Authors:Q. Zhang, Z. Qian, L. Pan, H. Li, and H. Zhu
Berberine, a primary pharmacological active constitute of Coptidis Rhizoma, could inhibit neuronal apoptosis in cerebral ischemia. Here, we aimed to investigate whether and how HIF-1 is implicated in the anti-apoptosis effect of berberine on neurons under hypoxia/ischemia. Viability of PC12 cells treated with berberine prior to or following CoCl2-induced hypoxia was evaluated. Annexin V-PI staining was employed to analyse cell apoptosis ratio. HIF-1α and apoptosis-associated molecules were detected via Western blotting. TUNEL and immunohistochemistry were used to demonstrate apoptosis, HIF-1α and p53 levels in cerebral tissue of middle cerebral artery occlusion (MCAO) rats. Berberine pretreatment promoted PC12 cells survival and inhibited apoptosis under hypoxia condition. At the same time, it decreased cell viability and enhancement of apoptosis were observed with berberine treatment under hypoxia. Decreased HIF-1α, caspase 9, caspase 3 and increased Bcl-2/Bax ratio were responsible for the anti-apoptosis of berberine pretreatment. However, pro-apoptosis by berberine under hypoxia was indicated with opposing regulation of those molecules. Significant reduction of apoptosis, HIF-1α and p53 were found in cerebral tissue of MCAO rats treated with berberine. The present study suggests that berberine regulates neuronal apoptosis in cerebral ischemia, which might be dependent on the degree of cell injury. HIF-1 and the followed apoptotic pathway are involved in those effects of berberine.
Authors:Y. Li, G. Fei, H. Xingen, L. Ruisen, and L. Zhen
Enthalpies of dilution at 298.15 K of aqueous solutions of THF and 1,4-dioxane have been determined using flow microcalorimetry.
The results obtained were used to determine the homotactic enthalpic interaction coefficients that characterize pair interactions
of THF and 1,4-dioxane in aqueous solution. These are briefly discussed from the point of view of intermolecular interaction
between the hydrated solute species.
Authors:J.R. Li, D.X. Li, L. Li, W.L. Deng, L.S. Ding, H.X. Xu, and Y. Zhou
A rapid and sensitive ultraperformance liquid chromatography-multiple reaction monitoring-multi-stage/mass spectrometry (UPLC-MRM-MS/MS) method has been developed for simultaneous quantification of salvianolic acid B and tanshinone IIA of salvia tropolone tablets in dog plasma. This was achieved by performing quantification using the MRM acquisition with two channels of MRM-MS/MS and MS full scan for more accuracy qualitative results, and the fragmentation transitions of m/z 295→249, 191 for tanshinone IIA and m/z 297→279, 251 for IS in positive mode, m/z 717→519, 321 for salvianolic acid B and m/z 295→267, 239 for IS in negative mode were selected. The UPLC separation was achieved within 3 min in a single UPLC run. Linear calibration curves were obtained over the concentration range of 10 pg/mL−1 ng/mL for tanshinone IIA and 100 pg/mL−1 for salvianolic acid B. Lower limit of quantitation (LLOQ) was 10 pg/mL and 100 pg/mL for tanshinone IIA and salvianolic acid B, respectively. The inter-day and intra-day precision (relative standard deviation, RSD) in all samples were less than 8.21%, and the recoveries were over 85.9% for both tanshinone IIA and salvianolic acid B. The two channels of MRM with MS full scan approach could provide both qualitative and quantitative results without the need for repetitive analyses and resulted in the reduction of further confirmation experiments and analytical time. The pharmacokinetic study of the two active components of salvia tropolone tablets following oral gavage administration of dogs was thus explored with this method.
Authors:Y. Li, H. Xingen, L. Ruisen, and X. Guiying
Enthalpies of dilution of aqueous L-serine, pyridine and methylpyridine solutions and their enthalpies of mixing have been determined by a mixing-flow microcalorimeter
at 298.15 K. The data have been analyzed in terms of McMillan-Mayer formalism to fit to virial polynomials from which the
heterotactic enthalpic pairwise interaction coefficients, hxy, betweenL-serine and pyridine and methylpyridine isomers have been evaluated. The results obtained in the present paper are compared
with those reported in the earlier paper about glycine and L-alanine in the same organic solvent aqueous solutions, giving a global insight of the interaction mechanism between the a-amino
acids and pyridine and methylpyridine from the point of view of solute-solute interactions and substituent effects of methyl
groups introduced into the pyridine ring.
