Antihepatotoxic and antioxidant activities of methanol extract and isolated compounds from Ficus chlamydocarpa

Free radicals, in particular radical oxygen species (ROS), play an important role in the aetiology and pathogenesis of various diseases. Current research in many countries focuses on the use of local medicinal plants as a promising source of liver protective agents. This paper describes the hepatoprotective effects of the methanol extract and four isolated compounds from Ficus chlamydocarpa on CCl4-induced liver damage, as well as the possible antioxidant mechanisms involved in this protection. The DPPH test, along with the beta-Carotene-Linoleic Acid Model System and Ferric-Reducing Antioxidant Power assays, as well as the inhibition of microsomal lipid peroxidation were used to measure radical-scavenging and antioxidant activities. Pretreatment of rats with the methanol extract of F. chlamydocarpa before CCl4 administration, significantly prevented serum increase of hepatic enzyme markers, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT), in a dose-dependent manner. The hepatoprotection was also associated with a significant enhancement in hepatic reduced glutathione (GSH) and a marked decrease of liver malondialdehyde (MDA). Among the four compounds 1-4, isolated from the methanol extract, alpha-amyrin acetate (1) and luteolin (4) showed a significant hepatoprotective activity, as indicated by their ability to prevent liver cell death and lactate dehydrogenase (LDH) leakage during CCl4 intoxication.     

A combined ab initio/Franck-Condon study of the A-X single-vibronic-level emission spectrum of CCl2 and the photodetachment spectrum of CCl2 -.

State-of-the-art ab initio calculations have been carried out on the X1A1, ?3B1 and A1B1 states of CCl2 and the X2B1 state of CCl2-. Franck-Condon factors including anharmonicity have been calculated, between the CCl2 states, and between the CCl2- X2B1 state and the CCl2 states. They are used to simulate the A-X single-vibronic-level (SVL) emission spectra of CCl2 determined by M.-L. Lui et al. [PCCP 2003, 5, 352] and the 364 nm laser photodetachment spectrum of CCl2- obtained by R. L. Schwartz et al. [J. Phys. Chem. A 1999, 103, 8213]. Comparison between simulated and observed spectra confirms the vibrational assignments of the X2B1 SVL emission spectra and the T0 position of the A1B1 state of CCl2. For the photodetachment spectrum of CCl2-, spectral simulation shows that the higher binding energy ?3B1(CCl2) <-- X2B1(CCl2-) band is well separated from the X1A1(CCl2) <-- X2B1(CCl2-) band. It is concluded that the observed second band, which overlaps heavily with the X1A1(CCl2) <-- X2B1(CCl2-) band in the photodetachment spectrum of CCl2- cannot be assigned to the CCl2(?3B1) + e --> CCl2-(X2B1) detachment process. Further ab initio calculations carried out in the present investigation support the suggestion that the second band in the 364 nm photodetachment spectrum of CCl2- is due to detachment from an excited state of CCl2-, a linear quartet state, to a triplet state of CCl2. These calculations identify the anionic state to be the lowest 4Sigmag- (4Sigma-) state, which photodetaches vertically to the 3Sigmag- (3Sigma-; adiabatically ?3B1) and/or 3Pi(u) (3Pi) states of CCl2 to give the second band observed in the 364 nm photodetachment spectrum of CCl2-.     

Further investigation of the photodissociation dynamics of dichlorocarbene near 248 nm

A further investigation of the 248 nm photodissociation of CCl(2), which expands upon our original study of this process [S. K. Shin and P. J. Dagdigian, Phys. Chem. Chem. Phys. 8, 3446 (2006)], is presented. The CCl(2) parent molecule and the CCl photofragment were detected by laser fluorescence excitation in a molecular beam experiment. From the dependence of the CCl(2) signals on the photolysis laser fluence, attenuation cross sections of the 0(0), 1(1), and 2(1) vibrational levels were determined; the cross sections for the excited vibrational levels were found to be significantly smaller than those for the ground vibrational level. The previously observed fragment CCl bimodal rotational state distribution was found to arise from the photolysis of more than one parent molecule. At low CHCl(3) mole fractions in the gas supplied to the pyrolysis beam source, it was concluded that CCl(2) is the photolysis precursor for both low-J and high-J CCl fragments. On the basis of the dependence of the CCl signals on the photolysis laser fluence, ground and vibrationally excited CCl(2), respectively, were assigned as the precursors to these two classes of fragments. The photofragment excitation spectra for low-J and high-J CCl fragments from the photolysis of CCl(2) were recorded in the wavelength range around 248 nm; both were found to be structureless. The 248 nm photodissociation dynamics of CCl(2) is discussed in light of our experimental observations and quantum chemical calculations of the CCl(2) excited electronic states.     

