Effects of (±)-kavain on inactivation of voltage-operated Na+ channels

Effects of a kava-pyrone (±)-kavain on fast inactivation of Na⁺ channels were studied in experiments on isolated neurons from the rat hippocampus. (±)-Kavain was found to block Na⁺ channels, and its effect was voltage-dependent. At the holding potentials of –100 and –80 mV, IC₅₀ for (±)-kavain was 744.9 and 178.8 µM, respectively. The inactivation characteristic of Na⁺ channels was satisfactorily described with the Boltzmann's equation both in the control and under (±)-kavain application. (±)-Kavain at a 330 µM concentration shifted theV _1/2 toward more negative values by 14.4 mV and concurrently modified the slope factor: the latter was 5.7 mV in the control, while under the influence of 330 µM (±)-kavain it reached 6.7 mV. In agreement with Hille's hypothesis of a modulated receptor, inactivated Na⁺ channels demonstrated an increased sensitivity to kavain. (±)-Kavain effects resulted in an increase in the rate of depolarization-related fast inactivation, while the process of recovery from inactivation became slower when the membrane was hyperpolarized. Our data show that under the (±)-kavain effect the probability of the inactivated state of Na⁺ channels increases, and the state of fast inactivation is stabilized.Neirofiziologiya/Neurophysiology, Vol. 28, No. 4/5, pp. 218–224, July–October, 1996.     

Effect of β-Aminobutyrie Acid on Anthocyanin of Leaves of Arabidopsis thaliana (Cruciferae)

To analyze the effect of β aminobutyrie acid (BABA) on anthocyanin of leaves of Arabidopsis, 30 old plants were sprayed with BABA while the control were sprayed with water. After treated with BABA, the content of anthocyanin was significantly lower than that of control. Furthermore, the results from RT PCR showed that CHS, LDOX, UF3GT were down regulated compared with contro1, while PAL showed an opposite trend. At the same time, the activity of PPO, which played an important role in the degradation of anthocyanin, showed higher level than control. In addition, the antioxidant capacity, the death rate of cells and electrical conductivity of leaves were also decreased with BABA treatment. All results suggested that BABA might inhibit the accumulation of anthocyanin in leaves of Arabidopsis in vitro.     

Studies on the chemical constituents of Kalimeris indica(Ⅱ)

采用冷渗漉提取的方法提取马兰的化学成分.经硅胶柱色谱和Sephadex LH-20进行分离纯化,通过理化方法和波谱数据分析进行结构鉴定.从80%乙醇冷渗漉提取物的水不溶物中分离并鉴定了12个化合物,分别为正十六烷酸(1)、6-羟基-桉烷-4(14)-烯(2)、β-谷甾醇(3)、α-菠菜甾醇(4)、香草醛(5)、β-20(21),24-二烯-达玛烷-3-酮(6)、豆甾醇(7)、木栓酮(8)、羽扇豆酮(9)、α-香树脂醇(10)、表木栓醇(11)、神经酰胺(12).化合物2、6、9、12均为首次从该种植物中分得.     

Effects of fenvalerate on the net-spinning behaviour of Hydropsych siltalai (Döhler) (Trichoptera: Hydropsychidae)

The effects of fenvalerate exposure on the net-spinning behaviour of Hydropsyche siltalai were examined in a laboratory study. The larvae were exposed to nominal pulse-doses of 0.25 and 0.5 μg fenvalerate l-1. Nets were collected and examined for anomalies after four days of exposure to fenvalerate. Additional nets were collected after another four day of exposure. The fenvalerate dissipated rapidly from the water column, and since only two doses of fenvalerate were given, the larvae were exposed to two pulse-doses of fenvalerate rather than to a constant concentration. In the 0.5 μg l-1-treatment the net-spinning behaviour was significantly affected, expressed as an increased mesh-opening and a decreased symmetry of the nets. No significant effects of fenvalerate exposure on the net-spinning behaviour were detected in the 0.25 μg l-1-treatment. Thus, with the conditions given in this experiment, exposure to fenvalerate starts to affect the net-spinning behaviour of Hydropsyche siltalai at a concentration between 0.25 and 0.5 μg l-1. The use of net-anomalies and Hydropsyche as bioindicators for monitoring pollutants in stream ecosystems are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antimutagenic Effect of Amino Acids on the Mutagenicity of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG)

The antimutagenic activity of protein-constituting amino acids except histidine on the mutagenicity of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) was investigated in vitro using Salmonella typhinurium TA-100 as an indicator bacterium (Ames test), and concentrations (IC₅₀) of amino acids that inhibit 50% of the mutagenecity were measured. Cysteine was found to be most active and glycine, tryptophan, lysine, and arginine were strong antimutagenic amino acids. Other amino acids showed moderate or weak antimutagenic activities, depending on the amino acids. The results indicate that amino acids play a substantial role in chemoprevention of N-nitroso amine-induced mutagenicity.     

