Dioxadispiroketal Compounds and a Potential Acyclic Precursor from Amomum aculeatum

Four new compounds having an unusual 1,7-dioxadispiro[5.1.5.2]-12-ene-11-one tricyclic ring system (1-4), their potential precursor, 5R-hydroxy-1-(4-hydroxyphenyl)-eicosan-3-one (5), and two known compounds, aculeatins A (6) and B (7), have been isolated from Amomum aculeatum. All compounds were characterized by spectroscopic methods and the configurations were established by 2D NOE correlations. Compounds 1-4, 6, and 7 showed cytotoxic activity against several human cancer cell lines.     

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.     

Bis-spiro-azaphilones and azaphilones from the fungi Chaetomium cochliodes VTh01 and C. cochliodes CTh05

Four new dimeric spiro-azaplilones, cochliodones A-D (1-4), two new azaphliones, chaetoviridines E and F (5 and 6), a new epi-chaetoviridin A (7), together with five known compounds, chaetoviridin A (8), ergosterol (9), chaetochalasin A (10), 24(R)-5α,8α-epidioxyergosta-6-22-diene-3β-ol (11), and ergosterol-β-d-glucoside (12) were isolated from the fungi Chaetomium cochliodes VTh01 and C. cochliodes CTh05. Structures and stereochemistry of the atropisomers 1-3 were determined by single-crystal X-ray diffraction analysis. Compounds 5, 10, and 11 exhibited antimalarial activity against Plasmodium falciparum, while 3, 5, 6, 10, and 11 showed antimycobacterial activity against Mycobacterium tuberculosis. In addition, 5 and 6 also showed cytotoxicity against the KB, BC1, and NCI-H187 cell lines.     

New cytotoxic sesquiterpenes from the red algae Laurencia obtusa and Laurencia microcladia

Three new sesquiterpenes (1-3), along with five known (5-9), were isolated from the organic extract of the red alga Laurencia obtusa, collected from the coastal rocks of Serifos in the Aegean Sea. A new dimeric sesquiterpene of the cyclolaurane-type (4) along with four previously reported (7, 10-12) metabolites, were isolated from the extract of Laurencia microcladia, collected at Chios island in the North Aegean Sea. The structures and the relative stereochemistry of the compounds are proposed on the basis of their spectral data. The cytotoxicity of the isolated metabolites was evaluated against several cell lines including human tumor cell lines.     

Polyketides from the mangrove-derived endophytic fungus Acremonium strictum

Five new polyketide derivatives, 6′-hydroxypestalotiopsone C (1), acropyrone (2), bicytosporone D (3), waol acid (4), and pestalotiopene C (5), together with seven known metabolites (6–12), were obtained from extracts of the endophytic fungus Acremonium strictum, isolated from the mangrove tree Rhizophora apiculata. The structures of the isolated compounds were elucidated on the basis of comprehensive NMR and MS analysis. Compounds 6, 7, and 9 showed moderate cytotoxic activity against human cisplatin-sensitive (IC₅₀ values 27.1, 76.2, and 8.3 μM, respectively) and resistant A2780 cell lines (IC₅₀ values 12.6, 30.1, and 19.0 μM, respectively), whereas only 9 exhibited antibacterial activity against Staphylococcus aureus (MIC value 14.3 μM).     

Aigialomycins and related polyketide metabolites from the mangrove fungus Aigialus parvus BCC 5311

Reinvestigation of the secondary metabolites from the marine mangrove fungus Aigialus parvus BCC 5311 led to the isolation of six new nonaketide metabolites, aigialomycins F (4) and G (5a/5b), 7′,8′-dihydroaigialospirol (7), 4′-deoxy-7′,8′-dihydroaigialospirol (8), and rearranged macrolides 9 and 10, along with six previously described compounds, hypothemycin (1), aigialomycins A (2) and B (3), aigialospirol (6), 4-O-demethylhypothemycin (11), and aigialone (12). The structures of the new compounds were elucidated by analyses of the NMR spectroscopic and mass spectrometry data in combination with chemical means.     

