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

By

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

Type

Article

Date of Publication

2022

Original Publication

MycoKeys

Volume

90

Pages

85--118

Subjects

antimicrobial , Cytotoxicity , Diaporthe , Endophytic fungi , one new species , secondary metabolites

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers 2011-

Identifiers

DOI: https://doi.org/10.3897/mycokeys.90.82871

 

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.<br> Graphical abstract<br> <br> <br>