Panax notoginseng for Cerebral Ischemia: A Systematic Review.

Panax notoginseng is the most widely used Chinese medicinal herb for the prevention and treatment of ischemic diseases. Its main active ingredients are saponins, including ginsenoside Rb1, ginsenoside Rg1, and notoginsenoside R1, among others. This review provides an up-to-date overview on the pharmacological roles of P. notoginseng constituents in cerebral ischemia. The saponins of P. notoginseng induce a variety of pharmacological effects in the multiscale mechanisms of cerebral ischemic pathophysiology, including anti-inflammatory activity, reduction of oxidative stress, anti-apoptosis, inhibition of amino acid excitotoxicity, reduction of intracellular calcium overload, protection of mitochondria, repairing the blood-brain barrier, and facilitation of cell regeneration. Regarding cell regeneration, P. notoginseng not only promotes the proliferation and differentiation of neural stem cells, but also protects neurons, endothelial cells and astrocytes in cerebral ischemia. In conclusion, P. notoginseng may treat cerebrovascular diseases through multiple pharmacological effects, and the most critical ones need further investigation.

Chirality-Selected Chemical Modulation of Amyloid Aggregation.

Due to the composed α-helical/ß-strand structures, ß-amyloid peptide (Aß) is sensitive to chiral environments. The orientation and chirality of the Aß strand strongly influence its aggregation. Aß-formed fibrils have a cascade of chirality. Therefore, for selectively targeting amyloid aggregates, chirality preference can be one key issue. Inspired by the natural stereoselectivity and the ß-sheet structure, herein, we synthesized a series of d- and l-amino acid-modified polyoxometalate (POM) derivatives, including positively charged amino acids (d-His and l-His) and negatively charged (d-Glu and l-Glu) and hydrophobic amino acids (d-Leu, l-Leu, d-Phe, and l-Phe), to modulate Aß aggregation. Intriguingly, Phe-modified POMs showed a stronger inhibition effect than other amino acid-modified POMs, as evidenced by multiple biophysical and spectral assays, including fluorescence, circular dichroism, NMR, molecular dynamic simulations, and isothermal titration calorimetry. More importantly, d-Phe-modified POM had an 8-fold stronger inhibition effect than l-Phe-modified POM, indicating high enantioselectivity. Furthermore, in vivo studies demonstrated that the chiral POM derivatives crossed the blood-brain barrier, extended the life span of AD transgenic Caenorhabditis elegans CL2006 strain, and had low cytotoxicity, even at a high dosage.

Acute hyperammonaemia induces a sustained decrease in vigilance, which is modulated by caffeine.

UNLABELLED: Hyperammonaemia is observed after prolonged, intense exercise, or in patients with hepatic failure. In the latter, it is associated with a set of neurological and psychiatric abnormalities termed hepatic encephalopathy. THE AIMS OF OUR STUDY WERE: 1. to measure vigilance in a condition of induced hyperammonaemia; 2. to assess whether caffeine modulates the effects of hyperammonaemia on vigilance, if any. Ten healthy volunteers (28.5 ± 5 years; 5 males) underwent three experimental sessions consisting of two-hourly measurements of capillary ammonia, subjective sleepiness (Karolinska Sleepiness Scale) and vigilance (Psychomotor Vigilance Task, PVT), in relation to the intake of breakfast (+/-coffee), an amino acid mixture which induces hyperammonaemia (amino acid challenge; AAC), and AAC+coffee (only for participants who had coffee with their standard breakfast). The AAC resulted in: 1. the expected increase in capillary ammonia levels, with highest values at approximately 4 h after the administration; 2. a significant increase in subjective sleepiness ratings; 3. a sustained increase in PVT-based reaction times. When caffeine was administered after the AAC, both subjective sleepiness and the slowing in RTs were significantly milder than in the AAC-only condition. In conclusion, acute hyperammonaemia induces an increase in subjective sleepiness and a sustained decrease in vigilance, which are attenuated by the administration of a single espresso coffee.

Safety assessment of animal- and plant-derived amino acids as used in cosmetics.

