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PubMed2002

Oxidative status and distribution of NADP-dependent isocitrate dehydrogenase and aconitate hydratase in rat cardiomyocytes under normal conditions and during ischemia.

Oxidative status of rat cardiomyocytes during ischemia induced by occlusion of the descending branch of the coronary artery was studied by the methods of Fe-induced chemiluminescence and spectrophotometry of primary and secondary lipid peroxidation product. The concentrations of low-molecular-weight antioxidants a-tocopherol and citrate and activities of NADP-dependent isocitrate dehydrogenase (EC 1.1.1.41) and aconitate hydratase (EC 4.2.1.3) were also measured. Ischemia was associated with intensification of free radical processes, increased antioxidant activity in subcellular fractions of the myocardium, activation of NADP-isocitrate dehydrogenase, accumulation of citrate, and inhibition of aconitate hydratase. Differential centrifugation, ion exchange chromatography on various ion exchangers, and electrophoresis in polyacrylamide gel revealed no redistribution of enzyme activity between the cytoplasmic and mitochondrial cardiomyocyte fractions during ischemia.

Aconitate Hydratase↗

PubMed2004

Free radical oxidation and catalytic activity of aconitate hydratase in rat liver under normal conditions and during toxic hepatitis.

We observed intensification of free radical oxidation, decrease in activity, and changes in catalytic properties of aconitate hydratase in the liver of rats with toxic hepatitis. The total yield and maximum flash intensity of biochemiluminescence increased by 2.2 and 1.7 times, respectively. Differences were revealed in the regulation of aconitate hydratase activity with Fe(2+), Ca(2+), H(2)O(2), and oxidized and reduced glutathione in the liver of rats with toxic hepatitis and control animals.

Aconitate Hydratase↗

PubMed2005

Allelopathic effects of aconitic acid on wild poinsettia (Euphorbia heterophylla) and morningglory (Ipomoea grandifolia).

High infestations of alexandergrass (Brachiaria plantaginea) in experimental area have reduced seedbank of some weed species in soil at a greater degree compared to those obtained with the use of an efficient herbicide. Aconitic acid (AA) has been identified in those plants in high concentration. Thus, two experiments were carried out in the laboratory to determine the effects of pure AA on weed seed germination and on endophytic fungi in wild poinsettia (Euphorbia heterophylla) and morningglory (Ipomoea grandifolia) weed species. Doses of AA (0, 0.5, 1.0, and 2.0 mM) were introduced in agar-water 0.5% medium and weed seeds treated with and without external sterilization by sodium hypochloride. Four replications of fifty seeds of each species by treatment were sown in plastic boxes with cover and maintained in germination chamber for 12 days. Reduction in germination rate, root and stem growth were observed in both species, as well as reduction in root number in morningglory were also observed at 2.0 mM concentration of AA. An increase in number of seeds with presence of endophytic fungi was also observed in both species, independently of seed sterilization, mainly of a green type fungi coloration in wild poinsettia. Aconitic acid presents allelopathic activity and can stimulate endophytic fungi species growth in weed seeds.

Aconitic Acid↗

PubMed1977

The structure and function of ribonuclease T1. XXIII. Inactivation of ribonuclease T1 by reversible blocking of amino groups with cis-aconitic anhydride and related dicarboxylic acid anhydrides.

Ribonuclease T1 [EC 3.1.4.8] was inactivated rapidly by treatment at pH 8.0 and 0 degrees C with cis-aconitic anhydride and related dicabroxylic acid anhydrides, including citraconic, maleic, and succinic anhydrides. Under reaction conditions used, roughly 90% inactivation occurred within 30 min. Analyses of the inactivated enzymes indicated that the reaction took place fairly specifically at the alpha-amino group of the N-terminal alanine and the epsilon-amino group of lysine-41. Upon incubation of these inactivated enzymes at pH 3.6 and 37 degreeC, the activity was regenerated to various extents, depending on the nature of the introduced acyl groups. Under these conditions, the enzyme modified with cis-aconitc anhydride or citraconic anhydride recovered much of the origninal activity after 48 h whereas the enzyme modified with maleic anhydride recovered its activity only partially. Practically no activity was regenerated in the case of the enzyme modified with succinic anhydride under these conditions. The inactivation appears to be due mainly to the effect of the carboxyl group introduced at the epsilon-amino group of lysine-41. The results suggest the usefulness of cis-aconitic anhydride as a reversible blocking reagent for amino groups in proteins.

