Acetogenin and Prenylated Flavonoids from Helminthostachys zeylanica with Inhibitory Activity on Superoxide Generation and Elastase Release by Neutrophils

One new acetogenin, 6-hydroxy-8-pentadecyloxocane-2,7-dione (1), and four new prenylated flavonoids, 4 '' a,5 '',6 '',7 '',8 '',8 '' a-hexahydro-5,3',4'-trihydroxy-5 '',5 '',8 '' a-trimethyl-4H-chromeno[2 '',3 '': 7,6] flavone (2), 4 '' a,5 '',6 '',7 '',8 '',8 '' a-hexahydro5,3', 4',-trihydroxy-5 '',5 '',8 '' a-trimethyl-4Hchromeno[2 '', 3 '': 7,8] flavone (3), 2-(3,4-dihydroxyphenyl)6-((2,2-dimethyl-6-methylenecyclohexyl) methyl)-5,7-dihydroxy-chroman-4-one (4), and 2-(3,4-dihydroxy-2-[(2,6,6-trimethylcyclohex-2-enyl) methyl] phenyl)-3,5,7-trihydroxy-4H-chromen-4-one (5), together with six known compounds, were isolated and purified from the rhizomes of Helminthostachys zeylanica by column chromatography and high performance liquid chromatography (HPLC) via bioactivity-guided fractionation isolation. The structures of the new isolates were elucidated by spectroscopic methods. Compounds 1, 3, and 5 showed inhibitory activities on either superoxide anion generation or elastase release by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine/cytochalasin B (FMLP/CB).