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PubMed1995

Local and Systemic Biosynthesis of Salicylic Acid in Infected Cucumber Plants.

Radiolabeling studies showed that salicylic acid (SA), an essential component in the signal transduction pathway leading to systemic acquired resistance, is synthesized from phenylalanine (Phe) and benzoic acid in cucumber (Cucumis sativus L.) plants inoculated with pathogens. Leaf discs from plants inoculated with either tobacco necrosis virus or Pseudomonas lachrymans incorporated more [14C]Phe into [14C]SA than mock-inoculated controls. The identity of SA was confirmed by gas chromatography-mass spectrometry. No reduction in specific activity of [14C]SA was observed for either free or bound SA between control and infected plants after feeding [14C]Phe. A specific inhibitor of Phe ammonia-lyase, 2-aminoindan-2-phosphonic acid, completely inhibited the incorporation of [14C]Phe into [14C]SA, although plants treated with 2-aminoindan-2-phosphonic acid could still produce [14C]SA from [14C]benzoic acid. Biosynthesis of SA in tissue inoculated with tobacco necrosis virus followed a transient pattern with the highest induction occurring 72 h postinoculation. Uninfected tissues from an infected plant synthesized de novo more SA than did controls. This suggests the involvement of a systemic signal triggering SA synthesis in tissue distant from the site of infection that display systemic acquired resistance.

Journal Article↗
PubMed2006

An essential role for salicylic acid in AtMYB30-mediated control of the hypersensitive cell death program in Arabidopsis.

Salicylic acid (SA) plays a central role in resistance and defense induction in response to pathogen attack, but its role in the activation of the hypersensitive response (HR), a form of programmed cell death associated with resistance of plants, remains to be elucidated. AtMYB30, a R2R3-MYB transcriptional factor which acts as a positive regulator of the HR, is a good model for studying the role of SA in programmed cell death. Here, we demonstrate that AtMYB30 expression in response to an HR-inducing bacterial pathogen is dependent on SA accumulation, but NPR1-independent. Alterations of AtMYB30 expression (overexpression, depletion by antisense strategy, T-DNA insertion mutant) modulate SA levels and SA-associated gene expression. Additionally, mutants or transgenic lines altered in SA accumulation (nahG, sid1, sid2), but not those affected in SA signalling (npr1), abolish the accelerated cell death phenotype conferred by over-expression of AtMYB30. These results suggest that AtMYB30 is involved in an amplification loop or signalling cascade that modulates SA synthesis, which in turn modulates cell death.

Apoptosis↗
PubMed2006

Proteomic investigation of the effect of salicylic acid on Arabidopsis seed germination and establishment of early defense mechanisms.

The influence of salicylic acid (SA) on elicitation of defense mechanisms in Arabidopsis (Arabidopsis thaliana) seeds and seedlings was assessed by physiological measurements combined with global expression profiling (proteomics). Parallel experiments were carried out using the NahG transgenic plants expressing the bacterial gene encoding SA hydroxylase, which cannot accumulate the active form of this plant defense elicitor. SA markedly improved germination under salt stress. Proteomic analyses disclosed a specific accumulation of protein spots regulated by SA as inferred by silver-nitrate staining of two-dimensional gels, detection of carbonylated (oxidized) proteins, and neosynthesized proteins with [35S]-methionine. The combined results revealed several processes potentially affected by SA. This molecule enhanced the reinduction of the late maturation program during early stages of germination, thereby allowing the germinating seeds to reinforce their capacity to mount adaptive responses in environmental water stress. Other processes affected by SA concerned the quality of protein translation, the priming of seed metabolism, the synthesis of antioxidant enzymes, and the mobilization of seed storage proteins. All the observed effects are likely to improve seed vigor. Another aspect revealed by this study concerned the oxidative stress entailed by SA in germinating seeds, as inferred from a characterization of the carbonylated (oxidized) proteome. Finally, the proteomic data revealed a close interplay between abscisic signaling and SA elicitation of seed vigor.

Adaptation, Physiological↗
PubMed2003

Arabidopsis local resistance to Botrytis cinerea involves salicylic acid and camalexin and requires EDS4 and PAD2, but not SID2, EDS5 or PAD4.

