Total Synthesis and Structure Determination of JBIR-108—A 2-Hydroxy-2-(1-hydroxyethyl)-2,3-dihydro-3(2H)-furanone Isolated from Streptomyces gramineus IR087Pi-4

Catalytic carboboration of dienylboronate for stereoselective synthesis of (E)-γ′,δ-bisboryl-anti-homoallylic alcohols

A Cu-catalyzed stereoselective carboboration of dienylboronate for the synthesis of (E)-γ′,δ-bisboryl-anti-homoallylic alcohols was developed.

Actinofuranones D-I from a Lichen-Associated Actinomycetes, Streptomyces gramineus, and Their Anti-Inflammatory Effects

Six new metabolites, actinofuranones D-I (compounds 1–6), were isolated together with three known compounds—JBIR-108 (7), E-975 (8), and E-492 (9)—from a fermentation broth of Streptomyces gramineus derived from the lichen Leptogium trichophorum. The structures of the new compounds 1–6 were established using comprehensive NMR spectroscopic data analysis, as well as UV, IR, and MS data. The anti-inflammatory activity of these isolated compounds were evaluated by examining their ability to inhibit nitric oxide (NO) production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 4, 5, 8, and 9 attenuated the production of NO due to the suppression of the expression of nitric oxide synthase (iNOS) in LPS-induced RAW 264.7 cells. Moreover, 4, 5, 8, and 9 also inhibited LPS-induced release of proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α).

Linfuranones B and C, Furanone-Containing Polyketides from a Plant-Associated Sphaerimonospora mesophila

Two new furanone-containing polyketides, linfuranones B and C, were isolated from a plant-associated actinomycete of the genus Sphaerimonospora. Their structures were determined by NMR and MS spectroscopic analyses, and the absolute configurations were established by anisotropic methods and chemical degradation approaches. In silico analysis of biosynthetic genes suggested that linfuranone B is generated from linfuranone C by oxidative cleavage of the polyketide chain. Linfuranones B and C induced preadipocyte differentiation into matured adipocytes at 20-40 μM without showing cytotoxicity.

Optimization of the Cytotoxic Activity of Three Streptomyces Strains Isolated from Guaviare River Sediments (Colombia, South America)

Three Streptomyces strains isolated from Guaviare sediments (Colombia, South America) with cytotoxic activity against prostate cancer (PC3), breast cancer (MDA-MB-231), and lung cancer (A549) line cells were studied. The present investigation reveals the enhancement of the cytotoxic activity evaluating different values of pH, carbon sources (sucrose, glucose, xylose, maltose, and starch), and nitrogen sources (malt extract, yeast extract, meat extract, peptone, and potassium nitrate). Based on the response surface methodology, the isolates Streptomyces aburaviensis (73) had the maximum activity for lung cancer (IC50= 25.00 ± 1.86 ppm) with 4% of yeast extract, 3% of starch, and a pH value of 7. Streptomyces gramineus (386) had the maximum activity against prostate cancer (IC50= 6.14 ± 2.07 ppm) with 5% of malt extract, 3% of glucose, and a pH value of 6. Finally, Streptomyces psammoticus (519) had the maximum activity against breast cancer (IC50= 35.53 ± 2.71 ppm) with 1% of yeast extract, 4% of starch, and a pH 8. The results suggest that the ethyl acetate extracts from isolates Streptomyces aburaviensis (73), Streptomyces gramineus (386), and Streptomyces psammoticus (519) have a potential for use in pharmaceuticals as cytotoxic agents.

Streptomyces sp. AT37 isolated from a Saharan soil produces a furanone derivative active against multidrug-resistant Staphylococcus aureus

A novel actinobacterium strain, named AT37, showed a strong activity against some multidrug-resistant Staphylococcus aureus, including methicillin-resistant S. aureus MRSA ATCC 43300, other clinical isolates of MRSA and vancomycin resistant S. aureus VRSA S1. The strain AT37 was isolated from a Saharan soil by a dilution agar plating method using chitin-vitamin agar medium supplemented with rifampicin. The morphological and chemical studies indicated that this strain belonged to the genus Streptomyces. Its 16S rRNA gene sequence was determined and a database search indicated that it was closely associated with the type strain of Streptomyces novaecaesareae NBRC 13368^T with 99.6% of similarity. However, the comparison of the morphological and the physiological characteristics of the strain with those of the nearest species showed significant differences. The strain AT37 secreted the antibiotic optimally during mid-stationary phase of growth. One active compound (AT37-1) was extracted from the culture broth with dichloromethane, separated on silica gel plates and purified by HPLC. Based on spectroscopic analysis of UV-Visible, infrared, and ¹H and ¹³C NMR spectra and spectrometric analysis, the chemical structure of the compound AT37-1 was identified as 5-[(5E,7E,11E)-2,10-dihydroxy-9,11-dimethyl-5,7,11-tridecatrien-1-yl]-2-hydroxy-2-(1-hydroxyethyl)-4-methyl-3(2H)-furanone. Minimum inhibitory concentrations and minimum biofilm inhibitory concentration (MBIC₅₀) of this compound showed significant activity against multidrug-resistant S. aureus with 15-30 and 10-15 μg/mL, respectively.

LC-MS-Guided Isolation of Penicilfuranone A: A New Antifibrotic Furancarboxylic Acid from the Plant Endophytic Fungus Penicillium sp. sh18

Penicilfuranone A (1), a novel furancarboxylic acid, and its proposed biosynthetic precursor, gregatin A (2), were isolated from the cultures of the fungus Penicillium sp. sh18 endophytic to the stems of Isodon eriocalyx var. laxiflora guided by HPLC-MS. X-ray crystallography was applied to the structure determination of furancarboxylic acid for the first time, allowing unambiguous assignment of 1. Penicilfuranone A displays a significant antifibrotic effect in activated hepatic stellate cells via negative regulation of transforming growth factor-β (TGF-β)/Smad signaling.