Volumetric, acoustical and viscometric behavior of glycine and DL-alanine in aqueous furosemide solutions at different temperatures

Investigation of intermolecular interactions of l-Valine and l-Phenylalanine with muscle relaxant drug mephenesin molecule prevalent in aqueous solution by various physico-chemical methods at T=298.15K-313.15K

A complete chemical analysis of significant intermolecular interactions of l-Valine (L-Val) and l-Phenylalanine (L-Phe) with Mephenesin (MEPN) molecules in aqueous solution has been studied by different physicochemical methodologies at various temperatures (T = 298.15 K-313.15 K at an interval of 5 K) and concentrations (0.001 mol kg-1, 0.003 mol kg-1, 0.005 mol kg-1) of aqueous MEPN solution. The limiting apparent molar volume (φ V 0 ) and experimental slope (S V * ) values are found from the equation of Masson, viscosity A and B-coefficient determined using the equation of Jones-Doles, molar refraction (RM) and limiting molar refraction (RM0) derived by the Lorentz-Lorenz equation, express that in our experimental solution of amino acids (AAs) in aqueous MEPN, the solute-solvent interaction predominates over the solute-solute and solvent-solvent interactions for these ternary solutions. These are also justified by the measurement of various thermodynamic parameters, free energy of activation of viscous flow per mole of solvent(Δμ1°#) and solute (Δμ2°#), activation of viscous flow of enthalpies (ΔH°#) and entropies (ΔS°#). The characteristics of structure-breaking of solutes in the aqueous drug solution have been identified by Hepler's method and dB/dT value. The spectroscopic methods like UV-visible and proton-NMR studies help to explicate the strong AA-MEPN interactions in the solution phase and obtain a good correlation with theoretical studies. Theoretical investigations are checked to authenticate the experimental observations and according to both studies, L-Phe-MEPN interaction is greater than L-Val-MEPN interaction. The experimental and correlated research data are useful for the development of model combinations of AAs with drug molecules in pharmaceutical and medicinal chemistry.

Volumetric and conductivity studies of the interaction between levocetirizine dihydrochloride and the amino acids l-alanine and l-glutamine in aqueous solutions

Levocetirizine dihydrochloride (LCTZ) is a second-generation antihistamine known for its efficacy without sedation. However, the binding mechanism with plasma protein which makes it devoid of sedative effects is yet to be uncovered. In this study, we elucidated thermodynamic parameters of solute-solvent and solute-cosolute interactions between LCTZ, and the amino acids l-alanine (Ala) and l-glutamine (Gln) in aqueous solutions. The volumetric and conductance parameters were calculated using the experimental density and conductance data of aqueous solutions of Ala and Gln (concentration range of 0.02-0.20 mol kg^-1) and LCTZ (concentration range of 0.01, 0.07, and 0.13 mol kg^-1) at 298.15, 303.15, 308.15, and 313.15 K. Volumetric analysis study revealed that the apparent molar volume (V_φ), limiting apparent molar volume (V_φ ⁰), and Masson's coefficient (S_v) values indicated predominantly solute-solvent interactions that were influenced by the solute's concentration and temperature. Meanwhile, partial molar expansibilities (E_φ ⁰), transfer volume Δ_trV_φ ⁰ and Hepler's constant (δ²V₀/δT²) established the solution system's structure-breaking tendency. The Gibb's free energy (ΔG₀) values derived from conductometry data indicated the system's spontaneity. These calculated constants provided a detailed understanding of the different types of intermolecular interactions found in the ternary (LCTZ + water + amino acids) system.

Investigations to Explore Molecular Interactions and Sweetness Response of Polyhydroxy Compounds with Amino Acids in Aqueous Systems

