Structural analysis of cerebrosides from Aspergillus fungi: the existence of galactosylceramide in A. oryzae

Abstract

Glucosylceramide and galactosylceramide were detected in three Aspergillus species: Aspergillus oryzae, Aspergillus sojae and Aspergillus. awamori, using borate-coated TLC. The cerebrosides from A. oryzae were further purified by ion exchange and iatrobeads column chromatographies with or without borate, and determined the composition of sugar, fatty acid and sphingoid base by GC/MS, MALDI-TOF/MS and (1)H-NMR. We identified them as β-glucosylceramide and β-galactosylceramide. The ceramide moiety of both cerebrosides consisted mainly of 2-hydroxystearic acid and either 9-methyl-octadeca-4, 8-sphingadienine or octadeca-4, 8-sphingadienine. To our knowledge, this is the first study to provide evidence for the presence of β-galactosylceramide in A. oryzae.

Chemical Analysis of the Sugar Moiety of Monohexosylceramide Contained in Koji, Japanese Traditional Rice Fermented with Aspergillus

“…A previous study by the other group [11] reported that 11.4 mg of galactosylceramide and 10.6 mg of glucosylceramide are contained in 30 g of mycelia of Aspergillus. The inconsistency of the ratio between their report and our report might be derived from the growth medium.…”

“…These results indicate that 30.3% of the sugar moiety of monohexosylceramide of yellow koji is galactose, 69.7% of that is glucose, 19.2% of that of white koji is galactose and 80.8% of that is glucose ( Figure 5). These results provide strong evidence that 70%-80% of monohexosylceramide of koji is N-2′-hydroxyoctadecanoyl-l-O-β-D-glucopyranosyl-9-methyl-4,8-sphingadienine and 20%-30% of that is N-2′-hydroxyoctadecanoyl-l-O-β-D-galactopyranosyl-9-methyl-4,8-sphingadienine. A previous study by the other group [11] reported that 11.4 mg of galactosylceramide and 10.6 mg of glucosylceramide are contained in 30 g of mycelia of Aspergillus. The inconsistency of the ratio between their report and our report might be derived from the growth medium.…”

“…Fungi have various forms of glycosylceramide. Ascomycetes, including Aspergillus, Candida and Cryptococcus, have monoglycoside on the 1-hydroyl position of the sphingoid base [9][10][11]. On the contrary, zygomycetes such as Rhizopus have di-or tri-glycosides in this position [12].…”

“…However, there are very few studies on galactosylceramide, including the existence of galatosylceramide in koji or the functionality of galactosylceramide. Recently, it was reported that the mycelia of A. oryzae, A. sojae and A. awamori cultured in synthetic liquid media contain both β-glucosylceramide and β-galactosylceramide [11]. However, the growth and metabolism of Aspergillus in synthetic medium and that on rice are different [22].…”

Sphingolipids as Targets for Treatment of Fungal Infections

“…Several works have elucidated the entire fungal sphingolipid pathway [74][75][76][77][78][79]. Certain fungi, particularly molds, can also make GalCer in addition to GlcCer [80] but studies addressing the enzyme(s) involved in its synthesis or its role in fungal biology and pathobiology are missing.…”