Sesquiterpenes from Syneilesis palmata and their cytotoxicity against human cancer cell lines in vitro.

The chromatographic separation of the MeOH extract from the aerial parts of Syneilesis palmata led to the isolation of a new sesquiterpene glycoside 4, together with four known compounds. Their structures were characterized to be 4beta,5beta-epoxy-caryophill-8,(15)-ene (1), 3beta-hydroxy-gultin-5-ene (2), 4alpha,5beta-dihydroxy-caryophill-8,(15)-ene (3), (-)-oplopan-4-one-10-alpha-O-beta-D-glucose (4) and 3-hexenyl-1-O-beta-D-glucopyranose (5), based on spectroscopic and chemical methods. Compound 2 showed moderate cytotoxicity against five human tumor cell lines in vitro with its ED50 values ranging from 5.90 to approximately 10.83 microg/mL.