Synthetic analogs of Peganum alkaloids VI. Photochemical oxidation of 2,3-polymethylene-quinazoline derivatives

The rates of the photochemical oxidation of quinazoline alkaloids — deoxypeganine, peganine, pentamethylenequinazoline, and peganol — to the corresponding oxo derivatives have been studied. It has been shown by HPLC that the oxidation of deoxypeganine proceeds through a stage of the formation of a carbinolamine (peganol); in the case of its hydrochloride, the reaction takes place by the same scheme but four times more slowly. Tetra- and pentamethylenequinazolines have been synthesized and information on their melting points in the literature has been corrected. In the series trimethylenequinazoline-pentamethyl-enequinazoline-tetramethylenequinazoline the stability falls from left to right.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 528–532, July–August, 1991.     

Quantum-chemical investigation of deoxypeganine and its salts I. Photochemical oxidation of deoxypeganine

Hypothetical models of the interaction of deoxypeganine molecules with a solvent have been considered by the MO LCAO quantum-chemical method in the AM1 approximation. Excited triplet states of deoxypeganine and its analogues have been calculated by the method of molecular interactions. A free-radical mechanism of photochemical oxidation has been proposed on the basis of the results obtained and of literature information. Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 546–548, September–October, 1992.     

Polysaccharides ofUngernia. XV. A study of the pectin substances of the leaves ofUngernia tadschicorum

Pectin substances have been isolated from the leaves ofUngernia tadschicorum and characterized. A galacturonan has been obtained by partial hydrolysis. On the basis of the results of IR spectroscopy and periodiate — nitric acid oxidation, its structure has been established as an α-1→4-bound polymer-homolog. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 62 73 48. Translated from Khimiya Prirodnykh Soedinenii, No. 3, 320–322, May–June, 1994.     

Chemical synthesis and enzymatic assembly of fragments of the DNA coding immunodominant epitopes of human immunodeficiency virus

More than twenty 13- to 55-membered oligo(poly)nucleotides have been synthesized by the H-phosphonate solid-phase method in the manual variant using an original procedure. From the oligonucleotides obtained, seven DNA duplexes coding immunodominant epitopes of HIV-1 proteins have been formed: 598–609 and 737–748 gp41, 91–115 and 105–115 gag, and 940–951 pol and a number of its mutants. The ligase assembly and polymerization of the DNA duplexes obtained has been carried out. The efficiency of ligation amounted to from 60 to 90%. The possibility of their directed polymerization was determined by the flanking of the duplexes by partially completed half-sites of restrictases BamHI and XhoI. Abbreviations adopted: HIV-1 — human immunodeficiency virus, type 1; (+)-chain — the coding chain — and (−)-chain the chain complementary to the coding chain of the DNA duplex; CPG — controlled-pore glass; PAAG — polyacrylamide gel; Py — pyridine.     

A quantum-chemical investigation of deoxypeganine and its salts II. The photochemical oxidation of deoxypeganine hydrochloride

The stability of deoxypeganine hydrochloride under the action of light has been established. The kinetics of the oxidation of deoxypeganine hydrochloride in aqueous solution in the presence of deoxyvasicinone hydrochloride have been studied. The structures and electronic conformations of hypothetical models of the salt DOP HCl in the ground and excited states have been considered by the MO LCAO method in the AM1 approximation. The difference in the resistance of the molecules of the base deoxypeganine and its hydrochloride to photochemical oxidation is discussed on the basis of the results of experiments and calculations.Abbreviations HPLC high-performance liquid chromatography - MO LCAO molecular orbitals as linear combinations of atomic orbitals - AM1 Austin Model 1 - DOP HCl deoxypeganine hydrochloride - DOV HCl deoxyvasicinone hydrochloride Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 729–733, September–October, 1993.     

Quantum-chemical investigation of deoxypeganine and its salts I. Photochemical oxidation of deoxypeganine

Hypothetical models of the interaction of deoxypeganine molecules with a solvent have been considered by the MO LCAO quantum-chemical method in the AM1 approximation. Excited triplet states of deoxypeganine and its analogues have been calculated by the method of molecular interactions. A free-radical mechanism of photochemical oxidation has been proposed on the basis of the results obtained and of literature information.Institute of Chemistry of Plant Substances, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 546–548, September–October, 1992.     

Distillation, on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS as a new combination for the determination of methylmercury in sediments and fish tissue

Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high performance liquid chromatography — ultra violet — post column oxidation — cold vapour atomic absorption spectrometry) for the determination of methylmercury at back-ground levels in sediments, soils and fish tissue. To prove the accuracy of this method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.     

A quantum-chemical investigation of deoxypeganine and its salts II. The photochemical oxidation of deoxypeganine hydrochloride

The stability of deoxypeganine hydrochloride under the action of light has been established. The kinetics of the oxidation of deoxypeganine hydrochloride in aqueous solution in the presence of deoxyvasicinone hydrochloride have been studied. The structures and electronic conformations of hypothetical models of the salt DOP HCl in the ground and excited states have been considered by the MO LCAO method in the AM1 approximation. The difference in the resistance of the molecules of the base deoxypeganine and its hydrochloride to photochemical oxidation is discussed on the basis of the results of experiments and calculations.     

