A polarographic investigation of the alkaloids of Ungernia

Summary In the investigation of the polarographic behavior of nine ungerine alkaloids, it was found that the reduction of narwedine forms the corresponding carbinol, while the reduction of hippeastrine, ungerine, and unsevine forms the corresponding tetrahydro derivatives. The catalytic hydrogen waves that all the ungerine alkaloids form can be used for analytical purposes.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 365–367, May–June, 1976.     

A polarographic investigation of benzylisoquinoline alkaloids

Summary 1. The polarographic behavior of seven alkaloids fromPeganum harmala have been investigated. The products of the electrode reaction in the reduction of vasicinone and deoxyvasicinone are the corresponding carbinols, and in the reduction of harmine the product is dihydroharmine.2. The possibility has been shown of using the polarographic method for studying the oxidation of peganine and deoxypeganine.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 363–365, May–June, 1976.     

Ungernia alkaloids

The review is devoted to the study of the alkaloids of plants of the genusUngernia (Amaryllidaceae). It gives their characteristic reactions and information on the determination of their structures and stereochemistry and on the dynamics of the accumulation of alkaloids in the plants of the genusUngernia. A dependence of the physiological activity of the alkaloids on their structure is shown.     

The dynamics of the accumulation of the alkaloids of the genus Ungernia

Summary A study ofU. victoris, U. tadshicorum, andU. trisphaera with respect to the vegetation periods and growth sites has shown that the maximum accumulation of alkaloids takes place in the early vegetation period and that naturally dried leaves do not contain alkaloids. The alkaloid content also depends on the growth site.In the period of the vigorous development of the epigeal part, some alkaloids are possibly converted into one another (hippeastrine into lycorine, galanthamine into narwedine, and narwedine into galanthamine).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 60–64, January, 1971.     

Polysaccharides of Ungernia. XIV. A mannan from Ungernia trisphaera bulbs

The group carbohydrate composition of the bulbs ofUngernia trisphaera has been studied. The homogeneous ungeromannan-Tr, acetylated in the native state, has been isolated. On the basis of the results of periodate oxidation, methylation, partial hydrolysis, and IR and¹³C NMR spectroscopy, it has been shown that ungeromannan-Tr consists of a linear polymer D-mannopyranose with -(1 4)-glycosidic bonds.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 21–25, January–February, 1986.     

A spectrophotometric and polarographic investigation of three new cyclohexene-substituted benzodiazepines

Three recently introduced benzodiazepine derivatives, tetrazepam (I), nortetrazepam (II) and menitrazepam (III) have been subjected to spectral and polarographic investigation. From the ultraviolet spectral data their pK(a)-values have been determined: 4.28 (I), 4.3 (II) and 3.5 (III). From the polarographic measurements it can be concluded that in I and II the 4,5 CN double bond is reduced with 2 electrons. For the first time for the benzodiazepine series it has been observed that in slightly alkaline solutions this process takes place in two separate 1-electron steps. In III, first the aromatic nitro group is reduced to a hydroxylamine group, then at more negative potentials the CN double bond is also reduced; its reduction wave mostly coalesces with that for the 6-electron reduction of the nitro group to an amino group. A differential pulse polarographic method is presented, for the determination of I, II, III at concentrations as low as 10(-7)M.     

A polarographic investigation of 5-nitrophenyl-2-furfurals and their derivatives

The polarographic behavior in dimethylformamide of the o-, p-, and m-isomers of 5-(nitrophenyl)-2-furfural and their benzoylhydrazones has been studied. These compounds give one one-electron and one three-electron wave of the reduction of the nitro group, the corresponding half-wave potentials being considerably more negative than the half-wave potentials of 5-nitro-2-furfural and the corresponding nitrobenzaldehydes. In the case of 5-(o-nitrophenyl)-2-furfural and its benzoylhydrazone, a hydrogen bond is formed between the nitro group and the furan ring or the amide grouping of the side chain, which leads to a considerable shift in the potentials in the negative direction. Because of the high electroreduction potentials, the benzoylhydrazones of the 5-(o-, p-, and m-nitrophenyl)-2-furfurals have no antibacterial and fungistatic activity.     

A pulse polarographic investigation of parathion and some other nitro-containing pesticides

The polarographic behaviour of parathion, its major metabolites (paraoxon and p-nitrophenol), and of methylparathion, EPN and pentachloronitrobenzene has been studied over a wide pH range. Differential pulse polarography is used to differentiate between parathion, p-nitrophenol and pentachloronitrobenzene. An indirect determination of parathion in the presence of paraoxon can be based on their respective rates of hydrolysis in 0.5 M sodium hydroxide solution. The electrochemical behaviour of these compounds has also been investigated in solutions containing tetraalkylammonium salts as the supporting electrolyte.     

NMR investigation of alkaloids

By the method of double proton resonance, in the alkaloids of the ajmaline type, ajmaline, majoridine, herbamine, quebrachidine (vincarine), vincamajine, and vincamedine a long-range stereospecific interaction through four σ-bonds between the H_6α and H_17α protons of about 1 Hz has been found and in compounds with C₂-βH and C₁₇-αH (ajmaline, majoridine), the H₂β and H_17α protons exhibit a NOE of the order of 10%. These facts can be used successfully in determining the orientation of the hydrogen atoms and the corresponding configurations of C₁₇ and C₂ asymmetric centers in such systems.     

NMR investigation of alkaloids

By the method of double proton resonance, in the alkaloids of the ajmaline type, ajmaline, majoridine, herbamine, quebrachidine (vincarine), vincamajine, and vincamedine a long-range stereospecific interaction through four -bonds between the H₆ and H₁₇ protons of about 1 Hz has been found and in compounds with C₂-H and C₁₇-H (ajmaline, majoridine), the H₂ and H₁₇ protons exhibit a NOE of the order of 10%. These facts can be used successfully in determining the orientation of the hydrogen atoms and the corresponding configurations of C₁₇ and C₂ asymmetric centers in such systems.For Communication I, see [1].Delivered at an All-Union Conference on Modern Advances in High-Resolution NMR spectroscopy, Tashkent, September, 1975 [2].Institute of the Chemistry of Plant Substances of the Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 608–613, September–October, 1981.     

A mass spectrometric investigation of alkaloids of the galanthamine type

Conclusions 1. Features of the mass spectrometric behavior of alkaloids of the galanthamine type have been established: the presence of strong M⁺ and M — 1 peaks, the contraction of ring C with the retention or with the expulsion of the nitrogen atom, and the elimination of the elements of ring B.2. Additional information on the structure of the alkaloid chlidanthine has been obtained.3. The similarity of the mass spectrometric behavior of a dihydro derivative of galanthamine (lycoramine) and of dihydro derivatives of alkaloids of the lycorine type have been shown.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 280–283, 1969     

NMR investigation of alkaloids

On the basis of a study of the spin-spin coupling constants J_CH and the¹³C chemical shifts of haplophyllidine an assignment has been made of the signals of the carbon atoms of the 5,6,7,8-tetrahydrofuranoquinoline alkaloids haplophyllidine, perforine, anhydroperforine, their derivative (IV), and the furanoquinoline base -fagarine.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 25–30, January–February, 1989.