[High performance liquid chromatographic determination of the main alkaloids in aconite].
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Aconitum↗
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[Case of poisoning with aconite tincture].
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Accidents, Home↗
Characterization of the lectin from the bulbs of Eranthis hyemalis (winter aconite) as an inhibitor of protein synthesis.
The lectin from Eranthis hyemalis has been previously characterized as consisting of two polypeptide chains covalently linked by disulfide bond(s) (Cammue, B. P., Peeters, B., and Peumans, W. J. (1985) Biochem. J. 227, 949-955). We have further characterized the biochemical properties of the lectin and demonstrated that it possesses the property of inhibition of protein synthesis using in vitro eukaryotic translation systems. The protein also possesses antiviral activity against the plant virus, alfalfa mosaic virus, and larvicidal activity against the southern corn rootworm, Diabrotica undecimpunctata howardii, a major insect pest of the maize plant. Both isoelectric focusing on gels and chromatofocusing indicated heterogeneity of the protein, with three species having isoelectric points in the range 4-5. The disulfide bond(s) can be rapidly reduced with beta-mercaptoethanol under native conditions. The reduced alkylated polypeptide chains remain associated under native conditions to form a species, EHL', that elutes at the same position as the native protein and has the same molecular weight by sedimentation equilibrium experiments. However, circular dichroism and fluorescence measurements indicated conformational differences between the species.
Amino Acid Sequence↗
[Hemosorption in the combination therapy of acute aconite poisoning].
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Aconitum↗
Aconite induced cardiac arrhythmias.
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Aconitum↗
Dual Mechanisms of Tricarboxylate Transport and Catabolism by Acidaminococcus fermentans.
Acidaminococcus fermentans utilized citrate or the citrate analog aconitate as an energy source for growth, and these tricarboxylates were used simultaneously. Citrate utilization and uptake showed biphasic kinetics. High-affinity citrate uptake had a K(t) of 40 muM, but the V(max) was only 25 nmol/mg of protein per min. Low-affinity citrate utilization had a 10-fold higher V(max), but the K(s) was greater than 1.0 mM. Aconitate was a competitive inhibitor (K(i) = 34muM) of high-affinity citrate uptake, but low-affinity aconitate utilization had a 10-fold-lower requirement for sodium than did low-affinity citrate utilization. On the basis of this large difference in sodium requirements, it appeared that A. fermentans probably has two systems of tricarboxylate uptake: (i) a citrate/aconitate carrier with a low affinity for sodium and (ii) an aconitate carrier with a high affinity for sodium. Citrate was catabolized by a pathway involving a biotin-requiring, avidin-sensitive, sodium-dependent, membrane-bound oxaloacetate decarboxylase. The cells also had aconitase, but this enzyme was unable to convert citrate to isocitrate. Since cell-free extracts converted either aconitate or glutamate to 2-oxoglutarate, it appeared that aconitate was being catabolized by the glutaconyl-CoA decarboxylase pathway. Exponentially growing cultures on citrate or citrate plus aconitate were inhibited by the sodium/proton antiporter, monensin. Because monensin had no effect on cultures growing with aconitate alone, it appeared that citrate metabolism was acting as an inducer of monensin sensitivity. A. fermentans cells always had a low proton motive force (<50 mV), and cells treated with the protonophore TCS (3,3',4',5-tetrachlorosalicylanide) grew even though the proton motive force was less than 20 mV. On the basis of these results, it appeared that A. fermentans was depending almost exclusively on a sodium motive force for its membrane energetics.
Journal Article↗
Aconitase: its source of catalytic protons.
