Description of four new Leptosillia species and their secondary metabolites. Leptosilliaceae: untapped hotspot of species and metabolite diversity

Leptosilliaceae represents a new family within the Xylariales, which are known for their diverse secondary metabolism. The family contains only the genus Leptosillia, which to date consists of nine members. This results in a total of seven fungi including four undescribed species. A chemotaxonomic study was carried out, as well as a molecular phylogenetic study of the internal transcribed spacer region, β-tubulin and translation elongation factor α genes to determine the taxonomic position of the undescribed species. In addition, the structure of five secondary metabolites of Leptosillia pistiaciae CCF4468 was elucidated and one metabolite (2) was subjected to a serial dilution assay to determine its biological activity. Phylogenetically and chemotaxonomically, it could observed that the undescribed fungi (L. sp. nov. 1-4) four new species from neotropis differ in their secondary metabolite profiles in contrast to the described species. It was also shown that the secondary metabolite profile correlates with the position of the fungi in the phylogenetic tree. In addition, fungi of clade B produce nectriapyrone (1), which can serve as a chemotaxonomic marker within the genus Leptosillia. Furthermore, it could be shown that the undescribed Leptosillia sp. nov. must be new, distinct species, which is genetically and chemically supported. In total, five compounds were isolated from Leptosillia pistaciae CCF4468. Of these five compounds, one is already known (1) and the rest represents new compounds (2-5). The compounds belong to the polyketides, naphthopyrones and anthraquinones. As explained, only one compound was subjected to a serial dilution test (2). This showed weak inhibition against gram-positive bacteria such as B. subtilis or S. aureus. Weak inhibition against gram-negative bacteria such as C. violaceum was also observed. The cytotoxicity assay of the compound 2 also showed weak activity against the cell lines KB3.1 and L929.