Salicylic acid (SA) is an important regulator of plant defense responses, and a variety of Arabidopsis mutants impaired in resistance against bacterial and fungal pathogens show defects in SA accumulation, perception, or signal transduction. Nevertheless, the role of SA-dependent defense responses against necrotrophic fungi is currently unclear. We determined the susceptibility of a set of previously identified Arabidopsis mutants impaired in defense responses to the necrotrophic fungal pathogen Botrytis cinerea. The rate of development of B. cinerea disease symptoms on primary infected leaves was affected by responses mediated by the genes EIN2, JAR1, EDS4, PAD2, and PAD3, but was largely independent of EDS5, SID2/ICS1, and PAD4. Furthermore, plants expressing a nahG transgene or treated with a phenylalanine ammonia lyase (PAL) inhibitor showed enhanced symptoms, suggesting that SA synthesized via PAL, and not via isochorismate synthase (ICS), mediates lesion development. In addition, the degree of lesion development did not correlate with defensin or PR1 expression, although it was partially dependent upon camalexin accumulation. Although npr1 mutant leaves were normally susceptible to B. cinerea infection, a double ein2 npr1 mutant was significantly more susceptible than ein2 plants, and exogenous application of SA decreased B. cinerea lesion size through an NPR1-dependent mechanism that could be mimicked by the cpr1 mutation. These data indicate that local resistance to B. cinerea requires ethylene-, jasmonate-, and SA-mediated signaling, that the SA affecting this resistance does not require ICS1 and is likely synthesized via PAL, and that camalexin limits lesion development.

Arabidopsis↗
PubMed1994

Effect of salicylic acid on the plasma protein binding and pharmacokinetics of misoprostol acid.

The in vitro serum protein binding and erythrocyte uptake of [3H]misoprostol acid ([3H]MPA; SC-30695), an active metabolite of the prostaglandin E1 (PGE1) analogue misoprostol, was determined in the blood of young (20-40 years) and elderly subjects (64 years or older) at concentrations ranging between 20 and 5000 pg/mL. The effect of selected other drugs on the displacement of [3H] MPA from the binding sites was also investigated. [3H]MPA serum binding (between 81 and 89 %) was similar and concentration independent in the young and elderly subjects and the erythrocyte partitioning coefficient was about 1, indicating the absence of a significant accumulation of MPA in red blood cells. Both the plasma and serum protein binding of [3H] MPA were substantially reduced in the presence of high (> 100 microg/mL) concentrations of salicylic acid. In an in vivo study, the single-dose pharmacokinetics of MPA did not change significantly when misoprostol (200 microg) was given alone or concomitantly with 975 mg of aspirin. These findings indicate that MPA is displaced from its protein binding sites only by high concentrations of salicylic acid and that this displacement is unlikely to be of clinical significance with the usual therapeutic doses of aspirin.

Adult↗
PubMed1980

Effect of sodium oleate on salicylic acid binding to human serum albumin.

The pharmacological activity of salicylates is related to the non-protein-bound fraction of drug in the plasma. Free fatty acids have been shown to displace bound drug and to increase the serum levels of salicylates. Continuous ultrafiltration was used to measure unbound salicylic acid at 37 degrees. A nonlinear analysis of the ultrafiltration data using whole number values for the number of binding sites indicates that sodium oleate displaces the salicylic acid competitively at both binding sites. Increased concentrations of fatty acids due to disease or the infusion of fatty acid emulsions perhaps may produce toxic levels of salicylic acid.

Binding Sites↗
PubMed1975

Effects of normal alcohols on intestinal absorption of salicylic acid, sulfapyridine, and prednisolone in rats.

