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At least 73 records · Page 4Linked to original sources
PubMed2000

Chromones and anthrones from Aloe marlothii and Aloe rupestris.

A phytochemical investigation of the leaf exudate of Aloe marlothii has resulted in the isolation of a new chromone (7-O-methylaloeresin A) and a new anthrone (5-hydroxyaloin A 6'-O-acetate). Furthermore 7-O-methylaloesin was isolated as a natural product for the first time from the leaf exudate of Aloe rupestris. The structure elucidation of these compounds was based on spectral data including 2D NMR. The chemotaxonomic value of 7-O-methylaloesin in Aloe series Asperifoliae and section Pachydendron is discussed.

Aloe↗
PubMed2002

Two benzophenone O-arabinosides and a chromone from Hypericum annulatum.

Two benzophenone O-arabinosides, annulatophenonoside (1) and acetylannulatophenonoside (2) were isolated from the methanol extract of the herb of Hypericum annulatum. The structures of the benzophenones were established as 2-O-alpha-L-arabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone (1) and 2-O-alpha-L-3"-acetylarabinofuranosyl-3',5',6-trihydroxy-4-methoxybenzophenone (2) based on spectral and chemical evidence. A chromone, 5,7-dihydroxy-3-methylchromone (3) was isolated from the chloroform extract. Although it has been previously synthesized it is encountered in a plant source for the first time. Co-occurrence of the two new benzophenone O-arabinosides along with the biogenetically related 1,5,7-trihydroxy-3-methoxyxanthone was not found.

Benzophenones↗
PubMed2003

Anti-HIV agents. Part 55: 3'R,4'R-Di-(O)-(-)-camphanoyl-2',2'-dimethyldihydropyrano[2,3-f]chromone (DCP), a novel anti-HIV agent.

3'R,4'R-Di-O-(-)-camphanoyl-2',2'-dimethyldihydropyrano[2,3-f]chromone (DCP) (2) was designed and synthesized on the basis of a structure-activity relationship study of 3'R,4'R-di-O-(-)-camphanoyl-(+)-cis-khellactone DCK (1) and its analogues. DCP (2), a pyranochromone, and DCK (1), a pyranocoumarin, have different skeletons. Compound 2 showed potent in vitro inhibition of HIV-1 replication in H9 lymphocyte cells with an EC(50) of 6.78 x 10(-4) microM and TI of 14,500. These values are comparable with those for DCK (1) and better than those of AZT in the same assay.

Anti-HIV Agents↗
PubMed2003

Coumarin, chromone, and 4(3H)-pyrimidinone novel bicyclic and tricyclic derivatives as antiplatelet agents: synthesis, biological evaluation, and comparative molecular field analysis.

As a further part of our chemical and biological studies in this field, we describe the multistep preparations of the properly substituted 2-(1-piperazinyl)chromone 1b, 4-(1-piperazinyl)coumarins 5c-h, their linear benzo-fused analogues 4a,b and 8a,b, bicyclic (15e-g) and tricyclic (15h,i) fused derivatives of 6-(1-piperazinyl)pyrimidin-4(3H)-one, and of the 4H-pyrido[1,2-a]pyrimidine derivatives 9b,c. The in vitro evaluation of their inhibitory properties towards human platelet aggregation induced in platelet-rich plasma by ADP, collagen, or the Ca (2+)ionophore A23187 showed the high activity of compounds 5d-g and 15f,g,i, among which the coumarins 5g and 5d proved to be, in that order, the most effective in vitro antiplatelet agents until now synthesized by us. Thus, in order to consider also the 4-aminocoumarin structural class, we developed a new statistically significant 3-D QSAR model, more general than the one previously obtained, through a further CoMFA study based on the antiplatelet activity data and molecular steric and electrostatic potentials of both the previously studied and herein described compounds.

Adenosine Diphosphate↗
PubMed2005

A plant type III polyketide synthase that produces pentaketide chromone.

A novel plant-specific type III polyketide synthase (PKS) that catalyzes formation of a pentaketide chromone, 5,7-dihydroxy-2-methylchromone, from five molecules of malonyl-CoA, was cloned and sequenced from aloe (Aloe arborescens). Site-directed mutagenesis revealed that Met207 (corresponding to Thr197 in CHS) determines the polyketide chain length and the product specificity of the enzyme; remarkably, replacement of a single amino acid residue, Met207, with Gly yielded a mutant enzyme that efficiently produces aromatic octaketides, SEK4 and SEK4b, the products of the minimal PKS for actinorhodin (act from Streptomyces coelicolor), from eight molecules of malonyl-CoA. This provided new insights into the catalytic functions and specificities of the CHS-superfamily type III PKS enzymes.

