Bioactive α-Pyrone Derivatives from the Endophytic Fungus Diaporthe sp. CB10100 as Inducible Nitric Oxide Synthase Inhibitors

Bioactive α-Pyrone Analogs from the Endophytic Fungus Diaporthe sp. CB10100: α-Glucosidase Inhibitory Activity, Molecular Docking, and Molecular Dynamics Studies

Two α-pyrone analogs were isolated from the endophytic fungus Diaporthe sp. CB10100, which is derived from the medicinal plant Sinomenium acutum. These analogs included a new compound, diaporpyrone F (3), and a known compound, diaporpyrone D (4). The structure of 3 was identified by a comprehensive examination of HRESIMS, 1D and 2D NMR spectroscopic data. Bioinformatics analysis revealed that biosynthetic gene clusters for α-pyrone analogs are common in fungi of Diaporthe species. The in vitro α-glucosidase inhibitory activity and antibacterial assay of 4 revealed that it has a 46.40% inhibitory effect on α-glucosidase at 800 μM, while no antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), Mycolicibacterium (Mycobacterium) smegmatis or Klebsiella pneumoniae at 64 μg/mL. Molecular docking and molecular dynamics simulations of 4 with α-glucosidase further suggested that the compounds are potential α-glucosidase inhibitors. Therefore, α-pyrone analogs can be used as lead compounds for α-glucosidase inhibitors in more in-depth studies.

Diaporpyrone E, an undescribed α-pyrone from the endophytic fungus Diaporthe sp. CB10100

An undescribed α-pyrone diaporpyrone E (1), and three known nucleotides, 5'-O-acetyl uridine (2), 5'-O-acetyl thymidine (3), and adenine (4), were identified from Diaporthe sp. CB10100, an endophytic fungus isolated from the medicinal plant Sinomenium acutum. The structure of 1 was determined by extensive analysis of its HRMS, 1D and 2D NMR spectroscopic data, as well as electronic circular dichroism calculations and comparison. The in vitro cytotoxic and antibacterial assays of 1 revealed that it has a 30.2% inhibitory effect on HepG2 cells at 50 μM, while no antibacterial activities against Staphylococcus aureus and Klebsiella pneumoniae at 64 μg/mL.

Potential of Secondary Metabolites of Diaporthe Species Associated with Terrestrial and Marine Origins

Diaporthe species produce versatile secondary metabolites (SMs), including terpenoids, fatty acids, polyketides, steroids, and alkaloids. These structurally diverse SMs exhibit a wide range of biological activities, including cytotoxic, antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory, and phytotoxic activities, which could be exploited in the medical, agricultural, and other modern industries. This review comprehensively covers the production and biological potencies of isolated natural products from the genus Diaporthe associated with terrestrial and marine origins. A total of 275 SMs have been summarized from terrestrial (153; 55%) and marine (110; 41%) origins during the last twelve years, and 12 (4%) compounds are common to both environments. All secondary metabolites are categorized predominantly on the basis of their bioactivities (cytotoxic, antibacterial, antifungal, and miscellaneous activity). Overall, 134 bioactive compounds were isolated from terrestrial (92; 55%) and marine (42; 34%) origins, but about half the compounds did not report any kind of activity. The antiSMASH results suggested that Diaporthe strains are capable of encoding a wide range of SMs and have tremendous biosynthetic potential for new SMs. This study will be useful for future research on drug discovery from terrestrial and marine natural products.

Chemical Investigation of Endophytic Diaporthe unshiuensis YSP3 Reveals New Antibacterial and Cytotoxic Agents

Chemical investigation of the plant-derived endophytic fungus Diaporthe unshiuensis YSP3 led to the isolation of four new compounds (1-4), including two new xanthones (phomopthane A and B, 1 and 2), one new alternariol methyl ether derivative (3) and one α-pyrone derivative (phomopyrone B, 4), together with eight known compounds (5-12). The structures of new compounds were interpreted on the basis of spectroscopic data and single-crystal X-ray diffraction analysis. All new compounds were assessed for their antimicrobial and cytotoxic potential. Compound 1 showed cytotoxic activity against HeLa and MCF-7 cells with IC₅₀ values of 5.92 µM and 7.50 µM, respectively, while compound 3 has an antibacterial effect on Bacillus subtilis (MIC value 16 μg/mL).

Two new ɑ-pyrone derivatives from the endophytic Diaporthe sp. ECN371

Diaportholides A (1) and B (2), two polyketides with ɑ-pyrone moieties, were isolated from the cultures of an endophytic Diaporthe sp. ECN371 isolated from Orixa japonica, together with four known polyketides, phomopsolide B (3), phomopsolidones A (4) and B (5), and 5-[(1R)-1-hydroxyethyl]-γ-oxo-2-furanbutanoic acid (6). The structures of 1 and 2 were determined by extensive analysis of NMR and MS spectroscopic data. Furthermore, the structure of 2 was confirmed by analyzing the single-crystal X-ray diffraction data. The luciferase reporter gene assay revealed that among all isolated compounds (1-6), 3, a known ɑ-pyrone derivative, exhibited agonistic activity against the peroxisome proliferator-activated receptor ɑ, which is an important regulator of lipid metabolism in humans.

Characterization of Chalkophomycin, a Copper(II) Metallophore with an Unprecedented Molecular Architecture

Metals play essential roles in life by coordination with small molecules, proteins, and nucleic acids. Although the coordination of copper ions in many proteins and methanobactins is known, the coordination chemistry of Cu(II) in natural products and their biological functions remain underexplored. Herein, we report the discovery of a Cu(II)-binding natural product, chalkophomycin (CHM, 1), from Streptomyces sp. CB00271, featuring an asymmetric square-coordination system of a bidentate diazeniumdiolate and a conjugated 1H-pyrrole 1-oxide-oxazoline. The structure of 1 may inspire the synthesis of Cu(II) chelators against neurodegenerative diseases or Cu(II)-based antitumor therapeutics.