Probing the interaction of amorphous solid water on a hydrophobic surface: dewetting and crystallization kinetics of ASW on carbon tetrachloride

Desorption of carbon tetrachloride from beneath an amorphous solid water (ASW) overlayer is explored utilizing a combination of temperature programmed desorption and infrared spectroscopy. Otherwise inaccessible information about the dewetting and crystallization of ASW is revealed by monitoring desorption of the CCl(4) underlayer. The desorption maximum of CCl(4) on graphene occurs at ~140 K. When ASW wets the CCl(4) no desorption below 140 K is observed. However, the mobility of the water molecules increases with ASW deposition temperature, leading to a thermodynamically driven dewetting of water from the hydrophobic CCl(4) surface. This dewetting exposes some CCl(4) to the ambient environment, allowing unhindered desorption of CCl(4) below 140 K. When ASW completely covers the underlayer, desorption of CCl(4) is delayed until crystallization induced cracking of the ASW overlayer opens an escape path to the surface. The subsequent rapid episodic release of CCl(4) is termed a "molecular volcano". Reflection absorption infrared spectroscopy (RAIRS) measurements indicate that the onset and duration of the molecular volcano is directly controlled by the ASW crystallization kinetics.     

Resonant dissociative electron transfer of the presolvated electron to CCl4 in liquid: Direct observation and lifetime of the CCl4*- transition state

We report a pump-probe femtosecond transient absorption spectroscopic study on the electron transfer reaction of CCl(4) in liquid ethanol. By direct observations of the presolvated electron and of the reaction transition state CCl(4) (*-), this study provides direct evidence of the resonant dissociative electron transfer (RDET) of the presolvated electron to CCl(4). Moreover, the lifetime of CCl(4) (*-) in ethanol is directly obtained from the decay kinetics and its measured value is found to be nearly identical to its gas-phase value. Hence, these results also imply that RDET can be an efficient process in an aqueous environment.     

Theoretical Study on the Reaction Mechanism between Dichlorocarbene and Armchair Single-walled Carbon Nanotubes

1 INTRODUCTION Carbon nanotubes have many potential applica- tions due to their unique structures and properties[1～4]. Physicists have been studying their electrical, me- chanical and other properties since their discove- ries[5, 6]. Recently, chemists are interested in carbon nanotubes because their properties can be altered by chemical functionalization[7～14], and these functiona- lized nanotubes can undergo further chemical trea- tment. So the potential application range of such na- …     

A New Target for Synthesis: Theoretical Prediction for the Reaction between Boron Nitride Nanotube and Dichlorocarbene

Understanding the chemistry of BNNT is a crucial step toward their ultimate practical use. A comparative study of Reactions A （ASWCNT （5,5） and CCl2） and B （ASWBNNT （5,5） and CCl2） have been performed by using ONIOM （B3LYP/6-31G＊： AM1） method in Gaussian03 program package. The results show that （1） the two reactions are both exothermic; （2） the mechanism of Reaction B is a two-step mechanism; （3） the difference in energy barriers suggests that the reaction of CCl2 with BNNT is easier than with CNT; （4） in reaction B, CCl2 prefers to attack the boron atom of BNNT first.     

Infrared study of 6-methylcoumarin in binary solvent mixtures

The infrared absorption spectra of the carbonyl stretching vibrations of 6-methylcoumarin (6MC) have been investigated in CCl4/ROH mixtures (CCl4/C2H5OH, CCl4/n-C3H7OH, CCl4/i-C3H7OH, and CCl4/t-C5H11OH). Two types of carbonyl stretching vibration bands for 6MC are found with the change of the mole fraction of the aprotic solvent CCl4(X CCl4 in binary solvent mixtures. The dependencies of the frequencies of carbonyl stretching vibrations upsilon(C=O) on X CCl4 allow a distinction and assignment of all species resulting from the solvent-solute interactions. Linear correlations between the upsilon(C=O) of each species and X CCl4 are found. The influence on the transformation of some species caused by the self-associated alcohols is discussed.     

