Saquinavir-Piperine Eutectic Mixture: Preparation, Characterization, and Dissolution Profile.

The dissolution rate of the anti-HIV drug saquinavir base (SQV), a poorly water-soluble and extremely low absolute bioavailability drug, was improved through a eutectic mixture formation approach. A screening based on a liquid-assisted grinding technique was performed using a 1:1 molar ratio of the drug and the coformers sodium saccharinate, theobromine, nicotinic acid, nicotinamide, vanillin, vanillic acid, and piperine (PIP), followed by differential scanning calorimetry (DSC). Given that SQV-PIP was the only resulting eutectic system from the screening, both the binary phase and the Tammann diagrams were adapted to this system using DSC data of mixtures prepared from 0.1 to 1.0 molar ratios in order to determine the exact eutectic composition. The SQV-PIP system formed a eutectic at a composition of 0.6 and 0.40, respectively. Then, a solid-state characterization through DSC, powder X-ray diffraction (PXRD), including small-angle X-ray scattering (SAXS) measurements to explore the small-angle region in detail, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a powder dissolution test were performed. The conventional PXRD analyses suggested that the eutectic mixture did not exhibit structural changes; however, the small-angle region explored through the SAXS instrument revealed a change in the crystal structure of one of their components. FT-IR spectra showed no molecular interaction in the solid state. Finally, the dissolution profile of SQV in the eutectic mixture was different from the dissolution of pure SQV. After 45 min, approximately 55% of the drug in the eutectic mixture was dissolved, while, for pure SQV, 42% dissolved within this time. Hence, this study concludes that the dissolution rate of SQV can be effectively improved through the approach of using PIP as a coformer.

Saquinavir potentiates itraconazole's antifungal activity against multidrug-resistant Candida auris in vitro andin vivo.

Candida species are highly opportunistic yeasts that are responsible for serious invasive fungal infections among immunocompromised patients worldwide. Due to the increase in drug resistance and incidence of infections, there is an urgent need to develop new antifungals and to identify co-drugs that can sensitize drug-resistant Candida to antifungals. The objective of this study was to assess the effect of saquinavir on the activity of azole antifungals against C. auris. The in vitro interaction of saquinavir and three azole antifungals (itraconazole, voriconazole, and fluconazole) was evaluated against a panel of C. auris isolates. The itraconazole/saquinavir combination exhibited a synergistic (SYN) relationship against all C. auris isolates tested with the fractional inhibitory concentration index ranging from 0.03 to 0.27. Moreover, a time-kill kinetics assay revealed that saquinavir restored the itraconazole's fungistatic activity against C. auris. Furthermore, saquinavir restored itraconazole's antifungal activity against other clinically important Candida species. The mechanistic investigation indicated that saquinavir significantly inhibited efflux pumps, glucose utilization, and ATP synthesis in Candida. Finally, a murine model of C. auris infection was used to evaluate the efficacy of the itraconazole/saquinavir combination in the presence of ritonavir (as a pharmacokinetic enhancer). The combination significantly reduced the fungal burden in the kidneys by 0.93-log10 colony-forming units (88%) compared to itraconazole alone. This study identified that saquinavir exhibits a potent SYN relationship in combination with itraconazole against Candida species, which warrants further consideration.

Candida auris is a multi-drug resistant fungal pathogen with limited treatment options. In this study, we identified that the antiviral drug, saquinavir, is capable of synergizing and restoring the activity of antifungals against C. auris.

HIV protease inhibitor saquinavir inhibits toll-like receptor 4 activation by targeting receptor dimerization.

