Development and validation of spectrofluorimetric method for determination of diflunisal and its impurity

A new sensitive, simple, rapid, accurate and precise spectrofluorimetric method for determination of diflunisal and its impurity is developed. Determination of diflunisal is based on first derivative spectrofluorimetric method, while its impurity can be determined by zero order spectrofluorimetric method. Diflunisal was measured at zero-crossing wavelength 394nm (zero crossing point with its impurity) which was selected for quantification of diflunisal. The impurity was measured directly at 334 nm, using 0.05 M phosphate buffer (pH = 9) as solvent. The analytical signal resulting from first derivative and zero order spectra were measured for diflunisal and its impurity, respectively. Linearity was over the range of 0.1-0.9 μg/mL for both with detection limit of 0.02 and 0.03 μg/mL and quantitation limit of 0.07 and 0.09 μg/mL for diflunisal and its impurity, respectively. The proposed method was validated as per ICH guidelines.The accuracy was checked by applying the proposed method for the determination of the drug and its impurity, the mean percentage recoveries were found to be 99.61±0.911 and 100.41±1.373 for diflunisal and its impurity, respectively. RSD values for repeatability testing were 0.268 and 0.569 and for intermediate precision were 0.224 and 0.259 for diflunisal and its impurity, respectively. The proposed method was effectively applied to analysis of studied drug in its tablet formulation. The results obtained by it were statistically compared with the reported method revealing high accuracy and good precision

Synthesis and preliminary biological screening of certain 5-aralkyl pyrrolidine-3-carboxylic acids as anticonvulsants

Synthesis of a series of 5-aralkyl pyrrolidine-3-carboxylic acid derivatives namely, 1-acetyl-4-hydroxy-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (3a-e), 1-H-4-hydroxy-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (4a-e), 1-acetyl-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (8a-e), 1-H-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (9a-e) have been accomplished. The structures of the new compounds were assigned from IR, 1H NMR, 13C NMR and elemental analyses. Compounds 3a-e, 4a-e, 8a-e and 9a-e were biologically screened for their anticonvulsant potential using the subcutaneous pentylenetetrazole seizures (scPTZ) assay and Gabapentin as reference standard. The 1-H-4-hydroxy-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (4a-e) showed the highest anticonvulsant activity. Compound 4b was found to be the most potent one which exhibited 100% protection

Complexation of manganese(II), cobalt(II), nickel(II) and copper(II) by a ligand derived from 1,2,4-triazole: Potentiometric studies and Density Functional Theory calculations

DFT calculations have been conducted to understand the conformational and tautomeric preference of 4-amino-5-(2-hydroyphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione ligand. The results suggest that the thione tautomer is found to be the most stable form in the gas phase, which is in very good agreement with the FT-IR and crystallographic data. The protonation constants of the ligand and the stability constants of its complexes with Mn(II), Co(II), Ni(II) and Cu(II) have been determined by potentiometry in water-ethanol (90:10, v:v) mixture. The absolute pKa values of the ligand have been calculated using DFT method to complement and help the assignment of potentiometric data. DFT calculations have also been carried out for some metallic complexes species formed in solution in order to propose their most probable structures

Synthesis, characterization of flavone, isoflavone, and 2,3-dihydrobenzofuran-3-carboxylate and density functional theory studies

We describe the oxidation of flavanones by employing phenyliodonium diacetate to form the flavone (15), isoflavone (8) and 2,3-dihydrobenzofurane (18) in this study. The oxidative method was found to be regioselective and dependent on the substitution pattern present on the two aromatic rings of the starting flavanone. The structures of products obtained were fully characterized by using IR, 1H and 13C NMR spectroscopy and Mass spectrometry. X-ray crystallography further confirms the structures of flavones and isoflavone. The density field theory calculations have also been performed to get more insight about the structures, electronic and spectroscopic properties of synthetic flavonoid derivatives. The geometrical parameters such as bond lengths and angels showed a good correlation with the values obtained through X-ray crystallography. Moreover, the theoretically simulated vibrational and UV-vis spectral values are in agreement with the experimental results

Application of 4-chloro-7-nitrobenzofurazan for the analysis of propafenone and diltiazem hydrochlorides using kinetic spectrophotometric and spectrofluorimetric methods

Several simple, sensitive, accurate and inexpensive spectrophotometric and spectrofluorimetric methods were developed for the determination of propafenone HCl and diltiazem HCl using 4-chloro-7-nitrobenzofurazan (NBD-Cl) accompanied with kinetic study, either in pure form or in pharmaceutical preparations. In this work, the cited drugs react with (NBD-Cl) in presence of borate buffer of pH = 7.6 at a fixed time of 30 minutes on thermostated water bath at (75-80 °C). The absorbance was measured using spectrophotometric technique at 489 and 481 nm for propafenone HCl and diltiazem HCl, respectively, or by using spectrofluorimetric technique after dilution at the specific wavelength of excitation and emission.The calibration curves were linear in the range of 4-44, 16-96 µg/mL when using spectrophotometric method, and 0.4-3.6, 1.6-8.8 µg/mL when spectrofluorimetric method was applied for propafenone HCl and diltiazem HCl, respectively. The limit of quantitation and the limit of detection were also calculated. The methods were applied successfully to commercial dosage form and can be further applied for their determination on a large scale in quality control laboratories. The obtained results statistically agreed with those obtained by reference methods. The determination of the studied drugs by the fixed concentration and rate constant methods is feasible with the calibration equations obtained, but the fixed time method proves to be more applicable

