Effect of transition metal cations on the local structure and lithium transport in disordered rock-salt oxides.

Lithium-excess oxides Li1.2Ti0.4Mn0.4O2 and Li1.3Nb0.3Mn0.4O2 with a disordered rock-salt structure and Mn3+/Mn4+ as a redox couple were compared to analyze the effect of different d0 metal ions on the local structure and Li+ ion migration. These cathode materials were obtained by mechanochemically assisted solid-state synthesis. Using XRD, 7Li NMR and EPR spectroscopy and transmission electron microscopy it was shown that the Mn ions are prone to form clusters, while d0 metal ions are evenly distributed in the crystal lattice. The presence of Nb5+ ions contributes to the formation of noticeably larger Mn clusters and larger gaps in the Li+ migration maps as compared to Ti4+. These results were confirmed by the geometrical-topological method, BVSE simulation and DFT calculations, and are in good agreement with the Li diffusion coefficient determined by GITT, which is 1.5 orders of magnitude higher in Li1.2Ti0.4Mn0.4O2 than that in Li1.3Nb0.3Mn0.4O2.

CYTOTOXIC PROPERTIES OF TRITERPENE SAPONIN TAUROSID SX1 AND ITS EFFECT ON HUMAN IMMUNODEFICIENCY VIRUS AND INFLUENZA VIRUS INFECTION IN MICE.

Triterpene saponin Taurosid Sx1 purified from leaves of the plant Crimean Ivy Hedera taurica Carr. (Araliaceae) was evaluated for its cytotoxic activity against lymphoblastoid cell lines MT-4, Jurkat-tat, U937, and human peripheral blood monocytes. The ability of saponin to influence HIV-1 replication was studied as well. In addition, the ability of Taurosid Sx1 to increase survival of mice infected with influenza virus А/WSN/1/33(H1N1) and its capacity for strengthening the immune responses in mice immunized with the influenza vaccine Grippol® have been studied. Taurosid Sx1 has been shown to inhibit MT-4 cell line at 25 µg ml-1 concentration, IC50 33,3 µmol l-1 (MTT assay). The saponin concentration of 5 µg ml-1 was non-toxic for all the cell lines studied and demonstrated a moderate inhibitory effect on HIV p24 production in Jurkat-tat cells. In the lower concentrations Taurosid Sx1 did not stimulate HIV p24 production. It was shown that oral administration of 200 µg Taurosid Sx1 to the influenza virus infected mice caused 1.5-fold increase in their survival. Taurosid Sx1 given orally amplified immunopotentiating ability of an intramusculary administered subunit influenza vaccine. Antibody production was significantly higher in animals fed Taurosid Sx1 after primary or secondary immunizatuion. In mice given 2 doses of vaccine, from 1 to 3 weeks apart, feeding 200 µg saponin resulted in 2 to 10-fold enhancement in production of anti-H1, anti-H3, and anti-inluenza type B hemagglutinin antibodies. Thus, Taurosid Sx1 can be considered as low-toxic promising immunopotentiating agent uncapable of enhancing HIV-1 replication.

[Antimicrobial activity of saponins from Hedera taurica C a r r]. / Izuchenyie antimikrobnoi aktivnosti saponinov iz pliushcha krymskogo (Hedera taurica C a r r.).

The antibacterial and antifungal action of saponins Sx1, taurozide H2, taurozide I and their effect on bioluminescent system of photobacteria Photobacterium phosphoreum (Cohn) Ford were investigated. Saponins H2 and I had no antimicrobial effect. Saponin Sx1 possessed antifungal activity in vitro with respect to Candida albicans, C. krusei, C. tropicalis. Saponin Sx1 is less toxic to P. phosphoreum than well-known antiseptics--chlorhexedin and miramistin.