Fungal Metabolism of Complex Glycosides: Ustilagic Acid.

Ustilagic acid is a water-insoluble glycolipid produced by Ustilago may&, the corn smut fungus. It was discovered by Haskins (l), and its structure was elucidated by Lemieux, Thorn, and Bauer (2, 3). Pilot plant quantities are being produced in Japan.’ Ustilagic acid was shown to be a mixture of acylated derivatives of /I-n-cellobiosyl-15u, l&dihydroxy-n-hexadecanoic acid (glucoustilic acid A) and @-D-cellobiosyl-2n, 15~~ 16-trihydroxy-n-hexadecanoic acid (glucoustilic acid B). The major components (Fig. 1) of the mixture were considered to be diesters of the glucoustilic acids with acetic acid and either n-P-hydroxyn-hexanoic or L-P-hydroxy-n-octanoic acid. Minor components may contain n-hexanoyl groups. This work on the digestion of the complex, insoluble ustilagic acids was undertaken to determine the effect of acylation on the degradation of glycosides by fungi.