Aconitic Acid↗

PubMedDate not supplied

[Catalytic properties of cytoplasmic and mitochondrial aconitate hydratase from rat cardiomyocytes].

Enzymatic activity of aconitate hydratase (aconitase, EC 4.2.1.3) from the rat heart is localized in the cytoplasm (65%) and mitochondria (35%). Cytoplasmic and mitochondrial forms of aconitate hydratase were separated by ion-exchange chromatography on CM-Cellulose and CM-Sephadex. The two forms have similar molecular weight, optimal pH range, and spectral properties; however, they have different chromatography properties, Km for citrate and isocitrate, as well as sensitivity to Fe2+ ions.

Aconitate Hydratase↗

PubMedDate not supplied

[Effect of gamma-aminobutyric shunt metabolites on NAD-, NADP-isocitrate dehydrogenases, and aconitate hydratase activities in higher plants].

We studied the influence of metabolites of gamma-aminobutyric shunt of the tricarboxylic acid cycle on the activities of aconitate hydratase (EC.4.2.1.3) as well as NAD- and NADP-specific isocitrate dehydrogenases (EC.1.1.1.41 and EC.1.1.1.42, respectively) using purified enzyme preparations from pea leaves (Pisum sativum L.) and maize scutellum (Zea mays L.). gamma-Aminobutyric acid and succinate proved to have no significant effect on these enzymes, while 0.1-0.2 mM glutamate considerably activated NADP isocitrate dehydrogenase from the both sources, particularly, at unsaturating concentration of the substrate. Succinic semialdehyde stimulated the activities of aconitate hydratase and NADP isocitrate dehydrogenase. The obtained data points to a similar pattern of the effect of intermediates of gamma-aminobutyric shunt on the studied enzymatic activities for both photosynthetic tissues (pea leaves) and those with acidifying, transport, and digestive functions (maize scutellum). However, the absence of pronounced control effects of most metabolites on the studied enzymes allows us to assign them to a relatively inert pool of metabolites.

Aconitate Hydratase↗

PubMed1985

Effect of iron on the activity of aconitate hydratase and synthesis of citric acid by Aspergillus niger.

Two strains of A. niger were cultivated on beet molasses medium by the surface method, and the effects of iron on the mycelium formation, the rate of sugar utilization, the activity of aconitate hydratase, and synthesis of citric acid were determined. Among various sources of di- and trivalent iron, ferrous sulphate was chosen for studies, which most effectively limited the synthesis of organic iron, ferrous sulphate was chosen for studies, which most effectively limited the synthesis of organic acids. The molasses solutions were purified with potassium ferrocyanide and FeSO4 at a concentration of 20 mg/100 ml (in terms of Fe2+) was added. It was found in both strains that such an amount of Fe2+, additionally introduced into the molasses medium, only slightly effected the synthesis of the mycelium biomass and the rate and extent of sugar utilization, when at the same time a high increase in the activity of aconitate hydratase occurred. Citric acid production, however, was strongly inhibited by this Fe2+-concentration in case of A. niger 23 (about 94%), whereas A. niger Lcz showed a relatively small decrease (about 20%).

Aconitate Hydratase↗

PubMed1976

Effect of acetic and trans-aconitic acids on citric acid production by Aspergillus niger.

The effect of acetic and trans-aconitic acids on citric acid production by A. niger at different pH values was studied. The presence of acetic acid at pH 2 prevented spore germination, while it decreased the fungal growth and citric acid production at other pH values. In the presence of trans-aconitic acid the inhibition was less marked at lower than at higher pH values.

Acetates↗

PubMedDate not supplied

Developmental changes of rat liver cytoplasmic and mitochondrial aconitate hydratases.

The developmental patterns of the activity of cytoplasmic and mitochondrial aconitate hydratses of rat liver have been studied. Both activities are low in foetal liver, with respect to adult levels, and begin to increase after birth. The activity of the mitochondrial enzyme reaches a maximum about two days after birth, then decreasing gradually to adult level. The activity of the cytoplasmic enzyme reaches its maximum level, nearly equal to adult level, about ten days after birth. The developmental pattern of the activity of the cytoplasmic aconitate hydratase may suggest a possible role of this enzyme in gluconeogenesis.

Aconitate Hydratase↗

PubMedDate not supplied

Quantification of Aconitum alkaloids in aconite roots by a modified RP-HPLC method.