OBJECTIVE: Toll-like receptor 4 (TLR4) is crucial in induction of innate immune response through recognition of invading pathogens or endogenous alarming molecules. Ligand-triggered dimerization of TLR4 is essential for the activation of NF-κB and IRF3 through MyD88- or TRIF-dependent pathways. Saquinavir (SQV), an FDA-approved HIV protease inhibitor, has been shown to attenuate the activation of NF-κB induced by HMGB1 by blocking TLR4-MyD88 association in proteasome independent pathway. This study aims to define whether SQV is an HMGB1-specific and MyD88-dependent TLR4 signaling inhibitor and which precise signaling element of TLR4 is targeted by SQV. MATERIALS AND METHODS: PMA differentiated human THP-1 macrophages or reconstituted HEK293 cells were pretreated with SQV before stimulated by different TLR agonists. TNF-α level was evaluated through ELISA assay. NF-κB activation was analyzed using NF-κB SEAP reporting system. The levels of MyD88/TRIF pathways-related factors were examined by immunoblot. TLR4 endocytosis was assessed by immunocytochemistry. TLR4 dimerization was determined using immunoprecipitation between different tagged TLR4 and an in silico molecular docking experiment was performed to explore the possible binding site of SQV on its target. RESULTS: Our data showed that SQV suppresses both MyD88- and TRIF-dependent pathways in response to lipopolysaccharide (LPS), a critical sepsis inducer and TLR4 agonist, leading to downregulation of NF-κB and IRF3. SQV did not suppress MyD88-dependent pathway triggered by TLR1/2 agonist Pam3csk4. In the only TRIF-dependent pathway, SQV did not alleviate IRF3 phosphorylation induced by TLR3 agonist Poly(I:C). Furthermore, dimerization of TLR4 following LPS or HMGB1 stimulation was decreased by SQV. CONCLUSION: We concluded that TLR4 receptor complex is one of the mammalian targets of SQV, and TLR4-mediated immune responses and consequent risk for uncontrolled inflammation could be modulated by FDA-approved drug SQV.

Understanding Drug Resistance of Wild-Type and L38HL Insertion Mutant of HIV-1 C Protease to Saquinavir.

Acquired immunodeficiency syndrome (AIDS) is one of the most challenging infectious diseases to treat on a global scale. Understanding the mechanisms underlying the development of drug resistance is necessary for novel therapeutics. HIV subtype C is known to harbor mutations at critical positions of HIV aspartic protease compared to HIV subtype B, which affects the binding affinity. Recently, a novel double-insertion mutation at codon 38 (L38HL) was characterized in HIV subtype C protease, whose effects on the interaction with protease inhibitors are hitherto unknown. In this study, the potential of L38HL double-insertion in HIV subtype C protease to induce a drug resistance phenotype towards the protease inhibitor, Saquinavir (SQV), was probed using various computational techniques, such as molecular dynamics simulations, binding free energy calculations, local conformational changes and principal component analysis. The results indicate that the L38HL mutation exhibits an increase in flexibility at the hinge and flap regions with a decrease in the binding affinity of SQV in comparison with wild-type HIV protease C. Further, we observed a wide opening at the binding site in the L38HL variant due to an alteration in flap dynamics, leading to a decrease in interactions with the binding site of the mutant protease. It is supported by an altered direction of motion of flap residues in the L38HL variant compared with the wild-type. These results provide deep insights into understanding the potential drug resistance phenotype in infected individuals.

Liposomal Delivery of Saquinavir to Macrophages Overcomes Cathepsin Blockade by Mycobacterium tuberculosis and Helps Control the Phagosomal Replicative Niches.

Mycobacterium tuberculosis is able to establish a chronic colonization of lung macrophages in a controlled replication manner, giving rise to a so-called latent infection. Conversely, when intracellular bacteria undergo actively uncontrolled replication rates, they provide the switch for the active infection called tuberculosis to occur. Our group found that the pathogen is able to manipulate the activity of endolysosomal enzymes, cathepsins, directly at the level of gene expression or indirectly by regulating their natural inhibitors, cystatins. To provide evidence for the crucial role of cathepsin manipulation for the success of tuberculosis bacilli in their intracellular survival, we used liposomal delivery of saquinavir. This protease inhibitor was previously found to be able to increase cathepsin proteolytic activity, overcoming the pathogen induced blockade. In this study, we demonstrate that incorporation in liposomes was able to increase the efficiency of saquinavir internalization in macrophages, reducing cytotoxicity at higher concentrations. Consequently, our results show a significant impact on the intracellular killing not only to reference and clinical strains susceptible to current antibiotic therapy but also to multidrug- and extensively drug-resistant (XDR) Mtb strains. Altogether, this indicates the manipulation of cathepsins as a fine-tuning strategy used by the pathogen to survive and replicate in host cells.

