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The analysis of methyl salicylate and salicylic acid from Chinese herbal medicine ingestion.

This paper presents a multi-drug fatality in which methyl salicylate was ingested. It is presented to inform the toxicological community that a particularly expeditious method of detection for methyl salicylate exists. Previously published methods for the analysis of methyl salicylate include a gas chromatographic-mass spectrometric method and an alkaline/acidic extraction followed by high-performance liquid chromatographic (HPLC) analysis. This article describes a method for analyzing methyl salicylate using HPLC, in which a simple, rapid extraction procedure is used. Using a previously published HPLC method, methyl salicylate and salicylic acid were easily identified in biological specimens. Methyl salicylate and salicylic acid were detected using an extraction solution of acetonitrile coupled with internal standard and then analyzed by HPLC-diode-array detection. Because of its concentrated liquid form, methyl salicylate ingestion can cause rapid onset salicylate toxicity. As the potentially fatal methyl salicylate forms are readily available and easily found on drugstore shelves, the need to rapidly detect and quantitate salicylic acid concentrations that are due to methyl salicylate ingestion may arise. In the case presented, the peripheral blood concentration of salicylic acid from methyl salicylate ingestion was 320 mg/L, and the concentration in gastric contents was 820 mg. It alone was not the cause of death, however. The discovery of the ability to detect and quantitate methyl salicylate was due to its suspected ingestion.

Acetonitriles↗

Salicylic acid: a link between aspirin, diet and the prevention of colorectal cancer.

Aspirin was introduced into clinical practice more than 100 years ago. This unique drug belongs to a family of compounds called the salicylates, the simplest of which is salicylic acid, the principal metabolite of aspirin. Salicylic acid is responsible for the anti-inflammatory action of aspirin, and may cause the reduced risk of colorectal cancer observed in those who take aspirin. Yet salicylic acid and other salicylates occur naturally in fruits and plants, while diets rich in these are believed to reduce the risk of colorectal cancer. Serum salicylic acid concentrations are greater in vegetarians than non-vegetarians, and there is overlap between concentrations in vegetarians and those taking low-dose aspirin. We propose that the cancer-preventive action of aspirin is due to its principal metabolite, salicylic acid, and that dietary salicylates can have the same effect. It is also possible that natural salicylates contribute to the other recognized benefits of a healthy diet.

Anti-Inflammatory Agents, Non-Steroidal↗

[Structure-activity relationships of salicylic acid and its analogs in the inhibitory action on beta-lactamase].

AIM: Nineteen compounds related to salicylic acid were evaluated for their in vitro activity of inhibiting beta-lactamase isolated from a resistant strain of Pseudomonas aeruginosa, and their structure-activity relationships were examined. METHODS: Nitrocefin method was used. RESULTS: The 50% inhibitory concentration (IC50) of salicylic acid inhibiting beta-lactamase was 22 mmol x L(-1); four analogs had IC50 lower than that of salicylic acid; fifteen analogs had IC50 higher than that of salicylic acid. CONCLUSION: Examination of the structure-activity relationships of the compounds revealed that carboxyl group and adjoining hydroxyl group were active group, and replacement of adjoining hydroxyl by carboxyl increased activity nearly 4-fold. Moreover, addition of a sulfonic group at C-5 and nitro group at C-3, 5 of benzenoic ring of salicylic acid resulted in a 2-fold to 3-fold increase in activity, addition of a amino group at C-5 of benzenoic ring of salicylic acid decreased activity, add addition of -Cl or -F at C-2,4 position of benzenoic ring of benzoic acid did not show activity.

Anti-Bacterial Agents↗

Salicylic acid blocks indomethacin- and aspirin-induced cyclo-oxygenase inhibition in rat gastric mucosa.