Absolute stereochemistry of antifouling cembranoid epimers at C-8 from the Caribbean octocoral Pseudoplexaura flagellosa. Revised structures of plexaurolones

Eight cembranoid epimers at C-8 (1-8) were isolated from the organic extract of the Colombian Caribbean octocoral Pseudoplexaura flagellosa. Compounds 2, 4, and 6 are reported for the first time. Although compounds 1, 3, 5, 7, and 8 have been reported previously, their structures and NMR assignments are revised, completed or corrected. The structures of these compounds were established on the basis of detailed analysis of their spectroscopic data. Furthermore, the relative configurations of compounds 1-3 and 7 were confirmed by single-crystal X-ray diffraction. The absolute configurations of compounds 1-8 were determined using a combination of the modified Mosher method and unambiguous chemical interconversions. Evaluation of their antifouling properties using quorum sensing inhibition (QSI) and biofilm inhibition bioassays showed that compounds 3, 6, and 7 have excellent QSI activity against Chromobacterium violaceum, as measured by inhibition of the production of violacein pigment, without interfering with its growth. Furthermore, compounds 3, 5, 6, and 8 exhibited inhibition of biofilm maturation without interfering in the growth of Pseudomonas aeruginosa, Vibrio harveyi, and Staphylococcus aureus. This is the first report of cembranoids as inhibitors of bacterial biofilm and as compounds that interfere with QS in C. violaceum.     

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.     

Bioactive pregnane-type steroids from the soft coral Scleronephthya gracillimum

Nine new steroids, sclerosteroids A-I (1, 5, 6, 8-13), along with 18 known metabolites (2-4, 7, 14-27), were isolated from the soft coral Scleronephthya gracillimum. These structures were elucidated on the basis of detailed spectroscopic analysis. The absolute configurations of sugar moieties in steroidal glycosides 10-13 were determined by HPLC analysis of the o-tolylthiocarbamate derivatives of the liberated sugars from hydrolysis of these steroidal giycosides. Cytotoxic and anti-inflammatory activities of these compounds were measured in vitro.     

3-Oxyanthranilic acid derivatives from Actinomadura sp. BCC27169

Eight new compounds including 9′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy) phenyl]nonanoic acid (1), 9′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl] nonanoic acid (2), 11′-[2-amino-3-(4″-O-methyl-α-rhamnopyranosyloxy)phenyl]undecanoic acid (3), 11′-[2-amino-3-(4″-O-methyl-α-ribopyranosyloxy)phenyl]undecanoic acid (4), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (5), 8-(4′-O-methyl-α-ribopyranosyloxy)-3,4-dihydroquinolin-2(1H)-one (6), 8-(4′-O-methyl-α-rhamnopyranosyloxy)-2-methyquinoline (7), and 8-(4′-O-methyl-α-ribopyranosyloxy)-2-methylquinoline (8) were isolated from Actinomadura sp. BCC27169. The chemical structures of these compounds were determined based on NMR and high-resolution mass spectroscopy. The absolute configurations of these monosaccharides were revealed by the hydrolysis of compounds 7 and 8. Compounds 3 and 8 exhibited antitubercular activity at MIC 50 μg/mL. Only compound 3 showed cytotoxicity against KB cell at IC₅₀ 18.63 μg/mL, while other isolated compounds were inactive at tested maximum concentration (50 μg/mL).     

Further studies on the constituents of the gorgonian octocoral Pseudopterogorgia elisabethae collected in San Andrés and Providencia islands, Colombian Caribbean: isolation of a putative biosynthetic intermediate leading to erogorgiaene

Chemical investigations of the MeOH-CH₂Cl₂ extract of Pseudopterogorgia elisabethae specimens collected in the islands of San Andrés and Providencia, Colombian Caribbean, yielded four new diterpenes (1, 3, 5, 7) along with seco-pseudopterosin J (8), and amphilectosins A (9) and B (10). The structures of the new compounds were established through spectral studies as an elisabethatriene analog named elisabethatrienol (1), 10-acetoxy-9-hydroxy- and 9-acetoxy-10-hydroxy-amphilecta-8,10,12,14-tetraenes (isolated as an interconverting mixture) (3), amphilecta-8(13),11,14-triene-9,10-dione (5), and a seco-pseudopterosin 7-O-α-l-fucopyranoside named seco-pseudopterosin K (7). Elisabethatrienol can be regarded as a biosynthetic intermediate leading to erogorgiaene.     

