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PubMed1998

Structure-dependent inhibitory action of the Aconitum alkaloids 14-benzoyltalitasamine and talitasamine in rat hippocampal slices.

In the present study the effects of the two Aconitum alkaloids 14-benzoyltalitasamine and talitasamine on neuronal activity were investigated in order to obtain further insight into structure-dependent effects of this group of alkaloids on central nervous activity. Both alkaloids are closely related to aconitine, the main alkaloid of plants of Aconitum species. However, they have shortened side chains at position C3 and C8 of the molecule. The experiments were performed as extracellular recordings of orthodromically and antidromically evoked population spikes as well as of field excitatory potentials (EPSPs) from the CA1 region of rat hippocampal slices. 14-Benzoyltalitasamine exerted a reversible inhibition of the field potentials in a concentration-dependent manner. The orthodromic population spike was attenuated at concentrations higher than 1 microM, while the field EPSP was already affected at a concentration of at least 0.3 microM. Both responses were completely blocked at a concentration of 30 microM. The alkaloid failed to affect the presynaptic fiber spike at concentrations less than 10 microM. There was only a up to 30% decrease in the antidromic population spike (10-100 microM). The inhibition of the antidromic spike was increased by using a higher stimulus frequency. In contrast to 14-benzoyltalitasamine, the alkaloid talitasamine which is lacking the benzoylester side chain was a less effective inhibitor of the orthodromic population spike and even failed to affect the antidromic spike. Furthermore, the effects of the alkaloids on experimentally induced epileptiform activity was examined. While talitasamine was lacking any significant effect at concentrations less than 100 microM, 14-benzoyltalitasamine reversibly reduced both stimulus-triggered epileptiform activity in area CA1 elicited by omission of Mg2+ from the bathing medium as well as spontaneously occurring epileptiform activity in CA3 elicited by omission of Mg2+ and elevation of K+ to 5 or 8 mM. The antiepileptiform efficacy of this compound was concentration-dependent (0.3-10 microM) and manifested itself as a decrease in burst frequency as well as in burst amplitude and was significantly increased by the higher K+ concentration.

Aconitine↗
PubMed2004

Transformation of opium poppy (Papaver somniferum L.) with antisense berberine bridge enzyme gene (anti-bbe) via somatic embryogenesis results in an altered ratio of alkaloids in latex but not in roots.

The berberine bridge enzyme cDNA bbe from Papaver somniferum L. was transformed in antisense orientation into seedling explants of the industrial elite line C048-6-14-64. In this way, 84 phenotypically normal To plants derived from embryogenic callus cultures were produced. The selfed progeny of these 84 plants yielded several T1 plants with an altered alkaloid profile. One of these plants T1-47, and its siblings T2-1.2 and T2-1.5 are the subject of the present work. The transformation of these plants was evaluated by PCR, and northern and Southern hybridisation. The transgenic plants contained one additional copy of the transgene. The alkaloid content in latex and roots was determined with HPLC and LC-MS. We observed an increased concentration of several pathway intermediates from all biosynthetic branches, e.g., reticuline, laudanine, laudanosine, dehydroreticuline, salutaridine and (S)-scoulerine. The transformation altered the ratio of morphinan and tetrahydrobenzylisoquinoline alkaloids in latex but not the benzophenanthridine alkaloids in roots. The altered alkaloid profile is heritable at least to the T2 generation. These results are the first example of metabolic engineering of the alkaloid pathways in opium poppy and, to our knowledge, the first time that an alkaloid biosynthetic gene has been transformed into the native species, followed by regeneration into a mature plant to enable analyses of the effect of the transgene on metabolism over several generations.

Agrobacterium tumefaciens↗
PubMed1983

Interaction of bovine glutamate dehydrogenase with isoquinoline alkaloids.

