Bioactive metabolites of licorice and thyme as potential inhibitors of Cox1 enzyme of phytopathogens of Capsicum annuum L.: In-silico approaches.

Cytochrome c oxidase subunit 1 (Cox1), a key enzyme, has a crucial role in cellular respiration in eukaryotes and prokaryotes. Generally, respiratory inhibitors are considered one of the types of chemical pesticides. Thyme oil and licorice aqueous extract have been reported to have antifungal activities against fungal phytopathogens of Capsicum annuum L., i.e., Colletotrichum capsici, Fusarium oxysporum, and Pythium aphanidermatum. The present study focuses on identifying the key bioactive molecules of thyme and licorice botanicals inhibiting the activity of the Cox1 enzymes of the above mentioned phytopathogens, employing the in-silico approach. From a wide range of bioactive molecules screened, the molecular docking indicated trans-carveol, carvacrol, kaempferol 3-rhamnoside 7-xyloside, kaempferitrin, and astragalin 7-rhamnoside as the potential inhibitors for Cox1 of C. capsici, ß-Caryophyllene, Caryophyllene acetate, hispaglabridin A, kaempferol 3-rhamnoside 7-xyloside and licorice glycoside A for Cox1 of F. oxysporum and (+)-Longifolen, Caryophyllene acetate, Hispaglabridin A, Neoliquiritin 2''-apioside and Licorice-saponin A3 for Cox1 of P. aphanidermatum. Most of the top-scoring bioactive molecules exhibited higher binding affinity with the targets than the chemical compound, i.e., carbendazim. Density functional theory (DFT) analysis confirmed the reactivity of the top-docked compounds. Molecular dynamic simulations confirmed the stability of docked complexes when evaluated through multiple descriptors. Additionally, MM/PBSA analysis supported the findings, indicating the spontaneous binding of the enzymes to the screened ligands. ADMET analysis revealed the safety of the selected bioactive compounds. The present findings could be useful in developing biopesticidal formulations as efficient and sustainable alternatives to chemical pesticides.Communicated by Ramaswamy H. Sarma.

Molecular docking, dynamics simulation and pharmacokinetic studies of Cyperus articulatus essential oil metabolites as inhibitors of Staphylococcus aureus.

Cyperus articulatus has been extensively studied for its essential oil (EO), active components and antibacterial activities against a wide range of bacteria such as Bacillus megaterium, Streptococcus pyogenes, Staphylococcus epidermidis, Escherichia coli and Staphylococcus aureus. However, knowledge of the biomolecular interaction of the individual EO metabolites responsible for its inhibition activities is lacking. The multi-drug-resistant bacteria S. aureus, which is of prime concern, has been reported to be inhibited by Cyperus articulatus rhizome EO. The present work analyzed the molecular interactions of the major Cyperus articulatus rhizome EO metabolites with the target enzyme TyrRS of S. aureus and studied the conformational dynamics and stability of the protein-ligand complexes. Molecular docking studies of selected EO metabolites such as mustakone, longifolenaldehyde, cyperotundone, α-copaene, ß-calacorene, α-calacorene and khusinol were conducted along with standard drug chloramphenicol for comparative analysis of their binding affinity with S. aureus TyrRS. The metabolites khusinol, mustakone, ß-calacorene and α-calacorene generated comparable docking scores (-6.4, -6.2, -6.1 and -6.2 kcal/mol, respectively) with that of the drug chloramphenicol (-6.3 kcal/mol). Most EO metabolites did not exhibit H-bonding with the S. aureus TyrRS residues and were stabilized through pi-interactions. The MD simulation study illustrated that compounds like mustakone could effectively bind to the receptors of S. aureus TyrRS with high stability and integrity. Pharmacokinetic, drug-like properties and toxicity analysis of the EO metabolites supported the candidature of mustakone and khusinol as pharmacologically important antibacterial drug ingredients. The study envisaged the structural framework of the EO metabolites for antibacterial drug design.Communicated by Ramaswamy H. Sarma.

