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1.
Ahmad I Fasihullah Q Vaid FH 《Journal of photochemistry and photobiology. B, Biology》2004,75(1-2):13-20
The photodegradation reactions of riboflavin (RF) in the presence of 0.05-2.00 M phosphate (pH 7.0) have been studied using a specific multicomponent spectrophotometric method. The reactions involve simultaneous photolysis (intramolecular photoreduction) and photoaddition (intramolecular photoaddition) leading to lumichrome (LC) and cyclodehydroriboflavin (CDRF), respectively, as major products. The contribution of each reaction in the overall photodegradation depends upon the phosphate concentration, i.e., higher the phosphate concentration higher the extent of photoaddition. The apparent first-order rate constants for the photodegradation of RF and for the formation of LC and CDRF at 0.25-2.00 M phosphate concentration range from 0.65 to 3.03 x 10(-2), and from 0.41 to 0.99 x 10(-2) and 0.12 to 1.63 x 10(-2) min(-1), respectively. The second-order rate constants for the phosphate catalysed photodegradation of RF and for the formation of LC and CDRF are 2.12 x 10(-4) and 0.61 x 10(-4) and 1.41 x 10(-4) M(-1)s (-1), respectively. Since the formation of CDRF by photoaddition is catalysed by HPO(4)(2-) ions, it is suggested that H(2)PO(4)(-) ions may be involved in the formation of LC by photolysis. Thus, both H(2)PO(4)(-) and HPO(4)(2-) ions may catalyse the two major reaction pathways of riboflavin photodegradation, respectively. 相似文献
2.
Alqasoumi Saleh I. Alam Prawez Al-Rehaily Adnan J. Shakeel Faiyaz Abdel-Kader Maged S. 《平面色谱法杂志一现代薄层色谱法》2011,24(1):48-52
JPC – Journal of Planar Chromatography – Modern TLC - A densitometric high-performance thin-layer chromatographic (HPTLC) method for analysis of hydroquinone has been developed and... 相似文献
3.
Development and validation of UHPLC‐MS/MS assay for rapid determination of a carvone Schiff base of isoniazid (CSB‐INH) in rat plasma: application to pharmacokinetic study
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In this study, a fast UHPLC‐MS/MS method was developed and validated for the determination of a novel potent carvone Schiff base of isoniazid (CSB‐INH) in rat plasma using carbamazepine as an internal standard (IS). After a single‐step protein precipitation by acetonitrile, CSB‐INH and IS were separated on an Acquity BEHTM C18 column (50 × 2.1 mm, 1.7 µm) under an isocratic mobile phase, consisting of acetonitrile: 10 mM ammonium acetate (95:5, v/v), at a flow rate of 0.3 mL/min. Quantification was performed on a triple quadrupole tandem mass spectrometer in multiple reactions monitoring mode by using positive electrospray ionization source. The precursor to product ion transitions were set at m/z 270.08 → 79.93 for CSB‐INH and m/z 237.00 → 178.97 for IS. The proposed method was validated in compliance with US Food and Drug Administration and European Medicines Agency guidelines for bioanalytical method validation. The method was found to be linear in the range of 0.35–2500 ng/mL (r2 ≥ 0.997) with a lower limit of quantification of 0.35 ng/mL. The intra‐ and inter‐day precision values were ≤12.0% whereas accuracy values ranged from 92.3 to 108.7%. In addition, other validation results were within the acceptance criteria and the method was successfully applied in a pharmacokinetic study of CSB‐INH in rats. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
4.