In conjunction with the development of people's living standards, the modern world demands good-quality food such as sweets, candies, chocolates, diet drinks, beverages, and so on, but because of obesity and other health issues people concentrate more on sugar-free or low-calorie products. Polyols are such a kind of food with desirable qualities, and they play a role in controlling the blood glucose level in diabetic patients. The density (ρ) and sound speed (u) of sugar alcohol in water and in (0.02, 0.04, and 0.06) mol kg^-1l-arginine solutions at different temperatures (293.15-318.15 K) and atmospheric pressure were measured by using Anton Paar DSA5000M. Experimental density and sound velocity data were further used to compute volumetric and acoustic parameters such as apparent molar volume (Ø_V), partial molar volume (Ø _V ⁰), compressibility (Ø _k ⁰), expansibility (Ø _E ⁰), and so on. The positive trends of apparent molar volume (Ø _V ), and partial molar volume Ø _V ⁰), values indicate strong hydrophilic interactions in ternary solutions. These interactions give a complete picture about solvation behavior, the effect of temperature, and hydrogen bonding present among (galactitol + l-arginine) mixtures. The apparent specific volume values were calculated, and it was found that these values of the investigated mixtures lie on the borderline with the reported values of sweeteners. This study may offer a new vision in elucidation of mechanistic modifications between sugar alcohol, amino acid, and their mode of interactions.

The effects of active double-layered furcellaran/gelatin hydrolysate film system with Ala-Tyr peptide on fresh Atlantic mackerel stored at -18 °C

This is the first time that active double-layered furcellaran/gelatin hydrolysate films containing Ala-Tyr peptide were developed and characterised for their properties. Afterwards, films were used on Atlantic mackerel stored at -18 °C for 4 months and samples were analysed for changes in their microbiological quality, TVB-N, biogenic amine content, fatty acid composition and TBARS. Active films had higher TS (13.4 MPa) and lower WS (62.8%). The films showed no DPPH radical scavenging properties but high FRAP (6.6 mMol Trolox/mg). No significant effects on the oxidation of fish samples were observed with TBARS increasing from 12.04 to 22.50 mg/kg. Freezing successfully inhibited the growth of microorganisms and no differences in microbiological growth or biogenic amine formation were observed. However, the application of films inhibited the formation of TVB-N. Antimicrobiological properties of the film should be further investigated during storage of perishable food products at temperatures above 0 °C.

Volumetric Investigations on Molecular Interactions of Glycine/l-alanine in Aqueous Citric Acid Solutions at Different Temperatures

Apparent molar volumes \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\phi_{V})$$\end{document}(ϕV) of glycine/l-alanine in water and in aqueous citric acid (CA) solutions of varying concentrations, i.e. (0.05, 0.10, 0.20, 0.30, 0.40 and 0.50) mol·kg⁻¹ were determined from density measurements at temperatures T = (288.15, 298.15, 308.15, 310.15 and 318.15) K and at atmospheric pressure. Limiting partial molar volumes \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\phi_V^{\text{o}})$$\end{document}(ϕVo) and their corresponding partial molar volumes of transfer \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\Delta_{\text{tr}} \phi_{V} )$$\end{document}(ΔtrϕV) have been calculated from the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\phi_{V}$$\end{document}ϕV data. The negative \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta_{\text{tr}} \phi_{V}$$\end{document}ΔtrϕV values obtained for glycine/l-alanine from water to aqueous CA solutions indicate the dominance of hydrophilic–hydrophobic/hydrophobic–hydrophilic and hydrophobic–hydrophobic interactions over ion/hydrophilic–dipolar interactions. Further, pair and triplet interaction coefficients, i.e.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(V_{\text{AB}} )\;{\text{and}}\; (V_{\text{ABB}} )$$\end{document}(VAB)and(VABB) along with hydration number \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(n_{\text{H}} )$$\end{document}(nH) have also been calculated. The effect of temperature on the volumetric properties of glycine/l-alanine in water and in aqueous CA solutions has been determined from the limiting partial molar expansibilities \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\partial \phi_{V}^{\text{o}} /\partial T)_{p}$$\end{document}(∂ϕVo/∂T)p and their second-order derivative \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\partial^{2} \phi_{V}^{\text{o}} /\partial T^{2} )_{{P}}$$\end{document}(∂2ϕVo/∂T2)P. The apparent specific volumes \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(\nu_{\phi} )$$\end{document}(νϕ) for glycine and l-alanine tend to approach sweet taste behavior both in the presence of water and in aqueous CA solutions. The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\nu_{\phi}$$\end{document}νϕ values for glycine/l-alanine increase with increase in concentration of CA at all temperatures studied. This reveals that CA helps in enhancing the sweet taste behavior of glycine/l-alanine which also supports the dominance of hydrophobic–hydrophobic interactions.