Spiro Fused Diterpene–Indole Alkaloids from a Creek-Bottom-Derived Aspergillus terreus

Abstract

Four metabolites, teraspiridoles A–D (2–5), formed from the merger of diterpene and modified indole scaffold were obtained from an Aspergillus terreus isolate. The structures and absolute configurations of these natural products were established using NMR, mass spectrometry, Marfey’s method, VCD, and ECD data. Teraspiridole B (3) exhibited weak inhibition of planaria regeneration/survival.

Transferring Fungi to a Deuterium-Enriched Medium Results in Assorted, Conditional Changes in Secondary Metabolite Production

“…Like 1, the HRESIMS data for compound 2 exhibited a cluster of ions with a Gaussian distribution in the range of m/z 483.3558 to 506.4615. 1 H, 13 C, and HSQC NMR (Figures S21, S23, S25; Table S1) confirmed that a majority of the carbons and hydrogens, except for two exchangeable amide protons (δ H 8.62, 10.39), were isotopically labeled. The 13 C NMR spectrum was recognized as identical to that of stephacidin A ( Figure S24), which had been previously purified by our group.…”

“…The 13 C and HSQC NMR results (Table S1) suggested the presence of four methylene, seven methine (including five olefinic), and five quaternary (including three olefinic and two carbonyl) carbons. Taking these NMR data into consideration, we returned to the MS results and concluded that the [M + Na] + ion at m/z 337.2688 indicated a molecular formula of 13 Figure S18) correlations supported the presence of phenylalanine and proline residues. These observations enabled us to reengage in a more informed dereplication search, which, when used in combination with the UV, IR, and optical rotation values obtained for 1, led us to identify the metabolite as isotope-labeled brevianamide F. 17, 18 Similarly, compound 2 was obtained as a white, amorphous solid.…”

“…HRESIMS spectra were measured using an Agilent 6538 Ultra High Definition (UHD) Accurate-Mass Q-TOF system. NMR spectra were obtained on Varian spectrometers (500 MHz for 1 H and 125 MHz for 13 C at the University of Oklahoma; 600 MHz for 1 H and 150 MHz for 13 C at the University of Florida) and Bruker Avance III spectrometer equipped with a nitrogen-cooled cryoprobe (600 MHz for 1 H and 150 MHz for 13 C at Bruker Biospin Corp.) using DMSO-d 6 and CDCl 3 (Aldrich) as solvents. Column chromatography was conducted using Sephadex LH-20.…”

(±)-Terreinlactone A, a Pair of 3-Substituted δ-Lactone Enantiomers Derived from Terrein from the Fungus <i>Aspergillus terreus</i>

“…Aspergillus terreus is a filamentous fungus distribute widely in natural world, and from the culture broth of it, a variety of natural products have been isolated, such as alkaloids, 1,2 meroterpenoids, 3,4 sesterterpenoids, 5 lignans, 2,6,7 , and so on. The most famous metabolite from A. terreus is lovastatin (named as mevinolin at first), which is an important HMG-CoA reductase inhibitor clinically used.…”

An intramolecular cascade cyclization of 2-aryl indoles: efficient methods for the construction of 2,3-functionalized indolines and 3-indolinones

“…[10] Moreover, N -fused indolines exist widely throughout nature and have considerable biological and pharmaceutical importance. [11–12] Therefore, development of efficient synthetic methods toward the formation of N -fused indolines is important for their utility in medicinal and biological chemistry. In connection with our work on the design and synthesis of ligands to probe enzyme active site, we became interested in functionalized indole derivatives.…”