Lipids and peptides on Pseudallescheria/Scedosporium fungal spores

摘要

Intact fungal spores have been used as a source of biomarkers that could, in principle, be used in the early stages upon infection (Figure 1). In this study, we have focused to low molecular weight compounds (Table 1). Two Pseudallescheria boydii isolates (CBS 119458 and CBS 116779), one of human and the other of animal origin, have been identified as cyclic peptide producers (Figure 2). Fungal strains were shown to produce mainly pseudacyclin A, a new cyclic hexapeptide containing three isoleucine residues (one of which is N-acetylated) and one residue of each of phenylalanine, ornithine, and proline (Figure 3). The molecule presents a unique structure of a type previously not reported. Pseudacyclin A and its minor analogues, probably of non-ribosomal origin, represent patented and unique lasso-peptide structures that can be used as extremely specific fungal markers (Figure 5). The most abundant representative – pseudacyclin A was quantified on fungal spores CBS 119458 (Figure 4). In Scedosporium prolificans intact fungal spores CBS 116906 and CBS 116904 (both of human origin) strong lipid signals were recorded (Figure 7). These were attributed to monohexosylceramides (neutral glycosphingolipids according to the lipid classification used by LipidMaps consortium), glycerophospholipids and phosphocholine-containing sphingolipids (Figures 8-10). In one (out of four) explored fungal strains a low molecular antitumour compound, Tyroscherin, was detected in the methanolic extract (Figure 6). It seems plausible that the analysis of pseudacyclins and some infection-specific lipids represents an objective technique that could help to establish an early diagnosis.