In the present study, the characteric-structure relationship of epoxidized soybean oils (ESO) with various degrees of epoxidation
has been investigated. FTIR analysis was used to identify the relative extent of epoxidation of the samples during the epoxidation
reaction. The viscosities of ESO were much higher than that of the raw oil, viscosity increased with degree of epoxidation.
The viscous-flow activation energy of ESO was determined to be higher than that of the raw oil (20.72 to 77.93% higher). Thermogravimetry
analysis (TG) of ESO was used to investigate the thermodynamic behavior of the samples. With increasing degree of epoxidation,
the thermal stability of the samples initially decreased, then increased at the final reacting stage. Differential scanning
calorimeter (DSC) indicated that the melting point of ESO was higher than that of soybean oil. Gel permeation chromatography
(GPC) indicated the molecular mass of the samples increased initially, then decreased, with an increase in the extent of epoxidation.
The effect of itaconic acid (IA) content and heating rate on the stabilization reactions in poly(acrylonitrile-co-itaconic
acid) (P(AN-co-IA)) was investigated by differential scanning calorimetry (DSC) with peak-resolving method. Increasing IA
content was effective in decreasing the initial temperature and the heat evolved, and found to enhance oxidative reactions
to some extent. While, promoting heating rate resulted in a shift of the exotherm to a higher temperature and a more rapid
liberation of heat. The percentage of area of the first exothermic peak increased with increasing heating rate, which would
be attributed to the enhancement of the free radical cyclization reactions.
Authors:W. Guan, L. Li, H. Wang, J. Tong, and J. Yang
A brown and transparent ionic liquid (IL), [C4mim][FeCl4], was prepared by mixing anhydrous FeCl3 with 1-butyl-3-methylimidazolium chloride ([C4mim][Cl]), with molar ratio 1/1 under stirring in a glove box filled with dry argon. The molar enthalpies of solution, ΔsHm, of [C4mim][FeCl4], in water with various molalities were determined by a solution-reaction isoperibol calorimeter at 298.15 K. Considering
the hydrolyzation of anion [FeCl4]− in dissolution process of the IL, a new method of determining the standard molar enthalpy of solution, ΔsHm0, was put forward on the bases of Pitzer solution theory of mixed electrolytes. The values of ΔsHm0 and the sum of Pitzer parameters:
were obtained, respectively. In terms of thermodynamic cycle and the lattice energy of IL calculated by Glasser’s lattice
energy theory of ILs, the dissociation enthalpy of anion [FeCl4]−, ΔHdis≈5650 kJ mol−1, for the reaction: [FeCl4]−(g)→Fe3+(g)+4Cl−(g), was estimated. It is shown that large hydration enthalpies of ions have been compensated by large the dissociation enthalpy
of [FeCl4]− anion, ΔdHm, in dissolution process of the IL.
AP/HTPB based composite
propellants with additives such as ammonium oxalate (AO), mixture of ammonium
oxalate and strontium carbonate (SC) was investigated by burning rate, TG-DTG
and FTIR experiments. The results show that the burning rates of these propellants
are decreased significantly. TG-DTG experiments indicate that decomposition
temperatures of AP with these additives are increased. Furthermore, the activation
energy of the decomposition reaction of AP is also increased in the presence
of AO or AO/SC. These results show that AO or AO/SC restrains the decomposition
of AP. The burning rates of these propellants are decreased. The burning rate
temperature sensitivity of AP/HTPB based propellants is reduced significantly
by the addition of AO or AO/SC. But the effect of AO is less than that of
AO/SC. AO/SC is better effect to reduce temperature sensitivity and at the
same time, to reduce pressure exponent. The reduced heat release at the burning
surface of AP/HTPB/AO is responsible for the reduced temperature sensitivity.
Synergetic action is probably produced between AO and SC within AP/HTPB based
propellants in the pressure range tested. This synergetic effect causes the
heat release to reduce and the burning surface temperature to increase. Moreover,
it makes the net exothermal reaction of condensed phase become little dependent
on T0. Thus, the
burning rate temperature sensitivity is reduced.