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[Activities of molecules similar to carboxyhydroxamic acid chromone-2 (sodium salt) in experimental mercury chloride poisoning; importance of the chromone cycle].

The carbo-hydroxamic-2 chromone acid (sodium salt) shows a higher protective action in vivo than in vitro against mercury chloride induced intoxications. The higher effect observed in vivo might be due to the activity itself of the chromone cycle which added up to that of the carbo-hydroxamic acid function. This latter alone appears in vitro. The antihyaluronidasic properties of this protective agent allow it to prevent the toxic substances to be diffused.

Animals

[Studies on the chemical constituents of Aquilaria sinensis(Lour.) Gilg. IV. Isolation and characterization of 2-(2-phenylethyl)chromone derivatives].

Six chromone derivatives were isolated from the ether soluble fraction of the alcoholic extract of Aquilaria sinensis(Lour.) Gilg. (Thymeleaceae) by silica gel chromatography. On the basis of spectrometric data (UV, IR, 1HNMR and 13CNMR as well as MS) and chemical synthesis one of them was found to be a new chromone, 6-hydroxy-2-[2-(4'-methoxylphenyl)ethyl]chromone(VI) and the other five known chromones are 2-(2-phenylethyl)chromone(I), 6-methoxy-2-(2-phenylethyl)chromone (II), 6.7-dimethoxy-2-(2-phenylethyl)chromone(III), 6-methoxy-2[2-(3'-methoxyphenyl)ethyl]chromone(IV) and 6-hydroxy-2-(2-phenylethyl) chromone(V). These compounds were obtained for the first time from this plant.

Chemical Phenomena

(Aminoalkoxy)chromones. Selective sigma receptor ligands.

A series of (aminoalkoxy)chromones has been prepared, members of which bind potently (16-100 nM) at the sigma binding site and bind weakly (greater than 1000 nM) at the dopamine D2 receptor and 33 other receptors, second messenger systems, and ion channels. At the sigma receptor, the preferred position of attachment for the aminoalkoxy side chain to the chromone ring followed the rank order: 7-position greater than 5-position greater than 6-position. Chromones that contained a 2-substituent that was not coplanar with the chromone ring system showed improved binding over compounds with coplanar substituents. The most potent compound at the sigma site, 7-[[7-(4-hydroxypiperidyl)heptyl]oxy]-2-phenylchromone (74), had receptor affinities (IC50) of 16 nM at the [3H]DTG site, 19 nM at the [3H]-(+)-3-PPP site, and 4000 nM (Ki) at the dopamine D2 receptor. The most selective compound examined, 6-[[6-(4-hydroxypiperidyl)hexyl]-oxy]-2-cyclopentylchromone (58), exhibited IC50s of 51 nM at the [3H]DTG site, 55 nM at the [3H]-(+)-3-PPP site, and 21,000 nM (Ki) at the dopamine D2 receptor. Compound 44 (6-[[6-(4-hydroxypiperidyl)hexyl]oxy]-3-methylflavone, NPC 16377) was systemically effective (ip and po) in two behavioral models predictive of antipsychotic compounds and systemically active in animal models of ischemia.

Chromones

[Studies on the chemical constituents of Aquilaria sinensis (Lour.) Gilg. V. Isolation and characterization of three 2-(2-phenylethyl) chromone derivatives].

Three 2-(2-phenylethyl) chromone derivatives were isolated from the ethyl acetate soluble fraction of the alcoholic extract of Aquilaria sinensis (Lous.) Gilg. (Thymeleaceae) by silica gel chromatography. Based on spectral data (UV, IR, 1HNMR, 13CNMR and MS) two of them are new compounds and their structures were identified as 5,8-dihydroxy-2-(2-p-methoxyphenylethyl) chromone (2) and 6,7-dimethoxy-2-(2-p-methoxyphenylethyl) chromone (3). The known compound siolated for the first time from this plant, was identified as 5,8-dihydroxy-2-(2-phenylethyl)-chromone (1).

Chemical Phenomena

Microbiological transformation of chromone, chromanone, and ring A hydroxyflavones.

Microbial transformation of chromone, chromanone, and 3 ring A hydroxyflavones (5-hydroxy-, 6-hydroxy-, and 7-hydroxyflavones) was attempted using thirty-two microorganisms. While chromone was not biotransformed, chromanone was transformed to chromone and chromanol by Aspergillus niger in 2% yield. Ring A hydroxylated flavones were transformed to the corresponding C-4' hydroxylated metabolites, and the yields and rate of product formation were found to correlate with the distance between the C-4 carbonyl group and the hydroxyl group in ring A.

Bacteria

Novel chromones from Spathelia sorbifolia.

Three new chromones, namely 10-(2',3'-dihydroxy-3'-methylbutanyl)-spatheliachromen, 10-(1',2',3'-trihydroxy-3'-methylbutanyl)spatheliachromen, and 6-(3'-hydroxy-3'-methyl-trans-but-1'-enyl)-O-methylisospatheliachrome n were isolated from the 10% aqueous MeOH extract of the twigs and leaves of Spathelia sorbifolia, together with five known chromones. Compound 2, the known spatheliabischromen, and 5-O-methylsorbifolin showed cytotoxicity against 9PS cells in culture.

Acetylation

A double-blind crossover study of the effect of a chromone carboxylic acid, FPL 52694, on overnight fasting gastric acid secretion.

