Depsides have garnered substantial interest due to the diverse biological activities exhibited by members of this class. Among these are the antibacterial aquastatins, glycosylated heteromeric depsides formed through the condensation of orsellinic acid with corticiolic acid. In this work, we isolated aquastatins and the recently described geministatins, along with several novel aquastatin-related depsides with different alkyl side chains from the fungus MST-FP2131.
View Article and Find Full Text PDFTwo new depside antibiotics, geministatins A (1) and B (2), were isolated from the fungus Austroacremonium gemini MST-FP2131 (Sordariomycetes, Ascomycota), which was recovered from rotting wood in the wet tropics of northern Australia. The structures of the geministatins were elucidated by detailed spectroscopic analysis, chemical degradation and comparison with literature values. Chemical degradation of 1 and 2 yielded three new analogues, geministatins C-E (3-5), as well as a previously reported compound dehydromerulinic acid A (6).
View Article and Find Full Text PDFWe have identified the biosynthetic gene cluster () for the sterol -acyltransferase inhibitor helvamide () from the genome of MST-FP2007. Heterologous expression of in produced a previously unreported analog helvamide B (). An α-ketoglutarate-dependent oxygenase Hvm1 was shown to catalyze intramolecular cyclization of to yield .
View Article and Find Full Text PDFTalcarpones A (1) and B (2) are rare bisnaphthazarin derivatives produced by Talaromyces johnpittii (ex-type strain MST-FP2594), a newly discovered Australian fungus, which is formally described and named herein. The talcarpones were isolated along with the previously reported monomeric naphthoquinone, aureoquinone (3), suggesting a biosynthetic link between these metabolites. Talcarpone A is a lower homologue of hybocarpone (4), which was first isolated from a mycobiont of the lichen Lecanora hybocarpa.
View Article and Find Full Text PDFThe brevijanazines are novel -nitrobenzoylated piperazines isolated from . Their structures were elucidated by spectroscopic analysis, X-ray crystallography and total synthesis. Heterologous biosynthesis, precursor feeding and microsomal assays unveiled the biosynthetic pathway to the brevijanazines, featuring a cytochrome P450 oxygenase that converts -aminobenzoic acid to -nitrobenzoic acid.
View Article and Find Full Text PDFLCMS-guided screening of a library of biosynthetically talented bacteria and fungi identified Streptomyces sp. MST- as a prolific producer of chlorinated metabolites. We isolated and characterised six new and nine reported compounds from MST-, belonging to three discrete classes - the depsipeptide svetamycins, the indolocarbazole borregomycins and the aromatic polyketide anthrabenzoxocinones.
View Article and Find Full Text PDFThe hancockiamides are an unusual new family of N-cinnamoylated piperazines from the Australian soil fungus Aspergillus hancockii. Genomic analyses of A. hancockii identified a biosynthetic gene cluster (hkm) of 12 genes, including two single-module nonribosomal peptide synthetase (NRPS) genes.
View Article and Find Full Text PDFReinvestigating antibiotic scaffolds that were identified during the Golden Age of antibiotic discovery, but have long since been "forgotten", has proven to be an effective strategy for delivering next-generation antibiotics capable of combatting multidrug-resistant superbugs. In this study, we have revisited the trichloro-substituted depsidone, nidulin, as a selective and unexploited antibiotic lead produced by the fungus Aspergillus unguis. Manipulation of halide ion concentration proved to be a powerful tool for modulating secondary metabolite production and triggering quiescent pathways in A.
View Article and Find Full Text PDFAspergillus hancockii sp. nov., classified in Aspergillus subgenus Circumdati section Flavi, was originally isolated from soil in peanut fields near Kumbia, in the South Burnett region of southeast Queensland, Australia, and has since been found occasionally from other substrates and locations in southeast Australia.
View Article and Find Full Text PDF