Novel drimane sesquiterpene esters from Aspergillus ustus var. pseudodeflectus with endothelin receptor binding activity

Cyclohexenone Derivative and Drimane Sesquiterpenes from the Seagrass-Derived Fungus Aspergillus insuetus

One new cyclohexenone derivative (1), and two undescribed drimane sesquiterpenes (2 and 3), together with another seven known drimane sesquiterpenes were isolated from a seagrass-derived fungus Aspergillus insuetus SYSU6925. Structures of these metabolites were elucidated by comprehensive spectroscopic analysis, including NMR analysis, mass spectrometry, and ECD calculations. Compounds 1-3, 5 and 7 displayed weak to moderate antifungal activities towards four phytopathogenic fungi, with Minimum inhibition concentration (MIC) values range from 50 to 200 μg/mL. Compound 1, a rare cyclohexenone derivative with n-propyl group exhibited more potent inhibitory activities (MIC, 50 μg/mL) against F. oxysporum than positive control (Triadimefon). Compounds 2 and 3 also exhibit potent anti-inflammatory activities by inhibiting the production of nitric oxide (NO) in RAW264.7 cells with IC50 values of 21.5±1.1 and 32.6±1.16 μM, respectively.

Seven drimane-type sesquiterpenoids from an earwig-associated Aspergillus sp

Drimane-type sesquiterpenoids are widely distributed in fungi. From the ethyl acetate extract of the earwig-derived Aspergillus sp. NF2396, seven new drimane-type sesquiterpenoids, named drimanenoids A-G (1-7), were isolated. Their structures were elucidated by diverse spectroscopic analysis including high-resolution ESI-MS, one- and two-dimensional NMR spectroscopy. Drimanenoids A-F (1-6) are new members of drimane-type sesquiterpenoid esterified with unsaturated fatty acid side chain at C-6. Drimanenoids C (3), D (4) and F (6) showed antibacterial activity against five types of bacteria with different inhibition diameters. Drimanenoid D (4) exhibited moderate cytotoxicity against human myelogenous leukemia cell line K562 with an IC₅₀ value of 12.88 ± 0.11 μmol·L^-1.

Sesquiterpenoids from the Mangrove-Derived Aspergillus ustus 094102

Four new drimane sesquiterpenoids (1–4) and three known ones (5–7) were isolated from the fermentation broth of the mangrove-derived Aspergillus ustus 094102. Compound 5 was further resolved as four purified compounds 5a–5d. By means of extensive spectroscopic and ECD analysis as well as the chemical transformation, their structures were identified as (2R,3R,5S,9R,10S)-2,3,9,11-tetrahydroxydrim-7-en-6-one (ustusol F, 1), (2R,3R,5R,9S,10R)-2,3,11-trihydroxydrim-7-en-6-one (9-deoxyustusol F, 2), (3S,5R,9R,10R)-3,11,12-trihydroxydrim-7-en-6-one (ustusol G, 3), (5S,6R,9S,10S, 11R,2′E,4′E)-(11-dideoxy-11-hydroxystrobilactone A-6-yl)-5-carboxypenta-2,4-dienoate (ustusolate H, 4), ((5S,6R,9S,10S)-strobilactone A-6-yl) (2E,4E)-6,7-dihydroxyocta-2,4-dienoate (ustusolate I, 5), (2′E,4′E;6′,7′-erythro)-ustusolate I (5a) and (2′E,4′E;ent-6′,7′-erythro)-ustusolate I (5b), (2′E,4′E,6′R,7′R)-ustusolate I (5c) and (2′E,4′E,6′S,7′S)-ustusolate I (5d), (5S,6R,9S,10S,2′E,4′E)-(strobilactone A-6-yl)-5-carboxypenta-2,4-dienoate (ustusolate J, 6), and (2S,5S,9R,10S)-2,9,11-trihydroxydrim-7-en-6-one (ustusol B, 7), respectively. Compound 5 showed antiproliferation against the human tumor cells CAL-62 and MG-63 with the IC50 values of 16.3 and 10.1 µM, respectively.