Cyclopeptides and polyketides from coral-associated fungus, Aspergillus versicolor LCJ-5-4

Three new cyclopentapeptides, versicoloritides A-C (1-3), a new orcinol tetramer, tetraorcinol A (4), and two new lactones, versicolactones A and B (5 and 6) together with three known metabolites, diorcinol, glyantrypine, and cordyol C were isolated from the fermentation broth of the coral-associated fungus Aspergillus versicolor LCJ-5-4. Their structures were elucidated by spectroscopic and chemical methods. The new compounds 1-4 were evaluated for their radical-scavenging activity and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, Bacillus subtilis, Pseudomonas aeruginosa, and Candida albicans and cytotoxicity against P388 and Hela cell lines. Compound 4 showed weak radical-scavenging activity against the DPPH radical with an IC₅₀ value of 67 μM.     

Dihydronaphthalenones from endophytic fungus Fusarium sp. BCC14842

Eleven new dihydronaphthalenones 1-11, together with five known compounds; 5-hydroxydihydrofusarubin C (12), javanicin, bostrycoidin, anhydrofusarubin, and 3-O-methylfusarubin, were isolated from the endophytic fungus Fusarium sp. BCC14842. Structures were elucidated by analyses of the NMR spectroscopic and mass spectrometry data. Javanicin, 3-O-methylfusarubin, compounds 3 and 7 exhibited antimycobacterial and cytotoxic activities. Javanicin also displayed antifungal activity with IC₅₀ of 6.16 μg/mL, while compounds 2, 4, 5, 8, and 12 showed only cytotoxic activity.     

Regioselective synthesis of novel 4-aryl-2-ethylthio-7-methyl pyrazolo[1,5-a]-[1,3,5]-triazines

Pyrazolo[1,5-a]-[1,3,5]-triazines 6a-d were obtained by an efficient one-step reaction from S,S-diethyl aroyliminodithiocarbonates 4a-d and 5-amino-3-methylpyrazole 5 or by an alternative two-step reaction from 5 and aroyl isothiocyanates 8a-d to give initially the thiourea derivatives 9a-d, which after S-ethylation and cyclization afforded compounds 6a-d. The intermediate 7a isolated from reaction between 4a and 5 permitted us to establish the orientation.     

Velutabularins A-J, phragmalin-type limonoids with novel cyclic moiety from Chukrasia tabularis var. velutina

Velutabularins A-J, ten novel phragmalin-type limonoids, were isolated from the stem bark of Chukrasia tabularis var. velutina. In structures of 1-6, the tetrahydrofuran ring from dehydration of OH-15 and OH-17, ring C and 13/14/18-cyclopropanyl moiety formed an unprecedented 8-oxatricyclo[4,3,1^1,6]decane. Compounds 7-10 are derivates of 1-6 opening the tetrahydrofuran ring. All of these compounds possess a novel C-16/C-30 δ-lactone ring, which were reported in phragmalins rarely. The structures of these novel compounds were elucidated based on extensive 1D and 2D spectroscopic analysis. The absolute configuration of 5 and 9 were determined by the calculated electronic circular dichroism (ECD) method. The anti-inflammatory activities of major compounds (2, 4, 5, 9) were evaluated for inhibitory activity against lipopolysaccharide (LPS) induced nitric oxide (NO) production in macrophage (RAW264.7) cell line.     