The Cosmetic Ingredient Review Expert Panel (Panel) reviewed the safety of animal- and plant-derived amino acid mixtures, which function as skin and hair conditioning agents. The safety of α-amino acids as direct food additives has been well established, based on extensive research through acute and chronic dietary exposures and the Panel previously has reviewed the safety of individual α-amino acids in cosmetics. The Panel focused its review on dermal irritation and sensitization data relevant to the use of these ingredients in topical cosmetics. The Panel concluded that these 21 ingredients are safe in the present practices of use and concentration as used in cosmetics.

Persistent fibrosis in the liver of choline-deficient and iron-supplemented L-amino acid-defined diet-induced nonalcoholic steatohepatitis rat due to continuing oxidative stress after choline supplementation.

Nonalcoholic steatohepatitis (NASH) is characterized by combined pathology of steatosis, lobular inflammation, fibrosis, and hepatocellular degeneration, with systemic symptoms of diabetes or hyperlipidemia, all in the absence of alcohol abuse. Given the therapeutic importance and conflicting findings regarding the potential for healing the histopathologic features of NASH in humans, particularly fibrosis, we investigated the reversibility of NASH-related findings in Wistar rats fed a choline-deficient and iron-supplemented l-amino acid-defined (CDAA) diet for 12weeks, with a recovery period of 7weeks, during which the diets were switched to a choline-sufficient and iron-supplemented l-amino acid-defined (CSAA) one. Analysis showed that steatosis and inflammation were significantly resolved by the end of the recovery period, along with decreases in AST and ALT activities within 4weeks. In contrast, fibrosis remained even after the recovery period, to an extent similar to that in continuously CDAA-fed animals. Real-time reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemical investigations revealed that expression of some factors indicating oxidative stress (CYP2E1, 4-HNE, and iNOS) were elevated, whereas catalase and SOD1 were decreased, and a hypoxic state and CD34-positive neovascularization were evident even after the recovery period, although the fibrogenesis pathway by activated α-SMA-positive hepatic stellate cells via TGF-ß and TIMPs decreased to the CSAA group level. In conclusion, persistent fibrosis was noted after the recovery period of 7weeks, possibly due to sustained hypoxia and oxidative stress supposedly caused by capillarization. Otherwise, histopathological features of steatosis and inflammation, as well as serum AST and ALT activities, were recovered.

Type-3 metabotropic glutamate receptors regulate chemoresistance in glioma stem cells, and their levels are inversely related to survival in patients with malignant gliomas.

Drug treatment of malignant gliomas is limited by the intrinsic resistance of glioma stem cells (GSCs) to chemotherapy. GSCs isolated from human glioblastoma multiforme (GBM) expressed metabotropic glutamate receptors (mGlu3 receptors). The DNA-alkylating agent, temozolomide, killed GSCs only if mGlu3 receptors were knocked down or pharmacologically inhibited. In contrast, mGlu3 receptor blockade did not affect the action of paclitaxel, etoposide, cis-platinum, and irinotecan. mGlu3 receptor blockade enabled temozolomide toxicity by inhibiting a phosphatidylinositol-3-kinase/nuclear factor-κB pathway that supports the expression of O(6)-methylguanine-DNA methyltransferase (MGMT), an enzyme that confers resistance against DNA-alkylating agents. In mice implanted with GSCs into the brain, temozolomide combined with mGlu3 receptor blockade substantially reduced tumor growth. Finally, 87 patients with GBM undergoing surgery followed by adjuvant chemotherapy with temozolomide survived for longer time if tumor cells expressed low levels of mGlu3 receptors. In addition, the methylation state of the MGMT gene promoter in tumor extracts influenced survival only in those patients with low expression of mGlu3 receptors in the tumor. These data encourage the use of mGlu3 receptor antagonists as add-on drugs in the treatment of GBM, and suggest that the transcript of mGlu3 receptors should be measured in tumor specimens for a correct prediction of patients' survival in response to temozolomide treatment.

Synthesis of a new trifluoromethylketone analogue of l-arginine and contrasting inhibitory activity against human arginase I and histone deacetylase 8.

