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At least 127 records · Page 7Linked to original sources
PubMed2003

Placidenes C-F, novel alpha-pyrone propionates from the Mediterranean sacoglossan Placida dendritica.

Four new alpha-pyrone-containing propionates (5-8) and an unprecedented hydroperoxide 9 have been isolated from the mantle extract of Placida dendritica, a Mediterranean sacoglossan that lives upon the green alga Bryopsis plumosa. The new metabolites co-occur with the related compounds 1-4, which have been described in previous studies of the mollusc. The presence of 9 opens intriguing perspectives on the ecological role of placidenes. This paper reports the isolation and structural elucidation of the new compounds 5-9.

Animals↗
PubMed2004

Cytotoxic flavonoids and alpha-pyrones from Cryptocarya obovata.

One alpha-pyrone, obolactone (1), two chalcones, kurzichalcolactone B (2) and obochalcolactone (3), and two flavanones, oboflavanones A (4) and B (5), have been isolated from the fruits and the trunk bark of Cryptocarya obovata. The structures of the new compounds were elucidated by spectroscopic interpretations. The absolute configuration of obolactone (1) was established by circular dichroism. Obolactone (1) and obochalcolactone (3) display significant activity in in vitro cytotoxic assays against the KB cell line. Biosynthetic pathways for oboflavanones and obochalcolactone are suggested.

Antineoplastic Agents, Phytogenic↗
PubMed1993

Structure and stereochemistry of pectinolides A-C, novel antimicrobial and cytotoxic 5,6-dihydro-alpha-pyrones from Hyptis pectinata.

By bioactivity-directed fractionation, three new antimicrobial and cytotoxic 5,6-dihydro-alpha-pyrones, pectinolides A-C, have been isolated from Hyptis pectinata (Lamiaceae). The absolute stereochemistry of pectinolide A [1] was established as 6S-[(3S-acetyloxy)-1Z-heptenyl]-5S-(acetyloxy)-5 ,6-dihydro-2H-pyran-2-one, on the basis of spectral, chiroptical, and chemical evidence. The structures of pectinolides B [2] and C [3] were determined as the monodeacetylated forms of 1 by comparison of their spectral data and chemical correlation with the prototype compound. Staphylococcus aureus and Bacillus subtilis were sensitive to pectinolide A [1] in the concentration range of 6.25-12.5 micrograms/ml. Compounds 1-3 exhibited significant cytotoxic activity (ED50 < 4 micrograms/ml) against a variety of tumor cell lines.

Animals↗
PubMed1998

Kalkipyrone, a toxic gamma-pyrone from an assemblage of the marine cyanobacteria Lyngbya majuscula and Tolypothrix sp.

Kalkipyrone, a novel alpha-methoxy-beta,beta'-dimethyl-gamma-pyrone possessing an alkyl side chain, was isolated from an assemblage of the marine cyanobacteria Lyngbyamajuscula and Tolypothrix sp. Its structure, including stereochemistry, was determined by NMR, UV, and IR analysis and by GC-MS of the natural product and key derivatives. Kalkipyrone is toxic to brine shrimp (LD50 1 microg/mL) and gold fish (LD50 2 microg/mL) and is structurally related to the actinopyrones that were previously isolated from Streptomyces spp.

Animals↗
PubMed2000

One-pot construction of medium- and large-sized ring substituted furans. Efficient conversion to dibenzofurans, coumestans, and 4-pyrones.

New efficient synthesis of medium- and large-sized ring substituted furans is achieved by 1,3-dicarbonyl compounds with vinyl sulfides in the presence of Ag(2)CO(3)/Celite (Fétizon's reagent) in a one-pot procedure. The synthesized furans can be further converted to biologically interesting compounds such as dibenzofurans, coumestans, benzofuroquinolinone, and 4-pyrone.

Benzofurans↗
PubMed2002

K(2)CO(3)-catalyzed Michael addition-lactonization reaction of 1,2-allenyl ketones with electron-withdrawing group substituted acetates. An efficient synthesis of alpha-pyrone derivatives.

[reaction: see text] Alpha-pyrone derivatives were synthesized via the base catalyzed or promoted reaction of 1,2-allenyl ketones and electron-withdrawing group substituted acetates. The reaction was believed to proceed through a Michael addition C-C double-bond migration-lactonization process.