Degradation of an ether–alcohol (3-ethoxypropan-1-ol) by photo-Fenton-generated <Superscript>•</Superscript>OH radicals: products analysis and formation pathways; relevance to atmospheric water-phase chemistry

We have chosen 3-ethoxypropan-1-ol (EtOPrOH) as a typical short-carbon-chain ether–alcohol used as industrial solvent and have analyzed the degradation products resulting from its attack by ^•OH radicals generated by the photo-Fenton reaction. The laboratory conditions were representative of those found in tropospheric water droplets. Twelve products have been identified by use of GC–MS analysis, either directly or after extraction by SPME fibers, and by HPLC–UV analysis with a special column for carboxylic acids and after reaction of carbonyl groups with 2,4-dinitrophenylhydrazine. These products contain one to three carbon atoms (instead of five in EtOPrOH), among which one or two are oxidized. According to the reaction pathways proposed, seven products—including methanal—can result from attack by one ^•OH only, three products imply attack by a second ^•OH, as expected from their higher oxidation number, and it is suggested that reaction between two organic radicals is needed for formation of only two products. The relevance of this investigation to the fate of EtOPrOH and similar ether–alcohols in the troposphere is briefly discussed.     

Triterpene and steroid glycosides of the genusMelilotus and their genins III. Funkioside B and protodioscin from the seeds ofMelilotus tauricus

Two steroid glycosides belonging to the furostan series — funkioside B and protodioscin — have been isolated from the seeds of the plantMelilotus tauricus (Bieb.). Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 766–770, November–December, 1994.     

Synthetic analogs of natural flavolignans. II. A new synthesis of benzodioxepane analogs of silandrin and hydnocarpin

Benzodioxepane analogs of chalcones have been obtained from which analogs of natural flavolignans — silandrin and hydnocarpin — have been synthesized. The PMR spectra of the new substances are given and are discussed. KIEN, Karakalpak Division, Academy of Sciences of the Republic of Uzbekistan, Nukus. Taras Shevchenko Kiev University, Ukraine. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 480–483, July–August, 1994.     

Ruthenium-mediated Selective Aromatic Thiolation in the Complex [RuII{o-S—C6H4-(p-R-)—N=N—C3H2NN(1)—R′}2]. Synthesis, Spectroscopic, e.p.r., Electro-chemical Characterization and Spectro-electrochemical Correlation

The reaction of ctc-[Ru(RaaiR′)₂Cl₂] (3a–3i) [RaaiR′=1-alkyl-2-(arylazo)imidazole, p-R—C₆H₄—N=N— C₃H₂NN(1)—R′, R=H, OMe, NO₂, R′=Me, Et, Bz] with KS₂COR′′ (R′′=Me, Et, Pr, Bu or CH₂Ph) in boiling dimethylformamide afforded [Ru^II{o-S—C₆H₄(p-R-)—N=N—C₃H₂NN(1)—R′}₂] (4a–4i), where the ortho-carbon atom of the pendant phenyl ring of both ligands has been selectively and directedly thiolated. The newly formed tridentate thiolate ligands are bound in a meridional fashion. The solution electronic spectra exhibit a strong MLCT band near 700 nm and near 550 nm, respectively in DCM. The molecular geometry of the complexes in solution has been determined by H n.m.r. spectroscopy. Cyclic voltammograms show a Ru(II)/Ru(III) couple near 0.4 V and an irreversible oxidation response near 1.0 V due to oxidation of the coordinated thiol group, along with two successive reversible ligand reductions in the range −0.80–0.87 V (one electron), −1.38–1.42 V (one electron). Coulometric oxidation of the complexes at 0.6 V versus SCE in CH₂Cl₂ produced an unstable Ru(III) congener. When R=Me the presence of trivalent ruthenium was proved by a rhombic e.p.r. spectrum having g₁=2.349, g₂=2.310.     

Modifications based on coumarins III. Synthesis of diesters of karatavic and galbanic acids and mixed diesters of coumarin acids and salicylic acid with sucrose

The synthesis of 6,6′-diesters of sucrose with natural coumarins — karatavic and galbanic acids — has been achieved by the transesterification of methyl esters of these acids with monosucrose esters of the same acids, and so has that of mixed 6,6′-diesters of these coumarin acids and salicylic acid by a reaction between methyl salicylate and a monoester of the corresponding coumarin acid. The structures of the compounds obtained have been confirmed by IR, UV, PMR, and¹³C NMR spectroscopies. A. B. Bektorov Institute of Chemical Sciences, Academy of Sciences, Republic of Kazakhstan, Almaty, fax (3272) 61 57 65. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 461–465, July–August, 1998.     

