(S)-Methyloxirane is a reactant that has been used in the synthesis of (-)-Pyrenophorol (P989610), the macrolide dilactone Pyrenophorol was originally isolated from Byssochlamys niveah and Stemphylium radicinum. Pyrenophorol was moderately active against the fungus Microbotryum violaceum. It is an anti-fungal antibiotic produced by the plant pathogenic fungi Pyrenophora avenue and Stemphylium radicinum, which is closely related structurally to (-)-Pyrenophorol.