Cytotoxic and anti-HIV-1 constituents from leaves and twigs of Gardenia tubifera

Two new natural cycloartanes, tubiferolide methyl ester (1) and tubiferaoctanolide (2), together with the known coronalolide (3) and coronalolide methyl ester (4) have been isolated from leaves and twigs of Gardenia tubifera. In addition, a new flavone 5,3′,5′-trihydroxy-7,4′-dimethoxyflavone (5), five known flavones 6-10 and hexacosyl 4′-hydroxy-trans-cinnamate (11) were also obtained from the same source. The structures were assigned on the basis of spectroscopic methods. Compounds 3, 7, 9, and 10 showed significant cytotoxic activities only in P-388 cell line. Compound 1 was cytotoxic against P-388, KB, Col-2 and Lu-1, while 4 was active in P-388 and BCA-1. Compounds 3 and 4 displayed significant anti-HIV activities in the HIV-1RT assay; compound 7 showed moderate activity in this assay. Compounds 5-10 were also found to be active in the ^ΔTat/RevMC 99 syncytium assay.     

Revisiting diterpene lactones of Suregada multiflora

Phytochemical investigations on the organic extracts of the leaves of Suregada multiflora have led to the isolation of ten tetracyclic diterpene lactones 1-10, members of a rare class of abiatene diterpene lactones. Compounds 1-5 were found to be new. The structures of gelomulides F (11), D (12) and E (13) were revised on the basis of 2D NMR and X-ray diffraction evidences. Compounds 1 and 2 contain an epoxy linkage between C-8 and C-14, whereas compounds 3-5 were identified as 8,14-dihydroxy analogues of diterpene lactones. The stereochemical assignments in new compound 1 are based on X-ray diffraction analysis. Compounds 6 and 7 were identified as the known gelomulides A, G. The structures of compounds 7-9 were unambiguously confirmed by X-ray diffraction analyses.     

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.     

Agelasines O-U, new diterpene alkaloids with a 9-N-methyladenine unit from a marine sponge Agelas sp.

New diterpene alkaloids, agelasines O-U (1-7), have been isolated from an Okinawan marine sponge Agelas sp. The gloss structures and relative stereochemistries of 1-7 were elucidated from the spectroscopic data. Agelasines O-R (1-4) were the third examples of diterpene alkaloid with a 9-N-methyladenine and a pyrrole units. Agelasine O (1) has a halimane skeleton, while agelasines P-R (2-4) have a clerodane skeleton. Agelasines S-U (5-7) were new diterpene alkaloids with a 9-N-methyladenine unit consisting of a halimane skeleton, a labdane skeleton, and a clerodane skeleton, respectively. Agelasines O-R (1-4) and T (6) showed antimicrobial activities against several bacteria and fungi.     

Synthesis of arylated highly congested indans using a domino sequence

A novel and efficient regioselective synthesis of various arylated highly congested 7-aryl-5-methylsulfanylindan-4-carbonitriles (3a-f), methyl 7-aryl-5-methylsulfanylindan-4-carboxylates (10a-e) and 7-aryl-5-methylsulfanylindan-4-carboxylic acids (11a-e) through base-catalyzed reaction of 6-aryl-4-methylsulfanyl-2-oxo-2H-pyran-3-carbonitriles (1a-f) and methyl 6-aryl-4-methylsulfanyl-2-oxo-2H-pyran-3-carboxylates (9a-e) by cyclopentanone (2) has been delineated. The synthetic potential of 2-pyranone was explored further to generate molecular diversity using 6-aryl-4-sec-amino-2-oxo-2H-pyran-3-carbonitriles (7a-h), 5,6-diaryl-4-methylsulfanyl-2-oxo-2H-pyran-3-carbonitriles (5a,b) and methyl 5,6-diaryl-4-methylsulfanyl-2-oxo-2H-pyran-3-carboxylates (12a,b) as precursors for the ring transformation by cyclopentanone to assess the effects of substituents on the course of the reaction to obtain highly congested indans, 6,7-diaryl-5-methylsulfanylindan-4-carbonitriles (6a,b), 7-aryl-5-(piperidin-1-yl)indan-4-carbonitriles (8a-h) and methyl 6,7-diaryl-5-methylsulfanylindan-4-carboxylates (13a,b).