Abstract
Hypoxylon, a large, cosmopolitan genus of Ascomycota is in the focus of our current poly-thetic taxonomic studies, and served as an excellent source for bioactive secondary metabolites at the same time. The present work concerns a survey of the Hypoxylon fuscum species complex based on specimens from Iran and Europe by morphological studies and high performance liquid chromatography coupled to mass spectrometry and diode array detection (HPLC-MS-DAD). Apart from known chemotaxonomic markers like binaphthalene tetrol (BNT) and daldinin F, two unprece-dented molecules were detected and subsequently isolated to purity by semi preparative HPLC. Their structures were established by nuclear-magnetic resonance (NMR) spectroscopy as 3′-malonyl-daldinin F (6) and pseudofuscochalasin A (4). The new daldinin derivative 6 showed weak cytotoxicity towards mammalian cells but bactericidal activity. The new cytochalasin 4 was compared to cytochalasin C in an actin disruption assay using fluorescence microscopy of human osteo-sarcoma U2OS cells, revealing comparable activity towards F-actin but being irreversible compared to cytochalasin C. Concurrently, a multilocus molecular phylogeny based on ribosomal and proteinogenic nucleotide sequences of Hypoxylon species resulted in a well-supported clade for H. fuscum and its allies. From a comparison of morphological, chemotaxonomic and phylogenetic evidence, we introduce the new species H. eurasiaticum and H. pseudofuscum.
Highlights
The Hypoxylaceae are a family of the Xylariales (Sordariomycetes) that presently comprises 19 genera and approximately 400 taxa [1]
In the present study we have examined several specimens belonging to the H. fuscum complex from Iran and Europe using the above described combination of morphology, chemotaxonomy and molecular phylogeny
All major groups and deeper, highly supported nodes were consistent between the Maximum Likelihood (ML) and Maximum Parsimony (MP) analyses, but topologies of deeper unsupported nodes differed in the MP tree; as these differences are not relevant within the context of our new species, they are not further considered here
Summary
The Hypoxylaceae are a family of the Xylariales (Sordariomycetes) that presently comprises 19 genera and approximately 400 taxa [1]. The generic concept of Hypoxylon was traditionally based on macromorphological features relating to the stromatal morphology until Ju and Rogers [4]. Restricted the genus to accommodate only those species that have a nodulisporium-like anamorph. They divided these anamorph stages into sub-types based on the complexity of the branching patterns of the conidiophores. Other genera whose species were traditionally placed in Hypoxylon (e.g., Nemania) are accommodated in the Xylariaceae sensu stricto (see overview by Daranagama et al [5]). The current concept of the Hypoxylaceae is based on a multi gene genealogy but was recently even validated by a phylogenomic study based on 12 representatives using third generation genome sequencing techniques like Oxford nanopore and PACBIO [8]
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