The chromone FPL 52694 is a preparation thought to act by stabilizing mast cell membranes, thus reducing free histamine in the gastric mucosa. The effect of FPL 52694 on overnight gastric secretion was tested in 15 dyspeptic individuals in a double-blind crossover study. Each individual received the chromone preparation or placebo for 1 week. After each of the treatment periods gastric secretion was collected after 6 h of fasting by continuous suction for 8 h during the night. A significant reduction of the total acid secretion was observed after active drug compared with placebo administration, mean reduction being 17% (median, 23%). No difference was observed between 30-min and 60-min periods. FPL 52694 had no significant effect on pepsin, intrinsic factor (IF) or volume secretion. The difference in the effect on pepsin and acid secretion, reflected in a significant increase in the pepsin to acid ratio, indicates that intrinsic histamine, similarly to extrinsic histamine, has a specific effect on parietal cells. The difference in effect on acid and IF secretion indicates that intrinsic histamine not only has a specific effect on parietal cells but also has different effects on the secretory substances contained in this cell. Since IF was not reduced by the use of FPL 52694, it may be that this substance will not influence vitamin B12 metabolism.

Adolescent

Chromone glycosides from Schumanniophyton magnificum.

Two new chromone glycosides, schumanniofiosides A and B have been isolated from the root bark of Schumanniophyton magnificum and their structures shown to be 2-methyl-5,7-dihydroxychromone 5-O-beta-D-glucopyranoside and 2-methyl-5,7-dihydroxychromone 7-O-beta-D-glucopyranosyl-(1----2)-apiofuranoside, respectively. The structures were elucidated by a combination of spectral data and chemical degradation.

Carbohydrate Conformation

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

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

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

Antiallergic action of 6-ethyl-3-(1h-tetrazol-5-YL) chromone (AA-344) on immediate hypersensitivity reaction in rats.

A newly synthesized compound, 6-ethyl-3-(1H-tetrazol-5-yl)chromone (AA-344) given intravenously or orally inhibited considerably the 72-hr passive cutaneous anaphylaxis (72-hr PCA) induced by IgE in rats. The antiallergic action of AA-344 was neither due to the antihistamine or antiserotonin effect nor was it mediated via adrenergic mechanisms. The results obtained in a double sensitization with two IgE antibodies suggest that AA-344 may not impair antigen-antibody combination but probably prevents the release of chemical mediators including histamine. This assumption was supported by observation that AA-344 inhibited a reduction in the skin histamine content caused by the 72-hr PCA, without effect on the compound 48/80-induced histamine reduction. AA-344 also partially inhibited the IgGa-mediated 3-hr PCA in rats. These results indicate that the inhibitory action of AA-344 on the immediate hypersensitivity reactions is due to prevention of the release of chemical mediators from the mast cells, by acting on some process in sequential events leading to the mediator release following antigen-antibody combination.

Adrenalectomy

Inhibitory action of 6-ethyl-3-(1H-tetrazol-5-YL)chromone (AA-344) on IgE, IgGa- or chemical agent-induced histamine release from isolated rat mast cells.

The antiallergic action of 6-ethyl-3-(1H-tetrazol-5-yl)chromone (AA-344) was studied on isolated rat peritoneal mast cells. AA-344 clearly inhibited the IgE-mediated release of histamine caused by various concentrations of antigen and the 50% inhibitory concentration was 0.1 microM. On the IgGa-mediated release of histamine, a peak inhibition of AA-344 was observed at 10 microM. The histamine release induced by chemical agents such as concanavalin A, dextran and compound 48/80 was depressed by AA-344 at the range of 0.1--1 mM. The results obtained in this study indicate that the antiallergic action of AA-344 is due to selective inhibition on the immunological release of the chemical mediator from mast cells.

Animals

Effect of 6-ethyl-3-(1H-tetrazol-5-yl)chromone (AA-344) on the immediate and delayed hypersensitivity reactions.

Effects of 6-ethyl-3-(1H-tetrazol-5-yl)chromone (AA-344) on the experimental models of the type I-IV allergic reactions were studied in comparison with those of disodium cromoglycate (DSCG), dexamethasone and other agents. AA-344 showed inhibitory effects on the homologous passive cutaneous anaphylaxis and the passive systemic anaphylaxis in guinea pigs. However, it had only a slight or little effect on the Forssman shock in guinea pigs, the complete-dependent cytolysis of mast cells in rats, the Arthus reaction in guinea pigs and the tuberculin reaction and the contact sensitivity in mice. DSCG was less effective, using these experimental models. Dexamethasone showed a suppressive effect on the type III and IV allergic reactions. The results indicate that AA-344 selectively suppresses the type I allergic reaction.

Animals

The inhibition of substance P-induced histamine release from mast cells by 6, 7-dihydro-6, 8, 8, 10-tetramethyl-8H-pyrano-[3, 2-g] chromone-2-carboxylic acid (EAA).

In the presence of extracellular Ca2+, 6,7-dihydro-6,8,8, 10-tetramethyl-8H-pyrano [3, 2-g] chromone-2-carboxylic acid (EAA) had an inhibitory effect on the substance P-induced histamine release from rat peritoneal mast cells. Not only Ca2+ but also Mg2+, Sr2+ and Ba2+ were effective in enhancing the activity of EAA. Marked tachyphylaxis to EAA developed irrespective of the presence or absence of extracellular Ca2+. Cross-tachyphylaxis was observed between EAA and disodium cromoglycate (DSCG). These results indicate that the mode of action of EAA is similar, but not identical, with that of DSCG.

Animals