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Inhibition of irritation and contact hypersensitivity by phenoxyacetic acid methyl ester in mice.

New anti-irritant treatments are required to prevent irritation and sensitization reactions to consumer medicines and dermatological drugs. We report here that phenoxyacetic acid methyl ester (PAME) is an effective agent to prevent and treat irritant and allergic contact dermatitis. Balb/c mice skin-treated with 1% PAME do not lose weight relative to vehicle-treated mice, nor is it irritating to mouse skin. Topical PAME prevents skin irritation to a wide variety of irritants including: arachidonic acid, capsaicin, sodium lauryl sulfate (SLS), disodium laureth sulfosuccinate and tetradecanoylphorbol-13-acetate. Histological studies showed that 1% PAME greatly diminished dermal neutrophilic infiltration and dermal capillary vessel dilation, and prevented epidermal hyperproliferation and hyperkeratosis that accompanies detergent (SLS)-induced skin irritation. Topical PAME inhibited ear swelling following ear challenge during the elicitation phase of contact hypersensitivity in mice sensitized with 1-chloro-2, 4-dinitrochlorobenzene (DNCB), oxazolone and the hair coloring dye rho-phenylenediamine (PPD). Finally, topical administration of 1% PAME prior to PPD or DNCB sensitization prevented the induction phase of contact hypersensitivity. These results indicate that PAME represents a potential new category of potent topical anti-inflammatory agents.

Administration, Topical↗

Lack of stereoselectivity in rat liver peroxisomal enzyme induction by optically active phenoxyacetic acids.

To ascertain if there is stereoselectivity in peroxisomal proliferation induced by chiral peroxisome proliferators, induction by stereoisomers of 2-methyl-4'-chlorophenoxyacetic acid and 2-methyl-2-(2'-4'-dichlorophenoxy)acetic acid were studied in rat in vivo and in vitro with isolated rat hepatocytes. No significant differences in the inducing potencies of the stereoisomers of the above two phenoxyacetic acid derivatives were found for cyanide-insensitive fatty acyl-CoA oxidizing system, fatty acyl-CoA oxidase, carnitine acetyltransferase or carnitine palmitoyltransferase. There was also no significant difference in the degree of hepatomegaly or lipid-lowering effect between the isomers. The findings with cultured rat hepatocytes agreed with those of the studies in vivo.

2,4-Dichlorophenoxyacetic Acid↗

Synthesis of phenoxyacetic acid derivatives as highly potent antagonists of gastrin/cholecystokinin-B receptors.

A novel series of phenoxyacetic acid derivatives was synthesized based on considerations of the three-dimensional structural similarity of YM022 and RP72540. The gastrin/cholecystokinin (CCK)-B and CCK-A receptor antagonist activities of these compounds were evaluated by investigation of their affinities for human gastrin/CCK-B receptors and human CCK-A receptors, respectively. It was found that N-methyl-N-phenyl-2-[2-[N-(N-methyl-N-phenyl-carbamoylmethyl)-N-[2 -[3-(3- methylphenyl)ureido]acetyl]amino]phenoxy]acetamide (20k, DZ-3514) exhibited high affinity for gastrin/CCK-B receptors and high selectivity over CCK-A receptors.

Acetamides↗

New mu-opioid receptor agonists with phenoxyacetic acid moiety.

New muq-opioid receptor (MOR) agonists containing 4-hydroxypiperidine, piperidine and piperazine moieties were synthesized and evaluated to find a peripheral opioid analgesic. Among the synthesized compounds, 12-[1-[3-(N,N-dimethylcarbamoyl)-3,3-diphenylpropyl]-4-hydroxypiperidin-4-yl]phenoxy]acetic acid (8: SS620) having phenoxyacetic acid and 4-hydroxypiperidine moieties showed the highest agonist potency on the MOR in an isolated guinea-pig ileum preparation, and it also had selectivity to the human MOR expressed in Chinese hamster ovary (CHO)-K1 cells compared with the same types of delta- and kappa-opioid receptors (DOR and KOR). In addition, compound 8 showed a 10 times more potent MOR agonist activity than loperamide. Furthermore, compound 8 showed a peripheral analgesic activity in vivo screening on rat.

Analgesics, Opioid↗

From phenoxyacetic acids to cellular telephones: is there historical evidence for the precautionary principle in cancer prevention?

