摘要：
A further chemical investigation of the plant Rubus corchorifolius L. f., collected in Hunan Province, afforded two new ent-kauranoids 6 and 7. Their structures were elucidated by various spectroscopic methods.
期刊：
Journal of Chemical Physics,2011年134(8):084103 ISSN：0021-9606
通讯作者：
Liu, Shubin
作者机构：
[Huang, Ying] Hunan Univ Chinese Med, Sch Pharm, Changsha 410208, Hunan, Peoples R China.;[Liu, Shubin] Univ N Carolina, Ctr Res Comp, Chapel Hill, NC 27599 USA.;[Zhong, Ai-Guo] Taizhou Coll, Dept Chem, Linhai 317000, Zhejiang, Peoples R China.;[Yang, Qinsong] PT TSG Chem, Bekasi 17520, Indonesia.
通讯机构：
[Liu, Shubin] U;Univ N Carolina, Ctr Res Comp, Chapel Hill, NC 27599 USA.
关键词：
density functional theory;isomerism;molecular moments;organic compounds
摘要：
The anomeric effect (the tendency of heteroatomic substituents adjacent to a heteroatom within the cyclohexane ring to prefer the axial orientation instead of the sterically less hindered equatorial position) is traditionally explained through either the dipole moment repulsion or the hyperconjugation effect. In this work, by employing our recent work in density functional steric analysis, we provide a novel two-component explanation, which is consistent with the common belief in chemistry that the effect has a stereoelectronic origin. With alpha-D-glucopyranose as the prototype, we systematically explore its conformational space and generate 32 isomers, leading to a total of 80 axial-equatorial conformation pairs. The energy difference analysis of these pairs shows that while statistically speaking the tendency is valid, the anomeric effect is not always true and can be violated. Three energy components, exchange-correlation, classical electrostatic, and density functional steric, are found to be directly proportional to the total energy difference between axial and equatorial isomers. We also found that the total dipole moment change, not the hyperconjugation effect, is a reasonable indicator of the total energy difference. However, all these correlations alone are not strong enough to provide a compellingly convincing explanation for the general validity of the effect. With the help of strong correlations between energy components, an explanation with two energy components, steric and electrostatic, was proposed in this work. We show that the axial-equatorial energy difference in general, with the anomeric effect as a special case, is dictated by two factors of the stereoelectronic origin, steric hindrance and classical electrostatic interactions, synchronously working together. Another explanation in terms of exchange-correlation and electrostatic interactions has also been obtained in this work. (C) 2011 American Institute of Physics. [doi:10.1063/1.3555760]
期刊：
Journal of Hazardous Materials,2010年179(1-3):742-747 ISSN：0304-3894
通讯作者：
Xiao, Xiaohe
作者机构：
[Kong, Weijun; Liu, Wei; Xiao, Xiaohe; Li, Xing-Feng; Zhao, Yanling; Jin, Cheng; Zhang, Ping] 302 Mil Hosp China, China Mil Inst Chinese Mat Med, Beijing 100039, Peoples R China.;[Kong, Weijun; Li, Zulun] Chengdu Univ Tradit Chinese Med, Coll Pharm, Chengdu 611137, Peoples R China.;[Liu, Wei] Jiangxi Univ Tradit Chinese Med, Coll Pharm, Nanchang 330004, Peoples R China.;[Li, Xing-Feng] Hunan Univ Tradit Chinese Med, Coll Pharm, Changsha 410208, Peoples R China.
通讯机构：
[Xiao, Xiaohe] 3;302 Mil Hosp China, China Mil Inst Chinese Mat Med, Beijing 100039, Peoples R China.
关键词：
Bile acid derivative;MANOVA;Microcalorimetry;PCA;S. aureus
摘要：
The effects of two bile acid derivatives, cholic acid (CA) and deoxycholic acid (DCA) on Staphylococcus aureus (S. aureus) growth were investigated and compared by microcalorimetry coupled with multiple analytical methods. The heat power (HP)-time curves of S. aureus growth affected by CA and DCA were studied by similarity analysis (SA), respectively. Then the quantitative thermo-kinetic parameters obtained from these curves were investigated by the multivariate analysis of variance (MANOVA) and principal component analysis (PCA). By analyzing the two main parameters, growth rate constant k(2) of the second exponential phase and the heat power P-2 of the second highest peak, together with the minimum inhibitory concentration (MIC) values of 10 mu g/mL for CA and 20 mu g/mL for DCA, it could be concluded that the antibacterial effect of CA was stronger than that of DCA. The existence of alpha-OH at C-7 position of steroid nucleus of bile acid derivatives enhanced the hydrophilicity of compound CA and its inhibitory effect on S. aureus. This study provides a useful method and idea to accurately evaluate the antibacterial effects of bile acid derivatives, which provides some references for screening out new antibacterial agents with high efficacy and low toxicity. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
作者机构：
[Wu Yan-shu; Zhang Qian; Jin Cheng; Xiao Xiao-he; Yan Dan] 302 Mil Hosp China, PLA Inst Chinese Mat Med, Beijing 100039, Peoples R China.;[Wu Yan-shu; Zhang Qian; Wang Jian] Chengdu Univ Tradit Chinese Med, Coll Pharm, Chengdu 611137, Peoples R China.;[Jiao Yi] Hunan Univ Tradit Chinese Med, Coll Pharm, Changsha 410002, Hunan, Peoples R China.;[Du Xiao-xi] State Food & Drug Adm, Ctr Drug Evaluat, Beijing 100038, Peoples R China.
