Analogs of oxytocin with L- and D-pentafluorophenylalanines in the second position

Summary 1. The separation of pentafluorophenylalanine into optical antipodes has been effected.2. Two new analogs of oxytocin — [2-L-pentafluorophenylalanine]oxytocin and [2-D-pentafluorophenylalanine]oxytocin — have been synthesized and their uterotonic activities have been studied.3. It has been shown that donor — acceptor interaction plays a fundamental role in the stimulation of the biological effect.A. A. Zhdanov Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 392–398, May–June, 1977.     

Rapid determination of telmisartan in pharmaceuticals and serum by the parallel catalytic hydrogen wave method

The polarographic characteristics of telmisartan have been investigated in 0.8 mol L^–1 NH₃.H₂O–NH₄Cl (pH 8.9)–0.01 mol L^–1 H₂O₂ as supporting electrolyte. The results demonstrate that the polarographic reduction wave at ca. –1.30 V in the absence of H₂O₂ is a catalytic hydrogen wave, and the reduction wave enhanced by H₂O₂ is a so-called parallel catalytic hydrogen wave. The analytical sensitivity of the parallel catalytic hydrogen wave is ca. 60 times higher than that of the corresponding catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave a novel method has been developed for determination of telmisartan by linear sweep polarography. The calibration curve is linear in the range 2.0×10^–8–2.0×10^–6 mol L^–1 and the detection limit is 1.0×10^–8 mol L^–1. The precision is excellent with relative standard deviations of 2.6% at a concentration of 1.0×10^–7 mol L^–1 telmisartan. The proposed method has been applied to the direct determination of the telmisartan in capsule forms and biological samples. The proposed method has been proved to be advantageous over existing CZE and MEKC methods in simplicity, rapidity, and reproducibility.     

Chemical and immunochemical investigation of the lipopolysaccharides ofVibrio alginolyticus

A chemical and immunochemical study of the LPSs of the microorganismsVibrio alginolyticus (strains 1385–80, 945–80, and 2076–80) has been made. A difference in the monosaccharide composition of the LPSs of the strains studied has been shown. It had been established that the LPSs of strains 945–80 and 2076–80 possess a high serological specificity, while the LPS of strain 1385–80 differ serologically from them. A suggestion is made of the role of different monosaccharides in the formation of the immunochemical determinants of the LPSs of the strains studied.Pacific Ocean Institute of Bioorganic Chemistry of the Far-Eastern Scientific Center of the USSR Academy of Sciences, Vladivostok. Translated from Khimiya Priorodnykh Soedinenii, No. 5, pp. 652–657, September–October, 1987.     

Hysteresis effect and autooscillation phenomena in the oxidation of 1-hexene on palladium

The gas-phase oxidation of 1-hexene on a palladium film has been investigated in a gradient-free reactor at atmospheric pressure and temperatures of 293–693 K, at flow rates of 0.3–0.15 liter/min and an initial concentration of hexene in air of 15.5·10^–4 M. Autooscillation phenomena have been observed and a hysteresis effect in the reaction rate as function of temperature, caused by the branched-chain heterogeneous-homogeneous reaction mechanism.Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 24, No. 1, pp. 107–110, January–February, 1988.     

Ab initio Calculation of the charge distribution and the ligand field splitting in the tetrahedral halo complexes CuCl 4 2− 4 and NiCl 4 2−

The charge distribution and the ligand field splitting in the tetrachloro complexes CuCl ₄ ^2– and NiCl ₄ ^2– have been investigated by means of the restricted Hartree-Fock method. A rather large basis set of contracted Gaussian type orbitals has been employed. The charge distributions have been analysed by means of Mulliken population analyses. The ligand field splitting 10Dq has been compared with literature results known for the octahedral cluster NiF ₆ ^4– occurring in KNiF₃. A detailed analysis has been carried out for CuCl ₄ ^2– . From calculations on a selected number of states of NiCl ₄ ^2– the Racah parameters B and C have been obtained.     

