Cinatrins D and E, and virgaricin B, three novel compounds produced by a fungus, Virgaria boninensis FKI-4958

Virgaricins C and D, new pramanicin analogs produced by Apiospora sp. FKI-8058

Two new pramanicin analogs, named virgaricins C (1) and D (2), were discovered by physicochemical screening from a static cultured material of Apiospora sp. FKI-8058. Their structures were elucidated by MS and NMR analyses and chemical derivatization. Compounds 1 and 2 showed moderate antimalarial activity and cytotoxicity.

The Novel Compounds with Biological Activity Derived from Soil Fungi in the Past Decade

The secondary metabolites isolated from soil fungi have received more and more attention, especially new compounds that exhibited good biological activities. In this review, a total of 546 new compounds are included in the relevant literature since 2011. The new compounds are isolated from soil fungi, We divided these compounds into seven categories, including alkaloids, terpenoids, steroids, ketones, phenylpropanoids, quinones, esters, lactones, etc. In addition, the biological activities and structure-activity relationships of these compounds have also been fully discussed. The activities of these compounds are roughly divided into eight categories, including anticancer activity, antimicrobial activity, anti-inflammatory activity, antioxidant activity, antiviral activity, antimalarial activity, immunosuppressive activity and other activities. Since natural products are an important source of new drugs, this review may have a positive guiding effect on drug screening.

The chemistry and biology of natural ribomimetics and related compounds

Natural ribomimetics represent an important group of specialized metabolites with significant biological activities. Many of the activities, e.g., inhibition of seryl-tRNA synthetases, glycosidases, or ribosomes, are manifestations of their structural resemblance to ribose or related sugars, which play roles in the structural, physiological, and/or reproductive functions of living organisms. Recent studies on the biosynthesis and biological activities of some natural ribomimetics have expanded our understanding on how they are made in nature and why they have great potential as pharmaceutically relevant products. This review article highlights the discovery, biological activities, biosynthesis, and development of this intriguing class of natural products.

Nitrogen-Containing Secondary Metabolites from a Deep-Sea Fungus Aspergillus unguis and Their Anti-Inflammatory Activity

Aspergillus is well-known as the second-largest contributor of fungal natural products. Based on NMR guided isolation, three nitrogen-containing secondary metabolites, including two new compounds, variotin B (1) and coniosulfide E (2), together with a known compound, unguisin A (3), were isolated from the ethyl acetate (EtOAc) extract of the deep-sea fungus Aspergillus unguis IV17-109. The planar structures of 1 and 2 were elucidated by an extensive analysis of their spectroscopic data (HRESIMS, 1D and 2D NMR). The absolute configuration of 2 was determined by comparison of its optical rotation value with those of the synthesized analogs. Compound 2 is a rare, naturally occurring substance with an unusual cysteinol moiety. Furthermore, 1 showed moderate anti-inflammatory activity with an IC₅₀ value of 20.0 µM. These results revealed that Aspergillus unguis could produce structurally diverse nitrogenous secondary metabolites, which can be used for further studies to find anti-inflammatory leads.

Elastase inhibitory activity of secondary metabolites from the fungus Virgaria nigra CF-231658

Three known compounds were isolated from Virgaria nigra CF-231658; 2,7-dihydroxy naphthalene (1), virgaricin B (2) and virgaricin (3). The isolated compounds was obtained from liquid-state and agar-supported fermentation using Amberlite XAD-16 solid-phase extraction during the cultivation step. Their structures were elucidated on the basis of 1D and 2D NMR as well as HRMS spectroscopic analyses. The isolated compounds were examined for their ability to inhibit elastase using normal human diploid fibroblasts. Compound 2 displayed the most potent activity with 76.7 ± 2.12% inhibition of the enzyme activity at 5 μM concentration.

Induction of New Lactam Derivatives From the Endophytic Fungus Aplosporella javeedii Through an OSMAC Approach

Fermentation of the endophytic fungus Aplosporella javeedii on solid rice medium in presence of either 3.5% NaNO3 or 3.5% monosodium glutamate caused a significant change of the fungal metabolite pattern compared to fungal controls grown only on rice. Chemical investigation of the former fungal extracts yielded 11 new lactam derivatives, aplosporellins A-K (2-12), in addition to the known compound, pramanicin A (1). All of these compounds were not detected when the fungus was grown on rice medium without these activators thereby indicating the power of this OSMAC approach. The structures of the new compounds were elucidated by one- and two- dimensional NMR spectroscopy, DFT-NMR calculations and by mass spectrometry as well as by comparison with the literature whereas the absolute configuration of the lactam core was determined by TDDFT-ECD and OR calculations. Pramanicin A (1) showed strong cytotoxicity against human lymphoma (Ramos) and leukemia (Jurkat J16) cells with IC50 values of 4.7 and 4.4 μM, respectively. Mechanistic studies indicated that 1 activates caspase-3 and induces apoptotic cell death.

Callyspongidic Acids: Amphiphilic Diacids from the Tropical Eastern Pacific Sponge Callyspongia cf. californica

The first chemical study of the marine sponge Callyspongia cf. californica widely distributed along the coasts of the Tropical Eastern Pacific led to the identification of a new family of amphiphilic derivatives called callyspongidic acids. The four isolated metabolites 1-4 feature a hydrophilic diacid end opposed to both an aromatic moiety and a long alkyl chain. They were evaluated against a panel of pathogenic microbes and seven tumoral cell lines, displaying moderate inhibitory properties against the A2058 melanoma cell line with an IC₅₀ of 3.2 μM for callyspongidic acid C13:0 (2).

Streptomyces boninensis sp. nov., isolated from soil from a limestone cave in the Ogasawara Islands

Actinomycete strain K11-0400^T was isolated from a soil sample collected in the Ogasawara Islands (also known as the Bonin Islands), Tokyo, Japan. Mature spore chains of strain K11-0400^T had more than 20 spores per chain. The strain contained ll-diaminopimelic acid as the diamino acid in whole-cell hydrolysates, and MK-9(H6) and MK-9(H4) were the predominant menaquinones. The polar lipids were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylinositol, and no diagnostic whole-cell sugar was detected. The G+C content of the genomic DNA was 72 mol%. These morphological and chemical features of strain K11-0400^T indicated that it belonged to the genus Streptomyces. Strain K11-0400^T showed the highest 16S rRNA gene sequence similarity to Streptomyces naganishii NBRC 12892^T (97.58 %). However, the DNA-DNA relatedness value between strain K11-0400^T and the related strain was below 70 %. Based on morphological, cultural and physiological characteristics, and DNA-DNA relatedness data, strain K11-0400^T should be classified as a new species of the genus Streptomyces, for which the name Streptomyces boninensis sp. nov. is proposed. The type strain of S. boninensis is K11-0400^T (=NBRC 113073^T, TBRC 7755^T).