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21.
Khan KM Shujaat S Rahat S Hayat S Atta-ur-Rahman Choudhary MI 《Chemical & pharmaceutical bulletin》2002,50(11):1443-1446
Eight new beta-N-substituted acyl hydrazides along with their corresponding acyl derivatives were synthesized and screened for in vitro beta-glucuronidase inhibition and found to be active against the enzyme. All of these compounds were found to be noncompetitive inhibitors except for N'-(2-cyanoethyl)-4-hydroxy benzohydrazide (10), which was found to be an uncompetitive inhibitor. Structure-activity relationship studies indicated that the benzyloxy group present in compounds 12 and 13 is responsible for the beta-glucuronidase inhibition activity. 相似文献
22.
In solution, the [(tim)Co](2+) complex (tim = 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene) reacts only slowly with O(2), but upon adsorption on graphite electrodes, it becomes an active catalyst for the reduction of O(2) to H(2)O(2). The electroreduction of O(2) proceeds in a single voltammetric step at close to the diffusion-controlled rate at a relatively positive potential (0.25 V vs SCE). The remarkable enhancement in catalytic activity is attributed to a higher affinity for O(2) of the adsorbed complex as a result of its interactions with functional groups on the surface of roughened or oxidized graphite. A possible mechanism for the catalytic reduction of O(2) is proposed. It differs from the one employed by the analogous [(hmc)Co](2+) complex (hmc = C-meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) which operates at less positive potentials and exhibits two separated voltammetric steps in the reduction of O(2), via [(hmc)CoOOH](2+), to H(2)O(2). 相似文献
23.
I. Ihsanullah Y. Iqbal T. N. Khattak 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(2):361-366
Summary Date samples were irradiated with different doses using a gamma-irradiator. Levels of moisture, protein, fibre and fats were
determined on monthly basis for 5 months. Generally, the moisture contents of control date samples packed in white polythene
decreased from 14.1±1.1 to 9.7±0.8% over a 5-month period while the irradiated samples were in the range of 10.4-11.2%, however,
no proper pattern of change was observed. After 5-month storage, the protein level of irradiated samples was reduced to 1.00-1.30%,
while the percent fibre levels were found to be in the range of 2.40-2.48. Similarly, the fat level decreases from 1.06±0.12
to 0.68±0.06 for control date sample while after 5-month the decrease in fat content was 0.45±0.04%, 0.44±0.04%, 0.44±0.05%,
0.42±0.05% and 0.40±0.04% for samples irradiated with 20, 50, 100, 200 and 300 krads, respectively. 相似文献
24.
John R. Beswick W. David Cotterill Muhammad Iqbal Robert Livingstone 《Journal of heterocyclic chemistry》1993,30(3):623-626
Reaction between some naphtho[2,1-b]pyrans and 1,1-diphenylethene affords 9,9-diphenyl-1,9,10,10a-tetrahydro-2H-phenaleno[1,9-bc]pyrans. 相似文献
25.
Z. Iqbal 《Chemical physics letters》1976,40(1):41-44
The phase changes in polycrystalline ammonium nitrate and its fully deuterated analogue have been studied by Raman scattering. The phase V and IV transition was found to be associated with the softening and intensity decrease of a NO3? librational mode. The Raman line-width data suggest that the VII to V phase transition involves a change in the degree of orientational order of the ions without incurring a change in lattice structure. 相似文献
26.
The present paper describes the synthesis of 5‐azido‐6‐ketones (14) and 6‐hydroxy‐5‐ketone (20) from Hajos Wiechert ketone as chiral building blocks for cephalostatin analogues. The synthesis of symmetric cephalostatin analogue from 6‐hydroxy‐5‐ketone has also been reported. The characterization of the each synthesized compounds was carried out by IR, 1H‐NMR, 13C‐NMR and High resolution Mass Spectrometry. 相似文献
27.
Some new N‐glycosides of 4‐(2‐phenylethyl)‐5‐pyridyl‐1,2,4‐triazole‐3‐thiones were synthesised by the coupling reaction of halo sugar with 4,5‐disubstituted 3H‐1,2,4‐triazole‐3‐thiones in the presence of mercuric cyanide and dry nitromethane as solvent, followed by deprotection using dry ammonia in methanol. All of the above compounds were fully characterized by means of infrared, 1H NMR spectroscopy, mass spectroscopy and elemental analysis. 相似文献
28.
ViqarUddin Ahmad MuhammadAthar Abbasi Muhammad Zubair Naheed Fatima Umar Farooq M.Iqbal Choudhary 《Helvetica chimica acta》2004,87(1):67-72
Phytochemical investigation of Symplocos racemosa resulted in the isolation of two new glycosides, symploracemoside ( 1 ) and symplomoside ( 2 ), which are structurally related to the reported benzoylsalireposide ( 3 ) and salireposide ( 4 ). The structure elucidation of the isolated compounds was based primarily on 1D‐ and 2D‐NMR analysis, including COSY, NOESY, HMQC, and HMBC correlations. These glycosides showed inhibitory activity against snake‐venom phosphodiesterase I. 相似文献
29.
30.
Mehmood A Malik A Anis I Khan PM Riaz M Makhmoor T Choudhary MI 《Natural product letters》2002,16(6):371-376
Two new oleanane triterpenes; 2alpha,3alpha,24-trihydroxyolean-12-ene-28,30-dioic acid ([structure: see text]) and 2alpha,3alpha,24,28-tetrahydroxyolean-12-ene ([structure: see text]) have been isolated from the roots of Atropa acuminata. Anti-oxidant p-hydroxyphenethyl trans-ferulate ([structure: see text]), beta-sitosterol-3-O-beta-D-glucopyranoside ([structure: see text]) and oleanolic acid ([structure: see text]) have also been reported for the first time from this species. The structures were determined by spectroscopic studies including 2D-NMR. 相似文献