An ordinary isotope partition experiment was performed to determine the rate of dissociation of the proton from the donor site for the hydration of cis-aconitate. Aconitase in [3H]water was efficiently diluted into well-mixed solutions of cis-aconitate. Citrate and isocitrate that were formed within 2 s were more heavily labeled than could be explained by consideration of an isotope effect in the processing of one proton per enzyme equivalent. Control experiments indicate that mixing was much more rapid than catalytic turnover, ruling out incompletely diluted [3H]water as a significant isotope source. Therefore, it appears that significantly more than one enzyme-bound tritium atom (protons) must have been used in the course of the multiple turnover of the enzyme after the dilution was complete. Isotope incorporation reached values in excess of four proton equivalents as a limit with simple Michaelis dependence on cis-aconitate. From the half-saturation concentration value for trapping, 0.15 mM, the t 1/2 for exchange of each of these protons with solvent appears to be approximately 0.1 s at 0 degrees C. The large number of protons trapped seems to suggest the existence of a structurally stabilized pool of protons, or water, that communicates between the active site base and the medium in the hydration of cis-aconitate. The proton abstracted in the dehydration of [3H]citrate is transferred directly to undissociated cis-aconitate to form isocitrate without dilution, or cis-aconitate having dissociated, the tritium passes to the medium, presumably through the pool of bound protons indicated above. All of the citrate-derived protons can be found in isocitrate if cis-aconitate is added in sufficient concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
Aconitate Hydratase↗
Can we dispense with Ayurvedic samskaras?
Crude aconite is an extremely lethal substance. However, the science of Ayurveda looks upon aconite as a therapeutic entity. Crude aconite is always processed i.e. it undergoes 'samskaras' before being utilised in the Ayurvedic formulations. This study was undertaken in mice, to ascertain whether 'processed' aconite is less toxic as compared to the crude or unprocessed one. It was seen that crude aconite was significantly toxic to mice (100% mortality at a dose of 2.6 mg/mouse) whereas the fully processed aconite was absolutely non-toxic (no mortality at a dose even 8 times as high as that of crude aconite). Further, all the steps in the processing were essential for complete detoxification.
Aconitum↗
Clinical features and management of herb-induced aconitine poisoning.
STUDY OBJECTIVE: We define the potential sources, clinical manifestations, and treatment of aconitine poisoning. METHODS: The database of the National Poison Center in Taiwan was retrospectively searched for the diagnosis of aconitine poisoning for 1990 to 1999. The reasons for taking the aconite roots, the clinical features, management, and possible predisposing factors were noted. RESULTS: A total of 17 cases occurred and consisted of 9 men and 8 women aged 30 to 70 years. Thirteen patients ingested aconite roots as treatment for rheumatism and wounds. Two patients volunteered to test the effects of aconite roots in a drug study. Two patients accidentally ingested the aconite roots. After a latent period of 10 to 90 minutes, patients developed a combination of neurologic (n=17), cardiovascular (n=14), gastrointestinal (n=9), and other (n=5) features typical of aconitine poisoning. Four patients developed ventricular tachycardia. All patients received supportive treatment. Patients with ventricular tachycardia were also treated with charcoal hemoperfusion. All patients made a complete recovery. CONCLUSION: Life-threatening ventricular tachycardia can occur after the consumption of aconite roots. The risk is higher with inadequately processed aconite roots, large doses, or tincture preparations. With increasing popularity of herbal medicines, herb-induced aconitine poisoning may also be seen in Western countries.
Aconitine↗
Organic acids and iron translocation in maize genotypes.