Representatives of four different classes of isoquinoline alkaloids (aporphines, benzylisoquinolines, tetrahydroisoquinolines, and phthalideisoquinolines) inhibit glutamate dehydrogenase activity in both reaction directions. Representatives of five other groups of isoquinoline alkaloids have been without any significant effect on this enzyme. The structural requirements for the interaction of alkaloids with glutamate dehydrogenase and alcohol dehydrogenase are different. From the analysis of inhibition and from fluorescence-polarization data it follows that for an efficient binding of these alkaloids to glutamate dehydrogenase the presence of coenzyme is necessary. The effects of substrates on the interaction of the enzyme with alkaloids are small. Experiments with other ligands of glutamate dehydrogenase have been done to locate the binding site of the enzyme for alkaloids. The observed kinetic competition of isoquinoline alkaloids with thyroxine might indicate common or overlapping binding sites of glutamate dehydrogenase for these compounds.

Alkaloids↗
PubMed1995

The effect of the pyrrolizidine alkaloids, monocrotaline and trichodesmine, on tissue pyrrole binding and glutathione metabolism in the rat.

One day after in vivo administration of equitoxic doses of the hepatotoxic and pneumotoxic pyrrolizidine alkaloid, monocrotaline (65 mg/kg, i. p.) or the related hepatotoxic and neurotoxic alkaloid trichodesmine (15 mg/kg, i. p.) hepatic GSH levels are increased by more than 50%. These doses of alkaloids represent 60% of the LD50 values. Accompanying these changes in GSH levels is an increase in the overall rate of GSH synthesis in supernatants of alkaloid-exposed livers. The ability of the rat to metabolize the two alkaloids was shown by the appearance of tissuebound pyrrolic metabolites of pyrrolizidines in various organs. The levels of these metabolites appear to correlate with organ toxicity. For the hepatic and pneumotoxic alkaloid, monocrotaline, higher levels are found in liver (17 nmoles/g tissue) and lung (10 nmoles/g) than for trichodesmine (7 nmoles/g and 8 nmoles/g, respectively). For the neurotoxic alkaloid, trichodesmine, higher levels are found in brain (3.8 nmoles/g tissue) than for monocrotaline (1.7 nmoles/g tissue).

Alkaloids↗
PubMed1982

Pharmacological effects of Synclisia scabrida alkaloid B on some isolated muscle preparations.

Alkaloid B reversibly blocked the responses of rat diaphragm to electrically induced stimulations via the phrenic nerve. The alkaloid had no effect on the responses of the diaphragm elicited by direct electrical stimulation. The responses of frog rectus abdominis muscle to acetylcholine were inhibited by alkaloid B. Alkaloid B reversibly antagonised the responses of rabbit duodenum to exogenously applied acetylcholine. The contractile effect of oxytocin on rat uterus was specifically inhibited by alkaloid B. The effects of alkaloid B on isolated muscle preparations were concentration-dependent. However, the effect of dopamine and noradrenaline on rat vas deferens was not altered by alkaloid B.

Alkaloids↗
PubMed1990

Quantitative estimation of Holarrhena antidysenterica bark total alkaloids in crude drugs and in the body fluids of man and rat.

A turbidimetric method was developed for the quantitative estimation of the total alkaloids of kutaj bark (Holarrhena antidysenterica) in crude medicinal preparations and in the body fluids of man and rat. The alkaloids were colloidally precipitated with Dragendorff's reagent as complex salts of potassium iodobismuthate in extremely dilute solutions. The finely subdivided orange-brown precipitate gave a coloured, clear homogeneous suspension in the presence of gum arabic. Optical density of such suspensions changed linearly with the change in alkaloid concentration, when prepared within the standardized experimental conditions that included control of ion concentration and temperature of the reaction mixture. Observations revealed the reversible nature of the alkaloid-reagent reaction. Crude medicinal preparations from three different pharmaceutical sources contained varying concentrations of the alkaloids. Complete recovery of the alkaloids was possible from plasma and urine, while significant amounts of the alkaloids were lost to blood cells and faecal contents in man and rat.

Alkaloids↗
PubMed1990

Myopathy in cattle induced by alkaloid extracts from Thermopsis montanta, Laburnum anagyroides and a Lupinus sp.

