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Uptake of salicylic acid 2-O-beta-D-glucose into soybean tonoplast vesicles by an ATP-binding cassette transporter-type mechanism.

In soybean (Glycine max L.), salicylic acid (SA) is converted primarily to SA 2-O-beta-d-glucose (SAG) in the cytoplasm and then accumulates exclusively in the vacuole. However, the mechanism involved in the vacuolar transport of SAG has not been investigated. The vacuolar transport of SAG was characterized by measuring the uptake of [(14)C]SAG into tonoplast vesicles isolated from etiolated soybean hypocotyls. The uptake of SAG was stimulated about six-fold when MgATP was included in the assay media. In contrast, the uptake of SA was only stimulated 1.25-fold by the addition of MgATP and was 2.2-fold less than the uptake of SAG providing an indication that the vacuolar uptake of SA is promoted by glucosylation. The ATP-dependent uptake of SAG was inhibited by increasing concentrations of vanadate (64% inhibition in the presence of 500 microM) but was not very sensitive to inhibition by bafilomycin A(1) (a specific inhibitor of vacuolar H(+)-ATPase; EC 3.6.1.3), and dissipation of the transtonoplast H(+)-electrochemical gradient. The SAG uptake exhibited Michaelis-Menten-type saturation kinetics with a K(m) value of 90 microM for SAG. SAG uptake was inhibited 60% by beta-estradiol 17-(beta-d-glucuronide), but glutathione conjugates and uncharged glucose conjugates were only slightly inhibitory. Based on the characteristics of SAG uptake into soybean tonoplast vesicles it is likely that this uptake occurs through an ATP-binding cassette transporter-type mechanism. However, this vacuolar uptake mechanism is not universal since the uptake of SAG by red beet (Beta vulgaris L) tonoplast vesicles appears to involve an H(+)-antiport mechanism.

Journal Article↗

Metabolism and urinary excretion of 5-amino salicylic acid in healthy volunteers when given intravenously or released for absorption at different sites in the gastrointestinal tract.

In six healthy subjects serum concentrations of 5 amino salicylic acid (5ASA) and acetyl 5ASA were measured for up to 24 hours, and urinary excretion over 48 hours. After an intravenous injection of 3.26 mmol 5ASA serum concentrations fell rapidly with a distribution half-life of 17 +/- 2 min and an elimination half-life of 42 +/- 5 min. After 45 minutes acetyl 5ASA became the dominant compound and after seven hours serum concentrations of both components were almost unrecordable. Orally ingested 5ASA in three preparations to ensure its release in the stomach, small intestine and ileocaecal region respectively gave lower serum concentrations and urinary excretion than those obtained after an intravenous infusion. Bioavailabilities which ranged from 19% for ileocaecal release to 75% for release in the upper gastrointestinal tract, were calculated from areas under the serum concentration curves. Urinary excretion of 5ASA and its acetyl metabolite over 48 hours was 78%, 52%, 55%, and 21% respectively of the dose given intravenously and orally for gastric, small intestinal and ileocaecal release.

Adult↗

Comparison of topical treatment with desoxymethasone solution 0.25% with salicylic acid 1% and betamethasone valerate solution 0.1% in patients with psoriasis of the scalp.

A new preparation for treatment of psoriasis of the scalp, containing desoxymethasone 0.25%, salicylic acid 1% and polyol-fatty esters in ethanolic solution (Ibaril) was tested in patients with psoriasis of the scalp. In a double-blind study comprising forty patients there was a significant difference in favour of this solution in comparison with betamethasone valerate solution, 0.1% (Betnovat) after 2 weeks of treatment.

Administration, Topical↗

Cardiac microdialysis of salicylic acid to detect hydroxyl radical generation associated with sympathetic nerve stimulation.

We examined the relationship between norepinephrine (NE) and hydroxyl free radical (OH) generation on cardiac nerve stimulation. Salicylic acid in Ringer's solution (0.5 nmol microliter-1 min-1) was infused directly through a microdialysis probe to detect the generation of hydroxyl radicals (OH) as reflected by the formation of dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rats. Sympathetic nerve stimulation increased the release of NE and the formation of DHBA. A positive linear correlation between the release of NE and the formation of 2,3-DHBA (R2 = 0.982) or 2,5-DHBA (R2 = 0.976) was observed. These data indicate that the sustained elevation of NE in the extracellular fluid can be auto-oxidized, which in turn leads (possibly by an indirect mechanism) to the formation of cytotoxic OH free radicals.

