Isolation of amoenamide A and five antipodal prenylated alkaloids from Aspergillus amoenus NRRL 35600

A new prenylated alkaloid, Amoenamide A (6), was isolated from the fungus Aspergillus amoenus NRRL 35600. Previously, 6 was postulated to be a precursor of Notoamide E4 (21) converted from Notoamide E (16), which was a key precursor of the prenylated indole alkaloids in the fungi of the genus Aspergillus. We previously succeeded in the isolation of two pairs of antipodes, Stephacidin A (1) and Notoamide B (2), from A. amoenus and A. protuberus MF297-2 and expected the presence of other antipodes in the culture of A. amoenus. We here report five new antipodes (7–11) along with a new metabolite (12), which was isolated as a natural compound for the first time, from A. amoenus.     

Hyperinoids A and B,two polycyclic meroterpenoids from Hypericum patulum

Hyperinoids A (1) and B (2), two prenylated acylphloroglucinol related meroterpenoids, were isolated from Hypericum patulum. Compound 1 incorporates an unprecedented 11,12-dioxatetracyclo[5.4.3.0^1,7.0^4,14]tetradecane system, while 2 possesses a unique 10,11-dioxatetracyclo[5.3.3.0^1,7.0^4,13]tridecane system. Their structures were established by spectroscopic analysis and X-ray crystallographic data. Compounds 1 and 2 were identified as potent NF-κB inhibitors and suppressed the LPS-induced inflammatory responses in RAW 246.7 macrophages and primary mouse BMDM cells     

Penioxalamine A,a novel prenylated spiro-oxindole alkaloid from Penicillium oxalicum TW01-1

Penioxalamine A (1), a novel prenylated spiro-oxindole alkaloid having a unique seven-membered nitrogen heterocycle system, was isolated from the fungus Penicillium oxalicum TW01-1. The structure of 1 was elucidated on the basis of the spectral data, single-crystal X-ray diffraction, and CD analysis. Compound 1 showed moderate cytotoxicity against HL-60 cell line. The possible biosynthetic pathway of 1 was also proposed.     

Prenylated indole alkaloids and chromone derivatives from the fungus Penicillium sp. SCSIO041218

Four new prenylated indole alkaloids (1–4), and four new chromone derivatives (7–10), together with six known compounds (5, 6, and 11–14), have been isolated from the mangrove sediment derived fungus Penicillium sp. SCSIO041218, cultured in the 1% NaCl PDB substrate. The structures of new compounds were determined by analysis of the NMR and MS spectroscopic data. The absolute configuration of the prenylated indole alkaloids were elucidated based on the comparison of ECDs with known analogues. The absolute configurations of the chromone derivatives were determined by time-dependent density functional theory calculations of the ECD spectra. In all of these isolated compounds, penixanthones A and B (12 and 13) exhibited antiallergic activities in vitro.     

Isolation, synthesis, and neurite outgrowth-promoting activity of illicinin A from the flowers of Illicium anisatum

Two new prenylated C₆-C₃ compounds, illicinin A (1) and (4S)-illicinone I (2), were isolated from the flowers of Illicium anisatum. The structures of the new compounds were elucidated by spectroscopic methods. The absolute structure of (4S)-illicinone I was determined by comparing its CD spectrum and specific rotation with those of (4S)-illicinone A (4). Illicinin A (1) and 4-allyl-2,6-dimethoxy-3-(3-methylbut-2-enyl)phenol (3) were found to exhibit neurite outgrowth-promoting activity at concentrations ranging from 0.1 to 10 μM in primary cultured rat cortical neurons. Illicinin A and its derivatives were synthesized for structure-activity relationship studies by employing sequential Stille reactions to introduce a prenyl and an allyl group to the benzene ring, thereby indicating that an allylphenyl moiety in the molecule of 1 is essential for its neurotrophic properties.     

Nectrianolins A,B, and C,new metabolites produced by endophytic fungus Nectria pseudotrichia 120-1NP

Two sesquiterpene-epoxycyclohexenone conjugates, nectrianolins A (1) and B (2), together with a sesquiterpene, nectrianolin C (3), were isolated from the brown rice culture of Nectria pseudotrichia 120-1NP, an endophytic fungus isolated from Gliricidia sepium. Their structures were determined on the basis of 1D-/2D-NMR spectroscopy and HRESIMS data analyses in combination with chemical means. Nectrianolins A–C (1–3) exhibited cytotoxic activity against both HL60 and HeLa cells.     

