| Abstract | Aspergillus flavus PRL 932 grown on 2% yeast extract medium produced the following 1-hydroxy-2(1H)-pyrazinones (abbreviation, HPY): 3-isobutyl-6-isopropyl-HPY, 3,6-diisobutyl-HPY, 3-isobutyl-6-sec-butyl-HPY (aspergillic acid, the major product), and 3,6-di-sec-butyl-HPY.When the growth media consisted of 0.6% yeast extract plus 1% of certain amino acids, the structure of some of the HPYs produced suggested that the amino acid was a precursor in the biosynthesis. With a leucine supplement, the major product was 3,6-diisobutyl-HPY, and with an isoleucine supplement, the major product was 3,6-di-sec-butyl-HPY. With a valine supplement, the HPYs included 3,6-diisopropyl-HPY and 3-isobutyl-6-isopropyl-HPY. With a norvaline supplement, they included 3,6-dipropyl-HPY, 3-propyl-6-sec-butyl-HPY, and 3-isobutyl-6-propyl-HPY. From the structure of the HPYs, conclusions were drawn regarding the specificity of the biosynthesis.The HPYs were separated by reversed-phase partition chromatography and identified by their proton magnetic resonance spectra and mass spectra. |
|---|
