Monorden (1) and the novel resorcylic acid lactones pochonins A (2), B (4), C (6), D (7), and E (8) as well as tetrahydromonorden (5) and pseurotin A (22) were isolated from cultures of the clavicipitaceous hyphomycete Pochonia chlamydosporia var. catenulata strain P 0297. Fermentation of P 0297 in bromide-containing culture media led to a shift in secondary metabolite production and yielded monocillins III (3) and II (9) as major metabolites besides monorden (1) as well as the novel compounds pochonin F (10) and a monocillin II glycoside (11) as minor metabolites. Most of these compounds showed moderate activities in a cellular replication assay against Herpes Simplex Virus 1 (HSV1) and against the parasitic protozoan Eimeria tenella. In contrast to the structurally related zearalenone derivatives none of the metabolites of strain P 0297 were found to be active in a fluorescence polarization assay for determination of modulatory activities on the human estrogenic receptor ERbeta. Beta-zearalenol (17), but not zearalenone (15) and alpha-zearalenol (16), showed antiherpetic effects. We report the production, isolation, and structure elucidation of compounds 1-11 and their biological characterization.

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Natural products are an indispensable source for drug discovery. The major challenge for exploiting this evolutionary optimized pool of potential lead structures is the fast and reliable recognition of known compounds, i. e. dereplication. This task is essential for the discovery process in high-throughput screening scenarios, since it allows the focus to be placed on novel chemical structures at an early stage. Furthermore, information on identified compounds will help to rationalize observed bioactivities. This article describes an effective, library-supported strategy for the dereplication of crude extracts and pre-fractionated samples, using an HPLC-based multidetector platform and NMR techniques, respectively.

A novel antibacterial antibiotic, for which the name altersetin is proposed, was isolated from the culture broth of two endophytic Alternaria species. The relative and absolute configuration were assigned by NOESY or CD data, respectively. Altersetin is chemically related to equisetin and showed potent MIC against several pathogenic Gram-positive bacteria, whereas Gram-negative bacteria and pathogenic yeast were not or much less susceptible.Moderate in vivo efficiacy was observed for altersetin in a murine sepsis model.