Acyltransferases↗
PubMed1979

Studies on antianaphylactic agents. 6. Synthesis of some metabolites of 6-ethyl-3-(1H-tetrazol-5-yl)chromone and their analogues.

The metabolites of 6-ethyl-3-(1H-tetrazol-5-yl)chromone (AA-344) (1), an orally effective antiallergic agent, and their analogues were synthesized to confirm the proposed structures and to determine their activity in the rat passive cutaneous anaphylaxis (PCA) test. A glucuronic acid metabolite (6) was assigned the structure 24b, 1-deoxy-1-[5-(6-ethylchromon-3-yl)tetrazol-1-yl]-beta-D-glucopyranuronate, by the comparison of 13C NMR, mass spectra, and TLC of isomeric compounds. In 13C NMR spectra, the shift difference of the tetrazole ring carbons between a pair of isomers was more remarkable than that of the glycosidic carbons. Therefore, the former is a useful criterion for distinguishing between such isomers. Some of the metabolities and analogues were active when administered intravenously, and two metabolites (2 and 3) were also effective upon oral administration.

Animals↗
PubMed1977

Antagonists of slow reacting substance of anaphylaxis. Synthesis of a series of chromone-2-carboxylic acids.

A series of substituted chromone-2-carboxylic acids was synthesized and tested as antagonists of SRS-A induced contractions of isolated guinea pig ileum. This work led to the discovery of sodium 7-[3-(4-acetyl-3hydroxy-2-propylphenoxy)-2-hydroxypropoxy]-4-oxo-8-propyl-4H-1-benzopyran-2-carboxylate (FPL 55712) which is the first reported specific antagonist of SRS-A. Some structural requirements for biological activity within this series are discussed.

Animals↗
PubMed1975

Synthesis of ethyl 6-substituted-chroman- and -chromone-2-carboxylates. A comparative structure-activity study employing the 6-phenyl and phenoxy analogs in the triton hyperlipidemic rat model.

To explore the effect of lipophilicity on antilipidemic activity in the Triton WR-1339 induced hyperlipidemic rat model we synthesized the 6-cyclohexyl, phenyl, and phenoxy analogs of ethyl chroman-2-carboxylate. Results obtained were analyzed in light of the biological activity observed for the 6-chloro-substituted and unsubstituted chromans, the 6-chlorochroman-4-one ester, and the 6-chloro-, phenyl-, and phenoxychromone esters. The suggestion is made that chromones likely exert their antilipidemic effects by a somewhat different set of mechanisms than do the chromans and clofibrate. Whereas the 6-chlorochromanone ester is inactive, the 6-chlorochromone ester is active in both normal and hyperlipidemic Sprague-Dawley rats. The major differential effect was observed for ethyl 6-cyclohexylchroman-2-carboxylate which did not lower cholesterol levels but returned triglyceride levels to normal in hyperlipidemic rats.

Animals↗
PubMed2006

Optimization of chromone-2-carboxamide melanin concentrating hormone receptor 1 antagonists: assessment of potency, efficacy, and cardiovascular safety.

Evaluation of multiple structurally distinct series of melanin concentrating hormone receptor 1 antagonists in an anesthetized rat cardiovascualar assay led to the identification of a chromone-2-carboxamide series as having excellent safety against the chosen cardiovascular endpoints at high drug concentrations in the plasma and brain. Optimization of this series led to considerable improvements in affinity, functional potency, and pharmacokinetic profile. This led to the identification of a 7-fluorochromone-2-carboxamide (22) that was orally efficacious in a diet-induced obese mouse model, retained a favorable cardiovascular profile in rat, and demonstrated dramatic improvement in effects on mean arterial pressure in our dog cardiovascular model compared to other series reported by our group. However, this analogue also led to prolongation of the QT interval in the dog that was linked to affinity for hERG channel and unexpectedly potent functional blockade of this ion channel.

Acylation↗
PubMed2006

Yb(OTf)3-catalyzed reactions of 5-alkylidene Meldrum's acids with phenols: one-pot assembly of 3,4-dihydrocoumarins, 4-chromanones, coumarins, and chromones.

