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51.
Preparation, structure and spasmolytic activities of some derivatives of harmine series of alkaloids
Begum S Imran Hassan S Siddiqui BS Ifzal R Perwaiz S Kiran T Shaheen F Ghayur MN Gilani AH 《Natural product research》2006,20(3):213-227
Keeping in view the interesting chemistry and pharmacological importance of harmine series of bases -- the beta-carboline alkaloids, a number of new derivatives of tetrahydroharmine and harmalol have been prepared and characterized through spectral studies. Some of these derivatives showed spasmolytic activity. It was observed that all the N-acyl tetrahydroharmine derivatives are stable, not labile and no ring opening occurs in these compounds, as reported recently. 相似文献
52.
We discuss congruences of p-algebras. We characterize kernel ideals of a p-algebra. Indeed, we show that an ideal of a p-algebra is a p-ideal if and only if it is a kernel ideal. We study cokernel filters of a p-algebra. We construct a class of p-algebras in which every cokernel filter is a p-filter. We also give some characterizations of Boolean congruences of a p-algebra. 相似文献
53.
Sarkar D Subbarao PV Begum G Ramakrishna K 《Journal of colloid and interface science》2005,288(2):591-596
The dissociation of tris-(2,2'-bipyridyl) iron(II) ([Fe(bipy)3]2+) has been studied in the Triton X-100/hexanol/cyclohexane reverse micellar medium. The reaction obeys simple first-order kinetics with no evidence of autoinhibition. The first-order rate constant (k1) has been determined at different values of W ([H2O]/[Triton X-100]). The rate (k1) decreases with increasing value of W. k1 also increases with increase in Triton X-100 concentration at constant values of W, showing that the reaction takes place at greater speed at the micellar interface. The kinetic results can be interpreted by the monomolecular pseudo-phase model. The effect of W on rate (k1) is more pronounced in the range of W from 1.55 to 4.2 but less pronounced at higher W. The reaction is further accelerated by Cl- and SCN- ions and the kinetic results provide evidence for the formation of ion pairs between the cation [Fe(bipy)3]2+ and each of these anions. The formation of such ion pairs has not been observed in aqueous medium but has been reported earlier in aqueous-alcohol mixtures. This result therefore provides evidence for the lower micropolarity of solubilized water compared to ordinary water. 相似文献
54.
Gupta Kalyan Kali Sen Begum Bilkis Ara Ghosh Sakti Prosad 《Transition Metal Chemistry》1998,23(3):295-299
Oxidations of glycolaldehyde (GA) to glyoxal by osmium(VIII), iridium(IV) and platinum(IV) have been investigated in aqueous
solution, and the orders with respect to each [reactant] determined. The reaction involving iridium(IV) takes place through
intermediate formation of free radicals in a MeCO2Na-MeCO2H buffer medium, whereas a one-step two-electron transfer process occurs in the oxidations by OsVIII and PtIV in an alkaline medium. Mechanisms consistent with the experimental findings are proposed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
55.
Shakir Mohammad Parveen Shama Begum Nishat Chingsubam Poonam 《Transition Metal Chemistry》2004,29(2):196-199
Complexes of the type [M(tren)(abpt)](NO3)2(H2O)n
(1–6) [M = MnII, FeII, CoII, CuII, ZnII (n = 2), NiII (n = 2.25), tren = tris(2-aminoethyl)amine, and abpt = 4-amino-3,5-bis(pyridin-2yl)-1,2,4 triazole] have been prepared. The bonding mode and overall geometry of the complexes have been deduced by elemental analyses, molar conductance values, spectral studies (obtained from FT-IR), 1H-n.m.r., electronic spectral analyses and magnetic susceptibility measurements. A detailed molecular structure of complex (4) has been determined by single X-ray crystallography. 相似文献
56.
Noor Shahina Begum D. E. Vasundhara C. R. Girija G. D. Kolavi V. S. Hegde I. M. Khazi 《Journal of chemical crystallography》2007,37(3):193-198
Imidazo[2,1-b][1,3,4] thiadiazole derivatives are significant for their various pharmacological properties. This paper reports
the synthesis and structure of one of them, 2-cyclohexyl-6-(2-oxo-2H-chromen-3-yl)imidazo[2,1-b][1,3,4]thiadiazole-5-carbaldehyde.