Ahmad I Fasihullah Q Vaid FH 《Journal of photochemistry and photobiology. B, Biology》2005,78(3):229-234
The effect of phosphate buffer on aerobic photodegradation reactions of riboflavin (RF) at pH 7.0 has been studied. The photoproducts of the two major reactions, viz., intramolecular photoreduction and intramolecular photoaddition, have been determined by a specific multicomponent spectrophotometric method. The overall photodegradation of riboflavin in the presence of phosphate buffer involves the participation of both H2PO4-and HPO4(2-) species. The second-order rate constants for the H2PO4(-)-catalysed photodegradation of riboflavin (normal photolysis) to lumichrome (LC) and HPO4(2-)-catalysed photodegradation of riboflavin (photoaddition) to cyclodehydroriboflavin (CDRF) are 0.93 x 10(-4) and 4.0 x 10(-4) M(-1) s(-1), respectively. The addition of 0.25-2.00 M phosphate to RF solutions at pH 7.0 gives rise to RF-HPO4(2-) complex and hence the quenching of 4-36% fluorescence, respectively. This results in the suppression of normal photolysis leading to the formation of LC in favour of photoaddition to yield CDRF. The present study shows the involvement of H2PO4- anions in the base-catalysed degradation of riboflavin by normal photolysis vis-a-vis the involvement of HPO42- anions in photoaddition reactions of riboflavin suggested earlier [M. Schuman Jorns, G. Schollnhammer, P. Hemmerich, Intramolecular addition of the riboflavin side chain. Anion-catalysed neutral photochemistry, Eur. J. Biochem. 57 (1975) 35-48]. 相似文献
5.
Ahmed I. Foudah Sultan Alshehri Faiyaz Shakeel Mohammed H. Alqarni Tariq M. Aljarba Prawez Alam 《Molecules (Basel, Switzerland)》2022,27(13)
The study aimed to develop a new reverse-phase high-performance liquid chromatography (RP-HPLC) method with diode array detection (DAD) detection for simultaneous estimation of escitalopram (EST) and clonazepam (CZP) in tablet dosage forms with a quality by design (QbD) approach. The chromatographic conditions were optimized by Box-Behnken design (BBD) and developed method was validated for the linearity, system suitability, accuracy, precision, robustness, sensitivity, and solution stability according to International Council for Harmonization (ICH) guidelines. EST and CZP standard drugs peaks were separated at retention times of 2.668 and 5.046 min by C-18 column with dimension of 4.6 × 100 mm length and particle size packing 2.5 µm. The mobile phase was methanol: 0.1% orthophosphoric acid (OPA) (25:75, v/v), with a flow rate of 0.7 mL/min at temperature of 26 °C. The sample volume injected was 20 µL and peaks were detected at 239 nm. Using the standard calibration curve, the % assay of marketed tablet was founded 98.89 and 98.76 for EST and CZP, respectively. The proposed RP-HPLC method was able to detect EST and CZP in the presence of their degradation products, indicating the stability-indicating property of the developed RP-HPLC method. The validation parameter’s results in terms of linearity, system suitability, accuracy, precision, robustness, sensitivity, and solution stability were in an acceptable range as per the ICH guidelines. The newly developed RP-HPLC method with QbD application is simple, accurate, time-saving, and economic. 相似文献
6.
Noha M. Soliman Faiyaz Shakeel Nazrul Haq Fars K. Alanazi Sultan Alshehri Mohsen Bayomi Ahmed S. M. Alenazi Ibrahim A. Alsarra 《Molecules (Basel, Switzerland)》2022,27(14)
Various chitosan (CS)-based nanoparticles (CS-NPs) of ciprofloxacin hydrochloride (CHCl) have been investigated for therapeutic delivery and to enhance antimicrobial efficacy. However, the Box–Behnken design (BBD)-supported statistical optimization of NPs of CHCl has not been performed in the literature. As a result, the goal of this study was to look into the key interactions and quadratic impacts of formulation variables on the performance of CHCl-CS-NPs in a systematic way. To optimize CHCl-loaded CS-NPs generated by the ionic gelation process, the response surface methodology (RSM) was used. The BBD was used with three factors on three levels and three replicas at the central point. Tripolyphosphate, CS concentrations, and ultrasonication energy were chosen as independent variables after preliminary screening. Particle size (PS), polydispersity index (PDI), zeta potential (ZP), encapsulation efficiency (EE), and in vitro release were the dependent factors (responses). Prepared NPs were found in the PS range of 198–304 nm with a ZP of 27–42 mV. EE and drug release were in the range of 23–45% and 36–61%, respectively. All of the responses were optimized at the same time using a desirability function based on Design Expert® modeling and a desirability factor of 95%. The minimum inhibitory concentration (MIC) of the improved formula against two bacterial strains, Pseudomonas aeruginosa and Staphylococcus aureus, was determined. The MIC of the optimized NPs was found to be decreased 4-fold compared with pure CHCl. The predicted and observed values for the optimized formulation were nearly identical. The BBD aided in a better understanding of the intrinsic relationship between formulation variables and responses, as well as the optimization of CHCl-loaded CS-NPs in a time- and labor-efficient manner. 相似文献
7.