A purified alkaloid preparation containing N-methylcytisine, cytisine, 5,6-dehydrolupanine, thermopsine and anagyrine from Thermopsis montana induced prolonged recumbency and microscopic acute hyaline skeletal myodegeneration with myofibre regeneration in cattle similar in type and severity to that induced by Thermopsis montanta plant material. This indicates that the alkaloid(s) of Thermopsis montana are responsible for the myopathy caused by the plant. An alkaloid preparation containing mostly anagyrine from a Lupinus sp. and an alkaloid preparation containing only cytisine from Laburnum anagyroides each caused microscopic skeletal muscle degeneration and necrosis similar to, but less severe than, the alkaloid extract from T. montana, but without clinical recumbency. Dosage and severity of response suggest that neither of those two alkaloids alone can account for the effects induced by Thermopsis. The data suggest that quinolizidine alkaloids with a alpha-pyridone A-ring may be responsible for the lesions and that individual alpha-pyridones may have additive effects.

Alkaloids↗
PubMed2002

Quantitative analysis of tropane alkaloids in biological materials by gas chromatography-mass spectrometry.

A simple and rapid method for quantitation of tropane alkaloids in biological materials has been developed using an Extrelut column with gas chromatography-mass spectrometry (GC-MS). Biological materials (serum and urine) were mixed with a borate buffer and then applied to an Extrelut column. The adsorbed tropane alkaloids were eluted with dichloromethane before a GC-MS analysis. Atropine-d(3) was used as an internal standard. The extracted tropane alkaloids were converted to trimethylsilyl derivatives prior to GC analysis, to improve the instability of tropane alkaloids from heating and the property of them for a GC column. The recoveries of the compounds, which had been spiked to biological materials, were more than 80%. The GC separation of the derivatives from endogenous impurities was generally satisfactory with the use of a semi-polar capillary column. Tropane alkaloids showed excellent linearity in the range of 10-5000 ng/ml and the limit of detection was 5.0 ng/ml for biological materials. The present method is simple and more rapid than those previously reported, and was applied to a poisoning case. It is useful for the routine analysis of tropane alkaloids in cases of suspected tropane alkaloids poisoning.

Aged↗
PubMed2005

Pyrrolizidine alkaloids of Echium vulgare honey found in pure pollen.

The pyrrolizidine alkaloids previously identified in floral honey attributed to Echium vulgare (Boraginaceae) have been detected (8000-14 000 ppm) in pure pollen collected from the anthers of Echium vulgare. Pyrrolizidine alkaloids and/or their N-oxides were isolated from the aqueous acid extracts of pollen by use of strong cation-exchange, solid-phase extraction and identified by liquid chromatographic/mass spectrometric (LCMS) analysis. The pyrrolizidine alkaloids in the pollen are present mainly as the N-oxides. In addition to seven previously described pyrrolizidine alkaloids and/or their N-oxides (echimidine, acetylechimidine, uplandicine, 9-O-angelylretronecine, echiuplatine, leptanthine, and echimiplatine), one unidentified (echivulgarine), but previously found in honey, and two previously undescribed (vulgarine and 7-O-acetylvulgarine) pyrrolizidine alkaloids and/or their N-oxides were identified in the pollen. Tentative structures for these unidentified pyrrolizidine alkaloids are proposed on the basis of the mass spectrometric data and biogenetic considerations. The implications of these results for identifying the source and subsequent concentrations of pyrrolizidine alkaloids in honeys and commercial bee pollen are briefly discussed.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Antimicrobially active alkaloids from Tabernaemontana chippii.

From Tabernaemontana chippii root bark, forty-five alkaloids were isolated; thirty-four were fully characterized by means of their spectral data and/or co-tlc; eight alkaloids were new, four of them being 3-hydroxy derivatives of known dimeric voacamine type alkaloids. Most of the twenty-six known alkaloids belonged to the corynanthean, ibogan, or bisindole classes. The structures of eleven other alkaloids--all minor--were only partially elucidated, most of them being new alkaloids. All the dimeric alkaloids were shown to possess strong antimicrobial activity against gram-positive bacteria and moderate to weak activity against gram-negative bacteria.