As part of our continuing search for new amino acid inhibitors of metalloenzymes, we now report the synthesis and biological evaluation of the trifluoromethylketone analogue of L-arginine, (S)-2-amino-8,8,8-trifluoro-7-oxo-octanoic acid (10). While this novel amino acid was initially designed as a potential inhibitor of human arginase I, it exhibits no measurable inhibitory activity against this enzyme. Surprisingly, however, 10 is a potent inhibitor of human histone deacetylase 8, with IC(50)=1.5 ± 0.2 µM. Additionally, 10 weakly inhibits the related bacterial enzyme, acetylpolyamine amidohydrolase, with IC(50)=110 ± 30 µM. The lack of inhibitory activity against human arginase I may result from unfavorable interactions of the bulky trifluoromethyl group of 10 in the constricted active site. Since the active site of histone deacetylase 8 is less constricted, we hypothesize that it accommodates 10 as the gem-diol, which mimics the tetrahedral intermediate and its flanking transition states in catalysis. Therefore, we suggest that 10 represents a new lead in the design of an amino acid or peptide-based inhibitor of histone deacetylases with simpler structure than previously studied trifluoromethylketones.

Toxicity of non-protein amino acids to humans and domestic animals.

Non-protein amino acids are common in plants and are present in widely consumed animal feeds and human foods such as alfalfa (Medicago sativa), which contains canavanine, and lentil (Lens culinaris), which contains homoarginine. Some occur in wild species that are inadvertently harvested with crop species. Some non-protein amino acids and metabolites can be toxic to humans, e.g. Lathyrus species contain a neurotoxic oxalyl-amino acid. Some potential toxins may be passed along a food chain via animal intermediates. The increased interest in herbal medicines in the Western countries will increase exposure to such compounds.

Prolonged maternal amino acid infusion in late-gestation pregnant sheep increases fetal amino acid oxidation.

Protein supplementation during human pregnancy does not improve fetal growth and may increase small-for-gestational-age birth rates and mortality. To define possible mechanisms, sheep with twin pregnancies were infused with amino acids (AA group, n = 7) or saline (C group, n = 4) for 4 days during late gestation. In the AA group, fetal plasma leucine, isoleucine, valine, and lysine concentrations were increased (P < 0.05), and threonine was decreased (P < 0.05). In the AA group, fetal arterial pH (7.365 +/- 0.007 day 0 vs. 7.336 +/- 0.012 day 4, P < 0.005), hemoglobin-oxygen saturation (46.2 +/- 2.6 vs. 37.8 +/- 3.6%, P < 0.005), and total oxygen content (3.17 +/- 0.17 vs. 2.49 +/- 0.20 mmol/l, P < 0.0001) were decreased on day 4 compared with day 0. Fetal leucine disposal did not change (9.22 +/- 0.73 vs. 8.09 +/- 0.63 micromol x min(-1) x kg(-1), AA vs. C), but the rate of leucine oxidation increased 43% in the AA group (2.63 +/- 0.16 vs. 1.84 +/- 0.24 micromol x min(-1) x kg(-1), P < 0.05). Fetal oxygen utilization tended to be increased in the AA group (327 +/- 23 vs. 250 +/- 29 micromol x min(-1) x kg(-1), P = 0.06). Rates of leucine incorporation into fetal protein (5.19 +/- 0.97 vs. 5.47 +/- 0.89 micromol x min(-1) x kg(-1), AA vs. C), release from protein breakdown (4.20 +/- 0.95 vs. 4.62 +/- 0.74 micromol x min(-1) x kg(-1)), and protein accretion (1.00 +/- 0.30 vs. 0.85 +/- 0.25 micromol x min(-1) x kg(-1)) did not change. Consistent with these data, there was no change in the fetal skeletal muscle ubiquitin ligases MaFBx1 or MuRF1 or in the protein synthesis regulators 4E-BP1, eEF2, eIF2alpha, and p70(S6K). Decreased concentrations of certain essential amino acids, increased amino acid oxidation, fetal acidosis, and fetal hypoxia are possible mechanisms to explain fetal toxicity during maternal amino acid supplementation.

Grass roots chemistry: meta-tyrosine, an herbicidal nonprotein amino acid.

