Sporothriolide derivatives as chemotaxonomic markers forHypoxylon monticulosum

Abstract

During the course of a screening for novel anti-infective agents from cultures of tropical Xylariaceae originating from French Guiana and Thailand, pronounced antifungal activity was noted in extracts of cultures of Hypoxylon monticulosum. A bioassay-guided fractionation led to the known metabolite sporothriolide as active principle. In addition, three new derivatives of sporothriolide were isolated, for which we propose the trivial names sporothric acid, isosporothric acid and dihydroisosporothric acid. Their chemical structures were elucidated by high-resolution electrospray mass spectrometry in conjunction with two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. From earlier studies on the biogenesis of the chemically similar canadensolides, we postulate that the new compounds were shunt products, rather than biogenetic precursors of sporothriolide. Interestingly, this compound class, as well as strong antifungal activities, was only observed in multiple cultures of H. monticulosum, but not in several hundreds of Hypoxylon cultures studied previously or concurrently. Therefore, sporothriolide production may constitute a species-specific feature with respect to Hypoxylon and the Xylariaceae, although the compound was previously reported from non-related fungal taxa.

Observations on Texas hypoxylons, including two newHypoxylonspecies and widespread environmental isolates of theH. croceumcomplex identified by a polyphasic approach

“…Fermentation was aborted after free glucose has been consumed and the mycelia was separated from the culture broth by vacuum filtration. The extraction of both parts followed a previously published protocol (Surup et al 2014). The crude extracts were dissolved in acetone and analyzed with HPLC-MS according to Kuhnert et al (2014b).…”

Oryzines A & B, Maleidride Congeners from Aspergillus oryzae and Their Putative Biosynthesis

“…As various other transformants did not show increased production of oryzines it can be speculated that the regulation of gene expression within the oryzine BGC was influenced by the random insertion of the heterologous expressed tenS gene into the A. oryzae genome. Related compounds such as piliformic acid 10 are known to be derived from fatty acids and oxaloacetate [ 28 ]; while the furofuranones 4- epi -ethiosiloide 14 , sporothriolide 15 and discosiolide 16 , are also thought to be derived from fatty acids and oxaloacetate [ 29 , 30 ]. These compounds differ from 3 and 10 by having differing carbon-chain lengths, and by a different lactonisation pattern.…”

Identification of fungal fossils and novel azaphilone pigments in ancient carbonised specimens of Hypoxylon fragiforme from forest soils of Châtillon-sur-Seine (Burgundy)

“…However, the secondary metabolism of these fungi is so diverse that most compounds produced during their life cycle have not yet been identified. Many metabolites that exhibit prominent biological activities are indeed only produced by the cultures (Surup et al 2014) or in the growing stromata bearing the anamorph , and several were only identified after large-scale biotechnological production and extensive chromatographic work (Kuhnert et al 2015;Surup et al 2018).…”