Revealing the drug resistance mechanism of saquinavir due to G48V and V82F mutations in subtype CRF01_AE HIV-1 protease: molecular dynamics simulation and binding free energy calculations.

Human immunodeficiency virus-1 (HIV-1) protease is one of the important targets in AIDS therapy. The majority of HIV infections are caused due to non-B subtypes in developing countries. The co-occurrence of mutations along with naturally occurring polymorphisms in HIV-1 protease cause resistance to the FDA approved drugs, thereby posing a major challenge in the treatment of antiretroviral therapy. In this work, the resistance mechanism against SQV due to active site mutations G48V and V82F in CRF01_AE (AE) protease was explored. The binding free energy calculations showed that the direct substitution of valine at position 48 introduces a bulkier side chain, directly impairing the interaction with SQV in the binding pocket. Also, the intramolecular hydrogen bonding network of the neighboring residues is altered, indirectly affecting the binding of SQV. Interestingly, the substitution of phenylalanine at position 82 induces conformational changes in the 80's loop and the flap region, thereby favoring the binding of SQV. The V82F mutant structure also maintains similar intramolecular hydrogen bond interactions as observed in AE-WT.Communicated by Ramaswamy H. Sarma.

Repurposing Alone and in Combination of the Antiviral Saquinavir with 5-Fluorouracil in Prostate and Lung Cancer Cells.

Prostate and lung cancers are among the most common cancer types, and they still need more therapeutics. For this purpose, saquinavir (SAQ) was tested alone and in combination with 5-fluorouracil (5-FU). PC-3 and A549 cells were exposed to increasing concentrations of both drugs alone or in combination, with simultaneous or sequential administration. Cell viability was obtained using the MTT assay and synergism values using CompuSyn software. Results showed that SAQ was the more cytotoxic of both drugs in PC-3 cells, while 5-FU was the most cytotoxic in A549 cells. When these drugs were used in combination, the more synergistic combination in PC-3 cells was the IC50 of SAQ with various concentrations of 5-FU, particularly when 5-FU was only applied 24 h later. Meanwhile for A549 the most promising combination was 5-FU with delayed SAQ, but with a weaker effect than all combinations demonstrated in PC-3 cells. These results demonstrate that SAQ could be used as a new repurposed drug for the treatment of prostate cancer and this treatment potential could be even greater if SAQ is combined with the anticancer drug 5-FU, while for lung cancer it is not as efficient and, therefore, not of as much interest.

Charge converting nanostructured lipid carriers containing a cell-penetrating peptide for enhanced cellular uptake.

HYPOTHESIS: The aim of this study was the development of nanostructured lipid carriers (NLCs) decorated with a polycationic cell-penetrating peptide (CPP). A coating with polyphosphates (PP) enables charge conversion at target cells being triggered by the membrane bound enzyme intestinal alkaline phosphatase (IAP). EXPERIMENTS: The CPP, stearyl-nona-L-arginine (R9SA) was obtained by solid phase synthesis. Formed nanocarriers were characterized regarding size, polydispersity index, zeta potential and charge conversion in the presence of IAP and on Caco-2 cells. The BCS class IV drug saquinavir (SQV) was loaded into NLCs in different concentrations. Mucus diffusion ability of the NLCs was evaluated by the rotating tube method. Furthermore, cellular uptake was evaluated on Caco-2 cells and endosomal escape properties were investigated using erythrocytes. FINDINGS: All NLCs were obtained in a size range between 146 nm and 152 nm and a polydispersity index of 0.2. Incubation of PP coated PP-R9SA-NLCs with IAP led to a charge conversion from -41.8 mV to 6.4 mV (Δ48.2 mV). After four hours of incubation with IAP, phosphate release reached a plateau, indicating a faster polyphosphate cleavage than on Caco-2. Drug load and encapsulation efficiency of SQV was obtained up to 80.6% and 46.5 µg/mg. Mucus diffusion was increasing in the following rank order: R9SA-NLCs < blank NLCs < PP-R9SA-NLCs. R9SA-NLCs and PP-R9SA-NLCs increased the cellular uptake 15.6- and 13.2-fold, respectively, compared to the control NLCs. Erythrocytes interaction study revealed enhanced endosomal escape properties for R9SA-NLCs and PP-R9SA-NLCs when incubated with IAP.