Fine fescue grasses displace neighboring plants by depositing large quantities of an aqueous phytotoxic root exudate in the soil rhizosphere. Via activity-guided fractionation, we have isolated and identified the nonprotein amino acid m-tyrosine as the major active component. m-Tyrosine is significantly more phytotoxic than its structural isomers o- and p-tyrosine. We show that m-tyrosine exposure results in growth inhibition for a wide range of plant species and propose that the release of this nonprotein amino acid interferes with root development of competing plants. Acid hydrolysis of total root protein from Arabidopsis thaliana showed incorporation of m-tyrosine, suggesting this as a possible mechanism of phytotoxicity. m-Tyrosine inhibition of A. thaliana root growth is counteracted by exogenous addition of protein amino acids, with phenylalanine having the most significant effect. The discovery of m-tyrosine, as well as a further understanding of its mode(s) of action, could lead to the development of biorational approaches to weed control.

A heretofore undisclosed crux of eosinophilia-myalgia syndrome: compromised histamine degradation.

In contrast to early epidemiological evidence offering links between eosinophilia-myalgia syndrome (EMS) and microimpurities of L-tryptophan-containing dietary supplements (LTCDS), this account shows why reliance on a finite impurity from one manufacturer is both unnecessary and insufficient to explain the etiology of EMS. Excessive histamine activity has induced blood eosinophilia and myalgia (Greek: mys, muscle + algos, pain). Termination of the multiple actions of histamine is dependent on particular amine oxidases and histamine-N-methyltransferase. Histamine metabolism is rapid when these degradative reactions are operative. The latent effects of incurred histamine can be potentiated and aggravating when these mechanisms are impaired. Overloads of tryptophan supplements cause - among other relevant side-effects - an increased formation of formate and indolyl metabolites, several of which inhibit the degradation of histamine. Moreover, (non-EMS) subjects with hypothalamic-pituitary- adrenal (HPA) axis dysregulation have also manifested greatly increased sensitivities to incurred tryptophan and histamine. A final common pathway for syndromes characterized by eosinophilia with myalgia is now evident.

Nutritionally regulated hormonal factors in prolonged postnatal growth retardation and its associated adverse neurodevelopmental outcome in extreme prematurity.

Recent published data show that at hospital discharge, most infants born at <30 weeks of gestation would not achieve the median birth weight of the reference fetus at the same postconceptional age, and many would be less than the 10th centile. Estimating from the current recommendations of calorie and protein intakes, these infants accrue large deficits in intakes of protein and calorie during the first weeks of life. Postnatal growth retardation over a prolonged period of time is related to neurodevelopmental delays. While a total energy intake of 120 kcal/kg/day has generally been considered adequate, protein requirement in low gestation infants remains a matter for debate. Increasing the dietary protein:calorie ratio has previously been proposed as a strategy to enhance growth and to achieve a body composition similar to that of the reference fetus. Previous study data reveal that serum insulin-like growth factor I (IGF-I) concentration is positively correlated with protein intake, and nitrogen retention, in turn, is positively correlated with serum IGF-I concentration. Remarkably, elevated serum growth hormone but low serum IGF-I concentrations have been reported in low gestation infants and in infants with intrauterine growth retardation, suggesting IGF-I being a nutritionally regulated hormonal factor in the postnatal growth retardation. As neurodevelopment in extreme prematurity is likely affected by multiple factors, we hypothesize that a combined strategy of the previously proposed hormonal supplement with hydrocortisone and tri-iodothyronine together with increased dietary protein intake (progressively increasing from 1.5 g/kg/day intravenously administered amino acids immediately after birth, then 3.6 g/100 kcal at approximately 125 kcal/kg/day when enterally fed till the infant reaches a body weight of >or=1.8 kg and at >or=50th centile weight of the reference fetus at the same postconceptional age) would likely be synergistic and more effective in improving neurodevelopmental outcome.

Nonprotein amino acids of plants: significance in medicine, nutrition, and agriculture.

Those nonprotein amino acids found in food and fodder plants and known to be toxic to man and domestic animals are described. These include toxins from many legume genera including Lathyrus, from other higher plant families, from seaweeds, and from fungi. Some inhibit protein synthesis, while others are incorporated into proteins with toxic effects. Basic processes such as urea synthesis and neurotransmission may be disrupted. The probable roles of nonprotein amino acids in protecting plants against predators, pathogens, and competing plant species are considered. The need to learn more of the nutritive value of nontoxic nonprotein amino acids and to explore the potential of others either as drugs or as leads to drugs in human and veterinary medicine is emphasized.