Acetates↗
PubMed2002

A novel and highly stereoselective approach to aza-spirocycles. A short total synthesis of 2-epi-(+/-)-perhydrohistrionicotoxin and an unprecedented decarboxylation of 2-pyrones.

[reaction: see text] A novel and highly stereoselective synthesis of aza-spirocycles is described. An application of this methodology is illustrated as a short and concise total synthesis of 2-epi-(+/-)-perhydrohistrionicotoxin with high diastereomeric control at the aza-spirocenter. An unprecedented decarboxylation of the 2-pyrone ring is observed in this total synthesis effort.

Amphibian Venoms↗
PubMed2002

Three pyrone glucosidic derivatives from Conyza albida.

Three new pyrone glucosidic derivatives, together with the known pyromeconic acid glucoside, three acytelenes and two eudesmanes, were obtained from the aerial parts of Conyza albida. The structures were elucidated by high field NMR spectroscopy.

Asteraceae↗
PubMed1997

Antithrombotic action of the kava pyrone (+)-kavain prepared from Piper methysticum on human platelets.

(+)-Kavain, a 4-methoxy-alpha-pyrone prepared from Piper methysticum Forst. (Piperaceae), was investigated regarding its assumed antithrombotic action on human platelets which was deduced from its ability to suppress arachidonic acid (AA)-induced aggregation, exocytosis of ATP, and inhibition of cyclooxygenase (COX) and thromboxane synthase (TXS) activity, the latter two effects being estimated from the generation of prostaglandin E2 (PGE2) and thromboxane A2 (TXA2), respectively. Exogenously applied AA (100 mumol/l) provoked a 90% aggregation of platelets, the release of 14 pmol ATP, and the formation of either 220 pg TXA2 or 43 pg PGE2, each parameter being related to 10(6) platelets. An application of (+)-kavain 5 min before AA, dose-dependently diminished aggregation, ATP-release, and the synthesis of TXA2 and PGE2 with IC50 values of 78, 115, 71, and 86 mumol/l, respectively. The similarity of the IC50 values suggest an inhibition of COX by (+)-kavain as primary target, thus suppressing the generation of TXA2 which induces aggregation of platelets and exocytosis of ATP by its binding on TXA2-receptors.

Arachidonic Acids↗
PubMed1998

Antitumor activity of tricyclic pyrone analogs, a new synthetic class of microtubule de-stabilizing agents, in the murine EMT-6 mammary tumor cell line in vitro.

Novel tricyclic pyrone (TP) analogs synthesized in Hua's laboratory (code names H10, H14 and H16) were tested against a spectrum of known antimitotic drugs for their ability to disrupt microtubule (MT) dynamics, alter the mitotic index, and prevent murine EMT-6 mammary sarcoma cells from synthesizing DNA and proliferating in vitro. At 2-10 microM, H10 inhibits DNA synthesis, tubulin polymerization and tumor cell growth to a greater degree than H14, whereas H16 has no effect. A linear skeleton with a pyridyl ring at C-3 of the A-ring, a pyran B-ring and no alkylation at C-7 of the C-ring is required for the antitumor activity of these TPs. Since H10 mimics the effect of vincristine (VCR), but not that of paclitaxel, on tubulin polymerization, TPs may represent a novel synthetic class of MT de-stabilizing anticancer drugs. H10 is less potent than VCR against tubulin polymerization (IC50: 1.5 microM versus 0.15 microM) and tumor cell proliferation (IC50: 1.5 microM versus 5 nM) but inhibits DNA synthesis (IC50: 10 microM) more effectively than all other MT-disrupting agents tested, except tubulozole-C. Although TPs disrupt DNA synthesis and might affect several phases of the cell cycle, the ability of H10 to increase the percentage of mitotic cells indicates that these novel compounds may be cell cycle-specific anticancer drugs useful for arresting mammalian cells in M-phase.

Animals↗
PubMed1984

Naphtho-gamma-pyrone production by Aspergillus niger isolated from stored cottonseed.

