Showing papers on "Brucine published in 1998"

Sequential injection determination of chromium(VI) by transient oxidation of brucine with spectrophotometric detection and in-line dilution

Abstract: A sequential injection method for the determination of chromium(VI) in residual waters from electroplating baths and steels is proposed. The method is based on monitoring the absorbance at 525 nm due to an aminochrome intermediate compound resulting from oxidation of the alkaloid brucine. The intermediate brucichrome is unstable so that its analytical use is only possible in closed flowing systems where the precise and reproducible control of time and mixing is possible. The method gave a linear calibration curve from 0.2 to 2 mg l–1 Cr(VI) and a detection limit of 0.045 mg l–1 Cr(VI). A sampling frequency of 120 h–1 is possible. Industrial samples from electroplating baths and residual washing waters were analyzed, and in this case a sequential injection in line dilution was performed, permitting real time determination of samples with Cr(VI) concentrations up to 100 mg l–1 with a sampling frequency of 80 h–1.

Membrane potential responses of paramecium caudatum to bitter substances :existence of multiple pathways for bitter responses

Abstract: The membrane potential responses of Paramecium caudatum to the external application of bitter substances were examined by employing conventional electrophysiological techniques. Mutant cells defective in voltage-gated Ca2+ channels were used to record the potential responses in the absence of contamination by Ca2+ action potentials. The cells produced a transient depolarization followed by a transient hyperpolarization in response to a rapid whole-cell application of chloroquine, strychnine nitrate or brucine. Of these chemicals, chloroquine was the most potent. Cells produced a simple depolarization in response to a localized application of test chemicals to the anterior region, whereas they produced a transient hyperpolarization in response to an application to the posterior region. Membrane potential responses to an application of chloroquine declined with repeated application. The presence of chloroquine in the external bathing solution strongly inhibited the membrane potential responses to an application of brucine or strychnine. However, the presence of chloroquine did not affect the membrane potential responses to an application of quinine. It is suggested that chloroquine, strychnine and brucine share a common component of their transduction pathways, but that the transduction pathway for quinine is different.

Brucinium Hydrogen Fumarate Sesquihydrate and Brucinium Hydrogen Maleate

Abstract: As part of a general study of brucine (alternative name: 2,3-dimethoxystrychnidine-10-one) as a co-crystallizing agent, the structures of its salts with the stereoisomeric fumaric and maleic acids are reported. The packing in the hydrogen fumarate, C23H27N2O4.C4H3O4.{{3}\over{2}}H2O, is a variation of the corrugated sheet motif common to several brucine crystals, while the hydrogen maleate, C23H27N2O4.C4H3O4, shows a substantially different motif.

Separation and Purification of Strychnine from Crude Extract of Strychnos nux-vomica L. by High-Speed Countercurrent Chromatography

Abstract: High-speed countercurrent chromatography (CCC) was applied to the separation of strychnine and brucine from crude extract of Strychnos nux-vomica L. using a two-phase solvent system composed of chloroform/0.07 M sodium phosphate, 0.04 M citric buffer (pH 5.08) (1:1, v/v). Fractionated components were identified with authentic pure compounds on TLC and also analyzed by HPLC, IR and FTMS. The results showed that from 40 g of the seed powder, 48.2 mg of strychnine was purified at 99.9% purity (83.3% recovery) while 18.1 mg of brucine fraction was obtained after rechromatographed by preparative TLC improving the purity to 91.2%.

[Influence of processing methods on alkaloid, toxicity and effect of Strychnos nux-vomica L].

Abstract: Determination has been made on the contents of strychnine, brucine and ephedrin in different processed products of Strychnos nux-vomica. The acute toxicity, analgesic and antiphlogistic actions of these products have also been detected. The result shows that the product processed with Ephedra sinica can reduce toxicity and promote curative effect. Among the different processing methods the preparation with Ephedra and Liqorice root and the preparation with Ephedra and alcohol appear better and thus useful in practical application.

Optical resolution of (±)-Threo-9,10,16-trihydroxy hexadecanoic acid using (−)brucine

Abstract: The optical resolution of (±)threo-9,10,16-trihydroxy hexadecanoic acid was achieved by fractional crystallization using (−)brucine. Formation of an estolide during decomposition of the (−)brucine complex was observed to interfere with the separation of the optically pure material. This was corrected by converting the estolide to (+)-threo-9,10,16-trihydroxy hexadecanoic acid via alcoholic alkaline hydrolysis followed by neutralization. Enantiomeric purity was determined by chiral lanthanide nuclear magnetic resonance shift reagent.