The Arabidopsis-accelerated cell death gene ACD2 encodes red chlorophyll catabolite reductase and suppresses the spread of disease symptoms.

accelerated cell death 2 (acd2) mutants of Arabidopsis have spontaneous spreading cell death lesions and constitutive activation of defenses in the absence of pathogen infection. Lesion formation in acd2 plants can be triggered by the bacterial toxin coronatine through a light-dependent process. Coronatine-triggered and spontaneous lesion spreading in acd2 plants also requires protein translation, indicating that cell death occurs by an active process. We have cloned the ACD2 gene; its predicted product shows significant and extensive similarity to red chlorophyll catabolite reductase, which catalyzes one step in the breakdown of the porphyrin component of chlorophyll [Wüthrich, K. L., Bovet, L., Hunziger, P. E., Donnison, I. S. & Hörtensteiner, S. (2000) Plant J. 21, 189-198]. Consistent with this, ACD2 protein contains a predicted chloroplast transit peptide, is processed in vivo, and purifies with the chloroplast fraction in subcellular fractionation experiments. At some stages of development, ACD2 protein also purifies with the mitochondrial fraction. We hypothesize that cell death in acd2 plants is caused by the accumulation of chlorophyll breakdown products. Such catabolites might be specific triggers for cell death or they might induce cellular damage through their ability to absorb light and emit electrons that generate free radicals. In response to infection by Pseudomonas syringae, transgenic plants expressing excess ACD2 protein show reduced disease symptoms but not reduced growth of bacteria. Thus, breakdown products of chlorophyll may act to amplify the symptoms of disease, including cell death and yellowing. We suggest that economically important plants overexpressing ACD2 might also show increased tolerance to pathogens and might be useful for increasing crop yields.

In vitro effect of glutathione precursors on cytotoxicity of amino acids to human mesothelial cells.

Amino acids (AA) which were proposed as an alternative osmotically active agents in dialysates are toxic to human peritoneal mesothelial cells (HPMC) due to disturbance of the antioxidant-oxidant balance in cells by reducing level of glutathione. We assessed if the addition intracellular glutathione precursors: N-acetyl-cysteine (NAC), tioproline (TP), L--2-oxo--4-thiazolidine acid (PC), and glutathione (GSH) could reduce the cytotoxicity of AA, as measured by inhibition of cells proliferation and disorders of intracellular 86Rb transport. HPMC were obtained from omentum from nonuremic donors and cultured in in vitro conditions. The HPMC proliferation capacity was assessed indirectly by the 3H-methyl-thymidine incorporation assay. The injury to HPMC membrane integrity was assessed by the release of radioisotope molecules of 86Rb from the prelabelled cells. We have found that AA diminished the intracellular potassium (86Rb) influx. Supplementation of AA mixture with NAC enhanced the total 86Rb influx into HMC. Other precursors of intracellular glutathione (TP,PC,GSH) tested in the presence of AA significantly stimulated intracellular transport of 86Rb via Na,K-ATPase dependent channel, but the total intracellular transport of 86Rb was still lower than in control. HMC proliferation was significantly inhibited by AA what was measured by incorporation of H-metyl-tymidine. In the presence of NAC inhibition of HMC proliferation caused by AA was weaker. Our results suggest that some of intracellular glutathione precursors may reduce the disturbances of the HMC function caused by AA.

Developmental toxicity of metal chelating agents.

