Fungal metabolites. Part III. Isolation of secalonic acids fromPhoma terrestris
Abstract
Extraction of the dried mycelium of Phoma terrestris Hansen gave two yellow pigments to which are assigned the substituted 9,9′-dioxo-2,2′-bixanthen-10a,10a′-dicarboxylate structures (1a) and (2a). Compound (1a) has not been reported previously and we designate this secalonic acid E, although it appears to be enantiomeric with secalonic acid B. Compound (2a) has a structure already assigned to secalonic acid A but differs from the latter in some analytical details; reasons for these differences are suggested.