Production and structural analysis of PP-V, a homologue of monascorubramine, produced by a new isolate of Penicillium sp

A fungal strain newly isolated from soil has been found to produce a violet water-soluble pigment (PP-V) in high quantity when cultured in a medium consisting of soluble starch and citrate buffer. Glucose repressed the production of this pigment. PP-V has the molecular formula C23H25NO6 revealed by HR-FAB mass spectroscopy and has been shown to be composed of an isoquinoline skeleton, a n-octanoyl group, and a 2-propenoic acid group by NMR. In conclusion, PP-V is a novel compound, 3-(9a-methyl-3-octanoyl-2,9-dioxo-2,7,9,9a-tetrahydro-furo3,2-g]isoquinolin-6-yl)acrylic acid; a homologue of monascorubramine in which the 1-propenyl group is converted to a 2-propenoic acid group.