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Graphical Content

Synthesis of some novel pyridine and naphthyridine derivatives

2-[1-(Furan- or thiophen-2-yl)ethylidene)malononitriles (1a,b) undergo dimerization reactions in ethanol catalyzed by sodium ethoxide to afford 2-[4,6-di(furan- or thiophen-2-yl)-3-cyano-6-methyl-5,6-dihydropyridin-2(1H)-ylidene]malononitrile derivatives (2a,b), respectively. Compounds 2a and 2b couple with arene diazonium salts (3a-c) to afford the hydrazo derivatives (4a-f). They react also with hydrazines (5a,b) to afford the pyrazolo[3,4-H][1,6]naphthyridine derivatives (6a-d) and with urea derivatives (7a-c) to afford the pyrimido[4,5-H][1,6]naphthyridine derivatives (8a-f), respectively

The cytotoxic activity of Linum grandiflorum leaves

The CHCl3 and MeOH fractions of the leaves of Linum grandiflorum, showed cytotoxic activity against EL4 (Murine Leukemia) cell line with IC50 = 60 and 250 mg/mL respectively. Bioassay guided fractionation and isolation (BGFI) of the MeOH fraction resulted in the isolation of two new cytotoxic compounds 1 [luteolin 7-O-α-D-(6```-E-feruloyl)glucopyranosyl (1→2)-β-D-glucopyranoside] and 6 [2-[(3`-isopropoxy-O-β-D-glucopyranosyl)oxy]-2-methylbutane nitrile] against EL4 with IC50 = 0.2 and 0.3 mM/mL respectively, together with 2 [luteolin 7-O-β-D-glucopyranoside], 3 [vicenin-1], 4 [vicenin-2], 5 [vicenin-3], 7 [linamarin], 8 [lotaustralin], 9 [neolinustatin], and  10 [butan-2-O-β-D-glucopyranoside] which showed cytotoxicity against EL4 with IC50 = 0.2, 0.9, 0.8, 0.9, 0.4, 0.4, 0.2, 0.4 mM/mL respectively. BGFI of the CHCl3 fraction revealed the isolation of three cytotoxic aryltetrahydronaphthalene-type lignans identified as 11 [podophyllotoxin], 12 [deoxypodophylotoxin] and 13 [5-methoxypodophyllotoxin] against EL4 with IC50 = 0.2, 0.09 and 0.2 mM/mL respectively. The isolated compounds were structurally elucidated using 1D, 2D NMR, HR-ESI-MS, and HR-MALDI-MS techniques

Study of the optical properties of poly(vinyl chloride)-4-[(5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl]phenol complexes

The most widely practiced reaction of diazonium salts is azo coupling. In this process, the diazonium compound is attacked by an electron-rich substrate. When the coupling partners are arenes (phenols), the process is an example of electrophilic aromatic substitution. Poly (vinyl chloride) (PVC) react with 4-[(5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl]phenol (L) in THF to form the PVC-L compound, which have been characterized by spectroscopic methods. PVC-L has further been reacted with different metals ions to form PVC-L-MII complexes. The structure of these complexes has been characterized by FT-IR and UV-Vis spectrophotometry. The optical properties in the region from 200-900 nm were also studied using UV-Vis spectrophotometer. The optical data analyzed and interpreted in term of the theory of phonon assisted direct electronic transitions according to energy gap data the conductivity of PVC and the complexes

Synthesis and antimicrobial activity of novel oxime derivatives of phenothiazine

A series of 4-methyl-2-oxo-pyranyl-phenothiazines (IIIa-j) followed by 4-methylpyrano-(2, 3-β)-phenothiazine-2(11H)-one oxime (IVa-j) were synthesized by using 7-hydroxy-4-methylcoumarin (I). Further reaction of (I) was carried out with substituted aromatic amines (a-j) to convert into 7-arylamino-4-methyl-coumarin (IIa-j). Additionally (IIa-j) was treated with sulphur in presence of iodine to obtain a series of novel 4-methyl-2-oxo-pyranyl-phenothiazine (IIIa-j) derivatives, which on treatment with hydroxylamine hydrochloride afforded the title compounds i.e. 4-methylpyrano-(2,3-β)-phenothiazine-2(11H)-one oxime (IVa-j). The structures of these compounds were confirmed by IR, NMR and Mass spectral analysis. The newly synthesized compounds were evaluated for antibacterial and antifungal activity. The results show that compound IIIa, IIIe, IIIh, IIIj, IVa, IVi and IVj exhibited moderate to good antibacterial and antifungal activity at 5-100 mcg/mL