Salicylic acid reduces gastric mucosal lesions induced by aspirin and indomethacin. Aspirin and indomethacin reduce gastric mucosal cyclo-oxygenase activity. These studies were designed to determine whether or not salicylic acid interacts with gastric mucosal cyclo-oxygenase, decreasing the inhibitory effect of aspirin and indomethacin as has been observed in platelets and vascular tissue. The interaction between salicylic acid and two cyclo-oxygenase inhibitors, indomethacin and aspirin, was assessed on ex vivo prostaglandin generation in the rat gastric mucosa. Salicylic acid (100 mg/kg) was administered orally 30 min before the subcutaneous injection of either indomethacin (0.5-10 mg/kg) or aspirin (5.0-20 mg/kg). Pretreatment produced a shift of the mean 50% inhibitory dose for PGF2 alpha formation from 0.92 to 7.6 mg/kg for indomethacin and from 7.8 to 20 mg/kg for aspirin. Similar results were achieved with ex vivo prostacyclin synthesis as measured by the level of 6-keto-PGF 1 alpha. These data are consistent with competitive enzyme kinetics, and may, in part, explain the protective effect of salicylic acid against the ulcerogenicity of aspirin and indomethacin on the gastric mucosa.

Animals↗

Enlarged processing window of plasticized wheat gluten using salicylic acid.

The temperature window for the extrusion of glycerol-plasticized wheat gluten was increased by the use of salicylic acid, a known scorch retarder and radical scavenger. It was possible to extrude 30 wt % glycerol-wheat gluten films with a die-head temperature as high as 135 degrees C, rather than 95 degrees C, by incorporating only 1 wt % salicylic acid. Small effects of shear-induced heating during extrusion at the higher temperatures suggested that the acid acted as a lubricant and viscosity reducer. The latter was suggested to originate primarily from the salicylic-acid-induced reduction in the degree of protein aggregation/cross-linking, as indicated by size-exclusion high-performance liquid chromatography and chemiluminescence. Electron paramagnetic resonance spectroscopy on extruded films indicated that the beneficial effect of salicylic acid was due to its radical scavenging effect. Tensile tests on extrudates revealed that the materials produced at the substantially higher processing temperature were still ductile. The complex shear modulus increased more slowly with increasing salicylic acid content above 110-120 degrees C, indicating that the aggregation/cross-linking rate was slower with salicylic acid, that is, that it did have a scorch-retarding effect, besides yielding a lower final degree/complexity of aggregation.

Chromatography, High Pressure Liquid↗

Metabolism of salicylic acid in the isolated perfused rat kidney. Interconversion of salicyluric and salicyclic acids.

Renal metabolism of salicylic acid (SA) to salicyluric acid (SU), as well as the metabolism of SU to SA, was demonstrated in the isolated perfused rat kidney. SU formation was dependent upon the inclusion of a glycine pool and glycine concentration influenced the rate of SU excretion. The total conversion of SA to SU in 1 hr was 7.7% after the administration of 1 mg SA. Administration of increasing amounts of SA diminished this extent of SU formation. The addition of a competitive substrate, benzoic acid, produced a rapid formation and excretion of hippuric acid with a corresponding inhibition of SU formation and excretion. It is important to note that when isolated kidneys were perfused with 2.5 mg SU, 20--30% of the dose was metabolized to SA. Increasing the dose of SU to 10 mg decreased the amount of SA formed. In view of observed reversible SA/SU metabolism, a larger renal contribution to overall salicylate disposition is suggested.

Animals↗

Expression of the gene for a small GTP binding protein in transgenic tobacco elevates endogenous cytokinin levels, abnormally induces salicylic acid in response to wounding, and increases resistance to tobacco mosaic virus infection.

