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p. 1064-1082
Received: 6 September 2007; in revised form: 15 September 2007 / Accepted: 19 September 2007 / Published: 29 October 2007
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| Download PDF Full-text (395 KB) Abstract: Geometric parameters and FT-IR spectrum of 6-bromo-8-thia-1,4-epoxybicyclo[4.3.0]non-2-ene were computed by the HF, B3LYP, B3PW91 andmPW1PW91 methods in conjunction with the 6-31G(d,p) basis set. The calculated IRspectra are in a good agreement with the observed FT-IR spectrum. A general betterperformance of B3LYP, B3PW91 and mPW1PW91 versus HF was quantitativelycharacterized by using PAVF 1.0 program. Optimal uniform scaling factors calculated forthe title compound are 0.8952, 0.9552, 0.9520 and 0.9456 for HF, B3LYP, B3PW91 andMPW1PW91 methods, respectively.
p. 1083-1094
Received: 3 August 2007; in revised form: 29 September 2007 / Accepted: 22 October 2007 / Published: 31 October 2007
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| Download PDF Full-text (346 KB) Abstract: ATP is involved in numerous biochemical reactions in living cells interacting withdifferent proteins. Molecular docking simulations provide considerable insight into theproblem of molecular recognition of this substrate. To improve the selection of correctATP poses among those generated by docking algorithms we propose a post-docking rerankingcriterion. The method is based on detailed analysis of the intermolecularinteractions in 50 high-resolution 3D-structures of ATP-protein complexes. A distinctivenew feature of the proposed method is that the ligand molecule is divided into fragmentsthat differ in their physical properties. The placement of each of them into the bindingsite is judged separately by different criteria, thus avoiding undesirable averaging of thescoring function terms by highlighting those relevant for particular fragments. Thescoring performance of the new criteria was tested with the docking solutions for ATPproteincomplexes and a significant improvement in the selection of correct dockingposes was observed, as compared to the standard scoring function.
p. 1095-1110
Received: 1 September 2007; in revised form: 1 October 2007 / Accepted: 1 November 2007 / Published: 1 November 2007
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| Download PDF Full-text (475 KB) Abstract: The objectives of this study were to isolate various isoflavone fractions andextracts from soybean cake by preparative column chromatography and compare themwith isoflavone standards with regards to inhibition of HepG2 cancer cell proliferation.Four fractions, including malonylglucoside, glucoside, acetylglucoside and aglycone, andtwo isoflavone extracts, ISO-1 and ISO-2, were collected for evaluation. MTT test resultsshowed that most treatments were slightly protective against HepG2 cell growth at a lowdose of isoflavone (5 and 10 μg/mL). However, at elevated concentration of isoflavone(20-50 μg/mL), both aglycone and acetylglucoside fractions as well as a mixture ofisoflavone standards were the most effective in inhibition, demonstrating a possiblesynergistic phenomenon. Genistein showed a better retardation effect than daidzein. Forcell cycle analysis, both aglycone and acetylglucoside fractions and a mixture ofisoflavone standards exhibited a high G2/M ratio, correlating well with the result of MTTtest. The presence of some other functional components in soybean cake like saponinsand phenolic compounds may also play a vital role in inhibiting HepG2 cell growth.
p. 1111-1124
Received: 28 August 2007; in revised form: 8 November 2007 / Accepted: 12 November 2007 / Published: 21 November 2007
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| Download PDF Full-text (312 KB) Abstract: A set of 13 fatty acids was transformed into their phenacyl esters by reaction withphenacyl bromide in acetonitrile using 18-crown-6 as phase-transfer catalyst. Conditions forthe RP-18 HPL chromatographic separation of most of the esters has been worked out.Using this standard the fatty acid spectra from skin surface sebum lipids of 17 test personswas taken after microwave-assisted hydrolysis, neutralization and extraction with n-hexane.Quantitative evaluation of the chromatograms exhibits that oleic acid predominates in thesebum of all test persons. In the second part of the work the chromatographic mobility (REvalues) of fatty acid phenacyl esters is correlated with calculated physico-chemicalparameters of the corresponding acids. The best linear correlation was found between the REand the logP values. This is helpful for the structural elucidation of un-identified fatty acidsin a chromatogram.