Saquinavir: From HIV to COVID-19 and Cancer Treatment.

Saquinavir was the first protease inhibitor developed for HIV therapy, and it changed the standard of treatment for this disease to a combination of drugs that ultimately led to increased survival of this otherwise deadly condition. Inhibiting the HIV protease impedes the virus from maturing and replicating. With this in mind, since the start of the COVID-19 outbreak, the research for already approved drugs (mainly antivirals) to repurpose for treatment of this disease has increased. Among the drugs tested, saquinavir showed promise in silico and in vitro in the inhibition of the SARS-CoV-2 main protease (3CLpro). Another field for saquinavir repurposing has been in anticancer treatment, in which it has shown effects in vitro and in vivo in several types of cancer, from Kaposi carcinoma to neuroblastoma, demonstrating cytotoxicity, apoptosis, inhibition of cell invasion, and improvement of radiosensibility of cancer cells. Despite the lack of follow-up in clinical trials for cancer use, there has been a renewed interest in this drug recently due to COVID-19, which shows similar pharmacological pathways and has developed superior in silico models that can be translated to oncologic research. This could help further testing and future approval of saquinavir repurposing for cancer treatment.

Drug Resistance Mechanism of M46I-Mutation-Induced Saquinavir Resistance in HIV-1 Protease Using Molecular Dynamics Simulation and Binding Energy Calculation.

Drug-resistance-associated mutation in essential proteins of the viral life cycle is a major concern in anti-retroviral therapy. M46I, a non-active site mutation in HIV-1 protease has been clinically associated with saquinavir resistance in HIV patients. A 100 ns molecular dynamics (MD) simulation and MM-PBSA calculations were performed to study the molecular mechanism of M46I-mutation-based saquinavir resistance. In order to acquire deeper insight into the drug-resistance mechanism, the flap curling, closed/semi-open/open conformations, and active site compactness were studied. The M46I mutation significantly affects the energetics and conformational stability of HIV-1 protease in terms of RMSD, RMSF, Rg, SASA, and hydrogen formation potential. This mutation significantly decreased van der Waals interaction and binding free energy (∆G) in the M46I-saquinavir complex and induced inward flap curling and a wider opening of the flaps for most of the MD simulation period. The predominant open conformation was reduced, but inward flap curling/active site compactness was increased in the presence of saquinavir in M46I HIV-1 protease. In conclusion, the M46I mutation induced structural dynamics changes that weaken the protease grip on saquinavir without distorting the active site of the protein. The produced information may be utilized for the discovery of inhibitor(s) against drug-resistant HIV-1 protease.

A New Saquinavir Mesylate-Sodium Decyl Sulfate Salt Discovered by Serendipity during an Anomalous Dissolution Test.

PURPOSE: To understand the anomalous behavior of Saquinavir Mesylate (SQVM) in sodium decyl sulfate (SDS) medium during a dissolution test through a crystallographic analysis of the crystal obtained. As a result, it will be possible to elucidate its crystal structure and carry out a complete solid-state characterization of the API. METHODS: The solid form obtained was characterized by a structural analysis through X-ray single crystal and powder diffraction. The crystallographic structures of the new salt and the SQVM were compared. In addition, a complete solid-state characterization of SQVM raw material was carried out by techniques such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Raman spectroscopy, scanning electron microscopy and a dissolution method. RESULTS: A new salt consisting of SQVM and SDS was crystallized and its crystal structure was elucidated and reported herein for the first time. The anionic part of SDS interacts with the cationic segment of SQVM to obtain a new salt designated as SQV-DS, which precipitates. The main difference between the two structures occurs in the c-axis expansion, which increases from 15.966 (5) to 21.1924 (14), respectively. CONCLUSIONS: Some of the strategies to enhance the dissolution rate of poorly aqueous soluble APIs include the use of surfactants such as SDS in the dissolution medium, as well as in the formulated products. However, there have been constant reports of a dissolution rate slowdown by some surfactants. The interaction mechanisms between the APIs and the dissolution medium containing surfactants need to be carefully investigated in current pharmaceutical formulations. Graphical Abstract.