In the late 1970s, the author and his colleagues published the first scientific evidence of an association between exposure to phenoxyacetic acids and chlorophenols and certain malignant tumors; the study subjects were also exposed to contaminating dioxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The results have been corroborated in other studies. Over the years, industry and its allied experts have attacked these studies, but in 1997 IARC classified TCDD as a human carcinogen, Group I. The author and colleagues found an increased risk of non-Hodgkins lymphoma (NHL) for subjects exposed to these chemicals or to some persistent organic pollutants; the increasing incidence in Sweden leveled off in about 1990. The author postulated that the regulation of or ban on these chemicals in Sweden in the 1970s contributed to the now decreasing incidence of NHL. Recent findings of an association between cellular telephones and brain tumors have provoked much unfounded criticism from industry and from the Swedish Radiation Protection Authority. Thus the precautionary principle is prohibited and early warnings of a cancer risk ignored. The experience of cancer risks from certain chlorinated phenols may serve as a model of how the precautionary principle could be used to take early warnings seriously. Unfortunately, the lessons of history seem to go unheeded, as exemplified by the case of cellular telephones.

Acetates↗

[Chloroderivatives of phenoxyacetic acid as antagonists of thyroid hormones].

A 24-hour stay of the Rana temporaria tadpoles in solutions of the sodium and diethylamine salts of 2,4-dichlorophenoxyacitic acid (with 1 and 2 mg/l, respectively) significantly inhibits their metamorphosis. An addition of these salts to a solution containing thyroidin in a concentration of 1--5 mg/l hinders the action of hormone stimulating metamorphosis. The effect of the sodium salt of 2,4-dichlorophenoxyacetic acid prevents the destruction of some tadpoles by toxic concentrations of thyroidin. The above data justify referring the chloroderivatives of the phenoxyacetic acid to antagonists of the thyroid hormones.

2,4-Dichlorophenoxyacetic Acid↗

[Mutagenic activity of copper phenoxyacetate complexes].

The mutagenic activity of phenoxyacetatocopper (II) complexes of the composition Cu(R-COO)2Ln-R = phenoxymethyl, L represents H2O (n = 3), phenazone (1), 4-nitropyridine N-oxide (1)--as well free phenoxyacetic acid and uncoordinated 4-nitropyridine N-oxide was tested against strains of Salmonella typhimurium (TA 100, TA 97 and TA 102) with or without metabolic activation. Using Ames methods in vitro, of the above-mentioned compounds only the 4-nitropyridine N-oxide complex in a concentration of 75 micrograms/dish, with 27.7% content of this neutral ligand) and this molecule ligand alone (in a concentration of 12.5 micrograms/dish) exhibited genotoxic effects. The relationship between the coordination-chemical properties and the biological effects of the compounds tested is discussed.

Copper↗

Antithrombotic effects of the novel inhibitor of thrombin-induced offtelet aggregation and thrombus formation, 3-[2-[1,1':2',1"]-terphenyl-4'-yl)ethyl]phenoxyacetic acid.

The new compound 3-[2-([1,1':2,1"]-terphenyl-4'yl)ethyl]phenoxyacetic acid (F1070) was synthesized and its effects on platelet aggregation induced by thrombin, thrombin receptor agonist peptide (TRAP), ADP and collagen were evaluated in humans, guinea pigs and rats, and were compared with the effects of he thrombin antagonists argipidine and (D)Phe-Pro-Arg-CH2Cl (FPR). F1070 inhibited the platelet aggregation induced by these agonists and was highly selective in its inhibition of thrombin. F1070 inhibited fibrin formation induced by thrombin, but far less effectively than argipidine. In a guinea pig model of extracorporeal circulation thrombosis, F1070 (10 mg/kg p.o.) significantly inhibited the development of a thrombus. F1070 is thus a key compound that should facilitate the development of new orally active antithrombotic drugs that are specific for thrombin.

Animals↗

Distribution and cytogenetic test of 2,4-D and 2,4,5-T phenoxyacetic acids in mouse blood tissues.

The phenoxyacetic acids 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), extensively used as herbicides, were tested for cytogenetic effects by means of induced micronuclei in erythrocytes of mouse bone marrow. Because of the hig experimental resolution power this is a particularly suitable test system for the detection of weak chromosome breaking activity in mammals. The cytogenetic tests were supplemented with chemical analyses of the concentration the the test substances reaching the target cells...

2,4,5-Trichlorophenoxyacetic Acid↗

Mechanism of the lethal and mutagenic effects of phenoxyacetic acids in Saccharomyces cerevisiae.

