共查询到20条相似文献,搜索用时 12 毫秒
1.
Nan Ji Erik Meredith Donglei Liu Christopher M. Adams Gerald D. Artman III Keith C. Jendza Fupeng Ma Nello Mainolfi James J. Powers Chun Zhang 《Tetrahedron letters》2010,51(52):6799-6801
A series of 1-substituted-3-aminopyrazoles were prepared via Chan-Lam coupling reactions, alkylation, and pyrazole ring formation. 相似文献
2.
Relationship between topochemical indices and anti-HIV-1 (HTLV-III) inhibitory activity of 1-alkoxy-5-alkyl-6-(arylthio)uracils
has been studied. Superadjacency, an adjacency-cum-distance-based, topochemical index and Wiener’s, a distance-based, topochemical
index were calculated for a set of 36 1-alkoxy-5-alkyl-6-(arylthio)uracils. Resulting data were analyzed and suitable models
were developed after identification of the active ranges. Subsequently, a biological activity was assigned to each of the
compounds using these models and compared with the reported anti-HIV-1 activity. High accuracy of prediction was observed
using these models. Statistical analysis revealed significance of the proposed models as well as a lack of correlation between
the topochemical indices employed for the chosen data set. 相似文献
3.
Nesterkina Mariia Ognichenko Luidmyla Shyrykalova Angela Kravchenko Iryna Kuz’min Victor 《Structural chemistry》2020,31(3):947-954
Structural Chemistry - In the present study, quantitative structure-activity relationship (QSAR) models were developed to predict analgesic activity of some mono-/bicyclic terpenoids and their... 相似文献
4.
Herbert Hutter Peter Wilhartitz Manfred Grasserbauer 《Fresenius' Journal of Analytical Chemistry》1993,346(1-3):66-68
Summary The potential of 3D-SIMS for characterization of high molybdenum powder and sintered high purity molybdenum will be demonstrated. The concentration of the measured trace elements in the sintered molybdenum did not exceed 200 ppb. In the powder the concentration was found to be about 1 ppm. For material scientists it is very important to ascertain if the trace elements are homogeneously distributed or precipitated. Although the concentration of the elements of interest was rather low, qualitative images of the three dimensional distribution can be obtained. 相似文献
5.
Development of models for prediction of the antioxidant activity of derivatives of natural compounds
Antioxidants are important for maintaining the appropriate balance between oxidizing and reducing species in the body and thus preventing oxidative stress. Many natural compounds are being screened for their possible antioxidant activity. It was found that a mushroom pigment Norbadione A, which is a pulvinic acid derivative, shows an antioxidant activity; the same was found for other pulvinic acid derivatives and structurally related coumarines. Based on the results of in vitro studies performed on these compounds as a part of this study quantitative structure–activity relationship (QSAR) predictive models were constructed using multiple linear regression, counter-propagation artificial neural networks and support vector regression (SVR). The models have been developed in accordance with current QSAR guidelines, including the assessment of the models applicability domains. A new approach for the graphical evaluation of the applicability domain for SVR models is suggested. The developed models show sufficient predictive abilities for the screening of virtual libraries for new potential antioxidants. 相似文献
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The aim of this study was to determine the anti-tumour activity of tanshinone IIA in SKOV3 cells. Results suggested that tanshinone IIA could significantly inhibit (IC50 value = 19.6 μM) the proliferation and induce apoptosis of SKOV3 cells as demonstrated by flow cytometry analysis. In addition, tanshinone IIA treatment induced G2/M phase cell cycle arrest in SKOV3 cells. The results of Western blotting indicated that tanshinone IIA can suppress the expression of anti-apoptotic protein Bcl-2, increase (0.28 vs. 0.62) the expression of pro-apoptotic protein Bax (0.83 vs. 0.24) in SKOV3 cells. It can be concluded that the tanshinone IIA may be a possible therapeutic candidate having cytotoxic and anti-tumour potential. 相似文献
9.
