Polyketide derivatives of endophytic fungus Pestalotiopsis sp. isolated from the Chinese mangrove plant Rhizophora mucronata

A detailed chemical investigation of the minor metabolites produced by the endophytic fungus Pestalotiopsis sp. isolated from the Chinese mangrove Rhizophora mucronata afforded sixteen new compounds of polyketide origin, including pestalotiopyrones A-H (1-8), pestalotiopisorin A (10), pestalotiollides A-B (11-12), pestalotiopin A (13), and four amides pestalotiopamides A-D (14-17), along with three known compounds, nigrosporapyrone D (9), 2-anhydromevalonic acid (18), and p-hydroxy benzaldehyde (19). The structures of all compounds were unambiguously established from their spectroscopic data that included HR-ESIMS and 1- and 2-dimensional NMR spectroscopy, and by comparison with the literature.     

New pyridoacridine alkaloids from the purple morph of the ascidian Cystodytes dellechiajei

Two new pyridoacridine alkaloids, 13-didemethylaminocycloshermilamine D (1) and demethyldeoxyamphimedine (2), were isolated from the purple chromotype of the Western Mediterranean ascidian Cystodytes dellechiajei. This morph also contained the known shermilamine B (3), kuanoniamine D (4), N-deacetylshermilamine B (5), N-deacetylkuanoniamine D (6), styelsamines C (7), and D (8). The structures of new compounds were elucidated on the basis of spectroscopic data. A hypothetic biosynthetic pathway from the tetracyclic styelsamine D (8) was proposed for both compounds 1 and 2 and their antimicrobial potential was evaluated.     

Five novel norcembranoids from Sinularia leptoclados and S. parva

Three new norcembrane-based diterpenoids, leptocladolides A (1), B (4) and C (5), along with five known metabolites 6-10, have been isolated from the dichloromethane extract of a Taiwanese soft coral Sinularia leptoclados. Furthermore, a chemical investigation on the dichloromethane extract of S. parva has resulted in the isolation of two new related isomers, 1-epi-leptocladolide A (2) and 7E-leptocladolide A (3), in addition to 1 and 7. The structures of new metabolites 1-5 were elucidated on the basis of extensive spectroscopic analyses and their relative stereochemistries were determined by NOESY experiments. The new metabolites 1 and 3 have been shown to exhibit significant cytotoxic activity against KB and Hepa59T/VGH cancer cell lines.     

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.     

Bioactive meroditerpenes and indole alkaloids from the soil fungus Neosartorya fischeri (KUFC 6344), and the marine-derived fungi Neosartorya laciniosa (KUFC 7896) and Neosartorya tsunodae (KUFC 9213)

Two new metabolites including a new aszonalenin analogue (1c) and a new meroditerpene (3) were isolated, together with aszonalenin (1a), acetylaszonalenin (1b), 13-oxofumitremorgin B (2), aszonapyrone A (4b) and helvolic acid, from the culture of the soil fungus Neosartorya fischeri (KUFC 6344). While the ethyl acetate extract of the culture of the diseased coral-derived fungus Neosartorya laciniosa (KUFC 7896) furnished aszonapyrone B (4a), aszonapyrone A (4b), tryptoquivaline L and 3′-(4-oxoquinazolin-3-yl) spiro[1H-indole-3,5′-oxolane]-2,2′-dione, the ethyl acetate extract of the culture of the marine sponge-associated fungus Neosartorya tsunodae (KUFC 9213) yielded a new analogue of chevalone C (5) and helvolic acid. The structures of the new compounds were established based on 1D and 2D NMR spectral analysis as well as HR-ESIMS. Compounds 1a–c, 2, 3, 4a, 4b and 5 were evaluated for their in vitro growth inhibitory activity on the MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and A375-C5 (melanoma) cell lines by the protein binding dye SRB method.     

New microviridins from a water bloom of the cyanobacterium Microcystis aeruginosa

Three new microviridins namely, SD1684 (1), SD1634 (2), and SD1652 (3), were isolated from the hydrophilic extract of Microcystis aeruginosa. The planar structures of compounds 1-3 were determined by homonuclear and inverse-heteronuclear 2D-NMR techniques as well as by high-resolution mass spectrometry. The absolute configuration of the asymmetric centers was studied using Marfey's method for HPLC. Compounds 1-3 contain l-threo-β-hydroxy aspartic acid as a building block of the peptide chain. This is the first example where microviridins contain non-proteinogenic amino acid in their structure. Compound 2 is a mild serine protease inhibitor.     

