New Dibenzo-α-pyrone Derivatives with α-Glucosidase Inhibitory Activities from the Marine-Derived Fungus Alternaria alternata

Natural resorcylic lactones derived from alternariol

In this overview, naturally occurring resorcylic lactones biosynthetically derived from alternariol and almost exclusively produced by fungi, are discussed with view on their isolation, structure, biological activities, biosynthesis, and total syntheses. This class of compounds consists until now of 127 naturally occurring compounds, with very divers structural motifs. Although only a handful of these toxins (i.e., alternariol and its 9-O-methyl ether, altenusin, dehydroaltenusin, altertenuol, and altenuene) were frequently found and isolated as fungal contaminants in food and feed and have been investigated in significant detail, further metabolites, which were much more rarely found as natural products, similarly show interesting biological activities.

New Cytotoxic γ-Lactam Alkaloids from the Mangrove-Derived Fungus Talaromyces hainanensis sp. nov. Guided by Molecular Networking Strategy

The fungus Talaromyces hainanensis, isolated from the mangrove soil, was characterized as a novel species by morphology observation and phylogenetic analyses. Four new γ-lactam alkaloids talaroilactams A-D (1-4) and two reported compounds harzianic acid (5) and isoharzianic acid (6) were identified from the fungus T. hainanensis WHUF0341, assisted by OSMAC along with molecular networking approaches. Their structures were determined through ECD calculations and spectroscopic analyses. Moreover, the biosynthetic route of 1-4 was also proposed. Compound 1 displayed potent cytotoxicity against HepG2 cell lines, with an IC50 value of 10.75 ± 1.11 μM. In addition, network pharmacology was employed to dissect the probable mechanisms contributing to the antihepatocellular carcinoma effects of compound 1, revealing that cytotoxicity was mainly associated with proteolysis, negative regulation of autophagy, inflammatory response, and the renin-angiotensin system. These results not only expanded the chemical space of natural products from the mangrove associated fungi but also afforded promising lead compounds for developing the antihepatocellular carcinoma agents.

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.

Marine natural products

Covering: January to the end of December 2022This review covers the literature published in 2022 for marine natural products (MNPs), with 645 citations (633 for the period January to December 2022) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1417 in 384 papers for 2022), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of NP structure class diversity in relation to biota source and biome is discussed.

Investigation on Metabolites in Structure and Biosynthesis from the Deep-Sea Sediment-Derived Actinomycete Janibacter sp. SCSIO 52865

For exploring structurally diverse metabolites and uniquely metabolic mechanisms, we systematically investigated the chemical constituents and putative biosynthesis of Janibacter sp. SCSIO 52865 derived from the deep-sea sediment based on the OSMAC strategy, molecular networking tool, in combination with bioinformatic analysis. As a result, one new diketopiperazine (1), along with seven known cyclodipeptides (2-8), trans-cinnamic acid (9), N-phenethylacetamide (10) and five fatty acids (11-15), was isolated from the ethyl acetate extract of SCSIO 52865. Their structures were elucidated by a combination of comprehensive spectroscopic analyses, Marfey's method and GC-MS analysis. Furthermore, the analysis of molecular networking revealed the presence of cyclodipeptides, and compound 1 was produced only under mBHI fermentation condition. Moreover, bioinformatic analysis suggested that compound 1 was closely related to four genes, namely jatA-D, encoding core non-ribosomal peptide synthetase and acetyltransferase.