Felicia Phei Lin Lim Khai Ching Tan Giuseppe Luna Edward R.T. Tiekink Anton V. Dolzhenko 《Tetrahedron》2019,75(15):2314-2321
It was found that 3-amino-substituted 5-aminopyrazoles could be effectively prepared via hydrolytic decarboxylation of the corresponding 3,5-diaminopyrazole-4-carboxylates under microwave irradiation. The reactions required short time (4?min) and were successfully reproduced in a larger scale and under conventional heating mimicking the microwave heating pattern. X-ray crystallography identified two different types of tautomers in crystals of related 5-aminopyrazoles with p-toluidyl and p-anisidyl moieties at the position 3, respectively. 相似文献
10.
Gonzalo Cerruela-Garca Jos Prez-Parra Toledano Ada de Haro-Garca Nicols Garca-Pedrajas 《Journal of computer-aided molecular design》2020,34(3):305-325
In the construction of activity prediction models, the use of feature ranking methods is a useful mechanism for extracting information for ranking features in terms of their significance to develop predictive models. This paper studies the influence of feature rankers in the construction of molecular activity prediction models; for this purpose, a comparative study of fourteen rankings methods for feature selection was conducted. The activity prediction models were constructed using four well-known classifiers and a wide collection of datasets. The ranking algorithms were compared considering the performance of these classifiers using different metrics and the consistency of the ranked features. 相似文献
11.
Lipson V. V. Svetlichnaya N. V. Borodina V. V. Shirobokova M. G. Shishkina S. V. Shishkin O. V. Musatov V. I. 《Russian Journal of Organic Chemistry》2010,46(9):1388-1398
Three-component condensation of 5(3)-amino-3(5)-methylpyrazole with aromatic aldehydes and 1,3-cyclohexanedione afforded mixtures
of 3-methyl-4-aryl-2,4,6,7,8,9-hexa hydro-5H-pyrazolo[3,4-b]quinolin-5-ones and 2-methyl-9-aryl-5,6,7,9-tetrahydro pyrazolo[5,1-b]quinazolin-8(4H)-ones. The reaction of 3-aminopyrazolo-4-carbonitrile and ethyl 3-aminopyrazolo-4-carboxylate with aldehydes and cyclo hexanedione
or dimedome is regioselective and leads to the formation of partially hydrogenated pyrazolo [5,1-b]quinazolin-8-one systems.
In all compounds the dihydroazine ring exists in the enamine tautomeric form. 相似文献
12.
P. Giori A. C. Veronese C. B. Vicentini M. Guarneri 《Journal of heterocyclic chemistry》1985,22(4):1093-1096
Aryl and t-butylhydrazines react with 2-cyano-3-ethoxythiocrotonamide affording 2-cyano-3-aryl-t-butylhy-drazinothiocrotonamides. These intermediates can be easily cyclized to 4-thiocarbamoyl-5-aminopyrazoles by heating a few minutes in a strong base. Alkylhydrazines react with 2-cyano-3-ethoxythiocrotonamide yielding directly a mixture of the cyclized compounds 4-cyano-5-aminopyrazoles and 4-thiocarbamoyl-5-aminopyr-azoles. 相似文献
13.
A. A. Petrov A. N. Kasatochkin E. E. Emelina 《Russian Journal of Organic Chemistry》2012,48(8):1111-1120
Regioselectivity was examined of reactions between nine 3(5)-aminopyrazoles and 2-acetylcyclopentanone and 2-acetylcyclohexanone under various conditions. A series of cyclopenta[e]pyrazolo-[1,5-a]pyrimidines was obtained. The highest regioselectivity of the reaction was observed in alcohol at 20°C in the presence of a catalytic quantity of trifl uoroacetic acid. The regiostructure of compounds was established by 1H and 13C NMR spectroscopy. 相似文献
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15.
Topochemical investigation of ancient manuscripts 总被引:2,自引:0,他引:2
Wagner B Bulska E Hulanicki A Heck M Ortner HM 《Fresenius' Journal of Analytical Chemistry》2001,369(7-8):674-679
16.