Translocation of Fe was studied in WF9 (Fe-efficient) and ys(1)/ys(1) (Fe-inefficient) maize (Zea mays L.) genotypes. Iron-deficient WF9 translocated more Fe to the tops than Fe-deficient ys(1)/ys(1). Malate and citrate contents of root saps increased nearly 2-fold and aconitate increased over 4-fold in both genotypes as Fe of nutrient solutions increased from 0.1 to 3 milligrams per liter. Relative acid contents in root saps were as follows: malate > aconitate > citrate. Citric acid concentrations in stem exudates were nearly the same as in root sap. Malic acid concentrations were considerably lower in exudates than in root saps, and only a trace of aconitic acid was detected in the exudates. The concentration of Fe was 7-fold higher in exudate of WF9 than in exudate of ys(1)/ys(1) and the concentration of exudate P was about the same for both genotypes.Electropherograms of WF9 stem exudates showed that (59)Fe moved toward the anode as (59)Fe-citrate. Exudates of ys(1)/ys(1) contained insufficient (59)Fe to produce radiographs. When (59)Fe was added in vitro to ys(1)/ys(1) stem exudate, the (59)Fe moved as (59)Fe-citrate, indicating that sufficient citric acid was present in the exudate to chelate the Fe. Effectiveness of citric, isocitric, trans-aconitic, and malic acids in moving (59)Fe electrophoretically in acetate, citrate, isocitrate, trans-aconitate, and malate buffers was studied. Malic, acetic, and trans-aconitic acids were ineffective in moving Fe from the origin. Citric acid moved Fe anodically whenever present on the electropherogram and successfully competed with the other acids for Fe.Results with ys(1)/ys(1) roots indicate an absence of an efficient mechanism for transporting Fe from cortical cells to the xylem. If Fe can reach the xylem stream, the ys(1)/ys(1) genotype should be as efficient as WF9 in moving Fe to the leaves.
Journal Article↗
Production of tricarballylic acid by rumen microorganisms and its potential toxicity in ruminant tissue metabolism.
1. Rumen microorganisms convert trans-aconitate to tricarballylate. The following experiments describe factors affecting the yield of tricarballylate, its absorption from the rumen into blood and its effect on mammalian citric acid cycle activity in vitro. 2. When mixed rumen microorganisms were incubated in vitro with Timothy hay (Phleum pratense L.) and 6.7 mM-trans-aconitate, 64% of the trans-aconitate was converted to tricarballylate. Chloroform and nitrate treatments inhibited methane production and increased the yield of tricarballylate to 82 and 75% respectively. 3. Sheep given gelatin capsules filled with 20 g trans-aconitate absorbed tricarballylate and the plasma concentration ranged from 0.3 to 0.5 mM 9 h after administration. Feeding an additional 40 g potassium chloride had little effect on plasma tricarballylate concentrations. Between 9 and 36 h there was a nearly linear decline in plasma tricarballylate. 4. Tricarballylate was a competitive inhibitor of the enzyme, aconitate hydratase (aconitase; EC 4.2.1.3), and the inhibitor constant, KI, was 0.52 mM. This KI value was similar to the Michaelis-Menten constant (Km) of the enzyme for citrate. 5. When liver slices from sheep were incubated with increasing concentrations of tricarballylate, [14C]acetate oxidation decreased. However, even at relatively high concentrations (8 mM), oxidation was still greater than 80% of the maximum. Oxidation of [14C]acetate by isolated rat liver cells was inhibited to a greater extent by tricarballylate. Concentrations as low as 0.5 mM caused a 30% inhibition of citric acid cycle activity.
Aconitic Acid↗
Simultaneous determination of six Aconitum alkaloids in proprietary Chinese medicines by high-performance liquid chromatography.
By optimizing the extraction, separation and analytical conditions, a reliable and accurate high-performance liquid chromatography (HPLC) method coupled with photodiode array detector (DAD) was developed for simultaneous quantitative determination of six Aconitum alkaloids, i.e., aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine and benzoylhypaconine, in Chinese medicinal herbs, aconite roots, and 12 proprietary Chinese medicines containing processed aconite roots. The separation of these Aconitum alkaloids was achieved on an ODS column with gradient elution using solvents of acetonitrile and ammonium bicarbonate buffer (pH 10.0+/-0.2). Intra-assay and inter-assay precision of the analytes were less than 2.97%, and the average recovery rates obtained were in the range of 90-103% for all with RSDs below 3.28%. Good linear relationships were showed with correlation coefficients for the analytes exceeded 0.999. Quantitative analysis of the six Aconitum alkaloids in the unprocessed and processed aconite roots and in twelve proprietary Chinese medicines containing processed aconite roots showed that the contents of the alkaloids varied significantly. This method and quantitation results can provide a scientific and technical platform to the products manufacturers for setting up a quality control standard as well as to the public for quality and safety assurance of the proprietary Chinese medicines and other herbal preparations containing aconite roots.