Chelation therapy is the basis for the treatment of metal poisoning. A number of chelating agents have been widely used since the 1950s. Since these agents can be potentially given to a metal-intoxicated pregnant woman, their intrinsic developmental toxicities are a matter of concern. While the embryo/fetal toxic effects of some chelators have been reported to occur at doses higher than those currently given in the medical treatment of metal poisoning, according to experimental data the potential use of other metal antidotes is controversial. In those cases, the benefits and risks of usage should be carefully weighed. The developmental toxicity of known chelators of clinical interest is presented here. Chelating agents were divided according to the following structurally related categories: polyaminocarboxylic acids, chelators with vicinal -SH groups, beta-mercapto-alpha-aminoacids, hydroxamic acids, ortho-hydroxycarboxylic acids, and miscellaneous agents. Since it has been demonstrated that the teratogenic potential of most chelators is, at least in part, due to induced trace element deficiencies, the advisability of mineral supplements during chelation treatment is also discussed.

[A new class-III antiarrhythmic preparation among the dicyclohexylamides of aminocarboxylic acids]. / Novyi antiaritmicheskii preparat III klassa sredi ditsiklogeksilamidov aminokarbonovykh kislot.

The Institute of Pharmacology, Academy of Medical Sciences, jointly with AWD (Germany) has synthesized and tested a novel class III antiarrhythmic coded AWD-160-275, a derivative of dicyclohexylamides of aminocarboxylic acids. The compound was shown to prolong cardiac repolarization, to increase atrial and ventricular refractory periods, to decrease sinus nodal automatism, and to unchange intraventricular conduction. The compound proved to be superior to the reference drugs in the rate and duration of antiarrhythmic and antifibrillatory action. In therapeutical doses it has no antiarrhythmic effect. The specific feature of the agent is that there is no relation of longer effective refractory periods to the frequency of stimulation. This property may be useful in treating tachyarrhythmias.

Dietary N-3 fatty acids inhibit ischaemic and excitotoxic brain damage in the rat.

Arachidonic acid [20:4(N-6)] has been implicated in neurological damage induced by cerebral ischaemia. Membrane arachidonate concentrations can be reduced by changes in dietary fat intake. Therefore, in the present study, we have investigated the effects of N-3 fatty acid supplementation on neuronal damage induced by permanent focal cerebral ischaemia or pharmacological activation of striatal NMDA receptors. Weanling rats were fed either a control diet or an N-3 supplemented diet (1.75% by weight as N-3 fatty acids) for 6 weeks. N-3-supplemented animals reduced ischaemic damage following middle cerebral artery occlusion (36%, p < 0.05), and excitotoxic damage induced by infusion of the selective NMDA agonist (1-aminocyclobutane-cis-1,3-dicarboxylic acid, 43%, p < 0.001) compared to the control-fed group. These data are consistent with the proposed role of arachidonic acid in ischaemic and excitotoxic brain damage, and suggest that modest dietary supplementation with N-3 fatty acids may offer benefit to populations at high risk of stroke.

Differential activation and survival of basal forebrain neurons following infusions of excitatory amino acids: studies with the immediate early gene c-fos.

These experiments investigated, by studying patterns of c-fos expression, the distribution of neurons activated or destroyed by the infusion into the basal forebrain of various excitatory amino acids at toxic and subtoxic doses. The results of experiment 1 showed that N-methyl-D-aspartic acid (NMDA), quisqualic acid and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) differentially increased the expression of c-fos in magnocellular cholinergic nucleus basalis, dorsal and ventral pallidal neurons. AMPA was the most, and NMDA the least, effective in inducing FOS in nucleus basalis magnocellularis (nbM) neurons, with quisqualic acid having an intermediate effect, whereas the reverse was true in terms of the induction of FOS in pallidal neurons. In experiment 2, it was demonstrated that, in animals with ibotenic acid-induced lesions of the basal forebrain that were targetted on the nbM, virtually no pallidal neurons could be visualized that expressed FOS following AMPA-induced excitation of the dorsal and ventral striatum. By contrast, in animals with AMPA-induced lesions of the nbM, excitation of the striatum was followed by the expression of FOS in many dorsal and ventral pallidal neurons. Thus, infusions of AMPA into the basal forebrain appears preferentially to activate or destroy, depending on the concentration infused, cholinergic nbM neurons, whereas ibotenic acid or NMDA preferentially destroys or activates neurons of the dorsal and ventral pallidum. These results provide novel and complementary information regarding the organization of the basal forebrain and allow a clearer understanding of the different behavioural consequences of NMDA agonist-induced and non-NMDA agonist-induced excito-toxic lesions of this area.