The rates of intestinal absorption of salicyclic acid, sulfapyridine, and prednisolone from solutions containing no alcohol or 0.5% ethanol, n-butanol, or n-hexanol were determined. At the concentrations used, ethanol did not significantly affect drug absorption. Butanol reduced the rate of absorption of sulfapyridine but did not significantly affect the absorption rates of prednisolone or salicylic acid. Hexanol reduced the rates of absorption of sulfapyridine and salicylic acid and increased the rate of absorption of prednisolone. The absorption-altering effects of the alcohols were concentration dependent and rapidly reversible. Histological studies indicated that the structure of the epithelium was not altered by the alcohols. While the absorption rate of water from the drug solutions was increased by the alcohols, their absorption-altering effects could not be attributed solely to increased water flux. In addition, the absorption-altering effects of the alcohols could not be attributed to formation of drug-alcohol complexes nor to alcohol-induced alterations in the extent of binding of the drugs to nondialyzable materials in the intestinal drug solution.

Alcohols↗
PubMed1997

Salicylic acid activates a 48-kD MAP kinase in tobacco.

The involvement of phosphorylation/dephosphorylation in the salicylic acid (SA) signal transduction pathway leading to pathogenesis-related gene induction has previously been demonstrated using kinase and phosphatase inhibitors. Here, we show that in tobacco suspension cells, SA induced a rapid and transient activation of a 48-kD kinase that uses myelin basic protein as a substrate. This kinase is called the p48 SIP kinase (for SA-Induced Protein kinase). Biologically active analogs of SA, which induce pathogenesis-related genes and enhanced resistance, also activated this kinase, whereas inactive analogs did not. Phosphorylation of a tyrosine residue(s) in the SIP kinase was associated with its activation. The SIP kinase was purified to homogeneity from SA-treated tobacco suspension culture cells. The purified SIP kinase is strongly phosphorylated on a tyrosine residue(s), and treatment with either protein tyrosine or serine/threonine phosphatases abolished its activity. Using primers corresponding to the sequences of internal tryptic peptides, we cloned the SIP kinase gene. Analysis of the SIP kinase sequence indicates that it belongs to the MAP kinase family and that it is distinct from the other plant MAP kinases previously implicated in stress responses, suggesting that different members of the MAP kinase family are activated by different stresses.

Amino Acid Sequence↗
PubMed2006

OsBISAMT1, a gene encoding S-adenosyl-L-methionine: salicylic acid carboxyl methyltransferase, is differentially expressed in rice defense responses.

We isolated and identified a full-length cDNA, OsBISAMT1 [Oryza sativa L. benzothiadiazole (BTH)-induced SAMT 1], which encodes a putative S-adenosyl-L: -methionine:salicylic acid carboxyl methyltransferase (SAMT) from rice. OsBISAMT1 contains an ORE of 1128 bp, which predicts to encode a 375 aa protein. The OsBISAMT1 protein sequence shows a high level of identity to known plant SAMTs and contains a conserved characteristic methyltransferase domain. OsBISAMT1 is a member of a small gene family in the rice genome. Expression of OsBISAMT1 in rice leaves was induced by treatments with benzothiadiazole and salicylic acid, which are capable of inducing rice disease resistance. OsBISAMT1 was also up-regulated in both incompatible and compatible interactions between rice and the blast fungus, Magnaporthe grsiea, but the induced expression of OsBISAMT1 was greater and more rapid in the incompatible interaction than that in the compatible one. Moreover, mechanical wounding also activated OsBISAMT1 expression. The results suggest that OsBISAMT1 may be involved in disease resistance responses as well as in wound response in rice.

Amino Acid Sequence↗
PubMed2006

Effects of endogenous salicylic acid on nodulation in the model legumes Lotus japonicus and Medicago truncatula.

The exogenous addition of salicylic acid (SA) was previously shown to inhibit indeterminate but not determinate-type nodulation. We sought to extend these results by modulating endogenous levels of SA through the transgenic expression of salicylate hydroxylase (NahG) in both stably transformed Lotus japonicus and composite Medicago truncatula plants. NahG expression in L. japonicus resulted in a marked reduction of SA levels. This reduction correlated with an increase in the number of infections and mean nodule number when compared to controls. However, a complicating factor was that NahG-expressing plants had greater root growth. Spot inoculations of NahG-expressing L. japonicus plants confirmed increased nodulation in these plants. Consistent with the reported inhibitory effects of exogenous SA on indeterminate-type nodulation, NahG expression in M. truncatula plants led to enhanced nodulation and infection. These data point to an important role for SA-mediated plant defense pathways in controlling nodule formation on both determinate and indeterminate nodule-forming hosts.