Enols of amides activated by the 2,2,2-trichloroethoxycarbonyl group

Reaction of isocyanates XNCO (X = Ar, i-Pr, t-Bu) with CH(2)(Y)CO(2)CH(2)CCl(3) (Y = CO(2)Me, CO(2)CH(2)CCl(3), CN) gave 15 amides XNHCOCH(Y)CO(2)CH(2)CCl(3) (6) or enols of amides XNHC(OH)=C(Y)CO(2)CH(2)CCl(3) (5) systems. The amide/enol ratios in solution depend strongly on the substituent Y and the solvent and mildly on the substituent X. The percentage of enol for group Y increases according to Y = CN > CO(2)CH(2)CCl(3) > CO(2)Me and decreases with the solvent according to CCl(4) > C(6)D(6) > CDCl(3) > THF-d(8) > CD(3)CN > DMSO-d(6). With the most acidic systems (Y = CN) amide/enol exchange is observed in moderately polar solvents and ionization to the conjugate base is observed in DMSO-d(6). The solid-state structure of the compound with Y = CN, X = i-Pr was found to be that of the enol. The reasons for the stability of the enols were discussed in terms of polar and resonance effects. Intramolecular hydrogen bonds result in a very low delta(OH) and contribute to the stability of the enols and are responsible for the higher percentage of the E-isomers when Y = CO(2)Me and the Z-isomers when Y = CN. The differences in delta(OH), delta(NH), K(enol), and E/Z enol ratios from the analogues with CF(3) instead of CCl(3) are discussed.     

Photodissociation dynamics of dichlorocarbene at 248 nm

The dynamics of the 248 nm photodissociation of the CCl(2) molecule have been investigated in a molecular beam experiment. The CCl(2) parent molecule was generated in a molecular beam by pyrolysis of CHCl(3), and both CCl(2) and the CCl photofragment were detected by laser fluorescence excitation. The 248 nm attenuation cross sections was estimated from the reduction of the CCl(2) signal as a function of the photolysis laser fluence. The internal state distribution of the CCl photofragment was derived from analysis of laser fluorescence excitation spectra in the A (2)Delta- X (2)Pi band system. The CCl(X (2)Pi, nu = 0) rotational state distribution was found to be bimodal, with maximum populations at N approximately 10 and 85, and was dependent upon the source backing pressure, and hence upon the internal state distribution of the CCl(2) precursor. The 248 nm photodissociation dynamics appears to involve two separate channels, namely nearly impulsive rotational energy release and predissociation with little rotational energy imparted to the CCl fragment.     

Dynamics of the 193 nm photodissociation of dichlorocarbene

The dynamics of the 193 nm photodissociation of the CCl2 molecule have been investigated in a molecular beam experiment. The CCl2 parent molecule was generated in a molecular beam by pyrolysis of CHCl3, and both CCl2 and the CCl photofragment were detected by laser fluorescence excitation. The 193 nm attenuation cross section was estimated from the reduction of the CCl2 signal as a function of the photolysis laser fluence. The internal state distribution of the CCl photofragment was derived from analysis of laser fluorescence excitation spectra in the A 2Delta-X 2Pi band system. Most of the energy available to the CCl(X 2Pi)+Cl fragments appears as translational energy. The CCl fragment rotational energy is much less than predicted in an impulsive model. The excited electronic state appears to dissociate indirectly, through coupling with a repulsive state arising from the ground-state CCl(X 2Pi)+Cl asymptote. The identity of the initially excited electronic state is discussed on the basis of what is known about the CCl2 electronic states.     

Depolarization ratio and correlation between the relative intensity data and the abundance ratio of various isotopes of liquid carbon tetrachloride at room temperature

The room temperature Stokes and anti-Stokes Raman spectra of liquid CCl(4) have been recorded. The intensity ratios of anti-Stokes to Stokes Raman bands as a function of Raman shift are obtained in agreement with polarizability theory. The depolarization ratio rho (nu) as a function of Raman shift is obtained also in agreement with automatically scanned depolarization ratio rho (nu). Ratio of the intensity of the isotopic nu(1) bands indicates small deviation from the theoretical relative abundance of CCl(4) isotopes. The intensity ratio of the [nu(3)-nu(4), (nu(1)+nu(4))-nu(4)] and nu(1) bands is obtained. The consequences of the presence of different isotopes of CCl(4) on the depolarization ratio of its vibrational bands are discussed. The effects of impurities in liquid CCl(4) on depolarization ratio of the nu(1) band are estimated.     

