Effect of methotrexate and its photodegradation products on the temperature induced denaturation of human serum albumin

Impact of Sinapic Acid on Bovine Serum Albumin Thermal Stability

The thermal stability of bovine serum albumin (BSA) in Tris buffer, as well as the effect of sinapic acid (SA) on protein conformation were investigated via calorimetric (differential scanning microcalorimetry-μDSC), spectroscopic (dynamic light scattering-DLS; circular dichroism-CD), and molecular docking approaches. μDSC data revealed both the denaturation (endotherm) and aggregation (exotherm) of the protein, demonstrating the dual effect of SA on protein thermal stability. With an increase in ligand concentration, (i) protein denaturation shifts to a higher temperature (indicating native form stabilization), while (ii) the aggregation process shifts to a lower temperature (indicating enhanced reactivity of the denatured form). The stabilization effect of SA on the native structure of the protein was supported by CD results. High temperature (338 K) incubation induced protein unfolding and aggregation, and increasing the concentration of SA altered the size distribution of the protein population, as DLS measurements demonstrated. Complementary information offered by molecular docking allowed for the assessment of the ligand binding within the Sudlow's site I of the protein. The deeper insight into the SA-BSA interaction offered by the present study may serve in the clarification of ligand pharmacokinetics and pharmacodynamics, thus opening paths for future research and therapeutic applications.

Methotrexate degradation in artificial wastewater using non-thermal pencil plasma jet

The rising global cancer rate is driving up the consumption of anticancer drugs. This causing a noticeable increase in the levels of these drugs in wastewater. The drugs are not metabolized effectively by the human body, leading to their presence in human waste, as well as in the effluent from hospitals and drug manufacturing industries. Methotrexate is a commonly used drug for treating various types of cancer. Its complex organic structure makes it difficult to degrade using conventional methods. The present work proposed a non-thermal pencil plasma jet treatment for methotrexate degradation. The air plasma produced in this jet setup is electrical characterized and plasma species/radicals are identified using emission spectroscopy. The degradation of drug is monitored by studying the change in solution physiochemical properties, HPLC-UV analysis, and removal of total organic carbon, etc.Results show that a 9-min plasma treatment completely degraded the drug solution that followed first-order degradation kinetics with rate constant 0.38 min^-1 and 84.54% mineralization was observed. Additionally, an increase in electrical conductivity and dissolved solids compared to virgin water-plasma interaction indicated the formation of new, smaller compounds (2,4-Diaminopteridine-6-carboxylic acid, N-(4-Aminobenzoyl)-L-glutamic acid, etc.) after drug degradation. The plasma-treated methotrexate solution also showed lower toxicity toward freshwater chlorella algae compared to the untreated solution. Finally, it can be said that non-thermal plasma jets are economically and environmentally friendly devices that have the potential to be used for the treatment of complex and resistive anticancer drug-polluted wastewaters.

Profiling the interaction of a novel toxic pyruvate dehydrogenase kinase inhibitor with human serum albumin

To discover novel pyruvate dehydrogenase kinase (PDK) inhibitors, a new compound 2,2-dichloro-1-(4-((4-isopropylphenyl)amino)-3-nitrophenyl)ethan-1-one, namely XB-1 was identified, which inhibited PDK activity with a half maximal inhibitory concentration (IC₅₀) value of 337.0 nM, and reduced A549 cell proliferation with a half maximal effective concentration (EC₅₀) value of 330.0 nM. However, the compound appears to exhibit a negligible selectivity between cancer cell and normal one, indicating a potential toxicity existed for the compound. Herein, the interaction of the toxic XB-1 to human serum albumin (HSA) was firstly explored by spectroscopic approaches with the aim to reduce/avoid the toxicity of PDK inhibitors in the next hit-to-lead campaign. In detail, it was found that the XB-1 could effectively bind to HSA mainly via hydrogen bond interaction in PBS buffer (pH = 7.4, 10.0 mM), resulting in the formation of HSA-XB-1 complex. The negative value of ΔG showed that the binding of XB-1 to HSA is a spontaneous process. The result from site-selective binding assay suggested that the XB-1 bound to the site I of HSA by competing with warfarin, which was perfect in agreement with the molecular docking method. The results of this paper may offer a valuable theoretical basis to study the toxicity of biofunctional molecules and may offer thoughts about how to avoid/reduce toxicity for a small molecule.