Alphaproteobacteria↗
PubMed1988

Treatment of common warts with high-potency (26%) salicylic acid.

Treatment of common warts with topical keratolytic solutions is generally estimated to result in cure rates of 60% to 80% in 12 weeks. Problems with keratolytic solutions include irritation of surrounding normal skin and poor patient compliance. A product containing 26% salicylic acid in a novel polyacrylic vehicle was evaluated in 27 patients and found to cure or provide much improvement in 22 (81%) after only two weeks of treatment. This rapid response was accompanied by a low incidence of irritation. The results of this study suggest that high-potency salicylic acid promotes prompt resolution of warts, which may enhance patient compliance.

Administration, Topical↗
PubMed2006

Polyvinyl alcohol--gelatin patches of salicylic acid: preparation, characterization and drug release studies.

Polyvinyl alcohol-gelatin patches were developed and salicylic acid was incorporated at different stages of preparation of the patches. The patches were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry, tensile strength test, and scanning electron microscopy. The release patterns of the drug from the patches were also studied. The FTIR spectra of the blank patch indicated complete esterification of the free carboxylic groups of gelatin. The XRD studies indicated a crystalline form of the drug entrapped in the patches. Release of the drug from the patches followed Higuchian/Fickian kinetics indicating a diffusion-controlled release process.

Absorption↗
PubMed1992

Simultaneous spectrophotometric determination in solid phase of aspirin and its impurity salicylic acid in pharmaceutical formulations.

We report the simultaneous determination of aspirin and its hydrolysis product, salicylic acid, in solid phase by fluorescence spectrophotometry. Aspirin is often the most labile component in a combination-type analgesic compound. Therefore, its stability is often the initial concern in any formulation-screening program. Preliminary screening of a large number of potential formulations can be arduous, because most current methods of analysis generally consist of several steps: extractions or column separations followed by UV, colorimetric, or gas-liquid chromatographic assays. The method proposed here is quite suited to large numbers of assays because it is not time consuming, it is straightforward, and it is not subject to interference from the substances present in the pharmaceutical formulations. In addition, the method is nondestructive, not dependent on the sampling procedure, and, above all, quite sensitive.

Aspirin↗
PubMed2003

Inhibition of the gravitropic bending response of flowering shoots by salicylic acid.

The upward gravitropic bending of cut snapdragon, lupinus and anemone flowering shoots was inhibited by salicylic acid (SA) applied at 0.5 mM and above. This effect was probably not due to acidification of the cytoplasm, since other weak acids did not inhibit bending of snapdragon shoots. In order to study its mode of inhibitory action, we have examined in cut snapdragon shoots the effect of SA on three processes of the gravity-signaling pathway, including: amyloplast sedimentation, formation of ethylene gradient across the stem, and differential growth response. The results show that 1 mM SA inhibited differential ethylene production rates across the horizontal stem and the gravity-induced growth, without significantly inhibiting vertical growth or amyloplast sedimentation following horizontal placement. However, 5 mM SA inhibited all three gravity-induced processes, as well as the growth of vertical shoots, while increasing flower wilting. It may, therefore, be concluded that SA inhibits bending of various cut flowering shoots in a concentration-dependent manner. Thus, at a low concentration SA exerts its effect in snapdragon shoots by inhibiting processes operating downstream to stimulus sensing exerted by amyloplast sedimentation. At a higher concentration SA inhibits bending probably by exerting general negative effects on various cellular processes.

Acetic Acid↗
PubMed2006

Effect of 6-nonadecyl salicylic acid and its methyl ester on the induction of micronuclei in polychromatic erythrocytes in mouse peripheral blood.

