Isolation and biosynthesis of preussin B, a pyrrolidine alkaloid from Simplicillium lanosoniveum.

A new pyrrolidine alkaloid, preussin B (1), was isolated from the culture extract of the fungus Simplicillium lanosoniveurn TAMA 173 along with the known congener preussin (2). The structure and absolute configuration of 1 were determined by spectroscopic analysis and spectral comparison with 2. Feeding experiments with BC-labeled precursors revealed that the pyrrolidine ring of 1 was assembled from acetate and L-phenylalanine by a PKS-NRPS hybrid biosynthetic pathway.