The compound crystallizes in the monoclinic space group P21/c with a=17.316(3)?, b=6.5420(9)?, c =17.056(3)?, β=112.909(2)°, V=1779.7(4)?3, z=4. The, Imidazo[2,1-b][1,3,4] thiadiazole and the coumarin ring systems are each planar but inclined at an angle of 48.14(2)°
towards each other. The crystal structure is stabilized by C–H … O interactions. 相似文献
57.
Three new pentacyclic triterpenes ursoxy acid ( 1 ), methyl ursoxylate ( 2 ), and ursangilic acid ( 3 ), along with three known compounds dotriacontanoic acid, oleanolic acid acetate, and tetracosanoic acid, were isolated from the aerial parts of Lantana camara Linn . Structures of the new compounds were elucidated by chemical transformation and spectral studies including 1D (1H‐ and 13C‐NMR) and 2D (COSY‐45, NOESY, J‐resolved, HMQC, and HMBC) NMR spectroscopy. 相似文献
58.
Madhuchandra Kenchegowda Mohamed Rahamathulla Umme Hani Mohammed Y. Begum Sagar Guruswamy Riyaz Ali M. Osmani Mysore P. Gowrav Sultan Alshehri Mohammed M. Ghoneim Areej Alshlowi Devegowda V. Gowda 《Molecules (Basel, Switzerland)》2022,27(1)
Cancer is a group of disorders characterized by uncontrolled cell growth that affects around 11 million people each year globally. Nanocarrier-based systems are extensively used in cancer imaging, diagnostics as well as therapeutics; owing to their promising features and potential to augment therapeutic efficacy. The focal point of research remains to develop new-fangled smart nanocarriers that can selectively respond to cancer-specific conditions and deliver medications to target cells efficiently. Nanocarriers deliver loaded therapeutic cargos to the tumour site either in a passive or active mode, with the least drug elimination from the drug delivery systems. This review chiefly focuses on current advances allied to smart nanocarriers such as dendrimers, liposomes, mesoporous silica nanoparticles, quantum dots, micelles, superparamagnetic iron-oxide nanoparticles, gold nanoparticles and carbon nanotubes, to list a few. Exhaustive discussion on crucial topics like drug targeting, surface decorated smart-nanocarriers and stimuli-responsive cancer nanotherapeutics responding to temperature, enzyme, pH and redox stimuli have been covered. 相似文献
59.
Mohammad Shakir Shama Parveen Nishat Begum Yasser Azim 《Transition Metal Chemistry》2004,29(8):916-920
A series of transition metal complexes of the type [M(ah)3](ClO4)2 (1–6) [M = MnII, FeII, CoII, NiII, CuII and ZnII, ah = acetylhydrazine] have been prepared by the reaction of M(ClO4)2 · 6H2O with acetylhydrazine formed in situ by the reaction of hydrazine hydrate and acetylsalicylic acid methyl ester. The chelating behaviour of acetylhydrazine and overall geometry of these complexes have been spectroscopically investigated by means of FT-IR, 1H-n.m.r. and electronic spectral techniques, as well as by elemental analysis data, molar conductance values and magnetic susceptibility measurements. Single X-ray structure determination of complex (4) revealed three acetylhydrazine ligands coordinated to nickel ion in a bidentate manner maintaining an octahedral environment. In all other complexes too, an octahedral geometry has been proposed on the basis of results obtained by various physico-chemical studies. 相似文献
60.
Shubi F. Kaijage Yoshinori Namihira Nguyen H. Hai Feroza Begum S. M. Abdur Razzak Tatsuya Kinjo Hiroki Higa Nianyu Zou 《Optical Review》2008,15(1):31-37
In this paper, we present a dispersion controlling technique with a multiple defect-core hexagonal photonic crystal fiber
(MD-HPCF). By omitting air holes in the core region of the conventional HPCF and adjusting the size of air holes around the
newly formed core, we can successfully design low flattened dispersion PCF with low confinement loss, as well as high birefringence.
The low flattened dispersion feature, as well as the low confinement losses and high birefringence are the main advantages
of the proposed PCF structure, making it suitable as chromatic dispersion controller, dispersion compensator, and/or polarization
maintaining fiber. 相似文献