The three Aconitum alkaloids, aconitine (1), mesaconitine (2) and hypaconitine (3), are pharmacologically active but also highly toxic. A standardised method is needed for assessing the levels of these alkaloids in aconite roots in order to ensure the safe use of these plant materials as medicinal herbs. By optimising extraction, separation and measurement conditions, a reliable, reproducible and accurate method for the quantitative determination of all three Aconitum alkaloids in unprocessed and processed aconite roots has been developed. This method should be appropriate for use in the quality control of Aconitum products. The three Aconitum alkaloids were separated by a modified HPLC method employing a C18 column gradient eluted with acetonitrile and ammonium bicarbonate buffer. Quantification of Aconitum alkaloids, detected at 240 nm, in different batches of samples showed that the content of 1, 2 and 3 varied significantly. In general, the alkaloid content of unprocessed roots was higher than that of processed roots. These variations were considered to be the result of differences in species, processing methods and places of origin of the samples.

Aconitine↗

PubMed2006

Differentiation of three pairs of aconite alkaloid isomers from Aconitum nagarum var. lasiandrum by electrospray ionization tandem mass spectrometry.

Three pairs of isomers of aconite alkaloids from Aconitum nagarum var. lasiandrum have been investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) employing ion-trap and quadrupole time-of-flight mass spectrometers in positive mode. Based on the differences of their fragmentation pathways and special fragment ions, three pairs of isomers of aconite alkaloids were differentiated. In addition, fragmentation laws of some veatchines and the discrepancy of fragmentation mechanisms between veatchine-type and aconitine-type alkaloid were also concluded. In the case of veatchines, a radical would be formed by homolysis of C18--C4 or C18--H bonds, followed by elimination of a series of C(2)H(2) and C(2)H(4). Moreover, the retro-Diels-Alder (RDA) reaction occurred in the E-ring and double-electron transfer triggered by the positive charge on C1 led to the formation of diagnostic ions at m/z 216. With regard to aconitine-type alkaloids, the N-substituent is not eliminated easily. Although there is no carbonyl group on some aconitine-type alkaloids, with hydroxyl and methoxyl on C15 and C16 respectively, CO was readily eliminated through tautomerization.

Aconitum↗

PubMed1992

Aconite: a lethal Chinese herb.

Physicians and the public often assume that herbal preparations are harmless. Aconite is a Chinese herb used as an analgesic by homeopaths; its chief effects are on the cardiovascular and central nervous systems. The first two reported cases of aconite poisoning in Australia are described.

Aconitum↗

PubMed2000

Counter effects of higenamine and coryneine, components of aconite root, on acetylcholine release from motor nerve terminal in mice.

The counter effects of higenamine and coryneine, components of aconite root, on acetylcholine (ACh) release from motor nerve terminals in the mouse phrenic nerve-diaphragm muscle preparation were studied by a radioisotope method. Both nerve-evoked release and spontaneous release of [3H]-ACh from the preparation preloaded with [3H]-choline were measured. The change in the tetanic tension of muscle was simultaneously recorded in the same preparation. Higenamine (10 microM) augmented both the nerve-evoked and spontaneous ACh releases, and the muscle tension. The effects were inhibited by pretreatment with propranolol (10 microM), a beta-adrenoceptor antagonist. Coryneine reduced the nerve-evoked release of ACh, accelerated the decay of tetanic tension (tetanic fade) at 30 microM, and it depressed the peak amplitude of tetanic tension at a higher concentration of 100 microM. These results suggest that of the two components contained in aconite root, higenamine increases ACh release via activation of beta-adrenoceptor, and conversely coryneine depresses ACh release by preferentially acting at motor nerve terminal.

Acetylcholine↗

PubMed1992

Bidirectional tachycardia induced by herbal aconite poisoning.

This report details the clinical, electrocardiographic, and electropharmacological characteristics of an unusual case of bidirectional tachycardia induced by aconites present in a Chinese herbal decoction consumed by a previously healthy subject. The tachycardia showed marked susceptibility to vagotonic maneuvers, cholinesterase inhibition, and adenosine triphosphate. The incessant nature of the tachycardia, rapid recurrence after transient suppression, and failure to respond to direct current cardioversion suggested an automatic tachycardia mechanism consistent with known data on the cellular electrophysiological mechanism of aconitine-mediated arrhythmogenesis. A fascicular or ventricular myocardial origin of the tachycardia with alternating activation patterns, or dual foci with alternate discharge, appeared most plausible. The rootstocks of aconitum plants have been commonly employed in traditional Chinese herbal recipes for "cardiotonic" actions and for relieving "rheumatism." Multiple pitfalls could occur during the processing of these herbs that might have predisposed to aconite poisoning. The need for strict control and surveillance of herbal substances with low margins of safety is highlighted.