Isolation, structural elucidation, and chemical transformation of interconvertible 8,12-hemiketal germacranolide sesquiterpenoids from Salvia castanea Diels f. tomentosa Stib.

From the aerial parts of Salvia castanea Diels f. tomentosa Stib., four new hemiketal germacranolide sesquiterpenoids, castanins C-F (1-4), were obtained as two pairs of interconvertible forms along with their acetates, 5 and 6. Their structures were elucidated by spectroscopic methods and X-ray analysis of the uninterconvertible isomeric acetates, 5 and 6. The computational study explained that the ratios of 1 and 2, 3 and 4, and their acetates (5 and 6) in the mixtures were 1:1, 1:2, and 1:3, respectively. In addition, the semisynthesis of castanins C (1) and D (2) was conducted by the photooxidation of castanin B (8), the major constituent of this plant. Compounds 5, 6, and 8 were also tested for their inhibitory activity toward MCF-7, HeLa, and HepG2 cell lines.     

Synthesis and antibacterial activity of chalcones bearing prenyl or geranyl groups from Angelica keiskei

Chalcones bearing prenyl or geranyl groups from Angelica keiskei, such as 4-hydroxyderricin (1a), xanthoangelol (1e), xanthoangelol F (1f), xanthoangelol H (2), deoxyxanthoangelol H (3), and deoxydihydroxanthoangelol H (4) and their derivatives were synthesized. From the evaluation of antibacterial activity of the synthesized chalcones, 1a, isobavachalcone (1b), 1e, 1f, bavachalcone (5a), and broussochalcone B (5b) were found to inhibit Gram-positive bacteria.     

Perezoperezone and curcuperezone: bisabolane dimers from the soft coral Pseudopterogorgia rigida

Perezoperezone (1), curcuperezone (2), and diperezone (3), belonging to the rare class of bisabolane dimers, were isolated as minor constituents of the organic extract of the Caribbean soft coral, Pseudopterogorgia rigida. The structures of the new compounds 1 and 2 were established by detailed analyses of their NMR and MS data.     

Cyclooxygenase-2 enzyme inhibitory withanolides from Withania somnifera leaves

Four novel withanolide glycosides and a withanolide have been isolated from the leaves of Withania somnifera. The structures of the novel compounds were elucidated as physagulin D (1→6)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranoside (1), 27-O-β-d-glucopyranosyl physagulin D (2), 27-O-β-d-glucopyranosyl viscosalactone B (3), 4,16-dihydroxy-5β, 6β-epoxyphysagulin D (4), and 4-(1-hydroxy-2,2-dimethylcyclo-propanone)-2,3-dihydrowithaferin A (5) on the basis of 1D-, 2D NMR and MS spectral data. In addition, seven known withanolides withaferin A (6), 2,3-dihydrowithaferin A (7), viscosalactone B (8), 27-desoxy-24,25-dihydrowithaferin A (9), sitoindoside IX (10), physagulin D (11), and withanoside IV (12) were isolated. These withanolides were assayed to determine their ability to inhibit cycloxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes and lipid peroxidation. The withanolides tested, except compound 9, showed selective COX-2 enzyme inhibition ranging from 9 to 40% at 100 μg/ml. Compounds 4, 10 and 11 also inhibited lipid peroxidation by 40, 44 and 55%, respectively. The inhibition of COX-2 enzyme by withanolides is reported here for the first time.     

Structures of new alkaloids sessilifoliamides A-D from Stemona sessilifolia

Four new Stemona alkaloids, sessilifoliamides A-D (1-4), were isolated from the roots of Stemona sessilifolia, along with five known alkaloids, stenine (5), 2-oxostenine (6), stemoninoamide (7), tuberostemonone (8), and neotuberostemonol (9). The structures and absolute configurations of the new alkaloids were determined by the spectral studies (HRMS, IR, ¹H, ¹³C, and 2D NMR), single-crystal X-ray analyses, and chemical correlations. The absolute configuration of 7 was also determined by the modified Mosher's method.     

