Effect of ammonium nitrate on the production of PP-V and monascorubrin homologues by Penicillium sp. AZ

A fungal strain, Penicillium sp. AZ, has been found to produce the monascorubramine homologues, PP-V (10Z)-3-(9a-methyl-3-octanoyl-2,9-dioxo-2,7,9,9a-tetrahydro-furo3,2-g]isoquinolin-6-yl)-acrylic acid] and PP-R (10Z)-7-(2-hydroxyethyl)-monascorubramine] when cultured in a medium composed of soluble starch, ammonium nitrate, yeast extract, and citrate buffer, pH 5.0. When ammonium nitrate was omitted from the culture medium, PP-V and PP-R production was replaced by orange (PP-O) and yellow-orange (PP-Y) pigment production. The structures of these pigments were determined by FAB-MS and 1H and 13C NMR to be novel compounds, (10Z)-3-(9a-methyl-3-octanoyl-2,9-dioxo-9,9a-dihydro-2H-furo3,2-g]isochromen-6-yl)-acrylic acid and (10Z)-monascorubrin, respectively.