Effect of the alkaline cations on the stability of the model polynucleotide poly(dG-dC)·poly(dG-dC)

When the model polynucleotide poly(dG-dC)?poly(dG-dC) [polyGC] is titrated with a strong acid (HCl) in unbuffered aqueous solutions containing the chlorides of the alkali metals in the concentration range 0.010?M-0.600?M, two transitions in the absorbance vs. pH plots are evidenced, characterized by the constants pK(a(?)) and pK(a(?)). The limiting values at infinite saline concentrations of these two constants, namely pK(∞)(a(?)) and pK(∞)(a(?)) obtained making use of the "one site saturation constant" equation or, in turn, of the double logarithmic plot: pK(a) vs. log([salt]?1), exhibit a clear dependence on the nature of the cations. The effects of the different alkali cations on the pK(∞)(a) values follow the Hofmeister series. In fact, the pK(∞)(a(?)) and the pK(∞)(a(?)) values are smaller for Li+ and Na+ than for Rb+ and Cs+, with K+ at the border between the two, showing that the transitions require higher concentrations of protons to occur in the presence of high concentrations of the cosmotropic ions.     

Influence of Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) injury on the quality of cane juice

Mahanarva fimbriolata (St?l) is an important pest in Latin America and causes significant reduction in sugarcane productivity. There is no information regarding the effect of this pest on the quality of cane juice used for sugar and alcohol production. This work aimed at evaluating the quality of sugarcane juice from plants attacked by spittlebugs. The experiment was arranged in a completely randomized design with 15 replications, and comprised two treatments: control and chemical treatment with thiamethoxam. An average of 9.2 +/- 4.44 spittlebug nymphs m-1 were found in the plots prior to insecticide application. Nymphs were counted 18, 35, 55, and 82 days after the initial sampling (december/2003). During the mid growing season (July 2004), the juice was extracted from stalks and analyzed for Brix, Pol, RS, pH, fiber, purity, TRS, dextran, starch, and total phenolic compounds. Stalk yield was also measured. Chemical treatment was efficient in reducing spittlebug population, and elevated both stalk yield and juice pH. The accumulated infestation expressed as insect-days was significantly and negatively correlated to yield, Pol, pH, and purity. The concentration of phenolic compounds increased with pest infestation, while dextran and starch levels were not affected. The infestation of 2.4 and 7.3 nymphs m-1 day-1 caused reductions of 8.3% and 29.8% in yield; 1.9% and 5.8% in Pol; 0.4% and 1.1% in pH and 0.4% and 1.2% in purity, respectively, in comparison to areas where the pest population was extremely low (< 0.1 nymphs m-1).     

Immobilization of β-galactosidase (K. lactis) on solid phase Ni(II)-chelate

Summary Ni(II)-iminodiacetate-agarose achieved a near quantitative adsorption of -galactosidase (Kluyveromices lactis) with a yield of 96% of activity applied. A high percentage (90%) of -galactosidase activity was preserved after immobilization on the solid phase. The insoluble derivative could be used for lactose hydrolysis either in solution or in whey permeate.     

Effects of (±)-abscisin II on seed germination in four species of grasses

Summary Abscisin II (Ab II) inhibited germination of seeds of four species of grasses. The effects ranged from slight retardation of the onset of germination from the lowest concentration (0.1 mg/l) to complete inhibition throughout the 17-day test period from the highest concentration (10 mg/l). Intermediate concentrations induced some abnormalities of development.Seed viability was not destroyed even by the highest Ab II concentration applied, normal development and growth resuming when seeds were transferred from abscisin solutions to water.We are grateful to Dr. J. Van Overbeek for the (±)-abscisin II used in these experiments. It was synthesized by Shell Research, Ltd., Sittingbourne, Kent, England (Cornforth et al., 1965).     