Tobacco plants transformed with rgp1, a gene encoding a Ras-related small GTP binding protein, were previously shown to exhibit a distinct reduction in apical dominance with increased tillering. These abnormal pheno-types were later found to be associated with elevated levels of endogenous cytokinins (zeatin and zeatin riboside). Analysis of the expression of several genes known to be affected by cytokinins identified a clear increase in the mRNA levels of genes encoding acidic pathogenesis-related proteins in both transgenic plants and their progenies. This increase was directly attributable to elevated levels of the acidic pathogenesis-related protein inducers, salicylic acid (SA) and salicylic acid beta-glucoside, due to an abnormal and sensitive response of the transgenic plants to wounding. In contrast, mRNA levels of the gene for proteinase inhibitor II, which is normally induced by wounding, were generally suppressed in the same wounded plants, probably due to SA overproduction. The changes in SA and pathogenesis-related protein levels in the transgenic plants resulted in a distinct increase in their resistance to tobacco mosaic virus infection. In normal plants, the wound and pathogen-induced signal transduction pathways are considered to function independently. However, the wound induction of SA in the transgenic plants suggests that overexpression of this small GTP binding protein somehow interferes with the normal signal pathways, possibly by affecting cytokinin biosynthesis, and results in cross-signaling between these two transduction systems.

Journal Article↗

Distribution of salicylic acid in human stratum corneum following topical application in vivo: a comparison of six different formulations.

Distribution of salicylic acid in human stratum corneum from treatment of six different formulations was assessed by quantitation of drug content in sequentially tape-stripped stratum corneum after a single 2-h dose was applied unoccluded to skin on the ventral forearm of four female subjects. The profile and total amounts of stratum corneum removed in 20 tape-strips varied among different types of formulations. With or without normalization by the total stratum corneum weights removed, the extent of drug delivery to the stratum corneum decreased in the following order: SA (5%) > > SAC (10%), Duofilm (16.7%) > TSSS (2%) > SAO (10%), Salic (2.5%), the percentage in parentheses indicating the salicylic acid concentration in each formulation. The greatest topical bioavailability was observed for the alcoholic solution containing glycerol (SA). The 10% collodion formulation (SAC) was found to deliver an amount of salicylic acid into the stratum corneum 2-fold greater than 10% ointment formulation (SAO). Use of absorption ointment (TSSS) also increased the uptake of salicylic acid into the stratum corneum in comparison with formulations based on simple ointment (SAO) and oil in water (o/w) cream (Salic). The partitioning of salicylic acid from collodion formulations (SAC and Duofilm) appeared to be concentration-independent. The results of this study indicate that topical bioavailability of salicylic acid in the stratum corneum varies substantially among different formulations.

Adhesives↗

A novel chemiluminescent method for the determination of salicylic acid in bactericidal solutions.

A new flow-injection procedure has been developed for the determination of salicylic acid based on the enhancement of the chemiluminescence from the cerium(IV)-Tween 20 reaction by salicylic acid in acidic medium. The method is simple, selective and sensitive with a detection limit of 2.5x10(-9) g mL(-1). It is applicable to the determination of salicylic acid in the concentration range of 4.0x10(-9)-1.1x10(-6) g mL(-1). The relative standard deviation (RSD) is 0.85% for 4.0x10(-7) g mL(-1) salicylic acid (n=11). The method has been successfully applied to the determination of salicylic acid in bactericidal solutions. Furthermore, it is suggested that light emission from cerium(IV)-Tween 20 reaction is probably because of the formation of singlet oxygen 1O2* and the emitter is excited oxygen molecular pairs O2(1delta(g))O2(1sigma(g)-).

Anti-Bacterial Agents↗

Salicylic acid peels for the treatment of acne vulgaris in Asian patients.