Animals↗

The site of action of 2,4-dinitrophenol and salicylic acid upon the uncoupler-induced K+ efflux from non-metabolizing yeast.

Stimulation of K+ efflux from non-metabolizing yeast cells by 2,4-dinitrophenol or by salicylic acid occurs only after accumulation of the compounds into the cells, indicating that the site of action of the uncouplers is inside the cells. A correlation is found between the partition ratio of the lipophilic cation dibenzyldimethylammonium between cells and medium and the rate of K+ efflux.

Biological Transport↗

The promoter of the plant defensin gene PDF1.2 from Arabidopsis is systemically activated by fungal pathogens and responds to methyl jasmonate but not to salicylic acid.

The plant defensin PDF1.2 has previously been shown to accumulate systemically via a salicylic acid-independent pathway in leaves of Arabidopsis upon challenge by fungal pathogens. To further investigate the signalling and transcriptional processes underlying plant defensin induction, a DNA fragment containing 1184 bp and 1232 bp upstream of the transcriptional and translational start sites, respectively, was cloned by inverse PCR. To test for promoter activity this DNA fragment was linked to the beta-glucuronidase (GUS)-encoding region of the UidA gene as a translational fusion and introduced into Arabidopsis ecotype C-24. Challenge of the transgenic plants with the fungal pathogens Alternaria brassicicola and Botrytis cinerea resulted in both local and systemic induction of the reporter gene. Wounding of the transgenic plants had no effect on GUS activity. Treatment of the transgenic plants with either jasmonates or the active oxygen generating compound paraquat strongly induced the reporter gene. In contrast, neither salicylate nor its functional analogues 2,6-dichloroisonicotinic acid and 1,2,3-benzothiodiazole-7-carbothioic acid S-methyl ester resulted in reporter gene induction. These results are consistent with the existence of a salicylic acid-independent signalling pathway, possibly involving jasmonates as regulators, that is triggered by pathogen challenge but not by wounding. The transgenic plants containing the PDF1.2-based promoter-reporter construct will provide useful tools for future genetic dissection of this novel systemic signalling pathway.

Acetates↗

Simultaneous spectrofluorimetric determination of (acetyl)salicylic acid, codeine and pyridoxine in pharmaceutical preparations using partial least-squares multivariate calibration.

A partial least-squares calibration (PLS) method for the simultaneous spectrofluorimetric determination of salicylic acid (SA), codeine (CO) and pyridoxine (PY) is proposed. The determination of SA, CO, and PY has been carried out in mixtures of up to three components by recording the emission fluorescence spectra between 300 and 500 nm (lambda(exc) = 220 nm). Due to the fact of the strong spectral overlap among the excitation and also among the emission spectra of these compounds, a previous separation should be carried out in order to determine them by conventional spectrofluorimetric methodologies. Here, a full-spectrum multivariate calibration PLS method is developed. The experimental calibration matrix was constructed with 14 samples. The concentration ranges considered were 0.1-2.0 (SA), 0.25-3.0 (CO) and 0.10-2.0 (PY) mg x l(-1). The optimum number of factors was selected by using the cross-validation method. The method also allows the simultaneous determination of acetylsalicylic acid (ASA), CO and PY by previous alkaline hydrolysis of ASA to SA. To check the accuracy of the proposed method, it was applied to the determination of these compounds in synthetic mixtures and in pharmaceuticals.

Analgesics, Opioid↗

Slow-release 5-amino-salicylic acid (Pentasa) for the treatment of active Crohn's disease.

A double-blind, placebo-controlled trial of a slow-release preparation of 5-amino-salicylic acid (Pentasa) has been performed in 40 patients with active Crohn's disease. Over a 6-week period, Pentasa (1.5 g daily) was no different to the dummy tablet in terms of clinical activity (Harvey-Bradshaw Index) or laboratory indicators of inflammation. No serious adverse reactions occurred.

Adult↗

Does the acetyl group of aspirin contribute to the antiinflammatory efficacy of salicylic acid in the treatment of rheumatoid arthritis?