Chemical Diversity and Biosynthesis of Drimane-Type Sesquiterpenes in the Fungal Kingdom

Drimane-type sesquiterpenes are a class of compounds produced by a wide range of organisms, initially isolated and characterized in plants. Meanwhile, in the past 20-30 years, a large number of novel structures from many divergent fungi have been elucidated. Recently, the biosynthesis of drimane-type sesquiter-penes and their esters has been explained in two filamentous fungi, namely Aspergillus oryzae and Aspergillus calidoustus, disclosing the basic biosynthetic principles needed to identify similar pathways in the fungal kingdom.

(±)-Usphenethylones A-C, three pairs of heterodimeric polyketide enantiomers from Aspergillus ustus 3.3904

Three pairs of new heterodimeric polyketide enantiomers, (±)-usphenethylones A-C (1-3), were isolated from the culture extract of Aspergillus ustus 3.3904. Compounds 1-3 present two heterodimerization patterns by a phenylethyl unit connected to an α-pyrone moiety, of which usphenethylones A-B (1-2) feature a 2,6,18-trioxa-tetracyclo-[8.8.0.03,8.011,16]octadecane core and usphenethylone C (3) possesses a 2-phenyl-3,4-dihydro-pyrano[4,3-b]pyran-5-one scaffold. The structures of (±)-1-3 were elucidated based on spectroscopic data analyses, and their absolute configurations were determined by single-crystal X-ray diffraction analysis and ECD calculation. Plausible biosynthetic pathways for 1-3 were proposed. Compounds (+)-3 and (-)-3 exhibited moderate inhibitory effects against ConA-induced T cell and LPS-induced B cell proliferation.

Biosynthesis of Fungal Drimane-Type Sesquiterpene Esters

Drimane-type sesquiterpenes exhibit various biological activities and are widely present in eukaryotes. Here, we completely elucidated the biosynthetic pathway of the drimane-type sesquiterpene esters isolated from Aspergillus calidoustus and we discovered that it involves a drimenol cyclase having the same catalytic function previously only reported in plants. Moreover, since many fungal drimenol derivatives possess a γ-butyrolactone ring, we clarified the functions of the cluster-associated cytochrome P450 and FAD-binding oxidoreductase discovering that these two enzymes are solely responsible for the formation of those structures. Furthermore, swapping of the enoyl reductase domain in the identified polyketide synthase led to the production of metabolites containing various polyketide chains with different levels of saturation. These findings have deepened our understanding of how fungi synthesize drimane-type sesquiterpenes and the corresponding esters.

Antibacterial Drimane Sesquiterpenes from Aspergillus ustus

Bioactivity-guided isolation of Aspergillus ustus led to the discovery of five new drimane sesquiterpenes, named ustusal A, ustusolate F and G, and ustusoic acid A and B, 1-5 respectively. Structural elucidation of these fungal terpenes relied on 1D and 2D NMR techniques, high-resolution mass spectrometry, and chiroptical properties. Their relative configurations were determined by NMR methods, while the absolute configurations were established using comparative analyses of computed and experimental NMR chemical shifts and ECD spectra. The sesquiterpenes exhibited weak activity against the clinically relevant pathogens vancomycin-resistant Enterococcus faecium and multidrug-resistant Staphylococcus aureus; however, the activity of 5 was drastically enhanced when equal amounts of stromemycin (6), a known metabolite coisolated from the same fraction from A. ustus, was added.

Nanangenines: drimane sesquiterpenoids as the dominant metabolite cohort of a novel Australian fungus, Aspergillus nanangensis

Chemical investigation of an undescribed Australian fungus, Aspergillus nanangensis, led to the identification of the nanangenines - a family of seven new and three previously reported drimane sesquiterpenoids. The structures of the nanangenines were elucidated by detailed spectroscopic analysis supported by single crystal X-ray diffraction studies. The compounds were assayed for in vitro activity against bacteria, fungi, mammalian cells and plants. Bioinformatics analysis, including comparative analysis with other acyl drimenol-producing Aspergilli, led to the identification of a putative nanangenine biosynthetic gene cluster that corresponds to the proposed biosynthetic pathway for nanangenines.

