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21.
Study of the Degradation Kinetics of Carvedilol by Use of a Validated Stability-Indicating LC Method
Mohammad Rizwan Mohammed Aqil Adnan Azeem Yasmin Sultana Sushama Talegaonkar Asgar Ali 《Chromatographia》2009,70(7-8):1283-1286
The objectives of this investigation were to establish a validated stability-indicating LC method for assay of carvedilol and to study the degradation behaviour of the drug under different ICH-recommended stress conditions. Chromatographic separation was achieved on a C18 column with 55:45 (%, v/v) acetonitrile–0.02 m phosphate buffer, pH 3.5, as mobile phase at a flow rate of 1.0 mL min?1; detection was by UV absorbance at 242 nm. The method was validated for linearity, precision, accuracy, robustness, specificity, and sensitivity, with the bulk drug. The drug was subjected to forced degradation and peaks of all the degradation products were well resolved from that of the pure drug, with significantly different retention times, which indicates the specificity and stability-indicating properties of the method. First-order degradation kinetics of carvedilol were observed under acidic and alkaline conditions. When the utility of the method was verified by analysis of the drug in marketed tablets and a nano-emulsion formulation, the assay was found to be 98.60–99.61 and 99.52–99.87, respectively. These results indicate the method can be successfully used for routine analysis of carvedilol in the bulk drug and in pharmaceutical dosage forms. 相似文献
22.
Tamanna Sultana Jae Mok Jung Seong-Soo Hong Won-Ki Lee Yeong-Soon Gal Hyun Gyu Kim Kwon Taek Lim 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):207-212
Inclusion properties of the drug omeprazole (OMP) with peracetylated-beta-cyclodextrin (PAc-β-CD) prepared by green method, following supercritical carbon-dioxide (scCO2), were characterized through thermal (TGA and DSC), crystalline (XRD), NMR spectroscopic and dissolution studies. Comparison amongst PAc-β-CD, OMP, physical binary mixture (equimolar ratio of OMP: PAc-β-CD) and the solid inclusion complex (OMP/PAc-β-CD) revealed scCO2 as a successful technique for inclusion complex formation as well, identified characteristics performances of PAc-β-CD/OMP interactions. For instance, absence of characteristic DSC or XRD peaks of either chemical in the complex was quite noticeable with the shift of proton peaks in 1H NMR spectra. The formed inclusion complex also showed an important dissolution performance of OMP for controlled release applications partly due to the hydrophobic nature of PAc-β-CD. 相似文献
23.
Sultana N Arayne MS Khan MM Saleem DM Mirza AZ 《Journal of chromatographic science》2012,50(6):531-537
This paper describes tryptophan (TRP) estimation in raw human plasma and rat brain by reversed-phase high-performance liquid chromatography (RP-HPLC). Estimation was carried out on a Purospher STAR C18 column using water-acetonitrile (90:10 v/v, at pH 2.7) mixture at a rate of 1.5 mL/min as mobile phase. Eluents were monitored at 273 nm by an ultraviolet detector. The method was linear (R(2) > 0.999), precise (intra-day and inter-day precision <2%) in the range of 0.25-20 μg/mL. The detection and quantification limits were 0.0144 μg/mL and 0.0437 μg/mL, respectively. In human plasma, Day 1 and Day 2 precision were 0.054-2.29% and 1.66-3.7%; whereas precisions in rat brain were 1.23-2.3% and 0.677-4.2%, respectively. The method was applied to study TRP level in human smokers and in arthritic rat brain. An efficient RP-HPLC method was developed for TRP determination that worked for clinical and research purposes. 相似文献
24.
Zafar Iqbal Muhammad Nawaz Naeem Nazra Sultana Shahid Hussain Arshad Abdul Ghafar Shah 《应用数学和力学(英文版)》2009,30(11):1393-1404
The vibration characteristics of a functionally graded material circular cylindrical shell filled with fluid are examined with a wave propagation approach. The shell is filled with an incompressible non-viscous fluid. Axial modal dependence is approximated by exponential functions. A theoretical study of shell vibration frequencies is analyzed for simply supported-simply supported, clamped-simply supported, and clamped-clamped boundary conditions with the fluid effect. The validity and the accuracy of the present method are confirmed by comparing the present results with those available in the literature. Good agreement is observed between the two sets of results. 相似文献
25.
Masood Parvez Jehan Ara Viqar Sultana Rashida Qasim Viqar Uddin Ahmad 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):e96-e97
The crystal structure of caulerpin (dimethyl 6,13‐dihydrodibenzo[b,i]phenazine‐5,12‐dicarboxylate, C24H18N2O4), an indole alkaloid, reported in space group Cc with an acute β angle, has been redetermined in the correct space group, C2/c. The molecule has twofold crystallographic symmetry and is composed of two essentially planar indole groups fused to an eight‐membered cyclooctatetraene ring which adopts a boat conformation. The molecular dimensions are normal. The structure is stabilized by intermolecular and intramolecular interactions involving the indole N—H atom and carbonyl O atom [N?O 3.211 (4) and 2.836 (4) Å]. 相似文献
26.