Triterpene and steroid glycosides of the genusMelilotus and their genins IV. Trillin and dioscin from the seeds ofMelilotus tauricus

Two steroid glycosides belonging to the spirostan series — trillin and dioscin — have been isolated from the seeds of the plantMelilotus tauricus (Bieb.) Ser. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 770–772, November–December, 1994.     

Synthesis of 24-ethylcholesta-7, 22E-diene-3β, 5β-triol — A natural trihydroxysteroid from the bryozoan Myriapora truncata

24-Ethylcholesta-7, 22E-diene-3β,5α,6β-triol — a natural trihydroxysteroid from the bryozoanMyriapora truncata — has been synthesized from stigmasterol. Institute of Bioorganic Chemistry, Academy of Sciences of the Belorussian SSR, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 664–669, September–October, 1989.     

Composition and structure refinement of superconducting crystals Y1? x Tb x Ba2Cu3O6+δ ( x = 0.10; δ = 0.75)

Crystals of Y_0.90Tb_0.10Ba₂Cu₃O_6.75 have been prepared by spontaneous crystallization from slowly cooled non-stoichiometric melt of the system Y-Tb-Ba-Cu-O. Average size of platelet crystals having mirror surface is 2×2, the largest — 8×9 mm with thickness 0.1–0.2 mm. The crystals have been characterized by powder X-ray diffraction and electron microprobe analysis. Tetragonal symmetry of the crystals has been determined by X-ray diffraction. Magnetic susceptibility measurements have revealed that the crystals manifest transition to superconducting state without additional annealing (T _c = 60 K). Structures and compositions — Y/Tb ratio (σ = 0.01) and oxygen content (σ = 0.04) — have been refined for two single crystals. Possibility of rhombic distortion of the tetragonal symmetry is discussed. __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 6, pp. 1101–1107, November–December, 2008. Original Russian Text Copyright ? 2008 by L. P. Kozeeva, N. V. Podberezskaya, N. V. Kuratieva, M. Yu. Kamaneva, and A. G. Blinov     

Phytoecdysteroids of the plants of the genusSilene XV. Silenoside F — Brahuisterone 3-O-β-D-glucopyranoside fromSilene brahuica

A new brahuisterone glycoside — silenoside F — has been isolated from the epigeal part ofSilene brahuica Bois. (fam. Caryophyllaceae). Its structure has been established by an analysis of spectral characteristics: 3β,5,14α,22R,25-pentahydroxy-5β-cholest-6-one 3-O-β-D-glucopyranoside. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 734–737, November–December, 1994.     

Color reactions of hederagenin and its glycosides

The spectrophotometric reactions of triterpene compounds with concentrated sulfuric acid, a mixture of sulfuric acid and ethanol, and a mixture of sulfuric and acetic acids has been studied with hederagenin and its glycosides — caulosides A, C, and D, isolated from the Far Eastern plantCaulophyllum robustum Maxim — as examples. Conditions for performing the reaction which exclude the influence of the carbohydrate components of the glycosides from the determination of hederagenin have been suggested. The reaction with a mixture of sulfuric acid and ethanol has been used to determine the amounts of caulosides A and C in a total preparation after their separation by the TLC method. The relative error of the determination did not exceed 5 rel.%. Pacific Ocean Institute of Bioorganic Chemistry, Far-Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 643–646. September–October, 1980.     

Pyrolysis of N-doped organic aerogels with relation to sorption properties

Resorcinol–formaldehyde aerogels (five samples, three of them with addition of nitrogen containing precursors—3-hydroxypyridine, 3-aminophenol and melamine) have been prepared by sol–gel polycondensation, subcritical drying and pyrolysis. The pyrolysis of prepared organic aerogels has been studied by non-isothermal TG at constant heating rate. The process of pyrolysis has been found to consist of three steps with the total mass loss 40.2–61.7% (room temperature—1,000 °C). The resulted carbon aerogels have been tested as sorbents of Ni(II), Pb(II) and Cu(II) ions from aqueous solutions. Various relations have been found among the results obtained from the pyrolysis experiments and properties affecting adsorption. Besides the expected correlation between the mass loss gained from TG (isothermal step at 500 °C was applied) and from heating in the laboratory oven, the relationship between the mass loss during pyrolysis and sorption capacities for all three metal ions has been found. Other relations among pyrolysis behaviour, surface area and content of nitrogen have been also examined. Batch adsorption experiments show (with an exception of one sample) that N-doped samples have higher adsorption capacity for metal ions. In addition, changing of nitrogen functionalities during the pyrolysis has been considered and pyridinic-N (N-6) functionality has been contemplated as a suitable structure for the adsorption process.     

Synthesis of polybrominated diphenyl ethers of marine origin

Polybrominated diphenyl ethers — antimicrobial metabolites of the marine spongeDysidea fragilis — have been obtained by the reaction of 2,3,5-tribromonitrobenzene with 3,5-dibromo-2-methoxyphenol and the reaction of brominated diphenyliodonium salts with brominated phenols. Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 352–354, May–June, 1993.