Anti-inflammatory and cytotoxic cyathane diterpenoids from the medicinal fungus Cyathus africanus

Abstract

Five novel cyathane diterpenes, cyathins D-H (1-5), as well as three known diterpenes, neosarcodonin O (6), cyathatriol (7),and 11-O-acetylcyathatriol (8), were isolated from the solid culture of Cyathus africanus. The structures of the new compounds were elucidated by spectroscopic methods. The absolute configurations of compounds 2 and 8 were determined by single-crystal X-ray crystallographic analysis, whereas the absolute configuration of C-14 in 1 was determined via the circular dichroism data of the [Rh(2)(OCOCF(3))(4)] complex. Compounds 3, 5, 6, 8, and 9 showed potent inhibition against nitric oxide production in lipopolysaccaride-activated macrophages with an IC(50) value of 2.57, 1.45, 12.0, 10.73, and 9.45μM, respectively. Compounds 6 and 8 showed strong cytotoxicity against Hela and K562 cell lines with the IC(50) value less than 10μM.