Aconitum↗

PubMed2002

Purification and characterization of cis-aconitic acid decarboxylase from Aspergillus terreus TN484-M1.

cis-Aconitic acid decarboxylase (CAD) was assumed to be a key enzyme in the production of itaconic acid by comparing the activity of CAD from Aspergillus terreus TN484-M1 with that of CAD from the low-itaconate yielding strain Aspergillus terreus CM85J. The constitutive CAD was purified to homogeneity from A. terreus TN484-M1 by ammonium sulfate fractionation, and column chromatography on DEAE-toyopearl, Butyl-toyopearl, and Sephacryl S200HR, and then characterized. A molecular mass of 55 kDa for the native enzyme was determined by SDS-PAGE. The enzymic activity was optimal at a pH of 6.2 and temperature of 45 degrees C. The K(m) value for cis-aconitic acid was determined as 2.45 mM (pH 6.2, 37 degrees C). The enzyme was completely inactivated by Hg+, Cu2+, Zn2+, p-chloromercuribenzoate, and 5,5'-dithio-bis(2-nitrobenzoate).

Journal Article↗

PubMed1990

[Homicidal poisoning by aconite: report of a case from the viewpoint of clinical forensic medicine].

A case of homicidal poisoning by aconite is reported from the viewpoint of clinical forensic medicine and analytical chemistry. Jesaconitine was detected in the vomitus, stomach contents, plasma and urine at concentrations of 32.2, 5.48, 0.433 and 1.07 micrograms/ml, respectively. The total amount of jesaconitine in the stomach contents was 1.3 mg. Macroscopic autopsy revealed hemorrhagic pulmonary edema, and histologically, diffuse contraction-band necrosis was evident in the myocardium. Exogenous administration of adrenaline or endogenous release of catecholamines are known to induce hemorrhagic pulmonary edema and contraction-band necrosis, and aconitine is reported to cause release of endogenous catecholamines centrally and to induce neurogenic pulmonary edema and ventricular-type arrhythmia. Therefore, the chief cause of death in this case was considered to be aconite-induced centrogenic arrhythmia.

Aconitum↗

PubMed1990

[Determination of alkaloids in Aconite roots by HPLC].

Three alkaloids contained in Aconite roots, aconitine, mesaconitine and hypaconitine, were determined by HPLC. 15 samples (8 species) of Aconite roots were analysed. The results reveal that most of them contain the three alkaloids in different contents, and some of them contain one or two alkaloids.

Aconitine↗

PubMed1984

pH profiles and isotope effects for aconitases from Saccharomycopsis lipolytica, beef heart, and beef liver. alpha-Methyl-cis-aconitate and threo-Ds-alpha-methylisocitrate as substrates.

alpha-Methyl-cis-aconitate (cis-2-butene-1,2,3-tricarboxylate) was converted only to alpha-methylisocitrate (3-hydroxybutane-1,2,3-tricarboxylate) by aconitases from beef liver or S. lipolytica. While the kinetic parameters of beef liver (cytoplasmic) or heart (mitochondrial) aconitases did not vary over the pH range 4.9-9 with the natural substrates, and only slightly with the alpha-methyl substrates, the yeast aconitase exhibited a bell-shaped pH profile with all substrates and for binding of the competitive inhibitor, tricarballylate, with pK values around 7 and 9. The third pK of the substrates does not affect V/K, showing that these pK's are for catalytic groups on the enzyme. One of these catalytic groups presumably removes a proton to give the carbanion intermediate in the reaction, and the other protonates the hydroxyl group when it is eliminated to give water, possibly with the assistance of the Fe-S center. Beef liver aconitase showed a primary deuterium isotope effect of 1.12 (measured by equilibrium perturbation with deuterated alpha-methylisocitrate) which was pH independent and only slightly greater than the equilibrium isotope effect. Isotope effects with the yeast enzyme were also pH independent but about 1.22 on V/K (or when measured by equilibrium perturbation) and 1.7 on V. These data suggest a kinetic mechanism for beef aconitases in which product release occurs only by displacement by the substrate in a step independent of pH or of the protonation state of the substrate. With the yeast enzyme, product displacement either depends on the protonation state of the catalytic groups on the enzyme or can occur spontaneously at a finite rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aconitate Hydratase↗