The cyanogenic glucoside, prunasin (D-mandelonitrile-beta-D-glucoside), is a novel inhibitor of DNA polymerase beta.
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A DNA polymerase beta (pol. beta) inhibitor has been isolated independently from two organisms; a red perilla, Perilla frutescens, and a mugwort, Artemisia vulgaris. These molecules were determined by spectroscopic analyses to be the cyanogenic glucoside, D-mandelonitrile-beta-D-glucoside, prunasin. The compound inhibited the activity of rat pol. beta at 150 microM, but did not influence the activities of calf DNA polymerase alpha and plant DNA polymerases, human immunodefficiency virus type 1 reverse transcriptase, calf terminal deoxynucleotidyl transferase, or any prokaryotic DNA polymerases, or DNA and RNA metabolic enzymes examined. The compound dose-dependently inhibited pol. beta activity, the IC(50) value being 98 microM with poly dA/oligo dT(12-18) and dTTP as the DNA template and substrate, respectively. Inhibition of pol. beta by the compound was competitive with the substrate, dTTP. The inhibition was enhanced in the presence of fatty acid, and the IC(50) value decreased to approximately 40 microM. In the presence of C(10)-decanoic acid, the K(i) value for substrate dTTP decreased by 28-fold, suggesting that the fatty acid allowed easier access of the compound to the substrate-binding site. (+info)
Inhibitory effect of Artemisia asiatica alkaloids on acetylcholinesterase activity from rat PC12 cells.
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We screened 42 Korean traditional tea plants to determine the inhibitory effect of acetylcholinesterase and attenuation of toxicity induced by amyloid-beta peptide, which were related to the treatment of Alzheimer's disease (AD). The methanolic extract from Artemisia asiatica among tested 42 tea plants, showed the highest inhibitory effect (48%) on acetylcholinesterase in vitro. The methanolic extract was further separated with n-hexane, chloroform, and ethyl acetate of water, in order. The chloroform solubles, which were high in inhibitory effect of acetylcholinesterase, were repeatedly subjected to open column chromatography on silica gel. From the highest inhibitory fraction (78%) on acetylcholinesterase, the single compound was obtained by the Sep-Pak Cartridge (C18: reverse phase column). This compound was found to react positively on Dragendorff's reagent (potassium bismuth iodide), which typically reacted with the alkaloid. This compound was purified by HPLC (mu-bondapack C18 reverse phase column: 3.9 x 150 mm). The IC50 (the concentration of 50% enzyme inhibition) value of this compound was 23 micrograms/ml and the inhibitory pattern on acetylcholinesterase was mixed with competitive/non-competitive type. We examined the effects of this compound on toxicity induced by A beta (25-35) in rat pheochromocytoma PC12 cells. Pretreatment of the PC12 cells for 2 h with an alkaloid of Artemisia asiatica (1200 microg/ml) reduced the toxicity induced by A beta. This study demonstrated that an alkaloid of Artemisia asiatica, which was metabolized to small molecule in digestive tract and then could pass through the blood-brain barrier, appeared to be an acetylcholinesterase inhibitor with a blocker of neurotoxicity induced by A beta in human brain causing Alzheimer's disease. (+info)
Host-plant diversity of the European corn borer Ostrinia nubilalis: what value for sustainable transgenic insecticidal Bt maize?
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The strategies proposed for delaying the development of resistance to the Bacillus thuringiensis toxins produced by transgenic maize require high levels of gene flow between individuals feeding on transgenic and refuge plants. The European corn borer Ostrinia nubilalis (Hubner) may be found on several host plants, which may act as natural refuges. The genetic variability of samples collected on sagebrush (Artemisia sp.), hop (Humulus lupulus L.) and maize (Zea mays L.) was studied by comparing the allozyme frequencies for six polymorphic loci. We found a high level of gene flow within and between samples collected on the same host plant. The level of gene flow between the sagebrush and hop insect samples appeared to be sufficiently high for these populations to be considered a single genetic panmictic unit. Conversely, the samples collected on maize were genetically different from those collected on sagebrush and hop. Three of the six loci considered displayed greater between-host-plant than within-host-plant differentiation in comparisons of the group of samples collected on sagebrush or hop with the group of samples collected on maize. This indicates that either there is genetic isolation of the insects feeding on maize or that there is host-plant divergent selection at these three loci or at linked loci. These results have important implications for the potential sustainability of transgenic insecticidal maize. (+info)
Triterpenes and lignans from Artemisia caruifolia and their cytotoxic effects on meth-A and LLC tumor cell lines.
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One new triterpene, 3beta-hydroxy-29-norcycloart-24-one (1), and four new lignans, caruilignans (2-5), together with six known compounds were isolated from the aerial part of Artemisia caruifolia BUCH.-HAM. ex TOXB. Their structures were determined by various spectroscopic means. Most of the isolated lignans were moderately cytotoxic to Meth-A cells with ED50 values of 5-10 microg/ml, but not to Lowis lung carcinoma (LLC) cells. An oxime derivative of 1 showed more potent cytotoxic activity against Meth-A and LLC cells than the original triterpene 1. (+info)
Inhibitory effects on HIV-1 protease of tri-p-coumaroylspermidine from Artemisia caruifolia and related amides.
