Viridistratins A-C, Antimicrobial and Cytotoxic Benzo[j]fluoranthenes from Stromata of Annulohypoxylon viridistratum (Hypoxylaceae, Ascomycota).

Kevin Becker,J Jennifer Luangsa-Ard,Marc Stadler,Anna-Charleen Wessel

doi:10.3390/biom10050805

Abstract

During the course of our search for novel biologically active metabolites from tropical fungi, we are using chemotaxonomic and taxonomic methodology for the preselection of interesting materials. Recently, three previously undescribed benzo[j]fluoranthenes (1−3) together with the known derivatives truncatones A and C (4, 5) were isolated from the stromata of the recently described species Annulohypoxylon viridistratum collected in Thailand. Their chemical structures were elucidated by means of spectral methods, including nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HR-MS). The new compounds, for which we propose the trivial names viridistratins A−C, exhibited weak-to-moderate antimicrobial and cytotoxic activities in cell-based assays.

Highlights

The genus Annulohypoxylon belongs to the fungal family Hypoxylaceae, which was recently resurrected [1] to accommodate Hypoxylon and allied genera and is known for a remarkably diverse secondary metabolism [2]
Recent major phylogenetic studies [1,9], which were even confirmed by phylogenomics [10] have led to the segregation of the new genus Jackrogersella, which was segregated from Annulohypoxylon based on a combination of morphological and chemotaxonomic traits with the results of a multilocus molecular phylogeny
Examples of common naphthalene derivatives in Annulohypoxylon spp. are the rather ubiquitous 1,1’-binaphthalene-4,4’,5,5’-tetrol (BNT) [2], as well as oxidized derivatives thereof, such as truncatones [2,12], hypoxylonols [2,13,14] and daldinones [2,11], with the three latter ones belonging to the subclass of benzo[j]fluoranthenes

Summary

Introduction

The genus Annulohypoxylon belongs to the fungal family Hypoxylaceae (order Xylariales), which was recently resurrected [1] to accommodate Hypoxylon and allied genera and is known for a remarkably diverse secondary metabolism [2]. Examples of common naphthalene derivatives in Annulohypoxylon spp. are the rather ubiquitous 1,1’-binaphthalene-4,4’,5,5’-tetrol (BNT) [2], as well as oxidized derivatives thereof, such as truncatones [2,12], hypoxylonols [2,13,14] and daldinones [2,11], with the three latter ones belonging to the subclass of benzo[j]fluoranthenes The latter compound class has been exclusively found in Annulohypoxylon species and was so far not detected in Jackrogersella and Hypoxylon [2,4], even though binaphthalenes occur in other, more distantly related Hypoxylaceae such as Daldinia [5]

Methods

Results

Discussion

Conclusion