Amberlyst A-26 resin loaded with pyrocatechol violet—Preparation and applications as a preconcentrator in the atomic absorption spectrophotometric determination of lead and cadmium

Amberlyst A-26 loaded with pyrocatechol violet has been prepared and used for preconcentrating cadmium and lead before their flame atomic absorption Spectrophotometric determination. The optimum sorption pHs are 7.0–7.8 and 7.0–7.5 for Cd and Pb, respectively. The absorbance varies linearly in the concentration ranges of 0.1–1.0 and 1.5–7.5 μg cm⁻³, respectively, for the two metals. The sensitivity of the procedure for 1% absorption has been found to be 1.5 and 2.3 ng cm⁻³ of the solution to be analyzed, respectively, for Cd and Pb. The relative standard deviation is approximately 2.8%. The method has been used to determine Cd and Pb in the water of the Yamuna River (New Delhi, India) with a relative standard deviation between 4.3 and 5.1%.     

Molecular heterogeneity and antiviral and interferon-inducing activities of the drug Savrats

The molecular-mass distribution of the drug Savrats has been studied by gel filtration on HW-55 f. It has been shown that the drug is heterogeneous and that the fraction with a molecular mass of 25–25 kDa exhibits a high biological activity.Mirzo Ulugbek Tashkent State University, fax (3712) 46 24 72. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 112–114, January–February, 1998.     

Principles of modeling in the study of conformations of histones

A study has been made by the CD method of the conformational potentialities of the polypeptides (Gly-Lys-Gly)_n and (Ala-Lys-Ala)_n and fragments of the terminal sections of histones H4 (the sequence 1–16), H2B (1–21), and H1 (152–184), and they have been used as models of histones in complex formation with DNA under various conditions of the medium.V. I. Nikitin Institute of Chemistry, Tadzhik SSR Academy of Sciences, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 391–398, May–June, 1989.     

Determination of the dissociation energy of the C-At bond in substituted astatobenzenes

The dissociation energy of C–At bond /D_C–At/ in a number of astatobenzene derivatives has been determined by pyrolytic method. The values of D_C–At for the astatoaromatic compounds investigated have been found to be independent of the substituents and their relative position in the astatoaromatic system.Dedicated to Prof. V.D. Nefedov on the occasion of his 70th birhtday     

Voltammetric behaviour of the zirconium-phenylfluorone-hexadecyl pyridinium chloride system and the sensitizing effect of surfactants

The adsorptive voltammetric features of the zirconium-phenylfluorone (PF)-hexadecyl pyridinium chloride (CPC) system has been investigated. A sensitizing effect of the surfactant CPC on the adsorption current of the Zr-PF-CPC system were observed by linear potential sweep voltammetry. A new sensitive method determining Zr traces was established, the detection limit and linear relationship is 5.0×10^–9 mol/l and 7.7×10^–9–1.1×10^–7 mol/l, respectively. This method has been applied to mineral samples.     

Gas-chromatographic determination of the ratio of visnadin and dihydrosamidin in mixtures of them

Summary A gas-chromatographic method for determining the ratio of visnadin and dihydrosamidin in mixtures of them has been developed.All-Union Scientific-Research Institute of Medicinal Plants. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 711–714, November–December, 1974.     

Distribution of phospholipids in the organs of the cotton plant in the period of mass fruit-formation

The distribution of phosphorus in the vegetative and generative organs of the cotton plant of variety 159-F has been studied. It has been established that the various organs of the cotton plant differ with respect to the qualitative and quantitative compositions of their phospholipids.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 706–710, November–December, 1981.     

Synthesis and alkylation of 2-mercapto-4-quinazolone and the fungicidal activities of the compounds obtained

A convenient method of obtaining 2-mercapto-4-quinazolone has been developed and the alkylation of its ambidentate anions has been studied. It has been found that they exhibit a dual reactivity in alkylation reactions. It has been shown that alkylated 2-mercapto-4-quinazolones possess a moderate fungicidal activity.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 112–118, January–February, 1982.     

Direct determination of iron in ferritin using the polarographic catalytic current

A new method for the determination of iron in ferritin using the polarographic catalytic current has been developed. Iron is released in NaOH and triethanolamine (TEA) solution and subsequently determined based on the polarographic catalytic wave in the presence of bromate with the peak potential of –1.0 V (vs.SCE). The 2.5-derivative peak height of iron is linearly proportional to its concentration in the range of 8.0 × 10^–8–1.0 × 10^–6 g/ml with a correlation coefficient of 0.9991. The method has been applied to the determination of iron in human fetal liver and horse-spleen ferritin and the recovery is 95–112%.     

