A combined molecular dynamics simulation and quantum mechanics study on mercaptopurine interaction with the cucurbit [6,7] urils: Analysis of electronic structure

Chitosan - dextran phosphate carbamate hydrogels for locally controlled co-delivery of doxorubicin and indomethacin: From computation study to in vivo pharmacokinetics

The development of synergistic drug combinations is a promising strategy for effective cancer suppression. Here, we report all-polysaccharide biodegradable polyelectrolyte complex hydrogels (DPCS) based on dextran phosphate carbamate (DP) and chitosan (CS) for controlled co-delivery of the anticancer drug doxorubicin (DOX) and the non-steroidal anti-inflammatory drug indomethacin (IND). IND can induce more apoptosis in tumor cells by reducing the level of multidrug resistance-associated protein 1. Based on calculations using density functional theory and zeta potential analysis data, carriers with high drug loading were obtained. The release profile of both drugs from the hydrogels was tuned by changing the molecular weight and functional groups content of the polysaccharides. The optimized DPCS showed a steady release of DOX both in vitro and in vivo, and a gradual release of IND, which constantly induced the action of DOX. Considering all of these benefits, DOX- and IND-loaded DPCS offer a promising long-acting polysaccharide-based antitumor platform.

Biochemical, Ameliorative and Cytotoxic Effects of Newly Synthesized Curcumin Microemulsions: Evidence from In Vitro and In Vivo Studies

Curcumin is known to exhibit antioxidant and tissue-healing properties and has recently attracted the attention of the biomedical community for potential use in advanced therapies. This work reports the formulation and characterization of oil-in-water F127 microemulsions to enhance the bioavailability of curcumin Microemulsions showed a high encapsulation efficiency and prolonged release. To investigate the interactions of curcumin with one unit of the polymeric chain of surfactant F127, ethyl butyrate, and sodium octanoate, as well as the interaction between ethyl butyrate and one unit of the F127 polymer chain, the Density Functional Theory (DFT) calculations at the M06-2X level of theory, were performed in water solution. The MTT assay was used to assess the cytotoxicity of free and encapsulated curcumin on non-malignant and malignant cell lines. Combination effects were calculated according to Chou-Talalay's principles. Results of in vitro studies indicated that MCF7 and HepG2 cells were more sensitive to curcumin microemulsions. Moreover, a synergistic relationship was observed between curcumin microemulsions and cisplatin in all affected fractions of MCF7 and HepG2 cells (CI < 0.9). For in vivo investigation, thioacetamide-intoxicated rats received thioacetamide (100 mg/kg Sc) followed by curcumin microemulsions (30 mg/kg Ip). Thioacetamide-intoxicated rats showed elevated serum liver enzymes, blood urea nitrogen (BUN), and creatinine levels, and a significant reduction in liver superoxide dismutase (SOD) and catalase (CAT) activities (p < 0.05). Curcumin microemulsions reduced liver enzymes and serum creatinine and increased the activity of antioxidant enzymes in thioacetamide-treated rats in comparison to the untreated thioacetamide-intoxicated group. Histopathological investigations confirmed the biochemical findings. Overall, the current results showed the desirable hepatoprotective, nephroprotective, and anti-cancer effects of curcumin microemulsions.

Investigation of nanotubes as the smart carriers for targeted delivery of mercaptopurine anticancer drug

Mercaptopurine (MCP) is an anticancer drug that is used to treat acute lymphoblastic leukemia. The therapeutic effect of the mercaptopurine limits its severe side effects like other cytotoxic (anti-cancer) drugs. Nanostructures or nanoparticles can be widely used as potential drug carriers for diagnosis and treatment of cancer. In the current study, the boron nitride nanotube (BNNT) and carbon nanotube (CNT) were studied as the delivery carriers of MCP using the density functional theory (DFT) calculations and molecular dynamics (MDs) simulation studies. To further understand the electronic properties of mercaptopurine, the partial density of states (PDOS) was calculated. The PDOS results depicted that the electronic features of the MCP do not change after the adsorption on the surface of the nanotubes. More stability of the MCP/BNNT complexes may be attributed to the existence of the intermolecular hydrogen bonds (H-bonds) between the hydrogen atoms of the MCP molecule and the N atoms of the BNNT. The results of the quantum theory of atoms in molecules (QTAIM) confirmed the presence of H-bonds in these complexes. Moreover, MD simulation studies were done in the presence of five drug molecules. The results revealed that the strongest van der Waals (vdW) interaction energy was found between the BNNT and MCP among the studied nanotubes, indicating the BNNT is a better nanocarrier than carbon nanotube for delivery of the MCP drug within the biological systems. In general, the obtained results may present helpful information on the nature of the interactions between mercaptopurine anticancer drug with BNNT and/or CNT.Communicated by Ramaswamy H. Sarma.

