Chemical Diversity and Bioactivity of Natural Products Isolated from Basidiomycota
Department Microbial Drugs, Helmholtz Centre for Infection Research (HZI), German Centre for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, Germany
Basidiomycota represent the second largest phylum in the kingdom of fungi and are well known to show both a high biological diversity by comprising more than 35,000 species and a high chemical diversity of secondary metabolites, providing a rich source of complex, structurally diverse and bioactive compounds. Among these, terpenes are by far the largest class of natural products and the number of different congeners is constantly growing. An important representative of the Basidiomycota, that is well known for the production of protoilludene-type sesquiterpene aryl esters, is the globally distributed plant pathogenic genus Armillaria (Agaricales, Physalacriaceae). Although more than 70 members of this compound class were already described in literature, we isolated 17 new derivatives, including novel dimers, from submerged and solid rice cultures of Armillaria ostoyae. In total 38 protoilludene-type sesquiterpene aryl esters were isolated and assessed for their antimicrobial and cytotoxic effects. Besides Basidiomycota like Armillaria, which are known to produce a high number of various derivatives from the same compound class, there are other representatives that are capable of producing chemically diverse secondary metabolites of different compound classes. An outstanding example is the fungus Heimiomyces sp., that showed a vast chemical diversity of its secondary metabolism after cultivation in liquid and solid media, leading to the isolation of overall 21 compounds, of which 19 were new. Besides structure elucidation and characterization of the isolated natural products, the evaluation of their biological activities was also in the scope of our investigations.