Seulah Lee Man Hyung Koo Dong-Won Han Il-Chan Kim Jun Hyuck Lee Jeong-Hoon Kim Razia Sultana Sun Yeou Kim Ui Joung Youn Jin-Hyoung Kim 《Molecules (Basel, Switzerland)》2022,27(14)
Total fatty-acid (FA) contents of different organs (stomach, liver, brain, and skin) of two Antarctic fish, marbled rockcod (Notothenia rossii) and mackerel icefish (Champsocephalus gunnari), were examined using gas chromatography–mass spectrometry (GC–MS). N. rossii possessed higher contents of total omega-3, where eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the most represented omega-3 FAs, were distributed throughout all parts of the fish. The highest level of EPA was observed in the skin and that of DHA was observed in the brain of N. rossii. C. gunnari showed organ peculiarity in that most of the omega-3 FAs were found in stomach and skin. Specifically, the highest levels of EPA and DHA were both observed in the stomach. Although N. rossii and C. gunnari both inhabit the Antarctic Southern Oceans, their characteristics in terms of the composition of fatty acids were shown to vary. The extracts were also evaluated for matrix metalloproteinase-1 (MMP-1)-inhibitory activities in UVB-induced human dermal fibroblasts, where extracts of the skin and liver of N. rossii showed the most significant inhibition upon MMP-1 production. These findings provide experimental evidence that the extracts of the Antarctic fish could be utilized as bioactive nutrients, particularly in the enhancement of skin health. 相似文献
27.
Nabil A. Younes Md. Mezanur Rahman Ahmed A. Wardany Mona F. A. Dawood Mohammad Golam Mostofa Sanjida Sultana Keya Arafat Abdel Hamed Abdel Latef Lam-Son Phan Tran 《Molecules (Basel, Switzerland)》2021,26(9)
The increasing culinary use of onion (Alium cepa) raises pressure on the current production rate, demanding sustainable approaches for increasing its productivity worldwide. Here, we aimed to investigate the beneficial effects of licorice (Glycyrrhiza glabra) root extract (LRE) in improving growth, yield, nutritional status, and antioxidant properties of two high-yielding onion cultivars, Shandaweel and Giza 20, growing under field conditions in two consecutive years. Our results revealed that pretreatments of both onion cultivars with LRE exhibited improved growth indices (plant height and number of leaves) and yield-related features (bulb length, bulb diameter, and bulb weight) in comparison with the corresponding LRE-devoid control plants. Pretreatments with LRE also improved the nutritional and antioxidant properties of bulbs of both cultivars, which was linked to improved mineral (e.g., K+ and Ca2+) acquisition, and heightened activities of enzymatic antioxidants (e.g., superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase, and glutathione S-transferase) and increased levels of non-enzymatic antioxidants (e.g., ascorbic acid, reduced glutathione, phenolics, and flavonoids). LRE also elevated the contents of proline, total free amino acids, total soluble carbohydrates, and water-soluble proteins in both onion bulbs. In general, both cultivars displayed positive responses to LRE pretreatments; however, the Shandaweel cultivar performed better than the Giza 20 cultivar in terms of yield and, to some extent, bulb quality. Collectively, our findings suggest that the application of LRE as biostimulant might be an effective strategy to enhance bulb quality and ultimately the productivity of onion cultivars under field conditions. 相似文献
28.
Dr. Chanchal Kumar Roy Syed Shaheen Shah Akter H. Reaz Sharmin Sultana Dr. Al-Nakib Chowdhury Dr. Shakhawat H. Firoz Dr. Md. Hasan Zahir Dr. Mohammed Ameen Ahmed Qasem Dr. Md. Abdul Aziz 《化学:亚洲杂志》2021,16(4):296-308
We demonstrate a facile efficient way to fabricate activated carbon nanosheets (ACNSs) consisting of hierarchical porous carbon materials. Simply heating banana leaves with K2CO3 produce ACNSs having a unique combination of macro-, meso- and micropores with a high specific surface area of ∼1459 m2 g−1. The effects of different electrolytes on the electrochemical supercapacitor performance and stability of the ACNSs are tested using a two-electrode system. The specific capacitance (Csp) values are 55, 114, and 190 F g−1 in aqueous 0.5 M sodium sulfate, organic 1 M tetraethylammonium tetrafluoroborate in acetonitrile, and pure ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) electrolytes, respectively. The ACNSs also shows the largest potential window of 3.0 V, the highest specific energy (59 Wh kg−1) and specific power (750 W kg−1) in [BMIM][PF6]. A mini-prototype device is prepared to demonstrate the practicality of the ACNSs. 相似文献
29.
Sankarasubbier Narayanan Asima Sultana Kamasamudram Krishna 《Reaction Kinetics and Catalysis Letters》1994,52(1):205-210
A clear correlation between aniline alkylation over HZSM-5 zeolite and the acidity as measured by stepwise temperature programmed desorption (STPD) of NH3 and cumene dealkylation has been established. 相似文献
30.
NADPH‐cytochrome P450 reductase (CPR) serves as electron donor for cytochrome P450 catalyzed monooxygenase reactions utilizing flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) as electron transfer cofactors. Here, stable films of human and rabbit CPRs with didodecyldimethylammonium bromide (DDAB), dimyristoylphosphatidyl choline (DMPC), and poly(diallyldimethylammonium) (PDDA) were made on pyrolytic graphite (PG) electrodes for comparative structural and electrochemical studies. CD and UV‐VIS absorbance spectra suggested that near native CPR conformation is retained in PDDA films, and some conformational changes occur in DMPC or DDAB films. Cyclic voltammetry of these films gave quasireversible pairs of peaks at average formal potential ?0.246±0.008 V vs. NHE. In human CPR‐DDAB (H‐CPR‐DDAB), a second pair of peaks at +0.317 V vs. NHE was found that depended strongly on identity of buffer and salt. Excepting H‐CPR in DDAB, films showed similar voltammetry, formal potentials, and ks values. While CPR‐PDDA films had near native CPR structures, electrochemical parameters did not differ significantly from CPR‐DMPC films. The relative independence of film voltammetry from the influence of film materials for CPRs is in contrast with heme iron proteins that, while retaining near native structures, have formal potentials that depend significantly on identity of the film material. 相似文献