Evaluation of binding of potential ADMET/tox screened saquinavir analogues for inhibition of HIV-protease via molecular dynamics and binding free energy calculations.

Developing novel drug molecules against HIV is a scientific quest necessitated by development of drug resistance against used drugs. We report comparative results of molecular dynamics simulation studies on 11 structural analogues of Saquinavir (SQV) - against HIV-protease that were earlier examined for pharmacodynamic and pharmacokinetic properties. We reported analogues S1, S5 and S8 to qualify the ADMET criterion and may be considered as potential lead molecules. In this study the designed molecules were successively docked with native HIV-protease at AutoDock. Docking scores established relative goodness of the 11 analogues against the benchmark for Saquinavir. The docked complexes were subjected to molecular dynamics simulation studies using GROMACS 4.6.2. Four parameters viz. H-bonding, RMSD, Binding energy and Protein-Ligand Distance were used for comparative analyses of the analogues relative to Saquinavir. The comparison and analysis of the results are indicative that analogues S8, S9 and S1 are promising candidates among all the analogues studied. From our earlier work and present study it is evident that among the three S8 and S1 qualify the ADMET criterion and between S1 and S8, the analogue S8 shows more target efficacy and specificity over S1 and have better molecular dynamics simulation results. Thus, of the 11 de novo Saquinavir analogues, the S8 appears to be the most promising candidate as lead molecule for HIV-protease inhibitor and is best suited for testing under biological system. Further validation of the proposed lead molecules through wet lab studies involving antiviral assays however is required.Communicated by Ramaswamy H. Sarma.

Multi-material 3D printing of programmable and stretchable oromucosal patches for delivery of saquinavir.

Oromucosal patches for drug delivery allow fast onset of action and ability to circumvent hepatic first pass metabolism of drugs. While conventional fabrication methods such as solvent casting or hot melt extrusion are ideal for scalable production of low-cost delivery patches, these methods chiefly allow for simple, homogenous patch designs. As alternative, a multi-material direct-ink-write 3D printing for rapid fabrication of complex oromucosal patches with unique design features was demonstrated in the present study. Specifically, three print-materials: an acidic saquinavir-loaded hydroxypropyl methylcellulose ink, an alkaline effervescent sodium carbonate-loaded ink, and a methyl cellulose backing material were combined in various designs. The CO2 content and pH of the microenvironment were controlled by adjusting the number of alkaline layers in the patch. Additionally, the rigid and brittle patches were converted to compliant and stretchable patches by implementing mesh-like designs. Our results illustrate how 3D printing can be used for rapid design and fabrication of multifunctional or customized oromucosal patches with tailored dosages and changed drug permeation.

Polycaprolactone and polycaprolactone triol blends to obtain a stable liquid nanotechnological formulation: synthesis, characterization and in vitro - in vivo taste masking evaluation.

The use of polymeric blends is a potential strategy to obtain novel nanotechnological formulations aiming at drug delivery systems. Saquinavir, an antiretroviral drug, was chosen as a model drug for the development of new stable liquid formulations with unpleasant taste masking properties. Three formulations containing different polymeric ratios (1:3, 1:1 and 3:1) were prepared and properly characterized by particle size distribution, zeta potential, pH, drug content and encapsulation efficiency measurements. The stability was verified by monitoring the zeta potential, particle size distribution, polydispersity index and drug content by 90 days. The light backscattering analysis was used to early identify possible phenomena of instability in the formulations. The in vitro drug release and saquinavir cytotoxicity were evaluated. The in vitro and in vivo taste masking properties were studied using an electronic tongue and a human sensory panel. All formulations presented nanometric sizes around 200 nm and encapsulation efficiency above 99%. The parameters evaluated for stability remained constant throughout 90 days. The in vitro tests showed a controlled drug release and absence of toxic effects on human T lymphocytes. The electronic tongue experiment showed taste differences for all formulations in comparison to drug solutions, with a more pronounced difference for the formulation with higher polycaprolactone content (3:1). This formulation was chosen for in vivo sensory panel evaluation which results corroborated the electronic tongue experiments. In conclusion, the polymer blend nanoformulation developed herein showed the promising application to incorporate drugs aiming at pharmaceutical taste-masking properties.