多氟代烃类的反应II: 氟氯烯烃与三氯化铝的反应

研究了以CFCl2CF2CF=CF2(1)和CFCl2CF=CFCF2(2)为原料与三氯化铝的反应.结果获得重排产品CCl2=CF2CF2CF3(3).结果支持了从1到3的分子间重排反应的机理.在激烈条件下,3进一步与氯化铝反应得到CCl2=CFCCl2CF3(4),CCl2=CClCCl2CF3(5),CCl2=CClCCl2CClF(6),CCl2=CClCCl2CFCCl2(7)和CCl2=CClCCl2CCl3(8).由分离所得产品的结构可推断化合物3中氟原子被氯原子取代的稳定性按以下次序:CF3->CF=>=-CF2CF=.反应条件对产品得率的影响也被讨论了.     

CCl4的光解微观机制研究

利用激光光解瞬态吸收光谱技术,研究有氧和无氧条件下CCl4的激光光解.结果表明,在248 nm激光作用下, CCl4发生了单光子吸收,反应生成{CCl4－Cl}σ电荷转移复合物、(CCl3＋…Cl－)离子对、CCl3O2过氧自由基等瞬态物种,它们的衰减过程是表观一级反应. {CCl4－Cl}σ电荷转移复合物在有氧/无氧条件下的拟合衰减速率常数分别是3.38×106 s－1和3.65×106 s－1,它的形成不受氧气含量影响. (CCl3＋…Cl－)离子对在有氧/无氧条件下的拟合衰减速率分别为3.73×107 s－1和3.02×107 s－1,它的形成也不受氧气含量影响, CCl3O2过氧自由基需在有氧条件下形成,拟合衰减速率是2.32×104 s－1.     

分子束技术研究Ba与CHCl~3, CCl~4的反应

本文分别在交叉分子束和分子束-气体条件下, 利用化学发光方法, 研究了Ba(^3D)+CH~2Cl~2, CHCl~3,CCl~4和Ca(^1S~O),Ca(^3P),Ba(^1S～O)Ba(^3D)+CCl~4的反应, 实验得出了Ba(^3D)与CH~2Cl~2, CHCL~3, CCl~4反应时, A^2II,B~2Σ^+态BACl产物的发光截面对反应物碰撞能的依赖关系和反应阈能, 以及Ba(^3D)与CCl~4反应时, 产生电子激发态BaCl产物的光子产率。发现当Ba,Ca被激发到亚稳态时, Ba+CCl~4的反应电子基态BaCl产物的振动激发增加; 而Ca+CCl~4的反应电子基态CaCl产物的转动激发增加. 并针对以上结果进行分析讨论。     

Intermolecular vibrational modes and orientational dynamics of cooperative hydrogen-bonding dimer of 7-azaindole in solution

We observed the low-frequency Raman-active intermolecular vibrational modes of 7-azaindole in CCl(4) by femtosecond Raman-induced Kerr effect spectroscopy. To understand the dynamical aspects and vibrational modes of 7-azaindole in the solution, the ultrafast dynamics of 1-benzofuran in CCl(4) was also examined as a reference and ab initio quantum chemistry calculations were performed for 7-azaindole and 1-benzofuran. The cooperative hydrogen-bonding vibrational bands of 7-azaindole dimer in CCl(4) appeared at 89 cm(-1) and 105 cm(-1) represent the overlap of stagger and wheeling modes and the intermolecular stretching mode, respectively. They are almost independent of the concentration in the solution. We further found from the low-frequency differential Kerr spectra of the solutions with neat CCl(4) that the intermolecular motion in the low frequency region below 20 cm(-1) was less active in the case of 7-azaindole/CCl(4) than in the case of 1-benzofuran/CCl(4). The slow orientational relaxation time in 7-azaindole/CCl(4) is ~3.5 times that in 1-benzofuran/CCl(4) because of the nature of the dimerization of 7-azaindole.     

