Journal of Computational Biophysics and Chemistry

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes COVID-19, a disease currently spreading around the world. Some drugs are underway or being used to combat this disease. Several proteins of the virus can be targeted in therapeutic approaches. Two structural proteins, membrane (M), envelope (E) have critical roles in virus life cycle, such as assembly, budding, envelope formation and pathogenesis. Here, we employed the in silico strategies to identify and evaluate the selected potential compounds against M and E proteins. For this, the structures of proteins were modeled and then several groups of compounds as FDA approved, natural products or under clinical trials were screened from DrugBank and ZINC databases. The selected dockings were analyzed and the ligands with best binding affinity scores were subjected to evaluate drug-likeness and medicinal chemistry friendliness through prediction of ADMET properties. Normal mode analyses were also performed for six selected complexes to explore the collective motions of proteins. Molecular dynamic (MD) simulation was also performed to calculate the stability of two docked protein–ligand complexes. The results revealed that several compounds had high affinity to the proteins along with some acceptable profiles of mobility and deformability, especially, for M protein.

Pyruvate anion is important in a broad array of physicochemical processes ranging from glucose homeostasis to atmospheric reactions. However, the electronic polarizability of the moiety has not been investigated extensively. We present theoretical results from electronic structure calculations on the static and dynamic polarizability of microhydrated pyruvate anions. These investigations were carried out with the CH₃COCOO${}^{-}\cdot$n H₂O clusters ($n=1$–9) to mimic microhydration conditions. These density functional theory calculations were carried out at the B3LYP/aug-cc-PVTZ level to uncover the optimal geometry of the anion water cluster. Sadlej basis set functions with the B3LYP functional were used to calculate the static and dynamic polarizabilities. Multiple simulated annealing simulations were carried out to discover additional low-lying minima. It is observed that the electronic polarizability varies linearly with the size of the hydrated cluster. Expressions that describe the relationship between the dynamic polarizability and the field frequency are provided for each cluster.

The large chemical space universe can be traversed by screening libraries of compounds that possess novel medicinally relevant chemistries, properties and complexity criteria. These libraries can be populated with the use of exhaustive, de novo approaches or inspired, combinatorial approaches. By assuming that natural products within screening libraries may be classified as a source of feedstock for populating virtual libraries, they can act as scaffolds upon which exhaustive approaches may be used in exploring chemical space. In order to achieve this, we have built DerivatizeME as a tool that enumerates derivatives of query compounds in order to evaluate their relevance for further assessment and development. This technique was applied to natural products present in the South African natural compound database (SANCDB). By expanding the chemical space of SANCDB compounds through the generation of SANCDB derivatives, we were able to graduate some natural products that were in undesirable regions of medicinally relevant chemical space, to acceptable regions of this chemical space. These modified scaffolds are available for further development, testing and evaluation in a manner similar to natural product driven focused libraries. The natural product parent is used, through its derivatives, instead of being discarded from screening protocols. This approach has the potential to enhance the efficiency of the natural product library in providing successful hits, amplifying the potential that they possess to access both novel bioactives and privileged scaffolds which may have otherwise been overlooked.

Severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) main protease (M^Pro) is recognized as an important therapeutic target protein in the drug development for COVID-19. To date, clinical trials of many vaccine and other viral protease inhibitors (PI) are currently under investigation. Undoubtedly, there are chances of possible side effects and ineffectiveness. Thus, the search for natural bio-active molecules is of great interest that will exert antiviral activity as well as have least chances of toxicity. Fungi are considered as bio-enriched source of producing antiviral compounds. This study is focused on identifying potential fungal derived antiviral molecules with good binding affinity against SARS-CoV-2 M^Pro using molecular docking. Semicochliodinol B was identified as the best lead molecule with higher binding affinity ($-8.9$kcal/mol) as compared to the co-crystalized ligand ($-8.5$kcal/mol). The results of molecular docking confirm the hydrogen bond interaction of Semicochliodinol B with Glu166 and Asn142 as well as hydrophobic interactions with 20 amino acid residues of SARS-CoV-2 M^Pro. Semicochliodinol B also exhibited good binding affinity against SARS-CoV M^Pro and Middle east respiratory syndrome-related corona virus (MERS-CoV M^Pro), suggesting its broad-spectrum activity. Druglikeness, Absorption, distribution, metabolism, excretion (ADME) and toxicity studies also directed that Semicochliodinol B may become a promising drug candidate and thus it can be further investigated as a potential inhibitor of SARS-CoV-2 M^Pro.