The bark of Amphipterygium adstringens is widely used in the traditional Mexican medicine for treating ailments such as gastric ulcers, gastritis and stomach cancer. The 6-nonadecyl salicylic acid (anacardic acid) was isolated from the bark of this species. In previous papers have been informed that the anacardic acids possess anti-tumour, antimicrobial, antiacne, antibacterial and many others medicinal properties. Now we describe cytotoxic and genotoxic effects of this compound and its methyl ester. The cytotoxic and genotoxic effects of 6-nonadecyl salicylic acid (6NDSA) and its methyl ester (ME6NDSA) on CD1 male mice were determined with micronucleus assay at 24, 48 and 72h after oral administration of doses of 0.75, 2.5, 5.0 and 10.0mg/kg. Peripheral blood samples were drawn from the caudal vein and analyzed by Giemsa-stained technique. The results obtained showed that the ratios of polychromatic erythrocytes (PCE) to normochromatic erythrocytes (NCE) in mice treated with 10mg/kg of 6NDSA were statistically lower after 24h compared with its negative control animals, and that after 72h, PCE/NCE ratios were reduced in animals treated with 6NDSA at all tested dose levels. The methyl ester ME6NDSA showed no such cytotoxic activity. Neither of the test compounds increased the frequency of micronucleated polychromatic erythrocytes from which it appears that administration of 6NDSA and ME6NDSA may not lead to chromosome damage at the evaluated doses.

Anacardiaceae↗
PubMed2006

Salicylic acid, an ambimobile molecule exhibiting a high ability to accumulate in the phloem.

The ability of exogenous salicylic acid (SA) to accumulate in castor bean (Ricinus communis) phloem was evaluated by HPLC and liquid scintillation spectrometry analyses of phloem sap collected from the severed apical part of seedlings. Time-course experiments indicated that SA was transported to the root system via the phloem and redistributed upward in small amounts via the xylem. This helps to explain the peculiarities of SA distribution within the plant in response to biotic stress and exogenous SA application. Phloem loading of SA at 1, 10, or 100 microm was dependent on the pH of the cotyledon incubating solution, and accumulation in the phloem sap was the highest (about 10-fold) at the most acidic pH values tested (pH 4.6 and 5.0). As in animal cells, SA uptake still occurred at pH values close to neutrality (i.e. when SA is only in its dissociated form according to the calculations made by ACD LogD suite software). The analog 3,5-dichlorosalicylic acid, which is predicted to be nonmobile according to the models of Bromilow and Kleier, also moved in the sieve tubes. These discrepancies and other data may give rise to the hypothesis of a possible involvement of a pH-dependent carrier system translocating aromatic monocarboxylic acids in addition to the ion-trap mechanism.

Biological Transport↗
PubMed2004

Salicylic acid dependent signaling promotes basal thermotolerance but is not essential for acquired thermotolerance in Arabidopsis thaliana.

Salicylic acid (SA) is reported to protect plants from heat shock (HS), but insufficient is known about its role in thermotolerance or how this relates to SA signaling in pathogen resistance. We tested thermotolerance and expression of pathogenesis-related (PR) and HS proteins (HSPs) in Arabidopsis thaliana genotypes with modified SA signaling: plants with the SA hydroxylase NahG transgene, the nonexpresser of PR proteins (npr1) mutant, and the constitutive expressers of PR proteins (cpr1 and cpr5) mutants. At all growth stages from seeds to 3-week-old plants, we found evidence for SA-dependent signaling in basal thermotolerance (i.e. tolerance of HS without prior heat acclimation). Endogenous SA correlated with basal thermotolerance, with the SA-deficient NahG and SA-accumulating cpr5 genotypes having lowest and highest thermotolerance, respectively. SA promoted thermotolerance during the HS itself and subsequent recovery. Recovery from HS apparently involved an NPR1-dependent pathway but thermotolerance during HS did not. SA reduced electrolyte leakage, indicating that it induced membrane thermoprotection. PR-1 and Hsp17.6 were induced by SA or HS, indicating common factors in pathogen and HS responses. SA-induced Hsp17.6 expression had a different dose-response to PR-1 expression. HS-induced Hsp17.6 protein appeared more slowly in NahG. However, SA only partially induced HSPs. Hsp17.6 induction by HS was more substantial than by SA, and we found no SA effect on Hsp101 expression. All genotypes, including NahG and npr1, were capable of expression of HSPs and acquisition of HS tolerance by prior heat acclimation. Although SA promotes basal thermotolerance, it is not essential for acquired thermotolerance.

Acclimatization↗