Synthesis of (±)-Sundiversifolide Based on Lewis Acid-Mediated Claisen Rearrangement

A new and concise synthesis of (±)-sundiversifolide (1), an allelopathic bisnor-sesquiterpene lactone isolated from germinating sunflower (Helianthus annuus L.) seeds, was achieved by employing Lewis acid-mediated Claisen rearrangement as the key step.     

Effect of growth regulators on maturation of geranium (Pelargonium × hortorum) somatic embryos

Interactions of growth regulators and polyethylene glycol on maturation of geranium somatic embryos were investigated. Somatic embryos were induced on medium with 20 M thidiazuron for 3 days. The growth regulators used were 1 µM abscisic acid, jasmonic acid, napthaleneacetic acid and benzylaminopurine at 21 days from the start of induction. Benzylaminopurine and napthaleneacetic acid did not enhance abscisic acid effects on maturation frequency but only improved maturation frequency in the presence of polyethylene glycol. Abscisic acid significantly improved protein content in the presence of polyethylene glycol. Benzylaminopurine and napthalene acetic acid in combination with abscisic acid and jasmonic acid improved protein types in somatic embryos only in the absence of polyethylene glycol. Osmoticum effected by polyethylene glycol seems the main component required for protein synthesis. This study showed significant improvement of somatic embryo quality for artificial seed production.     

Studies on the UV spectrum of poly(γ-glutamic acid) based on development of a simple quantitative method

A simple and valid ultraviolet (UV) spectrophotometric method for the determination of poly(γ-glutamic acid) is developed. The method is based on the UV absorption spectrum of γ-PGA in aqueous solution, which exhibits a maximum absorption wavelength at 216 nm. The results obtained were comparable to those obtained with the reported high-performance liquid chromatography (HPLC) method according to ICH guidelines. Under the proposed procedure, the calibration graph is linear over the range of 20-200 μg/ml with regression correlation coefficient of 0.9997. Precision (%R.S.D.<1.50) and recovery (%R.>99.29%) are good. The limit of detection (LOD) and limit of quantitation (LOQ) are 0.39 and 1.19 μg/ml, respectively. These results agree well with those of HPLC method. Its spectrum properties studies showed that the spectrum of γ-PGA remarkably changed with an increase in temperature due to γ-PGA was digested into glutamate monomer. In spite of this, the determining procedure could carried out in a wide temperature range (25-50°C). In addition, the method is not influenced by the molecular weight, but the measurement system need to control in pH 3.0-10.0 and ionic strength not more than 0.5M. The proposed method is applied successfully for high-throughput quantification of poly(γ-glutamic acid) in biological samples. The advantages of the UV method are simplicity of operation, rapidity, sensitive, low-cost and high-throughput.     

Long-Term Effects of (–)-Epigallocatechin Gallate (EGCG) on Pristane-Induced Arthritis (PIA) in Female Dark Agouti Rats

Rheumatoid arthritis (RA)—a widespread chronic inflammatory disease in industrialized countries—is characterized by a persistent and progressive joint destruction. The chronic pro-inflammatory state results from a mutual activation of the innate and the adaptive immune system, while the exact pathogenesis mechanism is still under discussion. New data suggest a role of the innate immune system and especially polymorphonuclear granulocytes (PMNs, neutrophils) not only during onset and the destructive phase of RA but also at the chronification of the disease. Thereby the enzymatic activity of myeloperoxidase (MPO), a peroxidase strongly abundant in neutrophils, may be important: While its peroxidase activity is known to contribute to cartilage destruction at later stages of RA the almost MPO-specific oxidant hypochlorous acid (HOCl) is also discussed for certain anti-inflammatory effects. In this study we used pristane-induced arthritis (PIA) in Dark Agouti rats as a model for the chronic course of RA in man. We were able to shown that a specific detection of the HOCl-producing MPO activity provides a sensitive new marker to evaluate the actual systemic inflammatory status which is only partially detectable by the evaluation of clinical symptoms (joint swelling and redness measurements). Moreover, we evaluated the long-term pharmacological effect of the well-known anti-inflammatory flavonoid epigallocatechin gallate (EGCG). Thereby only upon early and continuous oral application of this polyphenol the arthritic symptoms were considerably diminished both in the acute and in the chronic phase of the disease. The obtained results were comparable to the treatment control (application of methotrexate, MTX). As revealed by stopped-flow kinetic measurements, EGCG may regenerate the HOCl-production of MPO which is known to be impaired at chronic inflammatory diseases like RA. It can be speculated that this MPO activity-promoting effect of EGCG may contribute to the pharmacological mode of action of this polyphenol.

