Thermal Stability Kinetics and Shelf Life Estimation of the Redox-Active Therapeutic and Mimic of Superoxide Dismutase Enzyme, Mn(III) meso-Tetrakis(N-ethylpyridinium-2-yl)porphyrin Chloride (MnTE-2-PyPCl5, BMX-010)

Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin chloride (MnTE-2-PyPCl5, BMX-010, and AEOL10113) is among the most studied superoxide dismutase (SOD) mimics and redox-active therapeutics, being currently tested as a drug candidate in a phase II clinical trial on atopic dermatitis and itch. The thermal stability of active pharmaceutical ingredients (API) is useful for estimating the expiration date and shelf life of pharmaceutical products under various storage and handling conditions. The thermal decomposition and kinetic parameters of MnTE-2-PyPCl5 were determined by thermogravimetry (TG) under nonisothermal and isothermal conditions. The first thermal degradation pathway affecting Mn-porphyrin structural integrity and, thus, activity and bioavailability was associated with loss of ethyl chloride via N-dealkylation reaction. The thermal stability kinetics of the N-dealkylation process leading to MnTE-2-PyPCl5 decomposition was investigated by using isoconversional models and artificial neural network. The new multilayer perceptron (MLP) artificial neural network approach allowed the simultaneous study of ten solid-state kinetic models and showed that MnTE-2-PyPCl5 degradation is better explained by a combination of various mechanisms, with major contributions from the contraction models R1 and R2. The calculated activation energy values from isothermal and nonisothermal data were about 90 kJ mol–1 on average and agreed with one another. According to the R1 modelling of the isothermal decomposition data, the estimated shelf life value for 10% decomposition ( t 90 % ) of MnTE-2-PyPCl5 at 25°C was approximately 17 years, which is consistent with the high solid-state stability of the compound. These results represent the first study on the solid-state decomposition kinetics of Mn(III) 2-N-alkylpyridylporphyrins, contributing to the development of this class of redox-active therapeutics and SOD mimics and providing supporting data to protocols on purification, handling, storage, formulation, expiration date, and general use of these compounds.

Influence of lipid nanoparticle physical state on β-carotene stability kinetics under different environmental conditions

Carotenoids are lipophilic compounds that provide important health-related benefits for human body functions.

Hydrogen Sorption Properties, Thermal Stability and Kinetics of Hydrogen Desorption From the Hydride Phase of The MgH2 of a Mechanical Alloys of Magnesium with Ti, Ni and Y

The mechanical alloys-composite MАs (Mg +10 % wt.Ti + 5 % wt.Y and Mg +10 % wt.Ni + 5 % wt.Y) were synthesized. The phase content, microstructure, the thermal stability, kinetics of hydrogen desorption from the MgH2 hydride phase of the obtained MAs were studiedby using XRD, SEM, TDS methods. It has been established that the addition of Ti + Y and Ni + Y to magnesium leads to significant improvement in the kinetics of hydrogen desorption from the MgH2 hydride phase, which is evidenced by a significant reduction (in 6 and 15 times)in the time of release of all hydrogen from MA1 and MA2, respectively. Due to, Ti, Ni,Y alloying, the decrease in the thermodynamic stability of MgH2 is not found.

Removal of cyanide in aqueous solution by oxidation with hydrogen peroxide catalyzed by copper oxide

This work is dedicated to the removal of free cyanide from aqueous solution through oxidation with hydrogen peroxide H2O2 catalyzed by copper oxide nanoparticles. Effects of initial molar ratio [H2O2]0/[CN−]0, catalyst dose, temperature, pH and the catalyst stability on cyanide removal have been investigated. The use of copper oxide has improved the reaction rate showing catalytic activity. The cyanide removal efficiency was increased from 60% to 94% by increasing in the dose of catalyst from 0.5 g/L to 5.0 g/L. Increasing the temperature from 20 °C to 35 °C promotes cyanide removal and the four successive times re-use of catalyst shows good stability. Kinetics of cyanide removal was found to be of pseudo-first-order with respect to cyanide. The rate constants have been determined.

Facet-mediated interaction between humic acid and TiO2 nanoparticles: implications for aggregation and stability kinetics in aquatic environments

Humic acid improves TiO2 nanocrystal stability in a facet dependent manner due to the facet-specific SRHA coordination on the TiO2 surface.