Diketopiperazines from Batnamyces globulariicola, gen. & sp. nov. (Chaetomiaceae), a fungus associated with roots of the medicinal plant Globularia alypum in Algeria

Abstract

Eight diketopiperazines including five previously unreported derivatives were isolated from an endophytic fungus cultured from the medicinal plant Globularia alypum collected in Algeria. The strain was characterised by means of morphological studies and molecular phylogenetic methods and was found to represent a species of a new genus in the Chaetomiaceae, for which we propose the name Batnamyces globulariicola. The taxonomic position of the new genus, which appears phylogenetically related to Stolonocarpus and Madurella, was evaluated by a multi-locus genealogy and by morphological studies in comparison to DNA sequence data reported in the recent monographs of the family. The culture remained sterile on several culture media despite repeated attempts to induce sporulation, and only some chlamydospores were formed. After fermentation in submerged culture and extraction of the cultures with organic solvents, the major secondary metabolites of B. globulariicola were isolated and their chemical structures were elucidated by extensive spectral analysis including nuclear magnetic resonance (NMR) spectroscopy, high-resolution electrospray ionisation mass spectrometry (HRESIMS), and electronic circular dichroism (ECD) measurements. The isolated compounds were tested for their biological activities against various bacteria, fungi, and two mammalian cell lines, but only three of them exhibited weak cytotoxicity against KB3.1 cells, but no antimicrobial effects were observed.