Alkaloids↗
PubMedDate not supplied

Estimated intakes of pyrrolizidine alkaloids by humans. A comparison with dose rates causing tumors in rats.

Pyrrolizidine alkaloid poisoning in humans is associated with the consumption of plants containing the alkaloids, either as contaminants of grains or as infusions for medicinal purposes. The alkaloids are carcinogenic in rats but have not been associated, so far, with tumors in humans. For the known instances of human intake of pyrrolizidine alkaloids, the main alkaloids involved and estimated consumption rates have been tabulated. These rates are compared with the dose rates of the same or similar alkaloids that lead to a significant tumor incidence in experimental rats. In the more chronic poisoning outbreaks, the intake rate is comparable with a carcinogenic dose in rats. The long-term observation of survivors of these outbreaks would offer an opportunity for determining whether pyrrolizidine alkaloids are carcinogenic in humans.

Adult↗
PubMed2005

Overexpression of tropinone reductases alters alkaloid composition in Atropa belladonna root cultures.

The medicinally applied tropane alkaloids hyoscyamine and scopolamine are produced in Atropa belladonna L. and in a small number of other Solanaceae. Calystegines are nortropane alkaloids that derive from a branching point in the tropane alkaloid biosynthetic pathway. In A. belladonna root cultures, calystegine molar concentration is 2-fold higher than that of hyoscyamine and scopolamine. In this study, two tropinone reductases forming a branching point in the tropane alkaloid biosynthesis were overexpressed in A. belladonna. Root culture lines with strong overexpression of the transcripts contained more enzyme activity of the respective reductase and enhanced enzyme products, tropine or pseudotropine. High pseudotropine led to an increased accumulation of calystegines in the roots. Strong expression of the tropine-forming reductase was accompanied by 3-fold more hyoscyamine and 5-fold more scopolamine compared with control roots, and calystegine levels were decreased by 30-90% of control. In some of the transformed root cultures, an increase of total tropane alkaloids was observed. Thus, transformation with cDNA of tropinone reductases successfully altered the ratio of tropine-derived alkaloids versus pseudotropine-derived alkaloids.

Alcohol Oxidoreductases↗
PubMed2006

Overexpression of Coptis japonica norcoclaurine 6-O-methyltransferase overcomes the rate-limiting step in Benzylisoquinoline alkaloid biosynthesis in cultured Eschscholzia californica.

Benzylisoquinoline alkaloids are one of the most important secondary metabolite groups, and include the economically important analgesic morphine and the antimicrobial agent berberine. To improve the production of these alkaloids, we investigated the effect of the overexpression of putative rate-limiting step enzymes in benzylisoquinoline alkaloid biosynthesis. We introduced two O-methyltransferase [Coptis japonica norcoclaurine 6-O-methyltransferase (6OMT) and 3'-hydroxy-N-methylcoclaurine 4'-O-methyltransferase (4'OMT)] expression vectors into cultured California poppy cells to avoid the gene silencing effect of endogenous genes. We established 20 independent lines for 6OMT transformants and 15 independent lines for 4'OMT transformants. HPLC/liquid chromatography-mass spectrometry (LC-MS) analysis revealed that the overexpression of C. japonica 6OMT was associated with an average alkaloid content 7.5 times greater than that in the wild type, whereas the overexpression of C. japonica 4'OMT had only a marginal effect. Further characterization of 6OMT in California poppy cells indicated that a 6OMT-specific gene is missing and 4OMT catalyzes the 6OMT reaction with low activity in California poppy, which supports the notion that the 6OMT reaction is important for alkaloid biosynthesis in this plant species. We discuss the importance of 6OMT in benzylisoquinoline alkaloid biosynthesis and the potential for using a rate-limiting step gene to improve alkaloid production.