BACKGROUND: Salicylic acid peels have been introduced as a useful modality in acne treatment. Few studies have examined its efficacy and safety, especially in darker skin. OBJECTIVE: To assess the efficacy and safety of salicylic acid peels as a treatment for acne vulgaris in Asian patients. METHODS: Thirty-five Korean patients with facial acne were treated with 30% salicylic acid peels biweekly for 12 weeks. Lesion counts and Dr. Cunliffe's score were assessed by a blinded evaluator. Safety assessments and patient's evaluations were also recorded. RESULTS: Both inflammatory and noninflammatory acne lesion counts were decreased in proportion to the duration of treatment. Dr. Cunliffe's acne grade was statistically significantly decreased after treatment. The side effects were tolerable in most cases, and all patients were pleased with their peel results. Stratum corneum hydration, skin surface lipid, skin pH, and transepidermal water loss were unchanged from baseline levels. CONCLUSION: Salicylic acid peels are an effective and safe therapy for acne vulgaris in Asian patients.

Acne Vulgaris↗

Detection of the action of salicylic acid on the normal stratum corneum.

The undoubted clinical usefulness of salicylic acid contrasts markedly with its barely detectable action on normal skin. In this study we have attempted to extend our understanding of the action of salicylic acid by monitoring its effect on the stratum corneum using newly developed techniques for assessing desquamation, as well as using conventional methods for measuring other aspects of epidermal activity. Our findings have succeeded in demonstrating that salicylic acid enhances the shedding of corneocytes and we suggest that this compound in some way decreases corneocyte to corneocyte cohesion. We have confirmed that salicylic acid has no effect on the mitotic activity of the normal epidermis.

Cell Count↗

Systemic Induction of Salicylic Acid Accumulation in Cucumber after Inoculation with Pseudomonas syringae pv syringae.

Inoculation of one true leaf of cucumber (Cucumis sativus L.) plants with Pseudomonas syringae pathovar syringae results in the systemic appearance of salicylic acid in the phloem exudates from petioles above, below, and at the site of inoculation. Analysis of phloem exudates from the petioles of leaves 1 and 2 demonstrated that the earliest increases in salicylic acid occurred 8 hours after inoculation of leaf 1 in leaf 1 and 12 hours after inoculation of leaf 1 in leaf 2. Detaching leaf 1 at intervals after inoculation demonstrated that leaf 1 must remain attached for only 4 hours after inoculation to result in the systemic accumulation of salicylic acid. Because the levels of salicylic acid in phloem exudates from leaf 1 did not increase to detectable levels until at least 8 hours after inoculation with P. s. pathovar syringae, the induction of increased levels of salicylic acid throughout the plant are presumably the result of another chemical signal generated from leaf 1 within 4 hours after inoculation. Injection of salicylic acid into tissues at concentrations found in the exudates induced resistance to disease and increased peroxidase activity. Our results support a role for salicylic acid as an endogenous inducer of resistance, but our data also suggest that salicylic acid is not the primary systemic signal of induced resistance in cucumber.

Journal Article↗

[Antiphlogistic effect of salicylic acid and its derivatives].

An overview of the literature on the effects of salicylic acid and its derivatives with particular consideration being given to their antiinflammatory properties is presented. While acetylsalicylic acid, in common with most non-steroidal anti-inflammatory drugs, has a marked inhibitory effect on cyclooxygenase in vitro, salicylic acid only weakly inhibits this enzyme. Animal inflammation models, however, have shown that the two substances are comparable in terms of efficacy. It is therefore assumed that the antiinflammatory properties of salicylic acid and its derivatives are also based on prostaglandin-independent mechanisms. Both salicylates and salicylic acid are used for topical applications. Their penetration into deeper tissue layers, as also their efficacy after local application have been demonstrated in both animal studies and clinical trials.

Animals↗

Distribution of pentobarbital and diphenylhydantoin between plasma and cells in blood: effect of salicylic acid, temperature and total drug concentration.

