Structure Elucidation of Sphingolipids from the Mycopathogen Sporothrix schenckii: Identification of Novel Glycosylinositol Phosphorylceramides with Core Manα1→6Ins Linkage

Abstract

Acidic glycosphingolipid components were extracted from the mycelium form of the thermally dimorphic mycopathogen Sporothrix schenckii. Two fractions from the mycelium form (Ss-M1 and Ss-M2), having the highest Rf values on HPTLC analysis, were isolated and their structures elucidated by 1- and 2-D 13C- and 1H-nuclear magnetic resonance spectroscopy, and electrospray ionization mass spectrometry with lithium adduction of molecular ions. The structures of Ss-M1 and Ss-M2 were determined to be Manα1→Ins1-P-1Cer and Manα1→ 3Manα1→Ins1-P-1Cer, respectively (where Ins = myo-inositol, P = phosphodiester). The Manα1→6Ins motif is found normally in diacylglycerol-based glycophosphatidylinositols of Mycobacteria, but this is the first unambiguous identification of the same linkage making up the core structure of fungal glycosylinositol phosphorylceramides (GIPCs). These results are discussed in relation to the structures of GIPCs of other mycopathogens, including Histoplasma capsulatum and Paracoccidioides brasiliensis.