New polyketides from the liquid culture of Diaporthebreyniae sp. nov. (Diaporthales, Diaporthaceae)

Blondelle Matio Kemkuignou; Lena Schweizer; Christopher Lambert; Elodie Gisèle M Anoumedem; Simeon F Kouam; Marc Stadler; Yasmina Marin-Felix

doi:10.3897/mycokeys.90.82871

New polyketides from the liquid culture of Diaporthebreyniae sp. nov. (Diaporthales, Diaporthaceae)

MycoKeys. 2022 Jun 14:90:85-118. doi: 10.3897/mycokeys.90.82871. eCollection 2022.

Authors

Blondelle Matio Kemkuignou^{1

2}, Lena Schweizer¹, Christopher Lambert^{1

2}, Elodie Gisèle M Anoumedem³, Simeon F Kouam³, Marc Stadler^{1

2}, Yasmina Marin-Felix^{1

2}

Affiliations

¹ Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), Partner Site Hannover/Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, Germany Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF) Braunschweig Germany.
² Institute of Microbiology, Technische Universität Braunschweig, Spielmannstraße 7, 38106 Braunschweig, Germany Technische Universität Braunschweig Braunschweig Germany.
³ Department of Chemistry, Higher Teacher Training College, University of Yaoundé I, Yaoundé P.O. Box 47, Cameroon University of Yaoundé I Yaounde Cameroon.

Abstract

During the course of a study on the biodiversity of endophytes from Cameroon, a fungal strain was isolated. A multigene phylogenetic inference using five DNA loci revealed that this strain represents an undescribed species of Diaporthe, which is introduced here as D.breyniae. Investigation into the chemistry of this fungus led to the isolation of two previously undescribed secondary metabolites for which the trivial names fusaristatins G (7) and H (8) are proposed, together with eleven known compounds. The structures of all of the metabolites were established by using one-dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) spectroscopic data in combination with High-Resolution ElectroSpray Ionization Mass Spectrometry (HR-ESIMS) data. The absolute configuration of phomopchalasin N (4), which was reported for the first time concurrently to the present publication, was determined by analysis of its Rotating frame Overhauser Effect SpectroscopY (ROESY) spectrum and by comparison of its Electronic Circular Dichroism (ECD) spectrum with that of related compounds. A selection of the isolated secondary metabolites were tested for antimicrobial and cytotoxic activities, and compounds 4 and 7 showed weak antifungal and antibacterial activity. On the other hand, compound 4 showed moderate cytotoxic activity against all tested cancer cell lines with IC₅₀ values in the range of 5.8-45.9 µM. The latter was found to be less toxic than the other isolated cytochalasins (1-3) and gave hints in regards to the structure-activity relationship (SAR) of the studied cytochalasins. Fusaristatin H (8) also exhibited weak cytotoxicity against KB3.1 cell lines with an IC₅₀ value of 30.3 µM. Graphical abstract.

Keywords: Antimicrobial; Diaporthe; cytotoxicity; endophytic fungi; one new species; secondary metabolites.

Blondelle Matio Kemkuignou, Lena Schweizer, Christopher Lambert, Elodie Gisèle M. Anoumedem, Simeon F. Kouam, Marc Stadler, Yasmina Marin-Felix.

Grants and funding

German Academic exchange service (DAAD) Postdoctoral stipendium received from Alexander-von-Humboldt Foundation, Germany. The World Academy of Sciences (TWAS) (grant 18‐178 RG/CHE/AF/AC_G‐FR 3240303654), and the Alexander von Humboldt Foundation (AvH) through the equipment subsidies (Ref 3.4 - 8151/20 002) and the Research Group Linkage (grant IP-CMR-1121341). F Deutsche Forschungsgemeinschaft for a Research Unit grant “Cytolabs” (DFG-FOR-5170).