p. 1125-1157
Received: 16 August 2007; in revised form: 9 November 2007 / Accepted: 13 November 2007 / Published: 22 November 2007
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| Download PDF Full-text (372 KB) Abstract: The paper presents a unitary approach of the use of a Molecular DescriptorsFamily in structure-property/activity relationships, particularly in modelling thechromatographic retention times of polychlorinated biphenyls. Starting from molecularstructure, viewed as a graph, and considering the bonds and bond types, atom types andoften the 3D geometry of the molecule, a huge family of molecular descriptors called MDFwas calculated. A preliminary selection of MDF members was done by simple linearregression (LR) against the measured property. The best fitted MDF subset is thensubmitted to multivariate linear regression (MLR) analysis in order to find the best pairs ofMDF members that produce a reliable QSPR (Quantitative Structure-PropertyRelationship) model. The predictive capability was finally tested by randomly splitting ofdata into training and test sets. The best obtained models are presented and the results arediscussed.
p. 1158-1164
Received: 19 October 2007; in revised form: 9 November 2007 / Accepted: 13 November 2007 / Published: 22 November 2007
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| Download PDF Full-text (177 KB) Abstract: We report the measured total charge-transfer (electron-capture) cross sectionsfor the ground state O2 + (X2 πg) ions with H2 and O2 molecular gases in the collisionenergy range between 0.50 and 2 keV. The time-of-flight technique has been used tomeasure the fast neutral products from O2 + charge transfer reactions. The analyzedprocess has cross sections that continue to increase slowly, as a function of incidentenergy. Measured cross sections for O2 + H2 , O2 systems are compared with previouslyavailable experimental and theoretical results in the literature.
p. 1165-1176
Received: 15 October 2007; in revised form: 14 November 2007 / Accepted: 15 November 2007 / Published: 26 November 2007
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| Download PDF Full-text (535 KB) Abstract: Acetylcholinesterase (AChE) activities in different brain parts were determinedquantitatively in rats treated with huperzine A, soman, and huperzine A followed bysoman, using histochemical and biochemical methods. Following soman intoxication (1.2x LD50, i.m.), AChE activity was decreased to 30-80% of control values depending on thebrain structure. The most sensitive area was the frontal cortex and the most relativelyresistant was ncl. ruber. Huperzine A treatment only caused a change in AChE activityvarying from 70 to 100 % of control values. In rats pretreated with huperzine A andintoxicated with soman, AChE activity was significantly higher than that observed aftersoman. In these animals, survival of rats pretreated with huperzine was observed whilethe mortality of unpretreated animals was near to 80 %. The results suggest that huperzineA is good candidate for further study for clinical use as a prophylactic drug against nerveagent poisoning.
p. 1177-1195
Received: 12 November 2007; in revised form: 16 November 2007 / Accepted: 21 November 2007 / Published: 27 November 2007
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| Download PDF Full-text (288 KB) Abstract: Ginkgolide B, the major active component of Ginkgo biloba extracts, can bothstimulate and inhibit apoptotic signaling. Here, we demonstrate that ginkgolide B caninduce the production of reactive oxygen species in MCF-7 breast cancer cells, leading toan increase in the intracellular concentrations of cytoplasmic free Ca2+ and nitric oxide(NO), loss of mitochondrial membrane potential (MMP), activation of caspase-9 and -3,and increase the mRNA expression levels of p53 and p21, which are known to be involvedin apoptotic signaling. In addition, prevention of ROS generation by pretreatment withN-acetyl cysteine (NAC) could effectively block intracellular Ca2+ concentrationsincreases and apoptosis in ginkgolide B-treated MCF-7 cells. Moreover, pretreatment withnitric oxide (NO) scavengers could inhibit ginkgolide B-induced MMP change andsequent apoptotic processes. Overall, our results signify that both ROS and NO playedimportant roles in ginkgolide B-induced apoptosis of MCF-7 cells. Based on these studyresults, we propose a model for ginkgolide B-induced cell apoptosis signaling cascades inMCF-7 cells.
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