Identification of some endogenous metabolites in the leaves of dwarf and tall lines of the cotton plant

The components of cottonplant leaves have been studied. A GC-MS analysis has been made of the secondary metabolites (SMs) in the total extractives of the leaves of cotton plants with different phenotypic characteristics. It has been found that a change in the genotype leads to a change in the composition of the SMs.Deceased.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 484–489, May–June, 1995. Original article submitted October 31, 1994.     

Choice of the best region for channel-by-channel summation of estimating the intensity of single photopeaks

The influence of partial peak width integration on the statistical error has been investigated. It has been shown that integration of the central photopeak part —±(0.55–0.64) FWHM for narrow peaks and ±(0.50–0.53) FWHM for wide peaks-allows to decrease the statistical error 1.5–2.0 times in comparision with the TPA method. The results obtained are valid both for real photopeaks and for smoothed spectra. The theoretical results have been confirmed by experimental data.     

Synthesis and properties of peptide fragments of the S-region of the surface protein of the heptatitis B virus

A peptide fragment with the 140–146 sequence of the main component of the surrace protein of the hepatitis B virus (HBsAG) and a number of its structural analogues have been synthesized by the classical method in solution. Conjugates of the peptides synthesized with bovine serum albumin and with a synthetic polypeptide analogue of polytuftsin have been obtained. The ability of the preparations to bind antibodies from the blood sera of hepatitis B patients has been studied. The possibility has been shown of their use for revealing antibodies to the heptatitis B virus in solid-phase enzyme-mediated immunoassay.Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 406–413, May–August, 1992.     

Integral intensities of the IR bands of the stretching vibrations of the NH,C=O,and C=C groups in theVinca alkaloids

Summary 1. The frequencies and integral intensities of the bands of the stretching vibrations of the NH, C=O, and C=C groups in some indoline, indole, and hydroxyindole alkaloids and certain other compounds have been investigated.2. From the changes in the intensities of the NH bands in vincanine, akuammicine, vinervine O-methyl ether, and their dihydro derivatives, it has been concluded that the first-mentioned compounds contain chelate bonds.3. On the basis of the results of the measurements of the intensities for vincanine and dihydrovincanine, the bands in the 1500–1700 cm^–1 region have been identified.4. The bands in the 1600–1700 cm^–1 region of a number of natural alkaloids are due to the complex vibrations of the whole grouping.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 3, pp. 185–192, 1966     

Interference of humic substances on the speciation analysis of inorganic selenium in waters and soils by DPCSV

A speciation scheme allowing the study of selenium speciation in environmental samples has been developed in order to study the transfer mechanism in the system water/soil/plant/animal. This scheme is based on a set of sample treatment procedures followed by Se(IV) determination by Differential Pulse Cathodic Stripping Voltammetry (DPCSV). Se(IV) may be determined with a detection limit close to 25 ng l^–1 and a linear response in the range 25–4000 ng l^–1. However, humic substances, present in some natural waters and soils, which are adsorbed at the mercury drop electrode (HMDE) surface may alter the signal. This may be caused by a competition between adsorption of organic matter and mercury(II) selenide formation at the electrode surface. As a consequence the detection limit has been increased to ca. 250 ng l^–1 in the presence of 1 mg l^–1 fulvic acids; the linear response range is then shifted to 250–10000 ng l^–1. After an extensive study of these interferences and using standard additions procedures, the Se(IV) content of various waters and soil extracts has been determined by DPCSV with a good reproducibility (RSD about 1%). Accuracy is satisfactory comparing the results obtained by DPCSV to those obtained by Hydride Generation/Quartz Furnace Absorption Atomic Spectrometry (HG/QFAAS).     

Photoreduction of rhenium(VII) in hydrochloric and sulfuric acids and their mixtures

Pulse photolysis has been used to investigate the photochemical reactions that take place in the series of oxochloride complexes of Re(VII), Re(VI), and Re(V) in concentrated hydrochloric and sulfuric acids and their mixtures. The kinetics of the formation and decay of the short-lived complex ReOCl ₅ ^– have been studied as a function, of the composition of the medium (the concentration of the acids and water). The causes of the stabilization of ReOC ₅ ^– in concentrated H₂SO₄ have been elucidated. It has been found that the anion radical Cl ₂ ^– formed in the photolysis of HCl oxidizes the complex ReOCl ₅ ^2– to ReOCl ₅ ^– .Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 3, pp. 296–302, May–June, 1986.