Immunomodulatory constituents from an ascomycete, Microascus tardifaciens

Abstract

Fractionation guided by the immunosuppressive activity of the defatted AcOEt extract of an Ascomycete, Microascus tardifaciens, afforded eight constituents, questin (emodin 8-O-methylether) (1), rubrocristin (2), 5,7- dihydroxy-4-methylphthalide (3), cladosporin (asperentin) (4), cladosporin 8- O-methylether (5), tardioxopiperazine A [cyclo-L-alanyl-5-isopentenyl-2- (1',1'-dimethylallyl)-L-tryptophan] (6), tardioxopiperazine B [cyclo-L- alanyl-7-isopentenyl-2-(1',1'-dimethylallyl)-L-tryptophan] (7), and asperflavin (8), among which 6 and 7 were new compounds. Compounds 1 and 2 showed considerably high immunosuppressive activity, 6 was moderate and, 3, 4, 5, 7 and 8 showed low activity.