Gravimetric and spectrophotometric method for the quantitative determination of triterpene glycosides in the fruit ofSophora japonica and other plants

For the quantitative determination of triterpene glycosides in the fruit of the Japanese pagoda tree,Sophora japonica, and of other plants, gravimetric and spectrophotometric methods of analysis with an error of the determination of the total glycosides of about 10% are proposed.Translated from Khimiya Prirodnykh Soedinenii, Vol. 33, No. 1, pp. 68–70, January–February, 1977.     

Organomelemental fragmentations : I. Direct and retro fragmentations in organometallic benzyl compounds. Aromatisational metallation

Organometallic benzyl compounds are known to react with eletrophilic agents via two paths, viz., by direct substitution of the metal by the agent, and by attack of the ortho- and para-positions of the ring. The latter reaction leads to expulsion of the metal and formation of unstable triene intermediates (1-methylene-2,4-cyclohexadienes and 1-methylene-2,5-cyclohexadienes). By attributing these processes to electrophilic fragmentations (referred to as F_E) a new process may be predicted to occur, electrpohilic addition of metal salts to the exo-methylene site of trienes of this type. This process can be regarded as the reverse of the fragmentation reaction. The F_E representation proposed here forms the basis for a new organometallic synthesis, aromatisational metallation. It is shown that interaction of 1-methylene-6-ethyl-2,4-cyclohexadiene and 1-methylene-4-ethyl-2,5-cyclohexadiene with mercury dichloride in ether results in the formation of o- and p-ethylbenzylmercury chlorides, respectively.     

Triterpene glycosides ofSophora japonica seeds

We have isolated from the seeds of Sophora japonica the known soyasaponogenol B-3-[O--D-glucopyranosyl-(12)-O--D-glucopyranuronoside] (adzukisaponin II), soyasapogenol B [3-O--galactopyranosyl-(12)-O--L-glucopyranuronoside] (soyasaponin III), soyasapogenol B 3-(O--L-rhamnopyranosyl-(12)-O--L-glucopyranosyl-(12)-O--D-glucopyranuronoside] (adzukisaponin V), soyasapogenol B 3-(O--D-rhamnopyranosyl-(12)-O--D-galactopyranosyl-(12)-O--D-glucopyranuronoside] (soyasaponin I), and the new glycoside (1) — soyasapogenol B 3-[O--D-glucopyranuronoside]. The structure of this glycoside has been established on the basis of the results of enzymatic, complete, and partial hydrolyses and¹³C NMR spectra.Simferopol' State University and Kursk State Medical Institute, Kursk. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 709–713, September–October, 1995. Original submitted March 3, 1995.     

Direct Heterogeneous Electron Transfer Reactions of Bacillus halodurans Bacterial Blue Multicopper Oxidase

Direct electron transfer reactions of Bacillus halodurans bacterial multicopper oxidase on bare spectrographic graphite, as well as bare and thiol‐modified gold electrodes were studied using cyclic voltammetry, potentiometry, amperometry, and spectroelectrochemistry. The redox potential of the T1 site of the enzyme was measured using mediatorless redox titration and found to be 325 mV±10 mV vs. NHE. From measurements with a mercaptopropionic acid‐modified gold electrode under aerobic conditions a midpoint potential of 360 mV vs. NHE for the T2/T3 copper cluster is deduced. Differing from most other characterized laccases of fungal and plant origins this bacterial enzyme exhibits bioelectrocatalytic activity at neutral pH and tolerates high chloride concentrations (200 mM), conditions that usually strongly inhibit catalysis. Moreover, it has the very high affinity towards molecular oxygen both in solution and in the adsorbed state (K_M≤50 μM).     

New family of polydentate tetrazole-pyrazoline ligands prepared by the azido-Ugi reaction

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Carpet—2 Search for Gamma Rays above 100 TeV in Coincidence with HAWC and IceCube Alerts

JETP Letters - We report on the search of astrophysical gamma rays with energies in the 100 TeV to several PeV range arriving in directional and temporal coincidence with public alerts from HAWC...     

Enhancement of Raman scattering by ultramarine using silver films on surface of germanium quantum dots on silicon

The germanium on silicon (Ge-on-Si) semiconductor nanostructures with a vacuum-deposited silver coating are tested as substrates for detecting microamounts of inorganic crystalline ultramarine pigment by enhanced Raman scattering (SERS). At least tenfold enhancement of Raman lines is obtained. The quantum-chemical calculations are performed and used to assign the bands in the Raman spectra. A significant electrooptic anharmonicity of vibrations of chromophore groups in the presence of an SERS-active compound is found.