Computational investigations on the potential role of hygrophorones as quorum sensing inhibitors against LasR protein of Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a gram negative, rod shape bacterium that infects people with compromised immune systems, such as those suffering from AIDS, organ transplantation and cancer. This bacterium is responsible for diseases like cystic fibrosis, chronic lung infection, and ulcerative keratitis. It is diagnosed in most of the patients who were on prolonged ventilation with long term critical care stay. P. aeruginosa develops rapid antimicrobial resistance that is challenging for the treatment and eventually it causes high mortality rate. Thus, the search for potential novel inhibitors that can inhibit the pathogenic activity of P. aeruginosa is of utmost importance. In P. aeruginosa, an important protein, LasR that participates in the gene regulations and expressions has been proposed to be a suitable drug target. Here, we identify a set of hygrophorone molecules as effective inhibitors for this LasR protein based on molecular docking and simulations studies. At first, large number of hygrophorone series of small molecules were screened against the LasR protein and their binding affinities were assessed based on the docking scores. Top scored molecules were selected for calculating various pharmacophore properties, and finally, their potential in inhibiting the LasR protein was delineated by atomistic molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area-based calculations. Both docking and simulations studies reveal that a subset of hygrophorone molecules have a good binding affinity for LasR protein and form stable LasR-inhibitor complexes. The present study illustrates that the hygrophorones can be effective inhibitors for the LasR protein and will spur further in vitro studies that would aid to the ongoing search for new antibiotics.Communicated by Ramaswamy H. Sarma.

Deciphering the Potential of Pre and Pro-Vitamin D of Mushrooms against Mpro and PLpro Proteases of COVID-19: An In Silico Approach.

Vitamin D's role in combating the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the virus causing COVID-19, has been established in unveiling viable inhibitors of COVID-19. The current study investigated the role of pre and pro-vitamin D bioactives from edible mushrooms against Mpro and PLpro proteases of SARS-CoV-2 by computational experiments. The bioactives of mushrooms, specifically ergosterol (provitamin D2), 7-dehydrocholesterol (provitamin-D3), 22,23-dihydroergocalciferol (provitamin-D4), cholecalciferol (vitamin-D3), and ergocalciferol (vitamin D2) were screened against Mpro and PLpro. Molecular docking analyses of the generated bioactive protease complexes unravelled the differential docking energies, which ranged from -7.5 kcal/mol to -4.5 kcal/mol. Ergosterol exhibited the lowest binding energy (-7.5 kcal/mol) against Mpro and PLpro (-5.9 kcal/mol). The Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) and MD simulation analyses indicated that the generated complexes were stable, thus affirming the putative binding of the bioactives to viral proteases. Considering the pivotal role of vitamin D bioactives, their direct interactions against SARS-CoV-2 proteases highlight the promising role of bioactives present in mushrooms as potent nutraceuticals against COVID-19.

Deciphering the role of Trichoderma sp. bioactives in combating the wilt causing cell wall degrading enzyme polygalacturonase produced by Fusarium oxysporum: An in-silico approach.

The cell wall degrading enzymes polygalacturonase (PG) secreted by Fusarium oxysporum f. sp. radicis-lycopersici (FOL) is testified to trigger Fusarium crown and root rot disease in tomato crops; instigated due to the degradation of the pectin. Trichoderma sp. is documented as a potential biocontrol agent playing a pivotal role in plant health and disease management. An in-silico approach employing homology modelling, molecular docking, molecular dynamics (MD) simulation and MMPBSA was employed to assess the prospective role of bioactives produced by Trichoderma sp. in combating the PG2 enzyme. The studies revealed that amongst the wide range of bioactives screened, Trichodermamide B produced by T. harzianum and Viridin, Virone, and Trichosetin produced by T. virens emerged as the potential inhibitors of the PG2. Docking results revealed that the complexes possessed most stable energy for Trichodermamide B (-8.1 kcal/mol) followed by Viridin (-7.7 kcal/mol), Virone (-7.1 kcal/mol), and Trichosetin (-7 kcal/mol), respectively. Interaction studies of FOL with T. virens and T. harzianum reported an inhibition of 83.33% and 75.87%, respectively. The structural rigidity and stability of the docked complex was confirmed through MD simulations evaluated across multiple descriptors from the simulation trajectories. Further, MMPBSA analysis validated the results that binding of the enzyme to the screened ligands was spontaneous. The study unravels new insights on the versatile potential of Trichoderma sp. Bioactives as a prospective agent for the inhibition of cell-wall degrading enzymes secreted by phytopathogens. The proposed study can be implemented for design of bioformulations that serve the role of biopesticide, promising a sustainable alternate to chemical-based products.

Finding potent inhibitors for COVID-19 main protease (Mpro): an in silico approach using SARS-CoV-3CL protease inhibitors for combating CORONA.

