ABSTRACT
The filamentous fungus Monascus ruber produces water-soluble red pigments in a submerged culture when grown in a chemically defined medium containing glucose as a carbon source and monosodium glutamate as a nitrogen source. Two new molecules with polyketide structures, N-glucosylrubropunctamine and N-glucosylmonascorubramine, constituting under some conditions 10% of the total extracellular coloring matter when glucose as a carbon source was in excess (20 g/liter), were isolated and structurally characterized by high-pressure liquid chromatography, Dionex methods, (sup1)H and (sup13)C nuclear magnetic resonance spectroscopy, and mass spectrometry. The occurrence of the electron donor-acceptor complex effect was demonstrated by UV spectroscopy, polarography, and thin-layer voltammetry. The use of n-butanol as an extraction solvent stabilized the pigments against the effects of daylight for several months, promoting the stability of this type of complex.
ABSTRACT
Following our investigations on red pigments and monascidin co-production by Monascus species, the antibiotic called monascidin A was characterized as citrinin. Evidence was given by qualitative methods, mass spectra and NMR. Citrinin, a nephrotoxic agent was produced both by Monascus purpureus and Monascus ruber, either in submerged culture of concentrations of 270 and 340 mg/l, respectively, or in solid state culture of concentration of 100 and 300 mg/kg dried matter, respectively. Since citrinin is a toxic product, it is essential that the production of red pigments as food additives from Monascus spp. avoid the occurrence of citrinin.
