The biochemistry of the ustilaginales. III. The degradation products and proof of the chemical heterogeneity of ustilagic acid.

Abstract

The D-glucolipid designated as ustilagic acid was shown to be a mixture of partially acylated derivatives of a di-D-glucosyl-dihydroxyhexadecanoic acid. The dihydroxyhexadecanoic acid was named "ustilic acid" and its di-D-glucosyl derivative was termed "glucoustilic acid". Alkaline hydrolysis of ustilagic acid yielded glucoustilic acid, acetic acid, dextro-β-hydroxy-n-caproic acid, dextro-β-hydroxy-n-caprylic acid and a small amount of n-caproic acid. The β-hydroxy-acids were characterized as dextro-β-hydroxy-n-caprohydrazide, m.p. 131–132°C., [α]D + 15.9° (water), and dextro-β-hydroxy-n-caprylhydrazide, m.p. 127–128°C., [α]D + 12° (water). Ustilic acid, m.p. 114–115°C., [α]D − 6.3° (methanol), yielded a methyl ester, m.p. 80−81.8°C, [α]D − 0.2 (chloroform). The methyl ustilate formed a di-phenylurethane derivative, m.p. 76–77°C. The infrared spectra of crystalline and amorphous samples of ustilagic acid are given. The specific rotation of glucoustilic acid, [α]D − 11° (methanol) was that expected of β-D-glucosides and the infrared spectrum of this substance showed a marked resemblance to that of methyl-β-D-glucopyranoside.