against KB cells with an IC50 value of 6.2μM. Compound 6 was also cytotoxic against MDR cancer cell lines (KB-C2 and K562/Adr), which was more potent than doxorubicin.