Takaneones A-C, prenylated butylphloroglucinol derivatives from Hypericum sikokumontanum

Three new prenylated butylphloroglucinol derivatives, takaneones A-C (1-3), were isolated from the MeOH extracts of the aerial parts of Hypericum sikokumontanum together with two new prenylated phloroglucinol derivatives, takaneols A and B (4 and 5). The structures of the isolated compounds were elucidated by exhaustive spectroscopic analysis. The cytotoxicities of the isolated compounds against human cancer cell lines were evaluated. Compounds 2-4 showed cytotoxicities against K562/Adr multi-drug resistant (MDR) cancer cells with IC₅₀ values ranging from 4.7 to 10.0 μg/mL, which were slightly more potent than doxorubicin. Their potency of cytotoxicities against MDR cancer cell lines (KB-C2 and K562/Adr) were similar to those against sensitive cell lines (KB and K562).     

Complanadine B, obscurumines A and B, new alkaloids from two species of Lycopodium

A new dimer of C₁₆N₂ type alkaloid, complanadine B (1), and two new C₁₆N type alkaloids, obscurumines A (2) and B (3), have been isolated from the club moss Lycopodium complanatum and L. obscurum, respectively. The structures and stereochemistry of 1-3 were elucidated by combination of 2D NMR spectra and chemical transformation. Complanadine A (4) isolated together with 1 induced secretion of neurotrophic factors from human astrocytoma cells.     

The chemical defense of nudibranch molluscs: Structure,biosynthetic origin and defensive properties of terpenoids from the dorid nudibranch dendrodoris grandiflora

Nudibranch molluscs, apparently defenseless against potential predators, possess secondary metabolites localized on the body wall which help them to escape from predation. These metabolites are largely of dietary origin; in one case the biosynthetic ability of a nudibranch to elaborate its own chemical defense has been shown.From the mantle extracts of Dendrodoris grandiflora polygodial (1) and 6β-acethoxyolepupuane (4), a new sesquiterpene triacetate, was isolated. These two drimane sesquiterpenoids, both endowed with antifeedant properties, are biosynthesized de novo by the nudibranch.Extracts from the digestive glands of the same nudibranch yielded the previously known sesquiterpene esters 3, microcionin-1, -2, -3, -4 (7–10), fasciculatin (11), furospongin-1 acetate (12), a new C-21 furanoterpene 14 and a mixture of new prenylated chromanols 17. All these compounds, with the exception of 3, appear to be of dietary origin.The structures of the new compounds were determined by spectral and chemical means.     

Asteropterin, an inhibitor of cathepsin B, from the marine sponge Asteropus simplex

A new pteridine derivative, asteropterin (1), was isolated as a cathepsin B inhibitor from the marine sponge Asteropus simplex. The structure of asteropterin (1) was elucidated by the analysis of spectral data.     

Yojironins A−D, meroterpenoids and prenylated acylphloroglucinols from Hypericum yojiroanum

Two new meroterpenoids, yojironins A (1) and B (2), were isolated from the whole plants of Hypericum yojiroanum, together with two new prenylated acylphloroglucinols, yojironins C (3) and D (4). Their structures were elucidated by spectroscopic data. Yojironins A (1) and B (2) are biogenetically unique meroterpenoids, which seem to be composed of two acetate units with a 2-methylbutanoyl group and three isoprene units. Yojironin A (1) exhibited antimicrobial activity.     

Cyclosmenospongine, a new sesquiterpenoid aminoquinone from an Australian marine sponge Spongia sp.

A new sesquiterpenoid aminoquinone, cyclosmenospongine (1), containing a dihydropyran ring, was isolated from an Australian marine sponge Spongia sp., along with the known metabolites, smenospongiarine, ilimaquinone and smenospongine. The structure of 1 was determined from spectroscopic data.     