Melicodenines A and B, novel Diels-Alder type adducts isolated from Melicope denhamii

Two novel Diels-Alder type adducts, melicodenines A (1) and B (2), were isolated from the leaves of Melicope denhamii (Seem.) T. G. Hartley and their structures were established by spectroscopic analyses, including extensive 2D NMR experiments. Compound 1 is a bisquinolinone alkaloid comprised of two N-methylflindersines (3), while compound 2 is the first naturally occurring quinolinone-acetophenone conjugate composed of 3 and an evodionol methyl ether (4).     

Pseudopterosins P-V, new compounds from the gorgonian octocoral Pseudopterogorgia elisabethae from Providencia island, Colombian Caribbean

Seven new diterpene glycosides, pseudopterosins P (1), Q (2), R (3), S (4), T (5), U (6) and V (7) along with two known compounds PsG and PsK have been isolated from the methanol/dichloromethane extract of the gorgonian octocoral Pseudopterogorgia elisabethae collected off Providencia Island, Colombian Caribbean. The structures of the new metabolites, including their relative and absolute configuration, were established by MS and NMR spectroscopic studies as well as their conversion to known compounds.     

Banchromene and other secondary metabolites from the endophytic fungus Fusarium sp. obtained from Piper guineense inhibit the motility of phytopathogenic Plasmopara viticola zoospores

A new chromene, (S)-banchromene (1), together with seven known compounds, ergosterol, beauvericin (2), fusaproliferin (3), radicinin (4), poly(3-hydroxybutyric acid) (PHB, 5), N-methylpyrrolidone and an inseparable mixture of isochromene derivatives 6a, 6b, were isolated from a culture of Fusarium sp. strain CAMKT24b1, an endophytic fungus from the leaves and twigs of Piper guineense (Piperaceae). The structures of these metabolites were elucidated on the basis of their spectroscopic data; the absolute configuration of 1 was determined by ab initio-calculation of the optical rotation. In tests with the zoospores of the grapevine downy mildew pathogen Plasmopara viticola, compounds 1–4 showed moderate to high levels of motility-impairing activity at concentrations as low as 2.5 μg/mL. Compound 2 was the most active, exhibiting both motility-halting and lytic activities. Furthermore, compounds 2 and 3 displayed significant cytotoxic activity against brine shrimp larvae (Artemia salina) at 10 μg/mL. This is the first report on motility inhibitory and lytic activities of metabolites from an endophytic Fusarium species against the zoospores of the downy mildew pathogen P. viticola.     

Conformational chirality and chiral crystallization of N-sulfonylpyrimidine derivatives

New N-sulfonylpyrimidine derivatives 1-(p-toluenesulfonyl)uracil (1), 1-(p-toluenesulfonyl)thymine (2), 5-bromo-1-(p-toluenesulfonyl)uracil (3), 1-(methanesulfonyl)uracil (4), 1-(1-naphthylsulfonyl)uracil (5), and 1-(1-naphthylsulfonyl)thymine (6) were prepared by the condensation reaction of silylated pyrimidine derivatives with selected sulfonyl chlorides in acetonitrile. Some members of the series showed unexpected crystal properties as a consequence of their conformational chirality in the solid state. Compounds 1 and 5 exhibited chiral crystallization, which was, in the case of 1, accompanied by the formation of racemically twinned crystals regardless of the solvent used, while 5 gave a conglomerate of enantiomorphous crystals. For 2, 3, and 6, substituents at the C-5 position of the pyrimidine ring prevented chiral crystallization by influencing the crystal packing. Analysis of the crystal structures of 1, 4, and 5, reveals the influence of the arylsulfonyl group on the occurrence or absence of chiral crystallization.     

Unusual enniatins produced by the insect pathogenic fungus Verticillium hemipterigenum: isolation and studies on precursor-directed biosynthesis

Two new enniatins H (3) and I (4), whose substituents on 2-hydroxycarboxylic acid moieties were different from those of known compounds, were isolated, together with known enniatins B (1) and B₄ (2), from the insect pathogenic fungus Verticillium hemipterigenum BCC 1449. Structures of these compounds were elucidated by spectroscopic means. Studies on precursor-directed biosynthesis with strain BCC 1449 led to the production and identification of three analogs, enniatins G (5), C (6) and MK1688 (7), as well as the stereochemical elucidation of 3 and 4. Enniatins 1-7 were evaluated for their antiplasmodial and antimycobacterial activities.     

A search for kinase inhibitors and antibacterial agents: bromopyrrolo-2-aminoimidazoles from a deep-water Great Australian Bight sponge, Axinella sp.