MCPA and salicylic acid, two compounds with similar structures and almost the same dissociation pattern, were tested for lethal and mutagenic effects on, and uptake by, cells of Saccharomyces cerevisiae strain rad18. The results obtained with the two compounds were similar, suggesting a common mechanism of action. It is proposed that they act by increasing the concentration of hydrogen ions within the cell, so that killing and mutation occur. Mutations were induced only when killing reached 95--99%. The compounds are considered weak mutagens for yeast cells. The methyl ester of MCPA also induced killing and reverse mutation, but only at concentrations about 100 times higher than for the undissociated acid. MCPA methyl ester did not increase the number of revertants in the Salmonella/liver microsome test. It is suggested that the effects of the methyl ester of MCPA depends on the ester being hydrolysed to the acid by yeast cells and the liver microsome preparation.

Drug Evaluation, Preclinical↗

Enhanced peroxisomal beta-oxidation of fatty acids and glutathione metabolism in rats exposed to phenoxyacetic acids.

Peroxisomal beta-oxidation of fatty acids and the activities of glutathione-metabolizing enzymes in rat liver were measured after administration of 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), clofibrate [ethyl], 2-(p-chlorophenoxy)-2-methylpropionate], glyphosate (N-phosphonomethyl glycine, a herbicide not structurally related to phenoxy acids) or saline for 14 days. beta-Oxidation increased by 6-fold in the group given clofibrate, 3-fold in the 2,4-D-treated group, and 2-fold in the MCPA-treated group over the level in the controls (saline-treated). Glyphosate did not increase beta-oxidation. No significant change in reduced glutathione content from that in controls was found in any of the treated groups. Glutathione reductase activity increased by about 40% after administration of either 2,4-D or MCPA, and glutathione peroxidase activity increased by 30% in animals given MCPA. A slight decrease in glutathione S-transferase activity was found in the group treated with clofibrate. The marked increases in peroxisomal beta-oxidation of fatty acids were accompanied by only minor changes in the activities of enzymes involved in glutathione-dependent inactivation of organic hydroperoxides and other oxygen-centred reactive agents.

2,4-Dichlorophenoxyacetic Acid↗

Phenoxyacetates.

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Agricultural Workers' Diseases↗

Gas-liquid chromatographic method with electron-capture detection for the determination of residues of some phenoxyacetic acid herbicides in water as their 2,2,2-trichloroethyl esters.

A gas-liquid chromatographic method with electron-capture detection was developed for the determination of residues of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylpenoxyacetic acid (MCPA) in water as their 2,2,2-trichloroethyl esters, and the sensitivity was compared with that for 2-chloro- and 2,2,2-trifluoroethyl esters. The residue is isolated by sorption of the phenoxy acid on Amberlite XAD-4, eluted with benzene and then esterified with 20% (v/v) 2,2,2-trichloroethanol in trifluoroacetic anhydride in the presence of sulphuric acid. The recoveries at the 0.4 ppb level are 92.1 +/- 3.4% (2,4-D) and 87.8 +/- 2.1% (MCPA) and the detection limits for a 1-1 sample of water are 0.096 ppb (2,4-D) and 0.06 ppb (MCPA).

2,4-Dichlorophenoxyacetic Acid↗

Radioiodinated phenoxyacetic acid derivatives as potential brain imaging agents. I. Efficient synthesis via trimethylsilyl intermediates.

The usefulness of radioiodination via demetallation of aryltrimethylsilanes was demonstrated. The radioiodination reaction was found to be very rapid and the regiospecific incorporation of radioiodine could be carried out with high radiochemical yields and high radiospecific activity. 125I-Labeled dimethylaminoethyl iodophenoxyacetate derivatives (5a--e), dimethylaminoethyl iodophenoxyacetamide derivatives (7a--c), iodophenoxyethyl ethylenediamine derivatives (9,14) and an iodophenoxyethylpiperazine derivative (18) were efficiently synthesized from the corresponding aryltrimethylsilyl intermediates (4a--e, 6a--c, 8, 13, 17) by this method.

Brain↗

Synthesis of phenoxyacetic acid derivatives as highly potent antagonists of gastrin/cholecystokinin-B receptors. II.

A series of phenoxyacetanilide derivatives was synthesized and their antagonist activities for human gastrin/cholecystokinin (CCK)-B and CCK-A receptors were evaluated. Among the compounds synthesized, 2-[3-[3-[N-[2-(N-methyl-N-phenylcarbamoylmethoxy)phenyl]-N-(N-meth yl-N- phenylcarbamoylmethyl)carbamoylmethyl]-ureido]phenyl]acetic acid (20i, DA-3934) exhibited high affinity for gastrin/CCK-B receptors and high selectivity over CCK-A receptors. DA-3934 and its methyl ester derivative inhibited pentagastrin-induced gastric acid secretion in rats in a dose-dependent manner.

Acetates↗