Asperaculanes A and B, Two Sesquiterpenoids from the Fungus Aspergillus aculeatus

Abstract

Abstract:Six sesquiterpenoids 1-6, including two new ones, an ent-daucane-type sesquiterpenoid, asperaculane A (1), and a nordaucane one, asperaculane B (2), and four known nordaucane derivatives, aculenes A-D 3-6, together with the known secalonic acid D (7), were isolated from a fermentation culture of the fungus Aspergillus aculeatus. Their structures and absolute configurations were established by analyses of their spectroscopic data, including 1D and 2D-NMR spectra, HR-ESIMS, electronic circular dichroism (ECD) data, and quantum chemical calculations. These metabolites were evaluated for in vitro cytotoxic activity against two cell lines, human cancer cell lines (HeLa) and one normal hamster cell line (CHO).

Does Osmotic Stress Affect Natural Product Expression in Fungi?

“…A list of known secondary metabolites associated with A. aculeatus was compiled from the literature in order to associate pseudomolecular ion signals (variables) with known molecules. Signal annotation was possible for fourteen metabolites (see Figure 1 ) based on reported metabolite elution order in RP chromatography and associated pseudomolecular ion m/z data: aculene A–D, aspergillusol A, asperaculane A, aculin A, acucalbistrin A and B, acu-dioxomorpholine, CJ-15183 (and a novel dihydro-analog), and secalonic acids B, D and F [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Assignment of the [M + H] + pseudomolecular ion was supported by observed adduct ions and known fragment ions sharing exact chromatographic peak shapes and retention times using single ion monitoring.…”

Molecular Diversity and Potential Anti-neuroinflammatory Activities of Cyathane Diterpenoids from the Basidiomycete Cyathus africanus

“…A preliminary conformational search was performed in Conflex6.7 using MMFF94s force field, according to previously reported methods 33 , 34 . Conformers were saved and further optimized using the density functional theory (DFT) method and CPCM solvent model at B3LYP/6–31 + G(d,p) level in Gaussian 09 software package.…”

The Biosynthesis of Norsesquiterpene Aculenes Requires Three Cytochrome P450 Enzymes to Catalyze a Stepwise Demethylation Process

“…Their structures contain a nordaucane skeleton linked to an l ‐proline moiety and are of mixed biosynthetic origin. The ent ‐daucane‐type sesquiterpenoid, asperaculane A ( 5 ) was purified from the same strain, thus suggesting that the nordaucane (C 14 ) structure is biosynthesized from the ent ‐daucane (C 15 ) skeleton ( 7 ), although the terpene cyclase has not been identified (Scheme ). The enzymes and mechanism involved in the biosynthesis of norsesquiterpenes have not been elucidated and characterized yet.…”

“…The Δ aneG mutant accumulated a major product, 5 ( m / z 289 [ M +Na] + ), along with two minor products, 8 ( m / z 233 [ M +H−H 2 O] + ) and 9 ( m / z 348 [ M +H] + ; Figure B, viii). Compound 5 was elucidated as asperaculane A . Compounds 8 and 9 were shown to be deoxygenated forms of 5 and are new compounds, which we named asperaculane C and 14‐prolyl asperaculane C, respectively (Scheme ).…”