Alkaloids↗
PubMed1992

Effects of antibacterial agents on in vitro ovine ruminal biotransformation of the hepatotoxic pyrrolizidine alkaloid jacobine.

Ingestion of pyrrolizidine alkaloids, naturally occurring plant toxins, causes illness and death in a number of animal species. Senecio jacobaea pyrrolizidine alkaloids cause significant economic losses due to livestock poisoning, particularly in the Pacific Northwest. Some sheep are resistant to pyrrolizidine alkaloid poisoning, because ovine ruminal biotransformation detoxifies free pyrrolizidine alkaloids in digesta. Antibacterial agents modify ruminal fermentation. Pretreatment with antibacterial agents may account for some animal variability in resistance to pyrrolizidine alkaloid toxicosis, and antibacterial agents can also be used for characterizing ruminal pyrrolizidine alkaloid-biotransforming microflora. The objective of this study was to evaluate the effects of antibacterial agents on biotransformation of a predominant S. jacobaea pyrrolizidine alkaloid, jacobine, in ovine ruminal contents. Ovine ruminal jacobine biotransformation was tested in vitro with 20 independent antibacterial agents. Low amounts of rifampin and erythromycin prevented jacobine biotransformation. Chlortetracycline, lasalocid, monensin, penicillin G, and tetracycline were slightly less effective at inhibiting jacobine biotransformation. Bacitracin, crystal violet, kanamycin, and neomycin were moderately inhibitory against jacobine biotransformation. Brilliant green, chloramphenicol, gramicidin, nalidixic acid, polymyxin B SO4, sodium azide, streptomycin, sulfisoxazole, and vancomycin had little to no effect on jacobine biotransformation. The antibiotics that were most effective at inhibiting biotransformation were those that are active against gram-positive bacteria. Therefore, gram-positive bacteria are most likely critical members of the jacobine-biotransforming consortia.

Animals↗
PubMed1985

Measurement of potato steroidal alkaloids in human serum and saliva by radioimmunoassay.

Radioimmunoassay methods are described for measuring potentially toxic potato glycoalkaloids and the aglycone solanidine in human serum and saliva. Solanidine and total alkaloid concentrations in serum and saliva during the summer are given for a group of subjects from the UK and a group from Sweden. Serum concentrations ranged from 3.2 to greater than 125 nmol/l for total alkaloid and 2.5 to 92.5 nmol/l for solanidine and were comparable in the two populations. Salivary total alkaloid concentrations were only about 10% of serum values. Salivary solanidine concentrations did not exceed 20% of the serum levels. Good correlation was found between serum and salivary alkaloid concentrations (r = 0.734, for solanidine; r = 0.892 for total alkaloid). Serum and salivary alkaloid concentrations were significantly raised in a group of Swedish subjects eating potatoes containing unusually high concentrations of alkaloids when compared with those in a group of subjects eating their normal diets.

Adult↗
PubMed2000

The anti-ulcerogenic effect of an alkaloidal fraction from Mikania cordata on diclofenac sodium-induced gastrointestinal lesions in rats.

