Structure-function studies of BPP-BrachyNH2 and synthetic analogues thereof with Angiotensin I-Converting Enzyme

Antiviral potential of diminazene aceturate against SARS-CoV-2 proteases using computational and in vitro approaches

Diminazene aceturate (DIZE), an antiparasitic, is an ACE2 activator, and studies show that activators of this enzyme may be beneficial for COVID-19, disease caused by SARS-CoV-2. Thus, the objective was to evaluate the in silico and in vitro affinity of diminazene aceturate against molecular targets of SARS-CoV-2. 3D structures from DIZE and the proteases from SARS-CoV-2, obtained through the Protein Data Bank and Drug Database (Drubank), and processed in computer programs like AutodockTools, LigPlot, Pymol for molecular docking and visualization and GROMACS was used to perform molecular dynamics. The results demonstrate that DIZE could interact with all tested targets, and the best binding energies were obtained from the interaction of Protein S (closed conformation −7.87 kcal/mol) and M_pro (−6.23 kcal/mol), indicating that it can act both by preventing entry and viral replication. The results of molecular dynamics demonstrate that DIZE was able to promote a change in stability at the cleavage sites between S1 and S2, which could prevent binding to ACE2 and fusion with the membrane. In addition, in vitro tests confirm the in silico results showing that DIZE could inhibit the binding between the spike receptor-binding domain protein and ACE2, which could promote a reduction in the virus infection. However, tests in other experimental models with in vivo approaches are needed.

Computational investigation of the alkaloids of Pilocarpus microphyllus species as phytopharmaceuticals for the inhibition of sterol 14α-demethylase protease of Trypanosoma cruzi

Trypanosoma cruzi is a protozoan transmitted by the insect Triatoma infestans, popularly known as kissing bug. This protozoan causes the Chagas disease, a Neglected Tropical Disease. This study aimed to investigate, through DFT method and B3LYP hybrid functional, the physicochemical, pharmacokinetic, and pharmacodynamic properties of the alkaloids present in the leaves of the species Pilocarpus microphyllus (jaborandi) as a potential inhibitory activity on the protease sterol 14α-demethylase of T. cruzi associated with the techniques of molecular docking, molecular dynamics, MM-PBSA and ADMET predictions. The molecules of isopilosine, epiisopiloturine, epiisopilosine, and pilosine showed up the lowest binding energies by molecular docking, good human intestinal absorption, low penetration in the blood-brain barrier, antiprotozoal and anticarcinogenic activities in ADMET studies. It has been observed a better binding affinity of the sterol 14α-demethylase protease with isopilosine in molecular dynamics and MM-PBSA studies, which indicates it as a potential drug candidate for Chagas disease.Communicated by Ramaswamy H. Sarma.

Constituents of buriti oil (Mauritia flexuosa L.) like inhibitors of the SARS-Coronavirus main peptidase: an investigation by docking and molecular dynamics

Statistics show alarming numbers of infected and killed in the world, caused by the Covid-19 pandemic, which still doesn't have a specific treatment and effective in combating all efforts to seek treatments and medications against this disease. Natural products are of relevant interest in the search for new drugs. Thus, Buriti oil (Mauritia flexuosa L.) is a natural product extracted from the fruit of the palm and is quite common in the legal Amazon region, Brazil. In the present work, the anti-Covid-19 biological activity of some constituents of Buriti oil was investigated using in silico methods of Molecular Docking and Molecular Dynamics Simulations. The main results of Molecular Docking revealed favorable interaction energies in the formation of the 2GTB peptidase complex (main peptidase of SARS-CoV) with the 13-cis-β-carotene ligands (ΔGbind = -10.23Kcal mol-1), 9-cis -β-carotene (ΔGbind = -9.82Kcal mol-1), and α-carotene (ΔGbind = -8.34Kcal mol-1). Molecular Dynamics simulations demonstrated considerable interaction for these ligands with emphasis on α-carotene. Such theoretical results encourage and enable a direction for experimental studies in vitro and in vivo, essential in the development of new drugs with enzymatic inhibitory action for Covid-19.Communicated by Ramaswamy H. Sarma.

In silico study of the interactions of Pilocarpus microphyllus imidazolic alkaloids with the main protease (Mpro) of SARS-CoV-2

The disease outbreak caused by SARS-CoV-2 continues to rise worldwide, even in countries which have considered it controlled. As new cases appear daily, infecting millions of people and causing thousands of deaths, the current in silico study aims to investigate the imidazolic alkaloids of the species Pilocarpus microphyllus (Jaborandi) as a potential inhibitory activity against the M^pro protease from SARS-CoV-2, since it plays a fundamental role in the processing of polyproteins that are translated from viral RNA. Jaborandi is distributed in some Brazilian biomes, being easily identified, yet little researched, with proven anti-inflammatory, contraceptive, anti-diabetic and gastroprotective activities. In this work, DFT calculation of thermodynamic properties, electrostatic potential surface, frontier molecular orbitals and descriptors of chemical reactivity of imidazolic alkaloids were associated with the use of molecular docking techniques, molecular dynamics and ADMET predictions. One can verify a good reactivity chemistry and energetic stability of epiisopiloturine, epiisopilosine, isopilosine and e pilosine with some residues of amino acids present in the active site of the main protease of COVID-19. In this sense, the results point out to the imidazolic alkaloids of Jaborandi as promising targets for in vitro and in vivo tests, as possible candidates for inhibitors of the enzyme M^pro.

Silver nanoparticle stabilized by hydrolyzed collagen and natural polymers: Synthesis, characterization and antibacterial-antifungal evaluation

In synthesis of silver nanoparticles (AgNPs), the composition of the stabilizer used can be closely related to the effectiveness of the synthesis and to the shape of the final nanoparticles. Recently, the use of collagen as an effective nanoparticle stabilization agent was reported. In this work, synthesis of silver nanoparticles using mixed capping agents is reported. The capping agents used were cashew gum-hydrolyzed collagen; kappa carrageenan-hydrolyzed collagen, and agar-hydrolyzed collagen. We evaluated antibacterial action against Gram-positive and Gram-negative bacteria, as well as antifungal activity and cytotoxicity. Homogenized mixtures of collagen and aqueous cashew gum, carrageenan or agar respectively were used to produce the nanoparticles AgNPcolCashew, AgNPcolCarr and AgNPcolAgar. AgNP characterization was performed using Uv-vis, XRD, TEM and DLS and the biological activities were assayed using MIC and MBC analyses for both antibacterial and antifungal application. Results showed that the AgNPcollcar sample showed the strongest bacterial inhibition with MIC values of 62.5 and 31.25 μM/mL Ag against E. coli and P. aeruginosa respectively. Interestingly, AgNPcollAgar also presented the lowest cytotoxicity when compared with other AgNPs and AgNO₃.