New bioactive metabolites from Penicillium purpurogenum MM

Three new bioactive compounds, namely (S)-tenellic acid B dimethyl acetal (1a), (3R, 3'R/S)-isotalarone (2), and (3R, 5R)-cis-5-methyl-3-(2-oxobutyl)-dihydrofuran-2-one (3), were isolated from the terrestrial fungus Penicillium purpurogenum MM, together with 15 known metabolites: talaroflavone, pestalasin A, altenuene, penicillide, 3'-O-methyl-dehydroisopenicillide, rubralactone, tenellic acid B, diaporthin, butyrolactone 1, butyrolactone-V, 4-hydroxy-2-methoxyacetanilide, ergosterol, ergosterol peroxide, linoleic acid, and glycerol monolinoleate. The chemical structures of the three new compounds were confirmed by extensive one-and two-dimensional NMR and electron spray ionization high-resolution mass spectra measurements and by comparison with literature data. The absolute configurations of the new compounds, and of talaroflavone (4a) and tenellic acid B (2b), were determined by ab initio calculations of ECD, ORD, and NMR data. The antimicrobial and cytotoxic activities of the crude extract and of the isolated compounds were studied using a set of microorganisms and brine shrimp assay, respectively. The isolation and taxonomic characterization of P. purpurogenum MM is reported.