Green analytical chemistry-driven response surface modeling to stability-indicating chromatographic method for estimation of cilnidipine and application of high-performance thin-layer chromatography–mass spectrometry for characterization of degradation products

Cilnidipine is a calcium channel blocker that is used to treat cardiac diseases such as angina and high blood pressure. Several column and planar chromatographic methods for estimating cilnidipine in pharmaceutical dosage forms have been documented. However, these method developments have been carried out employing organic solvents such as acetonitrile, methanol, toluene, chloroform, and others as mobile phase components or as sample pretreatment diluents. These organic solvents are neurotoxic and teratogenic to humans and aquatic animals, according to International Council for Harmonization Q3C (R8) recommendations. According to the green analytical chemistry approach, such organic solvents should be reduced or removed during the development of chromatographic methods for environmental protection and the safety of human and aquatic animal life. As a result, the stability-indicating chromatographic estimation of cilnidipine was performed utilizing less toxic organic solvents. To prevent organic solvent waste during method development, mobile-phase optimization was performed using the design of experiment-based response surface modeling. Cilnidipine has been subjected to hydrolysis, oxidation, photolysis, and dry-heat decomposition to determine its stability. The greenness profiles of the suggested and published chromatographic methods were examined using the national environment method index, analytical greenness calculator, green analytical procedure index software, and eco-scale assessment tool.     

Trigonometric approximation of functions in $$L_1$$ L 1 -norm

Periodica Mathematica Hungarica - In this paper, the authors have obtained $$L_1$$ -approximations of functions f in $$ {{\,\mathrm{Lip}\,}}(\alpha ,1) $$ $$ (0 < \alpha \le 1) $$ by...     

Ring Expansion of Thiolactams via Imide Intermediates: An Amino Acid Insertion Strategy

The Ag^I-promoted reaction of thiolactams with N-Boc amino acids yields an N-(α-aminoacyl) lactam that can rearrange through an acyl transfer process. Boc-deprotection results in convergence to the ring-expanded adduct, thereby facilitating an overall insertion of an amino acid into the thioamide bond to generate medium-sized heterocycles. Application to the site-specific insertion of amino acids into cyclic peptides is demonstrated.     

A chiral Rh–phosphite complex displaying high activity in the enantioselective Rh-catalyzed addition of arylboronic acids to carbonyl compounds: when and why atropos is better than tropos

The use of deoxycholic acid derived tropos and atropoisomeric phosphites as chiral ligands in the Rh-catalyzed enantioselective addition of arylboronic acids to arylaldehydes and 2,2,2-trifluoroacetophenone is presented. Screening of these phosphites showed the high activity of the Rh-complex obtained starting from one of the two atropoisomeric ligands, which afforded complete conversion of the carbonyl compounds in short reaction times under mild reaction conditions and with ee’s of up to 84%. A study aimed at getting information about the different behavior of tropos and atropoisomeric ligands is also reported.     

Protein-Templated Hit Identification through an Ugi Four-Component Reaction**

Kinetic target-guided synthesis represents an efficient hit-identification strategy, in which the protein assembles its own inhibitors from a pool of complementary building blocks via an irreversible reaction. Herein, we pioneered an in situ Ugi reaction for the identification of novel inhibitors of a model enzyme and binders for an important drug target, namely, the aspartic protease endothiapepsin and the bacterial β-sliding clamp DnaN, respectively. Highly sensitive mass-spectrometry methods enabled monitoring of the protein-templated reaction of four complementary reaction partners, which occurred in a background-free manner for endothiapepsin or with a clear amplification of two binders in the presence of DnaN. The Ugi products we identified show low micromolar activity on endothiapepsin or moderate affinity for the β-sliding clamp. We succeeded in expanding the portfolio of chemical reactions and biological targets and demonstrated the efficiency and sensitivity of this approach, which can find application on any drug target.     

Solving linear and nonlinear fractional diffusion and wave equations by Adomian decomposition

Adomian decomposition method has been used to obtain solutions of linear/nonlinear fractional diffusion and wave equations. Some illustrative examples have been presented.     

On calculus of local fractional derivatives

Local fractional derivative (LFD) operators have been introduced in the recent literature (Chaos 6 (1996) 505-513). Being local in nature these derivatives have proven useful in studying fractional differentiability properties of highly irregular and nowhere differentiable functions. In the present paper we prove Leibniz rule, chain rule for LFD operators. Generalization of directional LFD and multivariable fractional Taylor series to higher orders have been presented.     

Atomic electronegativity based on hardness and floating spherical gaussian orbital approach

Journal of Mathematical Chemistry - Electronegativity (χ) is an important property of any chemical species as it helps to predict the pattern of physico-chemical interactions. In the present...     

Intraventricular thrombus formation in the LVAD-assisted heart studied in a mock circulatory loop

Left ventricular assist devices (LVADs) are mechanical pumps that are surgically attached to the left ventricle and aorta. Clinical studies show that LVADs improve patient health and quality of life, and dramatically reduce the mortality of cardiac failure. During periods of high LVAD support, blood flow occurs entirely through the LVAD, the aortic valve is continuously closed, and the heart operates in series with the pump. Thus the normal fluid dynamics of intraventricular flow are altered and linked to the development of thrombus in both the native heart and LVAD. Our goal in this study was to simulate a patient with a recurring thrombus and quantify the variations in the flow field in the LV as the thrombus developed. Particle image velocimetry measurements of transparent silicone models were performed for a range of LVAD support conditions. Results show that the presence of a small thrombus in the LVOT creates a favorable condition for further growth, especially in the presence of high LVAD support. As the thrombus enlarges, it begins to affect the normal vortex-flow pattern, further reducing flow rate and pulsatility in the LVOT. Evaluation of vortex dynamics and stasis regions in both patients and experimental models of LVAD support yield quantitative metrics that can be used to assess the risk of thrombus and the development of strategies to reduce this risk in LVAD patients.