Predicted antiviral drugs Darunavir, Amprenavir, Rimantadine and Saquinavir can potentially bind to neutralize SARS-CoV-2 conserved proteins.

BACKGROUND: Novel Coronavirus disease 2019 or COVID-19 has become a threat to human society due to fast spreading and increasing mortality. It uses vertebrate hosts and presently deploys humans. Life cycle and pathogenicity of SARS-CoV-2 have already been deciphered and possible drug target trials are on the way. RESULTS: The present study was aimed to analyze Non-Structural Proteins that include conserved enzymes of SARS-CoV-2 like papain-like protease, main protease, Replicase, RNA-dependent RNA polymerase, methyltransferase, helicase, exoribonuclease and endoribonucleaseas targets to all known drugs. A bioinformatic based web server Drug ReposeER predicted several drug binding motifs in these analyzed proteins. Results revealed that anti-viral drugs Darunavir,Amprenavir, Rimantadine and Saquinavir were the most potent to have 3D-drug binding motifs that were closely associated with the active sites of the SARS-CoV-2 enzymes . CONCLUSIONS:  Repurposing of the antiviral drugs Darunavir, Amprenavir, Rimantadine and Saquinavir to treat COVID-19 patients could be useful that can potentially prevent human mortality.

Computational drug repurposing study of antiviral drugs against main protease, RNA polymerase, and spike proteins of SARS-CoV-2 using molecular docking method.

OBJECTIVES: The new Coronavirus (SARS-CoV-2) created a pandemic in the world in late 2019 and early 2020. Unfortunately, despite the increasing prevalence of the disease, there is no effective drug for the treatment. A computational drug repurposing study would be an appropriate and rapid way to provide an effective drug in the treatment of the coronavirus disease of 2019 (COVID-19) pandemic. In this study, the inhibitory potential of more than 50 antiviral drugs on three important proteins of SARS-CoV-2, was investigated using the molecular docking method. METHODS: By literature review, three important proteins, including main protease, RNA-dependent RNA polymerase (RdRp), and spike, were selected as the drug targets. The three-dimensional (3D) structure of protease, spike, and RdRp proteins was obtained from the Protein Data Bank. Proteins were energy minimized. More than 50 antiviral drugs were considered as candidates for protein inhibition, and their 3D structure was obtained from Drug Bank. Molecular docking settings were defined using Autodock 4.2 software and the algorithm was executed. RESULTS: Based on the estimated binding energy of docking and hydrogen bond analysis and the position of drug binding, five drugs including, indinavir, lopinavir, saquinavir, nelfinavir, and remdesivir, had the highest inhibitory potential for all three proteins. CONCLUSIONS: According to the results, among the mentioned drugs, saquinavir and lopinavir showed the highest inhibitory potential for all three proteins compared to the other drugs. This study suggests that saquinavir and lopinavir could be included in the laboratory phase studies as a two-drug treatment for SARS-CoV-2 inhibition.

Exploration of in vitro drug release testing methods for saquinavir microenvironmental pH modifying buccal films.

Buccal films containing a pH modifying excipient may be able to increase bioavailability of drugs with pH-dependent solubility such as saquinavir. Access to suitable in vitro drug release testing methods may facilitate buccal formulation development. This study aimed to explore two release testing methods for characterising buccal films and to elucidate the relationship between microenvironmental pH (pHM, i.e. the pH around the swelling films) and saquinavir release. The Franz diffusion cell method was applicable to investigate the effect of hydroxypropyl methylcellulose (HPMC) grade on saquinavir release. Films containing HPMC K3 LV had a faster saquinavir release than films containing HPMC K100 LV. A UV/Vis imaging method was developed to visualise saquinavir release and pHM changes during the initial dissolution. Within 5 min, the pHM decreased from 6.8 to around 5.4 for HPMC K100 LV-based films containing 11.1 % or 16.6 % (w/w) malic acid. Subsequently, the pHM increased due to increasing concentrations of saquinavir. An increase in malic acid content led to a faster saquinavir release. The combination of methods may be broadly applicable for excipient screening in development of buccal formulations. The imaging approach holds promise for characterizing other pH modifying formulation principles.