Novel trichothecanes, paecilomycine A, B, and C, isolated from entomopathogenic fungus, Paecilomyces tenuipes

Paecilomycine A (1), B (2), and C (3) were isolated from cultivated fruiting bodies of Paecilomyces tenuipes (Isaria japonica), which is a popular entomopathogenic fungus used in folk medicine and health foods in China, Korea, and Japan. The structures of 1-3 were deduced from their spectroscopic data and their absolute configurations were elucidated by preparing their MPA esters. Compound 1 showed activity in the neurotrophic factor biosynthesis in glial cells.     

Acremolin,a new 1H-azirine metabolite from the marine-derived fungus Acremonium strictum

Acremolin (1), a novel modified base, was isolated from the culture broth of the marine fungus Acremonium strictum. Based on combined spectroscopic analyses, the structure of this compound was that of a methyl guanine base containing an isoprene unit. In addition, the presence of a 1H-azirine moiety is unprecedented among natural products. This compound exhibited weak cytotoxicity against an A549 cell line.     

Turtschamide,a cytotoxic putrescine bisamide from Corydalis turtschaninovii

A putrescine bisamide with a unique cyclic structure derived from l-tyrosine, turtschamide (1), was isolated from the tubers of Corydalis turtschaninovii. The structure of 1 was established by extensive spectroscopic study, and its absolute configuration was determined by a combination of NOE experiment and application of the Marfey’s method. Turtschamide (1) exhibited cytotoxicity against the A549, SK-OV-3, SK-MEL-2, and HCT-15 cells.     

Kyanamide,a new Ahp-containing depsipeptide from marine cyanobacterium Caldora penicillata

Kyanamide (1), a new depsipeptide containing 3-amino-6-hydroxy-2-piperidone moiety, was isolated from the Caldora penicillata marine cyanobacterium collected in Okinawa. Its structure was determined by spectroscopic analysis and Marfey's analysis of acid hydrolysate. Kyanamide exhibited moderate cytotoxicity against HeLa S3 cells. 1 also exhibited potent protease inhibitory activity against elastase and chymotrypsin with IC₅₀ values of 0.13 nM and 1.1 μM.     

Sinuhirtins A and B,two uncommon norhumulene-type terpenoids from the South China Sea soft coral Sinularia hirta

Two new uncommon norhumulene-type norsesquiterpenoids, namely sinuhirtins A (1) and B (2), along with two known norcaryophyllene-type norsesquiterpenoids (3 and 4), were isolated from the South China Sea soft coral Sinularia hirta. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic data analyses, and computer-assisted methods including GIAO ¹³C NMR and TDDFT-ECD calculations. A plausible biogenetic relationship of 1–4 was proposed.     

Prenylated indole alkaloids from the marine-derived fungus Paecilomyces variotii

Two new prenylated indole alkaloids, namely, dihydrocarneamide A (1) and iso-notoamide B (2), were isolated from the marine-derived endophytic fungus Paecilomyces variotii EN-291. The structures of these metabolites were determined based on comprehensive spectral analysis, together with chiral HPLC analysis of the acidic hydrolysates. Unlike other prenylated indole alkaloids such as asperparalines, notoamides, and versicolamides, compounds 1 and 2 are the rare examples of C-5 prenylation, forming the fused dimethyldihydropyran ring at C-5 and C-6 of the indole ring. The cytotoxic activity of the isolated compounds was evaluated.     

Pompanopeptins A and B, new cyclic peptides from the marine cyanobacterium Lyngbya confervoides

A new 3-amino-6-hydroxy-2-piperidone (Ahp) containing peptolide, pompanopeptin A (1), and a novel N-methyl-2-amino-6-(4′-hydroxyphenyl)hexanoic acid (N-Me-Ahpha) containing cyclic pentapeptide connected with a sixth amino acid residue via a rare ureido linkage, pompanopeptin B (2), were isolated from the marine cyanobacterium Lyngbya confervoides collected from the southeastern coast of Florida. Their planar structures were determined by a combination of NMR spectroscopic analysis and mass spectrometry. The absolute configurations were established using advanced Marfey's method and chiral HPLC analysis of the chemical degradation products. Compound 1 selectively inhibited trypsin over elastase and chymotrypsin, with an IC₅₀ value of 2.4 μM; selectivity is conferred by an arginine residue in the cyclic core.