While select eudesmane sesquiterpenes exhibit anti-neoplastic activity, tumor-inhibition for costic-acids has not been established. Here biological activity of 3-oxo-γ-costic acid (1), previously isolated from Chiliadenus montanus, as well as new sesquiterpenes (2-5) and the known derivative,
Phytochemical study of Chiliadenus montanus aerial parts afforded six compounds; Intermedeol (1), 5α-hydroperoxy-β-eudesmol (2), 5,7-dihydroxy-3,3',4'-trimethoxyflavone (3), 5,7,4'-trihydroxy-3,6,3'-trimethoxyflavone (jaceidin) (4), eudesm-11,13-ene-1β,4β,7α-triol (5) and