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From a methanol extract of Artemisia caruifolia, which showed a moderate inhibitory activity on HIV-1 protease in a preliminary screening, N1,N5,N10-tri-p-coumaroylspermidine and three dicaffeoylquinic acids were isolated. The former compound was found to appreciably inhibit HIV-1 protease. Of related amides which were chemically synthesized, N1,N5,N10,N14-tetra-p-coumaroylspermine and N1,N4,N7,N10,N13-penta-p-coumaroylte-traethylenepentamine inhibited HIV-1 protease more potently than N1,N5,N10-tri-p-coumaroylspermidine. (+info)
Antioxidant properties of natural compounds used in popular medicine for gastric ulcers.
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There is evidence concerning the participation of reactive oxygen species in the etiology and physiopathology of human diseases, such as neurodegenerative disorders, inflammation, viral infections, autoimmune pathologies, and digestive system disorders such as gastrointestinal inflammation and gastric ulcer. The role of these reactive oxygen species in several diseases and the potential antioxidant protective effect of natural compounds on affected tissues are topics of high current interest. To consider a natural compound or a drug as an antioxidant substance it is necessary to investigate its antioxidant properties in vitro and then to evaluate its antioxidant functions in biological systems. In this review article, we shall consider the role of natural antioxidants derived from popular plants to reduce or prevent the oxidative stress in gastric ulcer induced by ethanol. (+info)
Fusion of farnesyldiphosphate synthase and epi-aristolochene synthase, a sesquiterpene cyclase involved in capsidiol biosynthesis in Nicotiana tabacum.
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A clone encoding farnesyl diphosphate synthase (FPPS) was obtained by PCR from a cDNA library made from young leaves of Artemisia annua. A cDNA clone encoding the tobacco epi-aristolochene synthase (eAS) was kindly supplied by J. Chappell (University of Kentucky, Lexington, KY, USA). Two fusions were constructed, i.e. FPPS/eAS and eAS/FPPS. The stop codon of the N-terminal enzyme was removed and replaced by a short peptide (Gly-Ser-Gly) to introduce a linker between the two ORFs. These two fusions and the two single cDNA clones were separately introduced into a bacterial expression vector (pET32). Escherichia coli was transformed with the expression vectors and enzymatically active soluble proteins were obtained after induction with isopropyl thio-beta-d-thiogalactoside. The recombinant enzymes were purified using immobilized metal affinity chromatography on Co2+ columns. The fusion enzymes produced epi-aristolochene from isopentenyl diphosphate through a coupled reaction. The Km values of FPPS and eAS for isopentenyl diphosphate and farnesyl diphosphate, respectively, were essentially the same for the single and fused enzymes. The bifunctional enzymes showed a more efficient conversion of isopentenyl diphosphate to epi-aristolochene than the corresponding amount of single enzymes. (+info)
Influence of macronutrients and activated charcoal on intake of sagebrush by sheep and goats.
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We determined if supplemental macronutrients or activated charcoal influenced intake of sagebrush, a shrub that contains terpenes. Sheep (lambs 3 mo age, 33 kg) and goats (kids 5 mo age, 28 kg) were fed supplements high in energy, high in protein, or offered a choice between the two supplements before and after receiving sagebrush for 4 h/d. The effect of activated charcoal, a compound that reduces bioavailability of toxins, was assessed by offering charcoal mixed with a carrier or the carrier alone while animals consumed sagebrush for 4 h/d. The effects of supplemental macronutirents were tested before and after charcoal supplementation. Activated charcoal did not increase intake of sagebrush by sheep or goats (P > 0.05), but supplemental macronutrients influenced intake of sagebrush by both species (P < 0.05). Intake of sage-brush was markedly higher for animals fed the high-protein supplement than for animals fed the high-energy supplement (P < 0.05). Lambs (before and after charcoal supplementation) and kids (after charcoal supplementation) offered a choice between the two supplements used sagebrush at levels comparable to animals supplemented with protein. They consumed more CP than animals fed the high-energy supplement and more ME than lambs fed the high-protein supplement (P < 0.05). Thus, providing a choice between supplements enhanced intake of sagebrush and enabled animals to achieve a more balanced intake of macronutrients. Preference for supplement and sagebrush also depended on an animal's immediate past history with a supplement. Sheep and goats previously fed the high-energy or the high-protein supplement preferred, respectively, the high-protein or the high-energy supplement when given a choice (P < 0.05). The changes in preference for supplement caused a decreased intake of sagebrush by groups that preferred the energy concentrate, and an increased intake of sagebrush by groups that preferred the protein concentrate. Thus, supplements of different energy and protein densities consistently altered intake of sagebrush by sheep and goats. (+info)