Aconitum↗
Structural basis for aconitase activity inactivation by butanedione and binding of substrates and inhibitors.
Aconitase (citrate(isocitrate)hydro-lyase, EC 4.2.1.3) prior to activation demonstrates a single binding site for substrates and inhibitors. On the basis of kinetic experiments, at pH 8.5 and 37 degrees C, with monomeric butanedione in borate, this binding site was found to contain a single arginine residue. Dissociation constants at pH 8.5 and 37 degrees C, determined from inhibitory effects on butanedione inactivation rates are: citrate, 0.74 mM; D-isocitrate, 0.33 mM: cis-aconitate, 0.52 mM; tricarballytate, 0.42 mM; trans-aconitate, 0.025 mM. Corresponding dissociation constants for the active enzyme are: tricarballylate, 0.39 mM; trans-aconitate, 0.14 mM. Active site Fe2+ added to the enzyme on activation is therefore not required for binding. Km values are: citrate, 0.23 mM and cis-aconitate 0.012 mM. Binding to active enzyme is considered to be transition state binding.
Aconitate Hydratase↗
In vitro conversion of propionate to pyruvate by Salmonella enterica enzymes: 2-methylcitrate dehydratase (PrpD) and aconitase Enzymes catalyze the conversion of 2-methylcitrate to 2-methylisocitrate.
Salmonella enterica serovar Typhimurium LT2 catabolizes propionate through the 2-methylcitric acid cycle, but the identity of the enzymes catalyzing the conversion of 2-methylcitrate into 2-methylisocitrate is unclear. This work shows that the prpD gene of the prpBCDE operon of this bacterium encodes a protein with 2-methylcitrate dehydratase enzyme activity. Homogeneous PrpD enzyme did not contain an iron-sulfur center, displayed no requirements for metal cations or reducing agents for activity, and did not catalyze the hydration of 2-methyl-cis-aconitate to 2-methylisocitrate. It was concluded that the gene encoding the 2-methyl-cis-aconitate hydratase enzyme is encoded outside the prpBCDE operon. Computer analysis of bacterial genome databases identified the presence of orthologues of the acnA gene (encodes aconitase A) in a number of putative prp operons. Homogeneous AcnA protein of S. enterica had strong aconitase activity and catalyzed the hydration of the 2-methyl-cis-aconitate to yield 2-methylisocitrate. The purification of this enzyme allows the complete reconstitution of the 2-methylcitric acid cycle in vitro using homogeneous preparations of the PrpE, PrpC, PrpD, AcnA, and PrpB enzymes. However, inactivation of the acnA gene did not block growth of S. enterica on propionate as carbon and energy source. The existence of a redundant aconitase activity (encoded by acnB) was postulated to be responsible for the lack of a phenotype in acnA mutant strains. Consistent with this hypothesis, homogeneous AcnB protein of S. enterica also had strong aconitase activity and catalyzed the conversion of 2-methyl-cis-aconitate into 2-methylisocitrate. To address the involvement of AcnB in propionate catabolism, an acnA and acnB double mutant was constructed, and this mutant strain cannot grow on propionate even when supplemented with glutamate. The phenotype of this double mutant indicates that the aconitase enzymes are required for the 2-methylcitric acid cycle during propionate catabolism.
Aconitate Hydratase↗
The use of transgenic Trypanosoma brucei to identify compounds inducing the differentiation of bloodstream forms to procyclic forms.
