Development of a bioanalytical method for the quantification of sinococuline in human plasma and its application in phase I clinical pharmacokinetic study

A selective, highly sensitive, precise, and novel bioanalytical method has been developed and validated to quantify sinococuline, an active constituent present in the phytopharmaceutical drug product containing Cocculus hirsutus plant extract, in vivo. Chromatographic separation was achieved on a Luna Omega Polar-C18 bonded analytical column maintained at 45°C. The isocratic mobile phase consisted of methanol and ammonium formate buffer (60:40, v/v) at acidic pH with a low flow rate of 0.250 mL/min. Detection was performed on an API 4000 mass spectrometer using electrospray ionization in positive polarity and multiple reaction monitoring mode to achieve a lower limit of quantification of 1.50 ng/mL. Excellent accuracy and precision were obtained after extracting the analyte from plasma samples using a chemical analogue as an internal standard in the absence of an isotope-labeled compound. The extraction efficacy was evidenced from recovery study, and the analyte was found to be stable in plasma. Validation study demonstrated linearity with coefficient of correlation, r ≥ 0.99, and minimal matrix effect. This bioanalytical method was successfully applied to evaluate pharmacokinetic parameters of sinococuline from a phase I clinical trial of an aqueous extract of C. hirsutus in healthy human volunteers.     

Direct electrosynthesis of halo and mixed-halo complexes of palladium(II and IV) by the dissolution of a sacrificial palladium anode in aqueous medium

A rapid single-step method for the electrosynthesis of chloro and bromo complexes of palladium(II and IV), viz. M₂[PdX₄] and M₂[PdX₆], by the dissolution of a palladium anode in chloride or bromide containing media is described. Electrolysis of dilute HX solution in the presence of pyridine, 2,2′-bipyridyl or 1,10-phenanthroline gives rise to non-electrolytes, e.g. trans-[PdX₂(py)₂], [PdX₂(bipy)] and [PdX₂(phen)]. Anodic oxidation of palladium in HX medium in the presence of acetonitrile and benzonitrile also gives the non-electrolytes trans-[PdX₂(CH₃CH₂NH₂)₂] and trans-[PdX₂(C₆H₅CH₂NH₂)₂], respectively.     

Synthesis and structural characterisation of a novel tris-methylene bridged compound (NO) 4Fe2 Se(μ-CH2)3

The tris-methylene bridged compound (NO)₄Fe₂Se(μ-CH₂)₃ has been isolated. It has been characterised by IR and ¹H, ¹³C, and ⁷⁷Se NMR spectroscopy. Its structure has been determined by single-crystal X-ray diffraction methods. The structure consists of a heavy atom triangle consisting of one Se and two Fe atoms. The Fe-Fe and the two Fe-Se edges are bridged by methylene groups.     

Reaction of N-(2-hydroxyethyl) ethylenediamine over zeolite and chromite catalysts

N-(2-hydroxyethyl) ethylenediamine reaction was observed over zeolite catalysts giving rise to only dehydrocyclization and over chromite catalysts showing dehydrocyclization together with dehydrogenation. The major product changes from the cyclized compound piperazine to pyrazine when the reactant is switched from zeolite to chromite catalyst. This process stands as a model reaction for characterizing lone acid sites and adjacent acid-base sites over zeolite and chromite catalysts, respectively.IICT Communication No. 3175     

4-t-Butylphenoxo complexes of oxovanadium(V)

Summary Complexes of composition [VOCl₂(OC₆H₄Bu-t-4)] (1) and [VOCl(OC₆H₄Bu-t-4)₂] (2) have been synthesized by the reaction of VOCl₃ with equimolar and bimolar amounts, respectively, of 4-t-BuC₆H₄OSiMe₃ in CCl₄ and characterized by physio-chemical techniques. The complexes react with -hydroxyaldehydes and ketones such as 2-hydroxybenzaldehyde (salicylaldehyde, salH), and 2-hydroxy-2-phenylacetophenone (benzoin, benzH), 2-hydroxyacetophenone (hapH) and also with the potassium salt of p-chlorobenzohydroxamic acid (KBHACl) in 11 and 12 molar ratios, to yield five- and six-coordinate complexes.     

Cyphostemmins A-B, two new antifungal oligostilbenes from Cyphostemma crotalarioides (Vitaceae)

Two new antifungal resveratrol dimers, cyphostemmins A-B (1–2), have isolated from the roots of Cyphostemma crotalarioides planch (Vitaceae) together with resveratrol 3 and previously known reseveratrol dimers (4–7). Structures of these new compounds have been established on the basis of their MS and ¹H and ¹³C NMR spectroscopic data.     

Errors in the determination of silica in lead-bearing samples caused by preliminary separation of lead sulphate

Some procedures for the gravimetric determination of silica in lead-bearing samples involve the extraction of lead sulphate with ammonium acetate. Results for silica are then low because some silica is dissolved in ammonium acetate solution. Correct results can be obtained only by avoiding fuming with sulphuric acid. If samples contain a large proportion of insoluble silica, preliminary fusion with sodium hydroxide is recommended.     

The application of levulinic acid and 5-nitro-2-furylmethylene diacetate in the total synthesis of some novel biologically active (5-nitro-2-furyl)azomethines

Summary The syntheses andin vitro antibacterial and antifungal evaluation of certain (5-nitro-2-furyl)azomethines with different heterocyclic nuclei are described.

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Die Anwendung von Lävulinsäure und 5-Nitro-2-furylmethylendiacetat in der Totalsynthese einiger neuer biologisch aktiver (5-Nitro-2-furyl)azomethine

Zusammenfassung Es wird die Synthese und diein-vitro-antibakterielle und antifungale Wirksamkeit für bestimmte (5-Nitro-2-furyl)azomethine mit verschiedenen heterocyclischen Kernen beschrieben.

     

Protective properties of redox polymer film deposited on stainless steel

We propose a novel composite organic-inorganic coating in the form of a redox polymer film for protection of stainless steel against general corrosion in strong acid medium (2 M H₂SO₄). We utilize an anion exchange polymer, protonated poly(4-vinylpyridine), into which hexacyanoferrate anions have been introduced. Owing to the presence of Fe(CN)₆^3–/4– at the interface formed by the film and the steel, a sparingly soluble metal hexacyanoferrate (mostly Prussian blue, PB) is formed as an overcoating on the steels surface, presumably on the passive (metal oxide) layer. The redox polymer film on the steel seems to act as a composite three-dimensional bilayer-type coating in which hexacyanoferrate(III,II) anions (that are capable of effective charge storage) exist in the outer portions of the film, whereas the inner PB layer improves the systems overall adherence and stability. By analogy to a conducting polymer (e.g. polyaniline, polypyrrole), introduction of the redox polymer composite film leads to stabilization of the steel substrates potential within the passive range.Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003)