Rat and human embryo and post-natal sera contain a potent endogenous competitor of estrogen-rat alpha-fetoprotein interactions

A highly active inhibitor of the binding of estrone and estradiol-17β to rat alpha-fetoprotein is demonstrated for the first time in embryo, immature and adult rat sera as well as in fetal and adult human sera. The competitive character and the narrow specificity of this inhibition effect is shown. The major compound responsible for this activity is isolated by successive column Sephadex LH₂₀ and thin layer chromatography : it is characterized as a nonpolar, nonphenolic, dialysable and thermostable substance, unreactive towards anti-estrone and anti-estradiol-17β anti-bodies. The possible biological role of an endogenous non-estrogen ligand of rodent fetoproteins is discussed.     

鹿衔草化学成分的研究：羟基肾叶鹿蹄草甙的结构鉴定

从鹿衔草（Ｐｙｒｏｌａ ｃａｌｌｉａｎｔｈａ Ｈ．Ａｎｄｒｅｓ）分离得到两个化合物。经光谱分析,确定其中１个化合物为新化合物,命名为羟基肾叶鹿蹄草甙（１, ｈｙｄｒｏｘｙｌｒｅｎｉｆｏｌｉｎ）,另一化合物为儿茶素（３）。     

Reconstruction of lignin and hemicelluloses by aqueous ethanol anti‐solvents to improve the ionic liquid‐acid pretreatment performance of Arundo donax Linn

Ionic liquid (IL)‐acid pretreatment is known to not only enhance the enzymatic hydrolysis efficiency of lignocellulose but also to generate deposits on the surface of fiber by conventional water regeneration, which retard the increment. In this study, ethanol aqueous solution regeneration was developed as a new method to change the substrates characteristics for IL‐acid pretreatment and their effects on the enzymatic hydrolysis were evaluated. Following the IL‐acid reaction, the biomass slurry was subjected to ethanol aqueous solution at various concentration. Results indicated that anti‐solvent choice significantly influenced the reconstruction of both hemicelluloses and lignin as a result of the competition between water and ethanol. The partial removal of hemicelluloses and suitable lignin re‐localization contributed to a more porous structure. Consequently, the cellulose digestibility of aqueous ethanol regenerated samples was dramatically enhanced to ～100% and approximately 11‐ and 2‐fold higher than that of untreated and conventional water regenerated pretreated samples, respectively. A giant leap in the initial rate of enzymatic hydrolysis was also detected in 50% ethanol aqueous solution regenerated samples and only about 10 hr was needed to convert 80% of cellulose to glucose due to the appearance of cellulose II hydrate‐like and more porous structure.     

Free-radical Scavengers and Antioxidants from Peumus boldus Mol. ("Boldo")

The dry leaves of Peumus boldus (Monimiaceae) are used in infusion or decoction as a digestive and to improve hepatic complains. Preliminary assays showed free-radical scavenging activity in hot water extracts of boldo leaves, measured by the decoloration of a methanolic solution of the 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH). Assay-guided isolation led to the active compounds. Catechin proved to be the main free-radical scavenger of the extracts. Lipid peroxidation in erythrocytes was inhibited by boldo extracts and fractions at 500 &#119 g/ml with higher effect for the ethyl acetate soluble and alkaloid fractions. The IC 50 for catechin and boldine in the lipid peroxidation test were 75.6 and 12.5 &#119 g/ml, respectively. On the basis of dry starting material, the catechin content in the crude drug was 2.25% while the total alkaloid calculated as boldine was 0.06%. The activity of boldine was six times higher than catechin in the lipid peroxidation assay. However, the mean catechin:total alkaloid content ratio was 37:1. The relative concentration of alkaloids and phenolics in boldo leaves and their activity suggest that free-radical scavenging effect is mainly due to catechin and flavonoids and that antioxidant effect is mainly related with the catechin content. The high catechin content of boldo leaves and its bioactivity suggest that quality control of Boldo folium has to combine the analysis of catechin as well as their characteristic aporphine alkaloids.     

Tea extracts differentially inhibit Streptococcus mutans and Streptococcus sobrinus biofilm colonization depending on the steeping temperature

Abstract

This study aimed to evaluate the effects of tea extracts on oral biofilm colonization depending on steeping temperature. S. mutans and S. sobrinus were cultured and treated with green or black tea extracts prepared under different steeping conditions. Biofilm formation, glucosyltransferase (GTF) levels, bacterial growth, and acidogenicity were evaluated. Biofilms were also assessed by gas chromatography-mass spectrometry and confocal laser scanning microscopy. All extracts with hot steeping showed higher inhibitory effects on biofilm formation and cell viability and lower GTF levels compared with those with cold steeping (p?<?0.05). Hot steeping significantly reduced bacterial growth (p?<?0.05) and maintained the pH. Catechins were only identified from hot steeping extracts. Within the limits of this study, extracts with cold steeping showed lower inhibitory effects on oral biofilms. The different effects between steeping extracts may be attributed to the difference in catechins released from tea extracts under the different steep conditions.     