The expression of procyclins is the earliest known marker of differentiation of bloodstream forms of Trypanosoma brucei to procyclic forms. We have generated transgenic bloodstream and procyclic forms in which the coding region of one procyclin gene was replaced by E. coli beta-glucuronidase (GUS). GUS activity can be monitored in a simple one-step colour reaction in microtitre plates; this assay is potentially suitable for large-scale screening for compounds that influence differentiation. GUS was stage-specifically expressed in procyclic forms and its synthesis occurred in parallel with that of procyclin when bloodstream forms were triggered to differentiate by the addition of cis-aconitate. GUS could also be induced by brief treatment with the proteases trypsin, pronase or thermolysin, but not with pepsin or thrombin. Interestingly, a combination of one of the active proteases with cis-aconitate resulted in increased GUS activity relative to either trigger alone. In contrast to cis-aconitate, protease treatment resulted in considerable cell death. Experiments with the pleomorphic strain AnTat 1.1 showed that long slender bloodstream forms were rapidly killed by proteases, whereas stumpy forms were largely resistant. Stumpy forms treated with trypsin differentiated synchronously and expressed procyclin with faster kinetics than when they were triggered by cis-aconitate. As predicted by the GUS assay, differentiation was even more rapid when both inducers were used simultaneously, with all cells expressing maximal levels of procyclin within 3 h.
Aconitic Acid↗
Arrow poisons in China. Part II. Aconitum--botany, chemistry, and pharmacology.
The botany of Chinese Aconitum species is briefly reviewed. Five species have been identified as sources of arrow poison: A. carmichaelii, A. nagarum, A. ouvrardianum, A. stylosum, and A. episcopale. The most important one, A. carmichaelii, has long served, together with A. kusnezoffii, as the main source of the Chinese medicinal aconite drugs--ts'ao wu (wu t'ou), the parent tuber, and fu tzu (ch 'uan wu), the daughter tuber. Two other aconite drugs have now been accepted into the Chinese materia medica: hsüeh shang i chih hao, from A. brachypodum, A. pendulum, and A. nagarum, and kuan pai fu, from A. coreanum. The folk-medicinal use of Aconitum species throughout China is also discussed. The alkaloid content and composition of Aconitum species known to occur in China are surveyed; and the effects of "processing", practised in order to diminish the toxicity of aconite drugs, are noted. Also the pharmacology of the aconites and their alkaloids is examined, in order to determine to what extent there may be a basis for the numerous medicinal properties attributed to the plants. Current understanding of the effectiveness of the drugs is incomplete and further study is required.
Aconitum↗
The transport of citrate and other tricarboxylic acids in two species of Pseudomonas.
When cells of Pseudomonas are grown on citrate as the sole carbon source they oxidize citrate and isocitrate rapidly. Fluorocitrate inhibits the oxidation of citrate. Fluorocitrate-treated cells accumulate [6-(14)C]citrate, as shown by a rapid Millipore-filtration technique. In the absence of fluorocitrate most of the [6-(14)C]-citrate is lost in the form of (14)CO(2). The isolation of a pseudomonad characterized by its ability to grow on tricarballylate as a sole carbon source has facilitated the study of the tricarboxylate-carrier specificity. Cells grown on citrate will exchange radioactive citrate for unlabelled citrate or isocitrate but not for cis-aconitate, trans-aconitate or tricarballylate. Cells grown on tricarballylate will exchange radioactive citrate for unlabelled citrate, cis-aconitate or tricarballylate, but not for isocitrate or trans-aconitate. The properties of the exchange system involved are compared with those of the related system in mitochondria.
Allyl Compounds↗
In vitro ruminal fermentation of organic acids common in forage.
Mixed rumen bacteria from cows fed either timothy hay or a 60% concentrate were incubated with 7.5 mM citrate, trans-aconitate, malate, malonate, quinate, and shikimate. Citrate, trans-aconitate, and malate were fermented at faster rates than malonate, quinate, and shikimate. Acetate was the primary fermentation product for all six acids. Quinate and shikimate fermentations gave rist to butyrate, whereas malate and malonate produced significant amounts of propionic acid. High-pressure liquid chromatography of fermentation products from trans-aconitate incubations revealed a compound that was subsequently identified as tricarballylate. As much as 40% of the trans-aconitate acid was converted to tricarballylate, and tricarballylate was fermented slowly. The slow rate of tricarballylate metabolism by mixed rumen bacteria and its potential as a magnesium chelator suggest that tricarballylate formation could be an important factor in the hypomagnesemia that leads to grass tetany.
Animals↗