Shakeel Faiyaz Haq Nazrul Alanazi Fars K. Alanazi Saleh A. Alsarra Ibrahim A. 《Journal of Thermal Analysis and Calorimetry》2020,142(4):1437-1446
Journal of Thermal Analysis and Calorimetry - The solubility and solution thermodynamic properties of a “bioactive nutraceutical” sinapic acid (SA) in different... 相似文献
8.
Prawez Alam Faiyaz Shakeel Abuzer Ali Mohammed H. Alqarni Ahmed I. Foudah Tariq M. Aljarba Faisal K. Alkholifi Sultan Alshehri Mohammed M. Ghoneim Amena Ali 《Molecules (Basel, Switzerland)》2022,27(2)
There has been no assessment of the greenness of the described analytical techniques for the simultaneous determination (SMD) of caffeine and paracetamol. As a result, in comparison to the greener normal-phase high-performance thin-layer chromatography (HPTLC) technique, this research was conducted to develop a rapid, sensitive, and greener reversed-phase HPTLC approach for the SMD of caffeine and paracetamol in commercial formulations. The greenness of both techniques was calculated using the AGREE method. For the SMD of caffeine and paracetamol, the greener normal-phase and reversed-phase HPTLC methods were linear in the 50–500 ng/band and 25–800 ng/band ranges, respectively. For the SMD of caffeine and paracetamol, the greener reversed-phase HPTLC approach was more sensitive, accurate, precise, and robust than the greener normal-phase HPTLC technique. For the SMD of caffeine paracetamol in commercial PANEXT and SAFEXT tablets, the greener reversed-phase HPTLC technique was superior to the greener normal-phase HPTLC approach. The AGREE scores for the greener normal-phase and reversed-phase HPTLC approaches were estimated as 0.81 and 0.83, respectively, indicated excellent greenness profiles for both analytical approaches. The greener reversed-phase HPTLC approach is judged superior to the greener normal-phase HPTLC approach based on numerous validation parameters and pharmaceutical assays. 相似文献
9.
Foudah Ahmed I. Alam Prawez Abdel-Kader Maged S. Shakeel Faiyaz Alqasoumi Saleh I. Salkini Ayman M. Yusufoglu Hasan S. 《平面色谱法杂志一现代薄层色谱法》2020,33(1):43-50
JPC – Journal of Planar Chromatography – Modern TLC - The proposed research study was undertaken to establish a simple, rapid and sensitive high-performance thin-layer chromatography... 相似文献
10.
Mohamed A. Ashour Waseem Fatima Mohd. Imran Mohammed M. Ghoneim Sultan Alshehri Faiyaz Shakeel 《Molecules (Basel, Switzerland)》2022,27(4)
Acacia seyal is an important source of gum Arabic. The availability, traditional, medicinal, pharmaceutical, nutritional, and cosmetic applications of gum acacia have pronounced its high economic value and attracted global attention. In addition to summarizing the inventions/patents applications related to gum A. seyal, the present review highlights recent updates regarding its phytoconstituents. Traditional, cosmetic, pharmaceutical, and medicinal uses with the possible mechanism of actions have been also reviewed. The patent search revealed the identification of 30 patents/patent applications of A. seyal. The first patent related to A. seyal was published in 1892, which was related to its use in the prophylaxis/treatment of kidney and bladder affections. The use of A. seyal to treat cancer and osteoporosis has also been patented. Some inventions provided compositions and formulations containing A. seyal or its ingredients for pharmaceutical and medical applications. The inventions related to agricultural applications, food industry, cosmetics, quality control of gum Arabic, and isolation of some chemical constituents (L-rhamnose and arabinose) from A. seyal have also been summarized. The identification of only 30 patents/patent applications from 1892 to 15 November 2021 indicates a steadily growing interest and encourages developing more inventions related to A. seyal. The authors recommend exploring these opportunities for the benefit of society. 相似文献