A new concept for topochemical activation of mechanical pulp fibres was investigated. The activation concept was based on attachment of precursors of peracids onto the surface of the fibres prior to hydrogen peroxide bleaching. The activators used in this work were: tetraacetylethylenediamine (water soluble), lactose octaacetate (LOA, colloidal particles, and low water solubility) and sucrose octaacetate (partially soluble in water). LOA showed promising results for application in the surface activation concept due to attachment of colloidal particles on the outmost surface of the fibres, simultaneously contributing to a brightness increase. Surface coverage by lignin on fibres had decreased after the bleaching process with activators, which was detected by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. 相似文献
17.
Stephen P. Watson Richard D. Wilson Duncan B. Judd Stephen A. Richards 《Tetrahedron letters》1997,38(52):179-9068
The development of a novel solid phase synthesis of some 5-aminopyrazoles and derivatives is described. Reaction of hydrazines with solid supported β-keto-nitrile (1) affords 5-aminopyrazoles (2) the amino group of which is readily acylated or sulphonylated. Generation of the solid supported β-keto-nitrile (1) is non trivial and represents a key step in the overall synthesis. 相似文献
18.
Topochemical investigations of peptide systems 总被引:4,自引:0,他引:4
M M Shemyakin Y A Ovchinnikov V T Ivanov 《Angewandte Chemie (International ed. in English)》1969,8(7):492-499
The basic principles of the topochemical approach to the investigation of the structure-function relation in peptide systems are formulated. This approach makes use of the new possibility of transforming natural peptides, consisting in the modification of the molecule as a whole and utilization of the resultant analogs to elucidate the boundaries of the stereoelectronic complementarity of the biologically active peptide to the corresponding receptor. In particular, on the example of depsipeptide antibiotics and their topochemical analogs the fruitfulness of using such compounds as tools in elucidating the physicochemical basis of functioning of biological membranes is shown. The topochemical principle has also been applied in preparing specific competitive inhibitors of proteolytic enzymes, whose study may shed light on the nature of the forces binding the substrate to the contact site of the corresponding enzyme. 相似文献
19.
Developing a structure-function relationship for anionic porphyrazines exhibiting selective anti-tumor activity 总被引:1,自引:0,他引:1
Vesper BJ Lee S Hammer ND Elseth KM Barrett AG Hoffman BM Radosevich JA 《Journal of photochemistry and photobiology. B, Biology》2006,82(3):180-186
The porphyrazines (pzs) are a class of porphyrin derivatives being studied for their use as optical imaging agents and photodynamic therapy (PDT) anti-tumor agents. A previous study revealed that the anionic pz, 18--of the form H2[pz(An;B4-n)], where A is [S(CH2)3CO2-], B is a fused beta',beta'-diisopropyloxy benzo group, with n=2 (trans)--selectively killed tumor cells, while analogous neutral and positively charged pzs lacked this property. In this report, we compare the properties of a suite of three H2[pz(An;B4-n)] pzs containing the same A and B groups as 18, but differing in their values of n: pzs 4 (n=4) and 11 (n=3), and 18 (n=2, trans) exhibit a progressive variation in charge due to the carboxylates, balance between hydrophobic/hydrophilic character, as well as a progressive variation in the singlet oxygen quantum yield (PhiDelta): PhiDelta (18)>PhiDelta (11)>PhiDelta (4). The biological activity of the pzs was tested in human lung carcinoma (A549) and SV40 transformed embryonic (WI-38 VA13) cell lines. Pzs 4 and 11 exhibited significant toxicity in both tumor and normal cells, while 18 showed selective anti-tumor cell activity in a dose-dependent manner. As the number of net negative charges decreased, the compounds became less toxic to normal cells, and the killing effect observed with these compounds was light independent. These observations indicate that the toxicity may have little to do with singlet oxygen quantum yields, but rather is more dependent on the net number of negative charges a pz contains. The study reported herein presents an example of how the porphyrazines can be easily modified to vary their biological behavior and specifically suggest that anionic porphyrazines pzs with lower n (fewer carboxylates, larger hydrophobic core) are more specific tumor killers, while those with larger n (increased net negative charge) are more potent tumor killers. 相似文献