Immunomodulatory constituents from an ascomycete, Emericella aurantio-brunnea

Fractionation monitored by the immunomodulatory activity of the AcOEt extra ct of an Ascomycete, Emericella aurantio-brunnea. afforded two known fungal sesterterpenes, variecolin (1) and variecolactone (2), two new variecolin congeners named variecoacetals A (3) and B (4), and a new sesquiterpenetrio l diester named emeremophiline (5), as the immunosuppressive constituents o f this fungus. The absolute configuration of 1, which was previously not de termined, was determined to be (2S,3S,6R,10S,11R,14S,15R,16S) from the NMR spectral data of the (6R,7R)-dimethyl-1,3,5-trioxacycloheptyl derivative of 1 (7), The absolute configurations of the other variecolin congeners, 2-4. and variecolol (6) are also proposed from biosynthetic considerations.