Highlights

• Epigallocatechin gallate (EGCG), upon early and continuous oral application, considerably attenuates the symptoms in Dark Agouti rats with pristane-induced arthritis (PIA)
• Arthritic symptoms are not only dampened in the acute but also in the chronic phase of the disease, which means a lower risk for the development of chronic recurring joint inflammation
• The therapeutic effect is comparable to the early injection of methotrexate (MTX) and is not observed upon late oral application or injection of EGCG
• Stopped-flow kinetic measurements show that epigallocatechin (EGC) derived from EGCG exhibits a considerable activity with Compounds I and II of myeloperoxidase (MPO)
• It can be guessed that the reactivation of the chlorinating MPO activity by EGCG may contribute to the anti-inflammatory effect of the polyphenol

     

Voltage dependence of the effects of (±)-kavain on the rate of inactivation of Na+ channels

The dependence of the efficacy of the influence of a kava-pyrone (±)-kavain (330 µM) on the frequency of activation of Na⁺ channels and voltage dependence of the effects of (±)-kavain on the rate of inactivation of these channels were studied in experiments on isolated neurons from the rat hippocampus. In all series of experiments, the holding potential equalled –100 mV. The efficacy of (±)-kavain-induced blockade of Na⁺ channels was independent of the frequency of stimulation within the range up to 10/sec. In the control experiments, the rate of inactivation increased with the rise of depolarization from –40 mV to +30 mV, and then the saturation effect was observed. At the membrane potential of –40 mV, the rate of (±)-kavain-evoked inactivation increased approximately by a factor of 2.5. At the more positive shifts of the membrane potential, the efficacy of the effects of (±)-kavain on the rate of inactivation became noticeably reduced, and at +30 mV (±)-kavain exerted no distinct influence on this parameter.Neirofiziologiya/Neurophysiology, Vol. 28, No. 6, pp. 312–315, November–December, 1996.     

Effect of anionic co-ligands on structure and magnetic coupling of bis(μ-phenoxo)-bridged dinuclear copper(II) complexes

Two phenoxo bridged dinuclear Cu(II) complexes, [Cu₂L₂(NO₂)₂] (1) and [Cu₂L₂(NO₃)₂] (2) have been synthesized using the tridentate reduced Schiff-base ligand 2-[(2-dimethylamino-ethylamino)-methyl]-phenol (HL). The complexes have been characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. The structures of the two compounds are very similar having the same tridentate chelating ligand (L) and mono-dentate anionic ligand nitrite for 1 and nitrate for 2. In both complexes Cu(II) is penta-coordinated but the square pyramidal geometry of the copper ions is severely distorted (Addison parameter (τ) = 0.33) in 1 while the distortion is quite small (average τ = 0.11) in 2. These differences have marked effect on the magnetic properties of two compounds. Although both are antiferromagnetically coupled, the coupling constants (J = −140.8 and −614.7 cm⁻¹ for 1 and 2, respectively) show that the coupling is much stronger in 2.     

Effect of antioxidant β-(4-hydroxy-3,5-ditertbutylphenyl)Propionic acid (phenosan) on the development of malignant neoplasms

The effect of different doses of synthetic antioxidant β-(4-hydroxy-3,5-ditertbutylphenyl)propionic acid (phenosan) on the development of spontaneous leukemia in AKR mice was studied. The drug efficiency was determined from the survival curves, animal life spans, and the incidence of leukemia. Phenosan exhibited a pronounced antitumor activity at therapeutic (10^?4 mol/kg, 4 administrations) and ultra-low (10^?14 mol/kg, 4 administrations) doses. The dose of 10^?4 mol/kg proved most efficient to increase the life span of the short-lived subpopulation, while the dose of 10^?14 mol/kg increased the life span of the long-lived subpopulation. The ultra-low dose of the drug seems promising as a prophylactic agent.     

Effects of benomyl on reproduction and population structure of enchytraeid oligochaetes (Annelida)—Sublethal tests on agar and soil

• 1.1. The toxicity of the fungicide benomyl to terrestrial enchytraeid species was tested under different conditions.
• 2.2. Despite a relatively low acute response even to higher concentrations in agar media, sensitive effects were observed for cocoon production and hatching success at the recommended concentration for agricultural application (5.9 ppm in the test medium).
• 3.3. These sublethal effects could be reconciled with population tests in larger quantities of soil: lower abundance was due to a very low number of juveniles in the benomyl-treated cultures.