[reaction: see text] The Yb(OTf)3-catalyzed annulation reactions of phenols with 5-alkylidene Meldrum's acids enabled the synthesis of structurally diverse heterocycles in high isolated yields. A series of 4-substituted 3,4-dihydrocoumarins, 2,2-disubstituted 4-chromanones, coumarins, and 2-substituted chromones were readily and efficiently assembled, including the naturally occurring coumarins citropten, scoparone, and ayapin. Addition of phenols to biselectrophilic 5-alkylidene Meldrum's acids proceeded through two distinct multibond-forming modes: Friedel-Crafts C-alkylation/O-acylation and Friedel-Crafts C-acylation/O-alkylation. The regioselectivity of the catalytic annulation reaction was controlled by the degree of substitution on the alkylidene moiety.

Acids↗
PubMed2002

The isolation of two new chromone derivatives from the New Zealand fungus Tolypocladium extinguens.

Two new chromone derivatives, 6-methoxymethyleugenin (1) and 2-hydroxymethyl-6-methoxymethyleugenin (2), and the previously reported 6-hydroxymethyleugenin (3) were isolated from the New Zealand fungus Tolypocladium extinguens. The structures of these compounds were elucidated on the basis of spectroscopic data. 6-Methoxymethyleugenin (1) showed moderate cytotoxicity against P388 leukemia cells.

Animals↗
PubMed2003

Novel chromone derivatives from the fungus Aspergillus versicolor isolated from the marine sponge Xestospongia exigua.

From the marine sponge Xestospongia exigua collected in Indonesia the fungus Aspergillus versicolor was isolated. Following cultivation in a seawater-based medium seven new angular tricyclic chromone derivatives (1-7) were obtained from the mycelia and culture filtrate. Compounds 2-7 contain an additional dihydropyran ring system which is replaced by a pyridine ring in 1. The structures of the new natural products were established on the basis of extensive one- and two-dimensional NMR spectroscopic studies (1H, 13C, COSY, HMQC, HMBC, NOE difference spectra) as well as on mass spectral analysis.

Animals↗
PubMed2003

Chromone studies. Part 13. Synthesis and electron-impact mass spectrometric studies of 5-hydroxy-2-isopropyl-7-methoxychromone, a constituent of the medicinal plant Baeckea frutescens, and side-chain analogues.

5-Hydroxy-2-isopropyl-7-methoxychromone (1d), a chromone constituent isolated from the aerial parts of Baeckea frutescens, and four analogues (1a-c and 1e), all of which exhibit toxicity to the brine shrimp Artemia salina, have been prepared from 2',4',6'-trihydroxyacetophenone. High-resolution mass spectrometric analysis has permitted elucidation of the fragmentation patterns exhibited by these systems following electron-impact ionization.

Animals↗
PubMed2006

Chromone derivatives from the filamentous fungus Lachnum sp. BCC 2424.

Five new chromones, named lachnones A-E (1-5), were isolated from the filamentous fungus Lachnum sp. BCC 2424 along with known (2E,6S)-2,6-dimethyl-2,7-octadiene-1,6-diol. Their structures were elucidated by spectroscopic methods. Lachnones B (2) and D (4) mildly inhibited the growth of Mycobacterium tuberculosis, both with MIC values of 200 microg/mL.

Antitubercular Agents↗
PubMed2005

A new chromone from Ficus lyrata.

A new chromone, named 5,6-dihydroxy-2-methylchromone (FL-2), along with seven known flavonoids, 5-hydroxy-7,3,3',4'-tetramethoxyflavone (FL-3), 5,4'-dihydroxy-6,7,8-trimethoxyflavone (FL-4), 5,4'-dihydroxy-7,8-dimethoxyflavone (FL-5), 4-methoxychalcone (FL-6), 7,4'-dimethoxyapigenin (FL-7), 5,7,4'-trihydroxy-2',3',6'-trimethoxyisoflavone (FL-8 a rare flavonoid), acacetin-7-O-glucoside (FL-9) and acacetin-7-O-neohesperidoside (FL-10), and beta-sitosterol-D-glucoside (FL-1) have been isolated from the leaves of Ficus lyrata. Their structures have been established on the basis of chemical and spectral evidence (IR, UV, 1H NMR, 13C NMR and mass spectra).

Chromones↗