Repurposing Saquinavir for Host-Directed Therapy to Control Mycobacterium Tuberculosis Infection.

Despite the available antibiotics, tuberculosis (TB) has made its return since the 90's of the last century as a global threat mostly due to co-infection with HIV, to the emergence of drug resistant strains and the lack of an effective vaccine. Host-directed strategies could be exploited to improve treatment efficacy, contain drug-resistant strains, improve immune responses and reduce disease severity. Macrophages in the lungs are often found infected with Mycobacterium tuberculosis (Mtb) and/or with HIV. The long-term survival of lung macrophages infected with Mtb or with HIV, together with their ability to produce viral particles, especially during TB, makes these niches major contributors to the pathogenicity of the infection. Among the available drugs to control HIV infection, protease inhibitors (PIs), acting at post-integrational stages of virus replication cycle, are the only drugs able to interfere with virus production and release from macrophages during chronic infection. For Mtb we recently found that the pathogen induces a general down-regulation of lysosomal proteases, helping bacteria to establish an intracellular niche in macrophages. Here we found that the PI saquinavir, contrary to ritonavir, is able to induce an increase of endolysosomal proteases activity especially of cathepsin S in Mtb infected macrophages and during co-infection with HIV. Our results indicate that saquinavir treatment of infected macrophages led not only to a significant intracellular killing of Mtb but also: (i) to an improved expression of the HLA class II antigen presentation machinery at the cell surface; (ii) to increased T-lymphocyte priming and proliferation; and (iii) to increased secretion of IFN-γ. All together the results indicate saquinavir as a potential host directed therapy for tuberculosis.

Comparative molecular investigation of the potential inhibitors against SARS-CoV-2 main protease: a molecular docking study.

Recent outbreak of novel coronavirus and its rapid pandemic escalation in all over the world has drawn the attention to urgent need for effective drug development. However, due to prolonged vaccine and drug development procedure against a newly emerged devastating SARS-CoV-2 virus pathogen, repurposing of existing potential pertinent drug molecules would be preferable strategy to reduce mortality immediately and further development of new drugs to combat overall global Covid-19 crisis in all over the world. Herein, we have filtered 23 prospective drug candidates through literature review. Assessing evidences from molecular docking studies, it was clearly seen that, Epirubicin, Vapreotida, and Saquinavir exhibited better binding affinity against SARS-CoV-2 Main Protease than other drug molecules among the 23 potential inhibitors. However, 50 ns molecular dynamics simulation indicated the less mobile nature of the docked complex maintaining structural integrity. Our overall prediction findings indicate that Epirubicin, Vapreotida, and Saquinavir may inhibit COVID-19 by synergistic interactions in the active cavity and those results can pave the way in drug discovery although it has to be further validated by in-vitro and in-vivo investigations.Communicated by Ramaswamy H. Sarma.

Taste-masked nanoparticles containing Saquinavir for pediatric oral administration.

This research has aimed to improve the stability and taste-masking properties by developing nanostructured dosage forms containing Saquinavir. Liquid formulations were developed using Eudragit RS100® and Pullulan as polymers. The physicochemical characteristics, stability, in vitro drug release, morphology, mucoadhesion and taste masking capacity were evaluated. The Saquinavir-nanoparticles had average diameters between 136 and 158 nm, with a Span below 1.4. These formulations presented a drug content above 80%, a high encapsulation efficiency (>97%), slightly acidic pH levels, low dynamic viscosity and controlled drug release. Electron microscopy revealed irregular spherical nanoparticles. The formulations prepared with higher amounts of Eudragit RS100® had greater mucoadhesion. Both polymers were able to improve drug stabilization, taste-masking properties and protection against drug cytotoxicity. The Saquinavir-nanoparticles exhibited stability and control releasing properties, thus making it a promising liquid dosage form with taste-masking properties intended for application in pediatric treatment.