Aspergillus niger was found to be the predominant fungal contaminant of stored cottonseed. Seven strains were isolated and grown on rice. The hexane-insoluble material from methylene chloride extracts of 2-week-old cultures contained components toxic to mice. Based on high-pressure thin-layer and liquid chromatographic analyses, the major components in the mixture were eight different naphtho-gamma-pyrones. Of these, the hydrated dimeric naphthopyrones aurasperones B and C occurred in higher yield than aurasperones A, iso-A, and D and the monomeric naphthopyrones flavasperone and rubrofusarin, all of which were present in the mixture. In addition, fonsecin monomethyl ether was isolated. This metabolite may be a precursor in the biosynthesis of the hydrated aurasperones; it has not been identified previously as a metabolite of A. niger. The relative amounts of the different naphthopyrones were dependent on both the growth substrate and the fungal isolate.

Aspergillus niger↗
PubMed1988

Cytotoxicity and antitumor activities of fungal bis(naphtho-gamma-pyrone) derivatives.

Cytotoxicities of twenty-seven fungal naphtho-gamma-pyrone derivatives to KB cells were examined. Chaetochromins A-D (1-4) and ustilaginoidins D (10) and E (11) exhibited strong effects and the structure-activity relationships are discussed. The antitumor effects in vivo of some of these compounds were examined but, due to their toxicity and to their marginal activity, development as antitumor agents was abandoned. Deoxyribonucleic acid, ribonucleic acid and protein synthesis in KB cells were equally inhibited by chaetochromin A (1), cephalochromin (5), and ustilaginoidin A (7) in parallel with the cytotoxicity of the drugs. Thus it was suggested that other still unknown mechanism(s) might induce cytotoxic lesion, resulting in the inhibition of the macromolecule syntheses.

Acremonium↗
PubMed1992

Isolation and structures of antibacterial binaphtho-alpha-pyrones, talaroderxines A and B, from Talaromyces derxii.

New compounds designated talaroderxines A (1) and B (2) were isolated from a new heterothallic ascomycetous fungus, Talaromyces derxii, cultivated on rice. The structures of 1a and 1b were elucidated by means of spectroscopic examination and chemical reactions. Talaroderxines A (1a) and B (1b) are atropisomers of a 6,6'-binaphtho-alpha-pyrone derivative, and have strong antibacterial activity against Bacillus subtilis.

Circular Dichroism↗
PubMed2002

Constituents with radical scavenging effect from Opuntia dillenii: structures of new alpha-pyrones and flavonol glycoside.

The aqueous ethanolic extract from the fresh stems of Opuntia dillenii HAW. showed potent radical scanvenging activity. Three new compounds, opuntioside I, 4-ethoxyl-6-hydroxymethyl-alpha-pyrone, and kaempferol 7-O-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranoside, were isolated from the extract. The structures of the new compounds were determined on the basis of chemical and physicochemical evidence and the radical scavenging effects of principal constituents were examined.

Flavonoids↗
PubMed2000

Studies on the 1,1-diphenyl-2-picrylhydrazyl radical scavenging mechanism for a 2-pyrone compound.

The radical scavenging mechanisms for the 2-pyrone compound, 4-hydroxy-3,6-dimethyl-2H-pyrane-2-one (1), and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (4) in several solvent systems were evaluated by the quantitative change in compounds detected at 270 nm and subsequent HPLC analyses. The HPLC profile for each condition suggested that the reaction proceeded by a different mechanism in each solvent system. In organic solvents (CHCl3, iso-propanol, and EtOH), 1-[4-(3,4-dihydro-3,6-dimethyl-2,4-dioxo-2H-pyran-3-yl) phenyl]-1-phenyl-2-picrylhydrazine (2) was produced as an adduct of the DPPH radical and 1. On the other hand, the reaction in a buffer solution (an acetate buffer at pH 5.5) gave several degradation products with 1[4-(2,3-dihydro-2,5-dimethyl-3-oxo-fur-2-yl) phenyl]-1-phenyl-2-picrylhydrazine (5), this being structurally elucidated by spectroscopic analyses. The decrease of the DPPH radical in each reaction system suggests that compound 1 could scavenge about 1.5-1.8 equivalents of the radical in organic solvents and about 3.5-3.9 in the buffer solution.

Bepridil↗