A study on the biosynthesis of hygrophorone B(12) in the mushroom Hygrophorus abieticola reveals an unexpected labelling pattern in the cyclopentenone moiety

Identification of the Amipurimycin Gene Cluster Yields Insight into the Biosynthesis of C9 Sugar Nucleoside Antibiotics

Feeding studies indicate a possible synthetic pattern for the N-terminal cis-aminocyclopentane carboxylic acid (ACPC) and suggest an unusual source of the high-carbon sugar skeleton of amipurimycin (APM). The biosynthetic gene cluster of APM was identified and confirmed by in vivo experiments. A C9 core intermediate was discovered from null mutants of ACPC pathway, and an ATP-grasp enzyme (ApmA8) was reconstituted in vitro for ACPC loading. Our observations allow a first proposal of the APM biosynthetic pathway.

Biological and chemical diversity go hand in hand: Basidiomycota as source of new pharmaceuticals and agrochemicals

The Basidiomycota constitutes the second largest higher taxonomic group of the Fungi after the Ascomycota and comprises over 30.000 species. Mycelial cultures of Basidiomycota have already been studied since the 1950s for production of antibiotics and other beneficial secondary metabolites. Despite the fact that unique and selective compounds like pleuromutilin were obtained early on, it took several decades more until they were subjected to a systematic screening for antimicrobial and anticancer activities. These efforts led to the discovery of the strobilurins and several hundreds of further compounds that mainly constitute terpenoids. In parallel the traditional medicinal mushrooms of Asia were also studied intensively for metabolite production, aimed at finding new therapeutic agents for treatment of various diseases including metabolic disorders and the central nervous system. While the evaluation of this organism group has in general been more tedious as compared to the Ascomycota, the chances to discover new metabolites and to develop them further to candidates for drugs, agrochemicals and other products for the Life Science industry have substantially increased over the past decade. This is owing to the revolutionary developments in -OMICS techniques, bioinformatics, analytical chemistry and biotechnological process technology, which are steadily being developed further. On the other hand, the new developments in polythetic fungal taxonomy now also allow a more concise selection of previously untapped organisms. The current review is dedicated to summarize the state of the art and to give an outlook to further developments.

Chaetolactone, A Skeletally New Cyclopentenone from Chaetomium sp. C521

Chaetolactone, a new polyketide with an unprecedented carbon skeleton, was constructed by Chaetomium sp. C521. Its structure was characterized by a combination of detailed spectroscopic analysis and ECD method, which facilitated the establishment of the absolute configuration for chaetolactone. The new compound was tested for anti-phytopathogenic activity against Botrytis cinerea, Alternaria solani, Gibberella saubinettii, and Magnaporthe oryzae, but exhibited negligible inhibition at a concentration of 20 μM.

Structure and Absolute Configuration of Pseudohygrophorones A(12) and B(12), Alkyl Cyclohexenone Derivatives from Hygrophorus abieticola (Basidiomycetes)

Pseudohygrophorones A(12) (1) and B(12) (2), the first naturally occurring alkyl cyclohexenones from a fungal source, and the recently reported hygrophorone B(12) (3) have been isolated from fruiting bodies of the basidiomycete Hygrophorus abieticola Krieglst. ex Gröger & Bresinsky. Their structures were assigned on the basis of extensive one- and two-dimensional NMR spectroscopic analysis as well as ESI-HRMS measurements. The absolute configuration of the three stereogenic centers in the diastereomeric compounds 1 and 2 was established with the aid of (3)JH,H and (4)JH,H coupling constants, NOE interactions, and conformational analysis in conjunction with quantum chemical CD calculations. It was concluded that pseudohygrophorone A(12) (1) is 4S,5S,6S configured, while pseudohygrophorone B(12) (2) was identified as the C-6 epimer of 1, corresponding to the absolute configuration 4S,5S,6R. In addition, the mass spectrometric fragmentation behavior of 1-3 obtained by the higher energy collisional dissociation method allows a clear distinction between the pseudohygrophorones (1 and 2) and hygrophorone B(12) (3). The isolated compounds 1-3 exhibited pronounced activity against phytopathogenic organisms.

Hot off the press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as salviaprione from Salvia prionitis.