Interaction of GC376, a SARS-COV-2 MPRO inhibitor, with model lipid membranes

Partitioning and effect of antiviral GC376, a potential SARS-CoV-2 inhibitor, on model lipid membranes was studied using dynamic light scattering (DLS), UV–VIS spectrometry, Excimer fluorescence, Differential scanning calorimetry (DSC) and Small- and Wide-angle X-ray scattering (SAXS/WAXS). Partition coefficient of GC376 between lipid and water phase was found to be low, reaching KP = 46.8 ± 18.2. Results suggest that GC376 partitions into lipid bilayers at the level of lipid head-groups, close to the polar/hydrophobic interface. Changes in structural and thermodynamic properties strongly depend on the GC376/lipid mole ratio. Already at lowest mole ratios GC376 induces increase of lateral pressures, mainly in the interfacial region of the bilayer. Hereby, the pre- and main-transition temperature of the lipid system increases, what is attributed to tighter packing of acyl chains induced by GC376. At GC376/DPPC ≥ 0.03 mol/mol we detected formation of domains with different GC376 content resulting in the lateral phase separation and changes in both, main transition temperature and enthalpy. The observed changes are attributed to the response of the system on the increased lateral stresses induced by partitioning of GC376. Obtained results are discussed in context of liposome-based drug delivery systems for GC376 and in context of indirect mechanism of virus replication inhibition.

Structural dynamics of chlorpromazine (CPZ) drug with dipalmitoylphosphatidylcholine (DPPC) lipid: a potential drug for SARS-CoV-2.

There is an urgent requirement for drug discovery and more importantly drug repositioning due to infectious new Severe Acute Respiratory Syndrome coronavirus 2. As per the recent report published in the journal L'Encéphale in May 2020, there is a planned ReCoVery Study examining the repurposing the chlorpromazine for the treatment of COVID-19. Here, we apply a combined Raman microspectroscopy and DFT-MD approach to investigate the structural dynamics of the Chlorpromazine (CPZ) drug with dipalmitoylphosphatidylcholine (DPPC) lipid bilayer, identifying the specific position of the drug in the DPPC lipid bilayer. The intensity ratios of the Raman peaks I2935/I2880, I1097/I1064 and I1097/I1129 are representative of the interaction of drugs with lipid alkyl chains and furnish conformation of lipid alkyl chains. Raman imaging microscopy for the study of the distribution of CPZ inside the lipid vesicles is reported. We also investigated the influence of order and disorder ratio in the CPZ on the DPPC liposomes prepared on phase transition temperature. HIGHLIGHTSDrug-membrane interactions using micromolar concentrations of both lipid and drugs.Neuroleptic drug and DPPC vesicles composed of DPPC/drug mixtures reveal qualitative differences between the Raman spectraThe temperature-controlled Raman microspectroscopic study has demonstrated that below phase-transition temperature, the fatty acid chains of the phospholipids are stiff and packed in a highly ordered array.DFT and MD simulations to understand molecular interactions, structural dynamics, and Raman spectra.Above phase-transition temperature, the chains are disordered and possess more motional freedom.Communicated by Ramaswamy H. Sarma.

Preparation and in vitro characterization of remdesivir-loaded liposomes for inhalation

Remdesivir-loaded liposomes for inhalation were prepared and the in vitro properties were evaluated. Firstly, preparation methods of remdesivir-loaded liposomes were screened, and single-factor experiments were conducted to optimize the prescription and preparation process. Then the physical property, deposition ratio and aerodynamic particle size distribution of remdesivir-loaded liposomes suspension for inhalation were comprehensively evaluated. As a result, the optimal liposomes were prepared by the thin-film dispersion method with pH 6. 5 phosphate-buffered saline as the hydration medium. In the prescription, the ratio of drug to DPPC was 1:20;the cholesterol accounted for 10% of total lipids;and 20% DSPE-mPEG 2000 was added as stabilizer. 4% trehalose was added as lyoprotectant when lyophilizing to obtain ideal appearance, good stability and a small particle size change after reconstitution. Remdesivir-loaded liposomes were spherical with smooth surface and uniform particle size distribution under transmission electron microscope. In vitro release tests showed no significant change for release curves of remdesivir-loaded liposomes suspension before and after nebulization. Deposition experiments indicated that the fine particles fraction of liposomes was 51. 4%, and the mass median aerodynamic diameter was less than 5 μm measured by next generation impactor. To sum up, remdesivir-loaded liposomes for inhalation with high encapsulation efficiency and stability can achieve a suitable particle size distribution to effectively deposit in the lung after nebulization, which provides a new approach for the treatment of COVID-19.

Mechanisms of the Effects of Short-Term Inhalations of Xe and O2 Gas Mixture in the Rehabilitation of Post-COVID Ventilation Failure.

The article presents a theoretical rationale and a clinical case of relief of post-COVID ventilation failure by inhalation of Xe and O2 gas mixture. Pneumonitis of coronavirus etiology transforms saturated phospholipids of surfactant into a solid-ordered phase, which disrupts surface tension, alveolar pneumatization, and alveolar-capillary gas exchange. Using molecular modeling (B3LYP/lanl2dz; GAUSSIAN09), we demonstrated that Xe atom due to the van der Waals dispersion interaction increases the distance between the phospholipid acyl chains providing a phase transition from the solid-ordered to liquid phase and restored the surface-active monolayer surfactant film. A clinical case confirmed that short-term inhalations of the Xe and O2 gas mixture relieved manifestations of ventilation insufficiency and increased SpO2 and pneumatization of the terminal parts of the lungs.

Exogenous pulmonary surfactant: A review focused on adjunctive therapy for severe acute respiratory syndrome coronavirus 2 including SP-A and SP-D as added clinical marker.

Type I and type II pneumocytes are two forms of epithelial cells found lining the alveoli in the lungs. Type II pneumocytes exclusively secrete 'pulmonary surfactants,' a lipoprotein complex made up of 90% lipids (mainly phospholipids) and 10% surfactant proteins (SP-A, SP-B, SP-C, and SP-D). Respiratory diseases such as influenza, severe acute respiratory syndrome coronavirus infection, and severe acute respiratory syndrome coronavirus 2 infection are reported to preferentially attack type II pneumocytes of the lungs. After viral invasion, consequent viral propagation and destruction of type II pneumocytes causes altered surfactant production, resulting in dyspnea and acute respiratory distress syndrome in patients with coronavirus disease 2019. Exogenous animal-derived or synthetic pulmonary surfactant therapy has already shown immense success in the treatment of neonatal respiratory distress syndrome and has the potential to contribute efficiently toward repair of damaged alveoli and preventing severe acute respiratory syndrome coronavirus 2-associated respiratory failure. Furthermore, early detection of surfactant collectins (SP-A and SP-D) in the circulatory system can be a significant clinical marker for disease prognosis in the near future.