INFLUENCE OF DIALKYLZINC IN RARE-EARTH TERNARY CATALYST ON THE COPOLYMERIZATION OF CARBON DIOXIDE AND PROPYLENE OXIDE

Rare-earth ternary catalysts Y（CCl3COO）3-ZnR2-glycerin were prepared for the copolymerization of carbon dioxide and propylene oxide （PO）, where dialkylzincs （ZnR2） were diethylzinc, di（n-propyl）zinc, di（n-butyl）zinc, di（i-propyl）zinc, di（i-butyl）zinc, di（s-butyl）zinc,respectively. The Y（CCl3COO）3-ZnR2-glycerin catalysts displayed the highest catalytic activity at the molar ratio of Y（CCl3COO）3：ZnR2：glycerin = 1：20：10. In the same copolymerization condition, catalysts containing dialkylzincs with branched alkyl group showed lower catalytic activity than that with primary alkyl group. For those catalysts including dialkylzincs with primary alkyl group, their catalytic activity decreases with increasing number of carbon atom in the alkyl group with the following sequence： Y（CCl3COO）3-ZnEt2-glycerin 〉 Y（CCl3COO）3-Zn（n- Pr）2-glycerin〉Y（CCl3COO）3-Zn（n-Bu）2-glycerin. However, the alkyl group in the dialkylzinc does not influence the insertion of PO into the propagation chain end.     

Geminate charge recombination in liquid alkane with concentrated CCl4: effects of CCl4 radical anion and narrowing of initial distribution of Cl-

Dynamics of radical cations and electrons in an admixture of a linear saturated hydrocarbon (n-dodecane) and halocarbon (carbon tetrachloride, CCl(4)) were investigated by picosecond electron beam pulse radiolysis. The decay of thermalized electrons (e(th)(-)) observed in infrared transient photoabsorption were simply accelerated by the addition of CCl(4), giving a high rate constant of 2.3 × 10(11) mol(-1) dm(3) s(-1). The decrease of the initial yield of e(th)(-) was quantified by C(37) (50 mmol), which is linked to the reaction of epithermal electrons (e(-)) with CCl(4). In contrast, the n-dodecane radical cation (RH(2)(?+)) monitored in the near-infrared indicated a convex-type dependence of the decay rate on CCl(4) concentration, although the initial yield of RH(2)(?+) remained almost constant up to a much higher CCl(4) concentration. The decay of RH(2)(?+) was analyzed by Monte Carlo simulations of geminate ion recombination with e(th)(-), chlorine anion (Cl(-)) formed via dissociative electron attachment, and CCl(4) radical anion. The results showed a good agreement with the experiments by considering two assumptions: (1) CCl(4) radical anion formed via e(th)(-) attachment and (2) narrowing of the initial distribution of Cl(-). The decrease in the initial yield of RH(2)(?+) at high CCl(4) concentration was well explained by immediate decomposition of CCl(4)(?+) to CCl(3)(+) and hole transfer from CCl(4)(?+) to adjacent RH(2) without diffusive motion of the reactants. Time-dependent density functional theory supported the spectroscopic assignment of intermediate species in the n-dodecane/CCl(4) system. The present results would be of help in understanding the electron capture reaction in multicomponent systems such as a chemically amplified resist in lithography.     

Evolution of the electronic properties of metallic single-walled carbon nanotubes with the degree of CCl2 covalent functionalization

The changes in energetic, structural, and electronic properties of the metallic (5,5) single-walled carbon nanotube (SWNT) with the degree of sidewall covalent functionalization of CCl(2) are investigated extensively by using density functional theory calculations. The saturation concentration of CCl(2) covalent functionalization is predicted to be 33.3%. The cycloadducts always adopt an open structure. A band gap opens as the functionalization concentration reaches 11% and then basically increases with increasing functionalization concentration. These results are in agreement with available experiments and can be applied to accurately predict the band gap of metallic SWNTs produced by the HiPco method at a given CCl(2) functionalization concentration.     

Increase in the plasma protein binding of weakly basic drugs in carbon tetrachloride-intoxicated rats.

Plasma protein binding of weakly basic drugs such as propranolol and quinidine was determined in rats with carbon tetrachloride (CCl4)-induced hepatic disease. Free fractions of propranolol and quinidine in the plasma of rats at 24 h after CCl4-intoxication were decreased by 41 and 30%, respectively, compared to those of control rats. An addition of Tris (butoxyethyl) phosphate (TBEP), a specific displacer for basic drugs from alpha 1-acid glycoprotein (AGP), to the plasma increased the free fractions of the basic drugs, resulting in no difference in the extent of the plasma free fraction of each drug between control and CCl4-intoxicated rats. Plasma concentration of AGP in CCl4-intoxicated rats was elevated 2.7-fold of that in control rats at 24 h after the CCl4 intoxication and reached a peak of 4.8-fold elevation at 48 h. A regression analysis revealed a high degree of positive correlation between ratios of bound to free fraction of propranolol and plasma concentrations of AGP. These results suggest that the plasma protein binding of the basic drugs was increased mainly due to the rise in the plasma AGP concentration in CCl4-intoxicated rats.