New insight into the molecular mechanism of the trehalose effect on urate oxidase stability

Urate oxidase (EC 1.7.3.3) is a key enzyme in the purine metabolism which is applied in the treatment of gout and also, as a diagnostic reagent for uric acid detection. In the current study, the trehalose (TRE) effects as an additive on the structural stability and function of uricase were investigated. For recombinant expression of UOX in E. coli BL21 cells, firstly the coding sequence was subcloned into the pET-28a vector and after induction with IPTG, the recombinant UOX was purified by affinity chromatography using a Ni-NTA agarose column. To specify the trehalose effects on the urate oxidase (UOX) structure, optimum pH, optimum temperature, kinetic and thermodynamic parameters and also, the intrinsic fluorescence of UOX in the absence and presence of trehalose were examined. The UOX half-life is 24.32 min at 40 °C, whereas the UOX-TRE has a higher half-life (32.09 min) at this temperature. Generally, our findings confirm that trehalose has a protective effect on the enzyme structure. Optimum pH and temperature were 9 and 25 °C, respectively for both the naked and treated enzymes and their activity retained 42.18 and 64.80%, respectively after 48 h of incubation at room temperature. Also, theoretical results indicate that the random coil of the enzyme was converted to α-helix and β-sheet in the presence of trehalose which may preserve the integrity of the active site of the enzyme and increased the enzymatic activity. The MD simulation results indicated greater stability of the uricase structure in the presence of trehalose.Communicated by Ramaswamy H. Sarma.

From in vitro to in silico: Modeling and recombinant production of DT-Diaphorase enzyme

DT-Diaphorase (DTD) belonging to the oxidoreductase family, is among the most important enzymes and is of great significance in present-day biotechnology. Also, it has potential applications in glucose and pyruvate biosensors. Another important role of the DTD enzyme is in the detection of Phenylketonuria disease. According to the above demands, at first, we tried to study molecular cloning and production of recombinant DTD in E. coli BL21 strain. We have successfully cloned, expressed, and purified functionally active diaphorase. The amount of enzyme was increased in 10-h using IPTG induction, and the recombinant protein was purified by Ni-NTA agarose affinity chromatography. After that, the kinetic and thermodynamic parameters of the enzyme, optimum temperature and pH were also investigated to find more in-depth information. In the end, to represent the connections between the structures and function of this enzyme, the molecular dynamics simulations have been considered at two temperatures in which DTD had maximum and minimum activity (310 and 293 K, respectively). The results of MD simulations indicated that the interaction between NADH with phenylalanine 232 residue at 310 K is more severe than other residues. So, to investigate the interaction details of NADH/PHE 232 the DFT calculations were done.

Assessment of the chitosan-functionalized graphene oxide as a carrier for loading thioguanine, an antitumor drug and effect of urea on adsorption process: Combination of DFT computational and molecular dynamics simulation studies

In this study, the interaction thioguanine (TG) anticancer drug with the functionalized graphene oxide (GO) nanosheet surface is theoretically studied in both gas phase and separately in physiological media using the density functional theory (DFT) calculations. DFT calculations indicated the adsorption and solvation energies are negative for f-GONS/TG complexes which propose the adsorption process of TG molecule onto the f-GONS surface is possible from the energetic viewpoint. QTAIM calculations confirm the nature of partially covalent-partially electrostatic between drug and nanosheet. These results are sorely relevant that an approach for loading of TG molecule is the chemical modification of GO using covalent functionalization which can serve as a nanocarrier to load drug molecules. Moreover, to understand the effect of urea on the nature of the interaction between TG and f-GONS, molecular dynamics (MD) simulation was employed. The results indicated that in the presence of urea the adsorption process gets affected and leads to instability of system, while the affinity of the TG for adsorption onto GO surface is increased in pure water. Communicated by Ramaswamy H. Sarma.