Pure and mixed monolayers of poly-L-methionine and poly-γy-methyl-L-glutamate with 1,2 dioleyl-L-α-phosphatidylcholine at air-water interface

Monolayers of poly-L-methionine (PM) and poly--methyl-L-glutamate (PMG), spread at an air-water interface, exhibit a high compressibility plateau region at 10 dyn/cm and 18 dyn/cm in their respective-A curves. This behaviour is related to a-helical conformation of the polypeptide molecules in the said interface.Comparative studies of the areas per residue observed in the spreading isotherms, with the areas calculated from molecular models, indicate that the polypeptide molecules should be associated in parallel, forming islets of at least 5-helix chains.Mixed monolayers corresponding to the poly-L-methionine (PM)-1,2 dioleyl-L--phosphatidylcholine (DOPC) and poly--methyl-L-glutamate (PMG)-1,2 dioleyl-L--phosphatidylcholine (DOPC) systems, follow, in every case, the additivity rule for monolayer composition, any indicating that its components are insoluble in the surface mixture. In the case of mixed monolayers of PM-DOPC, a certain degree of compatibility is possible among its components, as a modulation of the plateau region is observed in the spreading isotherms, while for the PMG-DOPC system the plateau region appears at the same surface pressure value as the isotherm corresponding to pure PMG polypeptide.Instituto de Química-Física Rocasolano, C.S.I.C. Madrid -6, España     

GC-MS characterization and quantification of sterols and cholesterol oxidation products

Summary A GC-MS method has been studied for characterization and quantification of phytosterols, cholesterol and cholesterol oxidation products. Baseline separations have been achieved between cholesterol, cholesterol 5-6-epoxide, 5-cholestene-3-ol-7one (7-keto-cholesterol), cholestene-3-5-6-triol, 5-cholestene-3-25-diol (25-hydroxycholesterol), 5-cholestene-3-20-diol (20-hydroxycholesterol), 5-cholestene-3-7-diol (7-hydroxycholesterol) and 5-cholestene-3-19-diol (19-hydroxycholesterol) as well as between -cholestane, cholesterol, stigmasterol, campesterol and -sitosterol. Excellent linearity of response has been obtained permitting reliable quantification. The characterization of each derivatized sterol has been performed by mass-spectrometry. The results confirm the utility of combined gas chromatography-mass spectrometry in the analysis and characterization of sterols and cholesterol oxidation products.     

α,β-Butenolides

,-Dibromo--('-carbethoxyacetony)-^,-butenolide (I) reacts with amines in diethyl ether solution to give -bromo-amino--('-carbethoxyacetony)-^,-butenolides. Compounds n are converted to -bromo-amino--('-carbethoxyacetony)-^,-butenolides on reaction with amines. The corresponding arylhydrazones (VI and VII) are obtained by the reaction of I and II with p-nitro- and 2,4-dinitrophenylhydrazines. Compound I reacts with phenylhydrazine to give furopyridazine VIII.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–871, July, 1972.     

Steroid compounds from the Pacific starfish Lysastrosoma anthosticta

Two new steroid compounds, 3,6-dihydroxy-5-cholesta-9(11),24-dien-23-one 3-sulfate and 3,6-dihydroxy-5-cholest-9(11)-en-23-one 3-sulfate, were isolated from the Pacific starfish Lysastrosoma anthosticta as the corresponding sodium salts and identified. Two previously known glycosides of 24(S)-5-cholestane-3,6,8,15,24-pentol were also isolated and identified as sodium 24-O--d-glucopyranoside 6"-sulfate (pycnopodioside C) and sodium 24-O--d-xylopyranoside 4"-sulfate (luridoside A).     

Analogs of pyrimidine nucleosides

N₁-(-Tetrahydrofuranyl)- and N₁-(-tetrahydropyranyl)uracils and the corresponding 6-azauracils have been obtained by the condensation of bistrimethylsilyl derivatives of uracils and 6-azauracils with-chlorotetrahydrofuran and-chlorotetrahydropyran. The superiority of the silyl method over the mercury method used previously has been demonstrated.For part III, see [9].     

13C NMR spectra of acetylated methyl glycosides of monosaccharides

Summary A comparative discussion of the signals in the¹³C NMR spectra of acetylated methyl - and -D-xylopyranosides, - and -D-glucopyranosides, - and -D-galactopyranosides, - and -L-arabinopyranosides, - and -L-fucopyranosides, and - and -L-rhamnopyranosides and of the corresponding free glycosides has shown a similarity of the effects of substitution at C₅ with a longer-range nature of these effects in the case of the acetylated glycosides.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center of the Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 6–8, January–February, 1979.     

Synthesis of triterpene glycosides

Summary The acyl -D-glucopyranoside, the acyl -D-xylopyranoside, the acyl D- and L--arabinopyranosides, and the acyl -D-lactoside of 18-glycyrrhetic acid, and also the acyl -D-lactoside of 18-glycyrrhetic acid have been synthesized. The acid and alkaline hydrolysis of the compounds obtained has been studied.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 1, pp. 13–19, 1968     

Complex polarizability as used to analyze dielectric relaxation measurements

The effect of representing dielectric properties in terms of the complex polarizability ^c = – i is examined. Loss curves ( and tan ) are shifted towards higher frequencies, revealing the existence of new relaxations and allowing the clarifications of ones already known. We have calculated the shift ratios (at maximum or tan )/ (at maximum or tan ) from the more conventional empirical equations representing the dielectric behavior. Some examples are given.     

<Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR spectra of some drimanic sesquiterpenoids

One- and two-dimensional homo- and heteronuclear correlation proton, carbon, proton—proton, and proton—carbon NMR spectra of fifteen drimanic sesquiterpenoids: 11,12-dibromodrima-5,8-dien-7-one, drim-8-en-7-one, 11-hydroxydrim-8-en-7-one, 11,12-dihydroxydrim-8-en-7-one, 11-hydroxy-11,12-epoxydrim-8-en-7-one, 11-hydroxy-11,12-epoxydrim-8-en-7-one, 8,9-epoxydriman-7-one, 8,9-epoxydriman-7-ol, 11,12-diacetoxydrim-8-en-7-ol, drimane-7,8,11-triol, 7,8-isopropylidenedioxydriman-11-al, 9, 11-dihydroxydrim-7-en-6-one, drimane-7,8,9-triol, drimane-7,8,11-triol, and drim-8-ene-7,11,12-triol were studied. The proton and carbon chemical shifts were assigned.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2589–2594, December, 2004.