Biological screening of a deep-water Great Australian Bight marine sponge, Axinella sp., detected inhibition against the neurodegenerative disease kinase targets CDK5/p25, CK1δ, and GSK3β, as well as significant levels of antibacterial activity. Chemical fractionation returned 18 secondary metabolites identified by detailed spectroscopic analysis as three new bromopyrrolo-2-aminoimidazoles, 14-O-sulfate massadine (1), 14-O-methyl massadine (2), and 3-O-methyl massadine chloride (3), together with the known metabolites massadine chloride (4), massadine (5), stylissadine B (6), axinellamines A-C (7-9), hymenin (10), stevensine (also known as odiline) (11), tauroacidin A (12), hymenidin (13), taurodispacamide A (14), oroidin (15), debromohymenialdisine (16), hymenialdisine (17), and aldisin (18). Armed with this focused natural product chemical diversity library, we re-established that 16 and 17 were nM kinase inhibitors, and determined that 3, 6, and 12-15 were sub μM antibacterials.     

Pheromone synthesis. Part 255: Synthesis and GC–MS analysis of pheromonal triacylglycerols of male Drosophila fruit flies

Pheromonal triacylglycerols and their analogs, 1A, 1B, 2A, 2B, 3A, 3B, and 3C, of male Drosophila fruit flies were synthesized and analyzed by GC–MS. Their GC retention times were found to be a reliable measure to analyze and identify these triacylglycerols with acetyl, oleoyl and tigloyl groups, although the stereo- and regioisomers of 1 (1A and 1B), 2 (2A and 2B), and 3 (3A, 3B, and 3C) could not be distinguished from each other by MS alone.     

Montamine, a unique dimeric indole alkaloid, from the seeds of Centaurea montana (Asteraceae), and its in vitro cytotoxic activity against the CaCo2 colon cancer cells

Reversed-phase HPLC analysis of the methanol extract of the seeds of Centaurea montana afforded a flavanone, montanoside (4), six epoxylignans, berchemol (7), berchemol 4′-O-β-d-glucoside (5), pinoresinol (10), pinoresinol 4-O-β-d-glucoside (8), pinoresinol 4,4′-di-O-β-d-glucoside (6), pinoresinol 4-O-apiose-(1→2)-β-d-glucoside (9), two quinic acid derivatives, trans-3-O-p-coumaroylquinic acid (1), cis-3-O-p-coumaroylquinic acid (2), and eight indole alkaloids, tryptamine (3), N-(4-hydroxycinnamoyl)-5-hydroxytryptamine (11), cis-N-(4-hydroxycinnamoyl)-5-hydroxytryptamine (12), centcyamine (16), cis-centcyamine (17), moschamine (13), cis-moschamine (14) and a dimeric indole alkaloid, montamine (15). While the structures of two new compounds, montanoside (4) and montamine (15), were established unequivocally by UV, IR, MS and a series of 1D and 2D NMR analyses, all known compounds were identified by comparison of their spectroscopic data with literature data. The antioxidant properties of these compounds were assessed by the DPPH assay, and their toxicity towards brine shrimps and cytotoxicity against CaCo-2 colon cancer cells were evaluated by the brine shrimp lethality and the MTT cytotoxicity assays, respectively. The novel dimer, montamine (15), showed significant in vitro anticolon cancer activity (IC₅₀=43.9 μM) while that of the monomer, moschamine (13), was of a moderate level (IC₅₀=81.0 μM).     

Seven new alkaloids from the roots of Stemona tuberosa

Seven new alkaloids, named as 1,9-epoxy-9a-hydroxystenine (1), tuberostemoline A (2), tuberostemoline B (3), tuberostemoninol C (4), oxotuberostemonine A (5), the mixture of bisdehydrotuberostemonine D (6), and bisdehydrotuberostemonine E (7), together with four known alkaloids neotuberostemonine (8), sessilifoline B (9), stemoxazolidinone F (10), and tuberostemoninol A (11), were isolated from the roots of Stemona tuberosa. The structures of 1–7 were elucidated through extensive spectroscopic analysis, and the relative configurations of 1–6 and 8 were further confirmed by X-ray crystallographic data. Compounds 8, 9 and the mixture of 6 & 7 exhibited potential acetylcholinesterase (AChE) inhibitory activities.