A decoction of Mikania cordata (Compositae) is commonly used for the treatment of gastric ulcer in the Rajbari district of Bangladesh. We have evaluated the anti-ulcerogenic effect of the alkaloidal fraction from the whole plant of M. cordata on diclofenac sodium-induced gastrointestinal lesion in rats. Long Evan's rats were divided into five groups. The control group was kept undisturbed. The vehicle group received vehicle after a 48-h fast. The diclofenac group received diclofenac sodium suspension (80 mg kg(-1)) after a 48-h fast. The diclofenac-ranitidine group (anti-ulcer drug used as a standard) received 35 mg kg(-1) ranitidine hydrochloride suspension 1 h after diclofenac sodium administration, after a 48-h fast. The diclofenac-extract group received alkaloidal fraction (50 mg kg(-1)) 1 h after diclofenac administration, after a 48-h fast. The biochemical, morphological and histological changes were studied. The data showed that the pH values of the stomach and duodenum were increased significantly (P < 0.001) in the alkaloidal-administered group compared with the control group (3.09 +/- 0.0429 vs 2.07 +/- 0.0339 and 6.79 +/- 0.1162 vs 6.19 +/- 0.1273, respectively). There were significant changes (P < 0.001) detected in the morphological study. The ulcer index of the stomach (0.268 +/- 0.0346) and of the duodenum (0.050 +/- 0.0129) in the alkaloidal-administered group were significantly lower than the diclofenac-only administered group (0.691 +/- 0.0184 and 0.0933 +/- 0.0138, respectively). According to the grading of tissue damage in the histological study, there were less or no lesions on the gastrointestinal mucosa of the alkaloidal-administered group compared with the diclofenac-only group (0 vs 5, respectively). When the results of the alkaloid extract group where compared with the ranitidine hydrochloride group a similar or more potent effect was observed with the alkaloidal extract group. The results of this study revealed that the bioactive principles of M. cordata have anti-ulcerogenic effects. The results validate the traditional use of this plant for the treatment of gastric ulcer in Bangladesh.

Alkaloids↗
PubMed1982

Antitumor activities of harringtonine and homoharringtonine, cephalotaxus alkaloids which are active principles from plant by intraperitoneal and oral administration.

Antitumor activities of harringtonine(HA) and homoharringtonine(HO) both belong to cephalotaxus alkaloids were compared with those of vinca alkaloids, vincristine (VCR) and vinblastine (VLB). HA and HO had significant activities against P388 leukemia, L1210 leukemia and B16 melanoma by intraperitoneal injection comparable to VCR and VLB. The therapeutic index (LD10/ED50) of HA and HO in B16 melanoma system was 1.90 and 2.31, while those of VCR and VLB were 1.38 and less than 1.00, respectively. The oral administration of these cephalotaxus alkaloids evoked a significant antitumor activity but that of vinca alkaloids induced no activity against P388 and B16 melanoma. The efficacy of HO on various tumor systems was equal or greater than that of HA when comparison was made between these two cephalotaxus alkaloids. In contrast to VCR and VLB, HA and HO demonstrated moderate activity against P388/VCR, a subline of P388 resistant to vincristine. The intraperitoneal injection of VCR or VLB produced an increase in the mitotic index of P388 cells as compared with the control values, but HA or HO decreased it. HA and HO, cephalotaxus alkaloids are a new class of active compounds of plant origin which may differ from the vinca alkaloids in the mechanism of antitumor activity.

Administration, Oral↗
PubMed2000

Application of liquid chromatography-atmospheric pressure chemical ionization mass spectrometry to the differentiation of stereoisomeric diterpenoid alkaloids.

High-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS) was successfully applied to seven stereoisomeric diterpenoid alkaloids at position 1 or 12. Comparison of the breakdown curves, observed by changing the potential difference between the first electrode and the second electrode of the APCI ion source, revealed stereochemical dependence of different fragmentations. The APCI spectra of alkaloids were predominantly the [M+H]+ ion and the major fragment ion, corresponding to the [M+H-H2O]+ ion or the [M+H-CH3COOH]+ ion, and comparison of the APCI spectra showed that the abundance of fragment ions was significantly higher for C-1 beta-form alkaloids than for C-1 alpha-form alkaloids, and for C-12 beta-form alkaloids than for C-12 alpha-form alkaloids. The characteristic fragment ions were formed due to the loss of an acetic acid or a water molecule at position 12. The fragmentation mechanisms depending on the stereochemistry of the precursor ion could be discerned by recording the spectra in a deuterated solvent system of 0.05 M ammonium acetate in D2O-acetonitrile-tetrahydrofuran. Loss of CH3COOD or D2O from the precursor ion gave the fragment ion. This result indicated that the proton of protonation was included in the leaving acetic acid and water molecule, respectively. The peak intensity ratio for R=[M+H]+/[M+ H-H2O]+ + [M + H-CH3COOH] + manifested the stereochemical differentiation of alkaloids at position 1 or 12.

Alkaloids↗