| Abstract: | Extracts of six fungi, four yeasts, and two species of Streptomyces were tested for antioxidant activity when added to lard. Extracts of Aspergillus niger, the microorganism that showed the strongest antioxidant activity, were subjected to adsorption and gel permeation chromatography. Two fractions that protected lard against oxidation were obtained by chromatography of A. niger extract on Sephadex LH-20 and Bio-Beads S-X2. One of these fractions contained a gummy brown pigment BR, the other a bright yellow crystalline pigment Y. Pigment BR showed strong carbonyl group and methyl-methylene group absorption in the infrared. Apparently, on the basis of spectral data, pigment Y has a linear naphthopyrone structure. Pigment BR was obtained consistently from A. niger mycelium, while pigment Y was formed sporadically. Results indicated that more than one substance in A. niger mycelium have antioxidant properties and that brown and yellow pigments apparently are associated with antioxidant activity. Synergistic effects may be important in the strong antioxidant activity of A. niger extracts. |