Formal synthesis of ( - )-pereniporin B and ( - )-cinnamosmolide

The paper describes a new pathway for an efficient synthesis of natural and bioactive drimanic compounds ( - )-pereniporin B (1) and ( - )-cinnamosmolide (2) from ketodiol 7, an intermediate obtained before from accessible labdane diterpenoid (+)-larixol (3). The key step involves allylic bromination of acetate 8 with N-bromosuccinimide. The in vitro antimicrobial and antifungal activities of all compounds are also reported. Their structures were confirmed by both spectroscopic data and chemical transformations.

Secondary metabolites from a marine-derived fungus Aspergillus carneus Blochwitz

Prenylated indole alkaloids, carneamides A-C (1-3), quinazolinone derivatives, carnequinazolines A-C (5-7), aryl C-glycosides, carnemycin A, B (8, 9) and a drimane sesquiterpenoid (10), together with known compounds (11-21) were isolated from the marine-derived fungus Aspergillus carneus (Trichocomaceae) KMM 4638. The antimicrobial and cytotoxic activities of the several alkaloids were examined.

Sesquiterpenoids and benzofuranoids from the marine-derived fungus Aspergillus ustus 094102

Eight drimane sesquiterpenes (1-8), six isochromane derivatives (9-14), and three known compounds, daldinin B (15), 9alpha-hydroxy-6beta-[(2E,4E,6E)-octa-2,4,6-trienoyloxy]-5alpha-drim-7-en-11,12-olide (16), and pergillin (17), were isolated from the EtOAc extract of the marine-derived fungus Aspergillus ustus 094102. The structures of the new compounds were elucidated on the basis of spectroscopic analysis. The cytotoxic effects on A549 and HL-60 cell lines were evaluated by SRB and MTT methods. Ustusorane E (13) showed significant cytotoxicity against HL-60 cells with an IC50 value of 0.13 microM. Ustusolates C (6) and E (8) exhibited moderate cytotoxicity against A549 and HL-60 cells with IC50 values of 10.5 and 9.0 microM, respectively, and ustusolate A (4) showed weak cytotoxicity against HL-60 and A549 cells with IC50 values of 20.6 and 30.0 microM, respectively.

Drimane sesquiterpenoids from the fungus Aspergillus ustus isolated from the marine sponge Suberites domuncula

Seven new drimane sesquiterpenoids (1-3, 6-9), along with the known compounds deoxyuvidin B (4), strobilactone B (5), and RES-1149-2 (10), were obtained from cultures of the fungus Aspergillus ustus, which was isolated from the marine sponge Suberites domuncula. Their structures were established by means of spectroscopic analyses including one- and two-dimensional NMR spectroscopy and high-resolution MS. Compounds 6, 7, and 10 showed cytotoxic activity against a panel of tumor cell lines, including L5178Y, HeLa, and PC12 cells, with 7 being the most active (EC(50) against L5178Y cell line: 0.6 microg/mL).

Polyphasic taxonomy of Aspergillus section Usti

Aspergillus ustus is a very common species in foods, soil and indoor environments. Based on chemical, molecular and morphological data, A. insuetus is separated from A. ustus and revived. A. insuetus differs from A. ustus in producing drimans and ophiobolin G and H and not producing ustic acid and austocystins. The molecular, physiological and morphological data also indicated that another species, A. keveiisp. nov. is closely related but distinct from A. insuetus. Aspergillus section Usti sensu stricto includes 8 species: A. ustus, A. puniceus, A. granulosus, A. pseudodeflectus, A. calidoustus, A. insuetus and A. keveii together with Emericella heterothallica.