Conformational study of a native monodisulfide bridge analogue of EETI II

Summary Trypsin inhibitor EETI II, possessing six cysteines engaged in three disulfide bridges, shares a common structural motif with other proteins of different origins and functions. To understand the principles that govern folding of this largely distributed basic scaffold, mainly composed of a small triple-stranded β-sheet, we have studied different stages in the folding of EETI II. The conformational properties of a synthetic analogue of EETI II possessing only one native (15–27) disulfide bridge were investigated with the combined use of¹H NMR and molecular modelling. Although two native-like reverse turns were observed, formation of β-sheet could not be evidenced in the one disulfide analogue, while the motif has been shown to be present in a folding intermediate with two native disulfide bridges (9–21 and 15–27). These results suggest that the structural motif requires stabilisation by two disulfide bridges.     

Four New Flavonoid C-Glycosides Isolated from Achyranthes aspera and Their Nitric Oxide Production Inhibitory Activities

A chemical study of the methanol extract of the aerial parts of Achyranthes aspera led to the isolation of four new flavonoid C-glycosides ( 1 – 4 ) along with eight known analogs ( 5 – 12 ). Their structures were elucidated by a combination of spectroscopic data analysis, HR-ESI-MS, 1D and 2D NMR spectra. All the isolates were evaluated their NO production inhibitory activity in LPS-activated RAW264.7 cells. Compounds 2 , 4 , and 8 – 11 showed significant inhibition with IC₅₀ values ranging from 25.06 to 45.25 μM, compared to that of the positive control compound, L-NMMA, IC₅₀ value of 32.24 μM, whereas the remaining compounds were weak inhibitory activity with IC₅₀ values over 100 μM. This is the first report of 7 from Amaranthaceae family, and 11 from the genus Achyranthes.     

Chemical Composition,Antimicrobial, Nitric Oxide Inhibition and Cytotoxic Activity of Essential Oils from Zanthoxylum acanthopodium DC. Leaves and Stems from Vietnam

This study was aimed to investigate the chemical composition and biological activities of leaf and stem essential oils of Zanthoxylum acanthopodium DC. from Vietnam. Their chemical composition was analyzed by GC/MS. Antimicrobial activities were evaluated by microdilution broth assay. Anti-inflammatory activity was evaluated by the ability to inhibit nitric oxide production in macrophage cells. Cytotoxic activity was evaluated using the sulforhodamine B assay on three human cancer cell lines. Forty-four compounds were identified in the leaf oil, among which dehydroaromadendrane (23.4 %), (E)-carpacin (17.6 %), 2-tridecanone (12.2 %), and 9-methyl-2-decanone (11.8 %) were the most abundant. The stem oil contained fifty-five identified constituents, mainly γ-gurjunene (51.1 %) and butyl acetate (11.8 %). Both oils exhibited inhibitory effects on three bacterial strains, namely S. aureus, E. coli, P. aeruginosa and a fungal strain C. albican, while showed insignificant effects on B. subtilis, L. fermentum, and S. enterica. Both oils showed weak NO production inhibition in LPS-induced RAW264.7 cells, but exhibited potent cytotoxic activity against all three tested cell lines SK-LU-1, MCF-7, and HepG2 with the IC₅₀ values ranging from 16.03±0.77 to 35.60±1.62 μg/mL. This is the first report on the antimicrobial, anti-inflammatory and cytotoxic activities of essential oils from the leaves and stems of Z. acanthopodium.     

Comparative Study of the Effect of Snake Venoms on the Growth of Ciliates Tetrahymena pyriformis: Identification of Venoms with High Antiprotozoal Activity

Doklady Biochemistry and Biophysics - To search for compounds with antiprotozoal activity, effects of snake venoms on the ciliates Tetrahymena pyriformis was studied. T. pyriformis from subkingdom...     

Change in water proton relaxation time during erythrocyte maturation

Erythrocyte populations from newborn and mature mice were characterized according to: size; ultrastructural features; water content; concentration of intraerythrocyte elements including Na, Cl, K, P, S, Mg, and Fe; and the spinlattice (T1) and spin-spin relaxation times of water protons as measured by nuclear magnetic resonance (NMR) spectroscopy. A significant increase in the T2 time from 142 +/- 3 msec to 184 +/- 3 msec occurred during erythrocyte maturation. This change in T2 time was correlated with a change from a polyribosome-rich hemoglobin-poor cell type to a polyribosome-absent hemoglobin-rich cell type. The change in T2 time could also be correlated to a significantly higher K and P concentration in the mature erythrocytes. The change in T2 time was not correlated to a change in cellular water content or to the concentration of any of the other elements measured by electron probe X-ray microanalysis. If the NMR relaxation times of water molecules truly reflect their average motional freedom, then the findings suggest that greater water ordering interaction occurs in the ribosome containing immature erythrocyte.