Molecular dynamics simulation of diffusion of hydrogen in binary hydrogen–tetrahydrofuran hydrate

The binary structure II hydrogen–tetrahydrofuran (THF) hydrate was studied with molecular dynamics simulation. The simulations were carried out at 300, 310 K and 10.1 MPa, and with various contents of hydrogen and THF. The migrations of hydrogen molecules from cage to cage were observed. The migration process of hydrogen was also analysed, and the diffusion coefficients of hydrogen in the hydrate were calculated. The calculated diffusion coefficients qualitatively agreed with the experimental data. Double and quintet occupancies of hydrogen molecules were observed in the small and large cages, respectively, without changing the hydrate structure.     

Molecular dynamics simulation on the decomposition of type SII hydrogen hydrate and the performance of tetrahydrofuran as a stabiliser

Molecular dynamics simulation is used to study the decomposition and stability of SII hydrogen and hydrogen/tetrahydrofuran (THF) hydrates at 150 K, 220 K and 100 bar. The modelling of the microscopic decomposition process of hydrogen hydrate indicates that the decomposition of hydrogen hydrate is led by the diffusive behaviour of H₂ molecules. The hydrogen/THF hydrate presents higher stability, by comparing the distributions of the tetrahedral angle of H₂O molecules, radial distribution functions of H₂O molecules and mean square displacements or diffusion coefficients of H₂O and H₂ molecules in hydrogen hydrate with those in hydrogen/THF hydrate. It is also found that the resistance of the diffusion behaviour of H₂O and H₂ molecules can be enhanced by encaging THF molecules in the (5¹²6⁴) cavities. Additionally, the motion of THF molecules is restricted due to its high interaction energy barrier. Accordingly, THF, as a stabiliser, is helpful in increasing the stability of hydrogen hydrate.     

Amelioration of cognitive impairment and neurodegeneration by catechin hydrate in rat model of streptozotocin-induced experimental dementia of Alzheimer’s type

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder resulting in cognitive decline and enhancement of oxidative loads in the brain. Flavonoids have been considered to exert human health benefits by anti-oxidant and anti-inflammatory properties. The present study is aimed to elucidate the neuroprotective effect of catechin hydrate (CH), a natural flavanoid with potential antioxidant and anti-inflammatory properties, on intracerebroventricular streptozotocin (ICV-STZ) induced neuronal loss and memory impairment. To test this hypothesis, male Wistar rats were pretreated with CH (10 and 20 mg/kg bwt) orally once daily for 21 days and then bilaterally injected with ICV-STZ (3 mg/kg bwt), while sham group rats receive the same volume of vehicle. After 2 weeks of ICV-STZ infusion, rats were tested for cognitive performance using Morris water maze (MWM) test and then sacrifice for biochemical and histopathological assays. CH was found to be successful in upregulating the antioxidant status and prevented the memory loss. The expression of choline acetyl transferase (ChAT) was decreased in ICV-STZ group and CH pretreatment increases the expression of ChAT. Moreover, inflammatory mediators like TNF-α, IL-1β levels and expression of iNOS were significantly attenuated by CH pretreatment. The study suggests that CH is effective in preventing memory loss, ameliorating the oxidative stress and might be beneficial for the treatment of sporadic dementia of Alzheimer’s type (SDAT).     

Interaction of Catechu Dye with DNA: Spectroscopic and In Silico Approach

Catechin, a yellow colored molecule obtained from the wood of Acacia catechu was analyzed for its interaction with synthetic DNA duplexes using spectroscopic analysis. UV-Visible spectroscopic analysis revealed the non-intercalative binding mode. Fourier Transform Infrared spectroscopy (FTIR) analysis expose chemical shift indicated by various vibrational stretches and an increase in the intensity of base stacking was observed by Circular Dichroism (CD), respectively. This inference was further confirmed through nuclear staining technique and also in electrophoretic technique; the dye quenches the fluorescent intensity of ethidium bromide. The result of fluorescence spectroscopy was in concordance with the electrophoretic technique. In addition, the spectroscopic results were in accordance with the molecular docking studies of specific catechin compound from the catechu dye with CT-DNA. This kind of site specificity is a gain in the medicinal field as the drug can be DNA targeted for cancer therapeutics. The present work reveals that catechu dye has a noteworthy application in the field of medical bioscience.