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, 4a,5,6,7,8,8a-hexahydro-5,3,4-trihydroxy-5,5,8a- trimethyl-4H-chromeno[2,3:7,6]flavone (2), 4a,5,6,7,8,8a-hexahydro-5,3,4, trihydroxy-5,5,8a-trimethyl-4H-chromeno[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).