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

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

Redisposition of apiosporous genera Induratia and Muscodor in the Xylariales, following the discovery of an authentic strain of Induratia apiospora

“…Partitions were regarded as unlinked and testing options set to BIC optimality criterion and test strategy set to test all. A phylogenetic inference using MrBayes 3.2.7a followed, with settings used and described by Kemkuignou et al (2022). Briefly, a random starting tree was used to calculate 200.000.000 generations with convergence controlled to arrive at an average split frequency of 0.01.…”

Studies on Argentine Phylacia species (Hypoxylaceae) using a polythetic taxonomic approach

“…Additionally, PartitionFinder2 (Lanfear et al 2016) was used to determine best-fit nucleotide substitution models restricted to the ones available in MrBayes 3.2.7a following the BIC criterion. Options for the Bayesian molecular phylogenetic inference were identical to the settings used by Matio Kemkuignou et al (2022). The topologies were compared and support values ≥ 50% (BS) or ≥ 0.95 (posterior probability, pp) assigned to the respective bipartitions.…”

Secondary metabolites of Diaporthe sp., isolated from the Cameroonian medicinal plant Trema guineensis (Schumach. & Thonn.) Ficalho

“…2 However, the production of biologically active compounds by filamentous fungi, especially those exclusive to their host plants, is not only important from a biomolecular standpoint but also from an ecological perspective. In continuation of our search for biologically active natural products from rare and hitherto unexplored fungi hosted in Cameroonian medicinal plants [5,6],…”

“…Unfortunately, some authors who have been working on these fungi ever since the 1F1N concept was established in 2013 are apparently not aware of the fact Diaporthe is the older name and therefore takes preference over Phomopsis. Regarding the potent talents of Diaporthe, we are on the quest to the exploration of structure-activity relationships of cytochalasins to establish their trends for various medical applications [5]. Along the same lines, we herein report the isolation and structural elucidation of a new polyketide (1) and a new acetylated alternariol derivative (2) as well as fifteen known compounds including three alternariol derivatives (3)(4)(5), one chromone (6), one biphenyl (7), seven cytochalasins (8)(9)(10)(11)(12)(13)(14), two cytosporones (15)(16), and one macrolide (17) from the endophytic fungus, Diaporthe sp.…”

“…Regarding the potent talents of Diaporthe, we are on the quest to the exploration of structure-activity relationships of cytochalasins to establish their trends for various medical applications [5]. Along the same lines, we herein report the isolation and structural elucidation of a new polyketide (1) and a new acetylated alternariol derivative (2) as well as fifteen known compounds including three alternariol derivatives (3)(4)(5), one chromone (6), one biphenyl (7), seven cytochalasins (8)(9)(10)(11)(12)(13)(14), two cytosporones (15)(16), and one macrolide (17) from the endophytic fungus, Diaporthe sp. isolated from the root of Trema guineensis, a Cameroonian medicinal plant from the family Ulmaceae [11].…”