通讯机构：
[Xiao Xiao-he] 3;302 Mil Hosp China, PLA Inst Chinese Mat Med, Beijing 100039, Peoples R China.
期刊：
JOURNAL OF PHYSICAL CHEMISTRY A,2008年112(2):305-311 ISSN：1089-5639
通讯作者：
Xiao, Xiaoming
作者机构：
[Rong, Chunying; Xiao, Xiaoming; Liu, Shubin; Huang, Ying] Hunan Normal Univ, Coll Chem & Chem Engn, Changsha 410081, Hunan, Peoples R China.;[Huang, Ying] Hunan Univ Tradit Chinese Med, Sch Pharm, Changsha 410007, Hunan, Peoples R China.;[Zhong, Aiguo] Taizhou Coll, Dept Chem, Linhai 317000, Zhejiang, Peoples R China.;[Liu, Shubin] Univ N Carolina, Renaissance Comp Inst, Chapel Hill, NC 27599 USA.
通讯机构：
[Xiao, Xiaoming] H;Hunan Normal Univ, Coll Chem & Chem Engn, Changsha 410081, Hunan, Peoples R China.
摘要：
Porphyrin and pincer complexes are both important categories of compounds in biological and catalytic systems. The idea to combine them is computationally investigated in this work. By employment of density functional theory (DFT), conceptual DFT, and time-dependent DFT approaches, structure, spectroscopy, and reactivity properties of porphyrin pincers are systematically studied for a selection of divalent metal ions. We found that the porphyrin pincers are structurally and spectroscopically different from their precursors and are more reactive in electrophilic and nucleophilic reactions. A few quantitative linear/exponential relationships have been discovered between bonding interactions, charge distributions, and DFT chemical reactivity indices. These results are implicative in chemical modification of hemoproteins and understanding chemical reactivity in heme-containing and other biologically important complexes and cofactors.
通讯机构：
Wuhan National Laboratory for Optoelectronics, Department of Electronics and Information Engineering, Huazhong University of Science and Technology, China
摘要：
A dye intermediate, 1-amino-8-naphthol-3,6-disulfonic acid sodium (ANDS) was first used to selectively recognize Hg(II) in aqueous solutions with its fluorescence being strong quenched. The fluorescence quenching of ANDS was attributed to the formation of an inclusion complex between Hg(II) and ANDS by 2:1 complex ratio (K= 6.2 x 10(9)), which has been utilized as the basis of the fabrication of the Hg(II)-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed chemosensor were investigated. The sensor shows a linear response toward Hg(II) in the concentration range 2.9 x 10(-6) to 5.5 x 10(-5) M with a limit of detection of 5.3 x 10(-7) M, and a working pH range from 5.0 to 9.0. It shows excellent selectivity for Hg(II) over a large number of cations such as alkali, alkaline earth and transitional metal ions. The proposed method was utilized successfully for the detection of Hg2+ in water samples. (C) 2007 Elsevier B.V. All rights reserved.
作者机构：
[彭姣凤; 何晓晓; 郑明彬; 吴萍; 王柯敏; 谭蔚泓] State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Univ., Changsha 410082, China;[吴萍] School of Pharmacy, Hunan University of Traditional Chinese Medicine, Changsha 410208, China
通讯机构：
State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Univ., China
作者机构：
[吴运东; 邓小强; 陈四海; 龙伯华; 向建南; 杨菘] College of Chemistry and Chemical Engineering, Hunan Univ., Changsha 410082, China;[向建南] Bio-Medicine Engineering Center, Hunan Univ., Changsha 410082, China;[杨菘] Pharmaceutical College, Hunan Univ. of Chinese Medicine, Changsha 410007, China
通讯机构：
College of Chemistry and Chemical Engineering, Hunan Univ., China
作者机构：
[刘平安; 贺福元; 刘文龙] Department of Pharmaceutics, Hunan College of TCM, Changsha 410007, China;[贺福元] School of Pharmacy, Chengdu University of TCM, Chengdu 610075, China;[邓常青] Institute of TCM's Diagnosis, Hunan College of TCM, Changsha 410007, China;[邓凯文] First Affiliated Hospital, Hunan College of TCM, Changsha 410007, China
通讯机构：
[He, F.-Y.] D;Department of Pharmaceutics, Hunan College of TCM, China