Malarial parasites have been reported for moderate-high resistance towards classical antimalarial agents and henceforth development of newer novel chemical entities targeting multiple targets rather than targeting single target will be a highly promising strategy in antimalarial drug discovery. Herein, we carried out molecular modeling studies on 2,4-disubstituted imidazopyridines as anti-hemozoin formation inhibitors by using Schrödinger’s molecular modeling package (2020_4). We have developed statistically robust atom-based 3D-QSAR model (training set, $R^2=0.8709$; test set, $Q^2=0.5287$; $F$ $\mathrm{\text{value}}=52.9$; root-mean-square error, $\mathrm{\text{RMSE}}=0.57$; standard deviation, $\mathrm{\text{SD}}=0.326$). Our molecular docking, in-silico ADMET analysis showed that dataset molecule 37, has highly promising results. Our ligand-based virtual screening resulted in top five ZINC hits, among them ZINC73737443 hit was observed with lesser energy gap, i.e. 7.85eV, higher softness value (0.127eV), and comparatively good docking score of $-$10.2kcal/mol. Our in-silico analysis for a proposed hit, ZINC73737443 showed that this molecule has good ADMET, in-silico nonames toxic as well as noncarcinogenic profile. We believe that further experimental as well as the in-vitro investigation will throw more lights on the identification of ZINC73737443 as a potential antimalarial agent.

It is of great importance for the pharmaceutical industry to find therapeutic substances extracted from natural sources, which are abundant, obtained with low costs and presenting the antiviral potential for the treatment of Zika virus (ZIKV) and COVID-19. Tangeretin (TAN) is a citrus polymethoxyflavone from Citrus reticulata peel oil with known antiviral activities, whose physico-chemical properties are not reported. The present study aimed to investigate by a theoretical screening of electronic, structural properties and pharmacodynamic and pharmacokinetic parameters that characterize TAN as a therapeutic drug in the treatment and prevention of zika fever and COVID-19. The molecule reached its minimum energy-forming state of $-$795.85747kJ/mol and the HOMO and LUMO boundary orbitals reactivity descriptors suggest that the compound is stable and does not tend to be reactive in intermolecular interactions. The ligand connects to the NS1 ZIKV receptor with strong H-bond interactions, also connects with the NS5 ZIKV receptor in a competitive effect with the SAM inhibitor and acts in a supplementary effect with the N3 inhibitor and the BRT drug in the Mpro SARS-CoV-2 receptor. The properties of ADMET shows that the compound suffers few amounts of drug alterations because it inhibits the metabolic enzymes CYP2C9 and CYP3A4 and penetrates the central nervous system, without accumulation of drug residues in the blood or in the lumen in the gastrointestinal tract, without risk of toxicity to the patient. With the results obtained, it is possible to identify TAN as a promising pharmacological tool for the treatment and prevention of Zika fever and COVID-19.

COVID-19 is the last disease caused by SARS-CoV-2 associated with a severe immune response and lung damage. The main protease (M^pro) has a vital role in SARS-CoV-2 proliferation. Moreover, humans lack homologous M^pro, which makes the M^pro a suitable drug target for the development of SARS-CoV-2 drugs. The purchasable L5000 library (Selleckchem Inc) includes 99,040 compounds that were used for virtual screening. After molecular docking and ADME studies, we selected a compound (WAY-604395) with a potent binding affinity to the M^pro active site and acceptable ADME properties compared to the reference drug (nelfinavir). Molecular dynamics (MD) simulation outcomes have proved that the M^pro-WAY604395 complex possesses a considerable value of flexibility, stability, compactness and binding energy. Our Molecular Mechanics Poisson–Boltzmann Surface Area (MM-PBSA) calculation demonstrates that WAY-604395 is more potent ($-$272.19kcal mol${}^{-1}$) in comparison with nelfinavir ($-$173.39kcalmol${}^{-1}$) against SARS-CoV-2 M^pro. In conclusion, we suggest that WAY-604395 has the potential for the treatment of SARS-CoV-2 by inhibition of the M^pro.

In this study, a new alkylaminophenol compound was synthesized and characterized by spectroscopic techniques (FT-IR, NMR, UV). The optimized molecular geometry and the vibrational wavenumbers were calculated using density functional theory (DFT) B3LYP/WB97XD and HF methods with 6-311++ G($d$, $p$) basis set. Thus, theoretical data were compared within themselves before comparing with experimental data. The detailed interpretation of the vibrational spectra has been carried out by VEDA program. ¹H-NMR and ${}^{13}$C-NMR chemical shifts of the compound were calculated using GIAO/IEFPCM method in CDCl3. Using time-dependent (TD-DFT) approach electronic properties such as HOMO and LUMO energies, the electronic spectrum of the title compound has been studied and reported. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Linear polarizability, anisotropic linear polarizability and hyperpolarizability values of the title compound were found to be higher than the values of the pNA compound that are used as a standard substance in the NLO analysis. Molecular electrostatic potential (MEP), the thermodynamic properties (heat capacity, entropy and enthalpy) were calculated. Also, to investigate the biological properties of the title compound, molecular docking was done with DNA(PDB ID: 414D). It has been observed that the effective interaction is hydrogen bonds.