The binding of pentobarbital, diphenylhydantoin and salicylic acid to cells in blood was found to be independent of total drug concentration within therapeutic levels. Salicylic acid displaced pentobarbital and diphenylhydantoin from plasma protein binding sites, but high levels of salicylic acid had no effect on the distribution of the other two drugs to washed blood cells. Thus, in whole blood the presence of salicylic acid decreased the fraction of pentobarbital or diphenylhydantoin bound to plasma proteins and increased the fraction of the drug in plasma water and in blood cells. Diphenylhydantoin was shown not to be bound irreversibly to blood cells and equilibration in between the inside and outside of the cells was found to be rapid (within 5 min), even at high concentrations. Binding to washed blood cells was the same at 37 degress C and 25 degrees C, in contrast to plasma protein binding. It is pointed out that these effects may cause certain analytical errors, resulting in changes in plasma concentration if plasma is separated at a low temperature.

Blood Cells↗

Intermediates of salicylic acid biosynthesis in tobacco

Salicylic acid (SA) is an important component of systemic-acquired resistance in plants. It is synthesized from benzoic acid (BA) as part of the phenylpropanoid pathway. Benzaldehyde (BD), a potential intermediate of this pathway, was found in healthy and tobacco mosaic virus (TMV)-inoculated tobacco (Nicotiana tabacum L. cv Xanthi-nc) leaf tissue at 100 ng/g fresh weight concentrations as measured by gas chromatography-mass spectrometry. BD was also emitted as a volatile organic compound from tobacco tissues. Application of gaseous BD to plants enclosed in jars caused a 13-fold increase in SA concentration, induced the accumulation of the pathogenesis-related transcript PR-1, and increased the resistance of tobacco to TMV inoculation. [13C6]BD and [2H5]benzyl alcohol were converted to BA and SA. Labeling experiments using [13C1]Phe in temperature-shifted plants inoculated with the TMV showed high enrichment of cinnamic acids (72%), BA (34%), and SA (55%). The endogenous BD, however, contained nondetectable enrichment, suggesting that BD was not the intermediate between cinnamic acid and BA. These results show that BD and benzyl alcohol promote SA accumulation and expression of defense responses in tobacco, and provide insight into the early steps of SA biosynthesis.

Journal Article↗

Direct gradient reversed-phase high-performance liquid chromatographic determination of salicylic acid, with the corresponding glycine and glucuronide conjugates in human plasma and urine.

A gradient reversed-phase HPLC analysis for the direct measurement of salicylic acid (SA) with the corresponding glycine and glucuronide conjugates in plasma and urine of humans was developed. The glucuronides were isolated by preparative HPLC from human urine samples. The concentration of the glucuronides in the isolated fraction were determined after enzymatic hydrolysis. Salicylic acid acyl glucuronide (SAAG) was not present in plasma. No isoglucuronides were present in acidic and alkaline urine of the volunteer. The limits of quantitation in plasma are: SA 0.2 microgram/ml, salicyluric acid (SU) 0.1 microgram/ml, salicylic acid phenolic glucuronide (SAPG) 0.4 microgram/ml and salicyluric acid phenolic glucuronide (SUPG) 0.2 microgram/ml. The limit of quantitation in urine is for all compounds 5 micrograms/ml. Salicylic acid acyl glucuronide is stable in phosphate buffer pH 4.9 during 8 h at 37 degrees C; thereafter it declines to 80% after 24 h. The subject's urine was therefore acidified by the oral intake of 4 x 1.2 g of ammonium chloride/day. With acidic urine, hardly any salicylic acid is excreted unchanged (0.6%). It is predominantly excreted as salicyluric acid (68.7%).

Acylation↗

Interconversion of the salicylic acid signal and its glucoside in tobacco.

Salicylic acid (SA) has been proposed to play a role in the induction of pathogenesis-related (PR) proteins and systemic acquired resistance (SAR) in tobacco. Since SA is rapidly converted to salicylic acid beta-glucoside (SAG) in tobacco, we have attempted to assess the role of SAG in pathogenesis by application of chemically synthesized SAG to tobacco leaves. SAG was as active as SA in induction of PR-1 gene expression. This induction was preceded by a transient release of SA, which occurred in the extracellular spaces. The existence of a mechanism that releases SA from SAG suggests a possible role for SAG in SAR.

Culture Techniques↗