In a multicenter, double-blind, parallel-group study, 233 patients with classical or definite RA who demonstrated disease flare during a prestudy washout period were randomized to 12 weeks of treatment with either the nonacetylated salicylate, salsalate (salicylsalicylic acid), or aspirin. Of the 150 patients who completed the study, 83 received salsalate and 67 were treated with aspirin. Doses of the two drugs were calculated to provide equal amounts of bioavailable salicylic acid. The efficacy of salsalate and aspirin, as measured by all the usual variables, was equivalent but aspirin-treated patients had a higher incidence of severe gastrointestinal problems. Thus, this study demonstrated that the acetyl group of aspirin does not enhance the anti-inflammatory efficacy of salicylic acid in RA.

Anti-Inflammatory Agents, Non-Steroidal↗

Questioning the role of salicylic acid and cytosolic acidification in mitogen-activated protein kinase activation induced by cryptogein in tobacco cells.

Elicitors of plant defence reactions, oligogalacturonides and cryptogein, an elicitin produced by Phytophthora cryptogea, were previously shown to induce a rapid and transient activation of two mitogen-activated protein kinases (MAPKs) in cells of tobacco [ Nicotiana tabacum L. cv. Xanthi; A. Lebrun-Garcia et al. (1998) Plant J 15:773-781]. We verified that these two MAPKs correspond to the salicylic acid-induced protein kinase (SIPK) and the wound-induced protein kinase (WIPK). The involvement of salicylic acid (SA) in cryptogein-induced MAPK activation was investigated using transgenic NahG tobacco cells expressing the salicylate hydroxylase gene and thus unable to accumulate SA. The large and sustained activation of both MAPKs by cryptogein was maintained in transgenic cells compared with non-transgenic tobacco cells. Moreover, weak acids, namely SA, 4-hydroxybenzoic acid, an ineffective analogue of SA in plant resistance, and butyric acid acidified the cytosol, a physiological event also induced by cryptogein, but activated both MAPKs only slightly and transiently in tobacco cells. These results indicate that MAPK activation by cryptogein is not mediated by SA, that cytosolic acidification can be transduced by MAPKs, and that in cryptogein-treated cells, cytosolic acidification should contribute poorly to MAPK activation.

Algal Proteins↗

Synthesis and characterization of methacrylic derivatives of 5-amino salicylic acid with pH-sensitive swelling properties.

The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensitive swelling and drug release properties. Methacrylic-type polymeric prodrugs with different content levels of 5-amino salicylic acid (5-ASA) were synthesized by free radical copolymerization of metacrylic acid (MAA), polyethylene glycol monomethacrylate (PEGMA), and a methacrylic derivative of 5-ASA (methacryloyloxyethyl 5-amino salicylate [MOES]). The copolymers were characterized, and the drug content of the copolymers was determined. The effect of copolymer composition on the swelling behavior and hydrolytic degradation was studied in simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF, pH 7.2). The swelling and hydrolytic behavior of the copolymers was dependent on the content of MAA groups and caused a decrease in gel swelling in SGF or an increase in gel swelling in SIF. Drug release studies showed that increasing content of MAA in the copolymer enhances the hydrolysis in SIF but has no effect in SGF. The results suggest that hydrogen-bonded complexes are formed between MAA and PEG pendant groups and that these pH-sensitive systems could be useful for preparation of a controlled-release formulation of 5-ASA.

Anti-Inflammatory Agents, Non-Steroidal↗

Kinetic-spectrophotometric method for the assay of copper(II) in human serum by catalytic oxidation of salicylic acid.

A very sensitive kinetic spectrophotometric method for the determination of copper(II) concentrations as low as 0.07 ng ml(-1) is described. This method is based on the oxidation of salicylic acid by hydrogen peroxide in ammoniacal medium, catalysed by copper(II) ion. The figures of merit of the procedure and the results of a study of interferences are given. The method is applied to the assay of copper in human blood serum.

Journal Article↗

Treatment of solar keratoses with a 5-fluorouracil and salicylic acid varnish.

In an attempt to avoid the side-effects of treating solar keratoses with 5% 5-fluorouracil (5-FU) ointment, a new pharmacological varnish containing 5% 5-FU and 5-10% salicylic acid to collodium was tried. Twenty patients with such lesions were treated. A drop of the varnish was applied on each lesion every 3 weeks. Only one to five applications on facial lesions were necessary to obtain apparent cure in all patients. Lesions reappeared in four patients, but were cured after a second and similar treatment. The keratoses of the hands were more resistant and needed seven applications in one patient and nine in the other.

Administration, Topical↗