SARS-CoV-2 is liable for the worldwide coronavirus disease (COVID-19) exigency. This pandemic created the need for all viable treatment strategies available in the market. In this scenario, computer-aided drug design techniques can be efficiently applied for the quick identification of promising drug repurposing candidates. In the current study, we applied the molecular docking approach in conjugation with molecular dynamics (MD) simulations to find out potential inhibitors against Mpro of SARS-CoV-2 from previously reported SARS-3CL protease inhibitors. Our results showed that N-substituted isatin derivatives and pyrazolone compounds could be used as a potent inhibitor and may possess an anti-viral activity against SARS-CoV-2. However, further experimental investigation and validation of the selected hits are required to find out their suitability for clinical trials. Communicated by Ramaswamy H. Sarma.

A combinatorial approach to screen structurally diverse acetylcholinesterase inhibitory plant secondary metabolites targeting Alzheimer's disease.

Alzheimer's disease (AD) is a form of Dementia known to diminish the brain's function by perturbating its structural and functional components. Though cholinesterase inhibitors are widely used to treat AD, they are limited by numbers and side effects. Hence, present study aims to identify structurally diverse Acetylcholinesterase (AChE) inhibitory plant secondary metabolites (PSM) by employing high throughput screening and computational studies. AChE inhibitory activity was performed using 390 crude extracts from 63 plant parts belongs to 58 plants. The lowest IC50 value was recorded by acetone extract of Cyperus rotundus rhizome at 0.5 mg/ml, followed by methanol extract of Terminalia arjuna bark (0.95 mg/ml) and water extract Acacia catechu stem (0.95 mg/ml). A virtual library containing 487 PSM belongs to 18 plants found positive for AChE inhibition (IC50≤5 mg/ml) was prepared. Through ADMET analysis, 78 PSM fulfilling selected drug-likeness parameters were selected for further analysis. Molecular docking studies of selected PSM against AChE recorded a wide range of binding energy from -3.40 to -10.90 Kcal/mol. Further molecular dynamics simulation studies also recorded stabilized interactions of AChE-ligand complexes in the term of RMSD, RMSF, Rg, SASA, and hydrogen bond interaction. MMPBSA analysis revealed the binding energy of selected PSM ranging from -123.757 to -261.697 kJ/mol. Our study demonstrated the potential of 12 PSM (Sugiol, Margolone, 7-Hydroxy-3',4'-(Methylenedioxy) flavan, Beta-cyprone, Ethenone, Isomargolonone, Serpentine, Cryptolepine, Rotundone, Strictamin, Rotundenol and Nootkatone) as AChE inhibitors. Further in vitro and in vivo experimental evaluations with pure PSM could be beneficial for therapeutic uses.

Unraveling the potential role of bioactive molecules produced by Trichoderma spp. as inhibitors of tomatinase enzyme having an important role in wilting disease: an in-silico approach.

Tomatinase; a saponin detoxification enzyme produced by Fusarium oxysporumf.sp. lycopersici is reported as a causative agent for wilting disease in tomato crops. The disease is instigated by inhibiting the activity of α-tomatine. Trichoderma spp. widely used as biocontrol agent play an essential role in plant growth and pathogen control. In the current study, an in-silico approach using substrate docking, molecular dynamics and MM/PBSA analysis was used to evaluate the potential role of bioactive metabolites produced by Trichoderma spp. The study aims to establish the efficacy of catalytic tendency of the bioactive metabolites to combat the effect of tomatinase enzyme employing α-tomatine as the substrate. By means of the integrated molecular modeling approach; novel bioactive metabolites namely, Trichodermamide B, Trichosetin and Virone were found to be the potential inhibitors against tomatinase enzyme secreted by Fusarium oxysporum f.sp. lycopersici. Molecular dynamic (MD) simulations displayed that the screened ligands bound tomatinase during 150 ns of MD simulations. Furthermore, the (MM-PBSA) free energy calculations depicted that screened molecules possess stable and favorable energies for Trichodermamide B (-7.1 kcal/mol), Trichosetin (-7.4 kcal/mol) and Virone (-7.9 kcal/mol) thereby instigating robust binding with the enzyme's binding site. The results attained in this study, reflects that these bioactive metabolites may serve as potential substrates to control and inhibit the tomatinase enzyme; playing an integral role in combating the wilt disease.Communicated by Ramaswamy H. Sarma.

Molecular docking and dynamics studies of curcumin with COVID-19 proteins.

Coronavirus disease 2019 (COVID-19) is caused by a Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2), which is a positive-strand RNA virus. The SARS-CoV-2 genome and its association to SAR-CoV-1 vary from ca. 66 to 96% depending on the type of betacoronavirideae family members. With several drugs, viz. chloroquine, hydroxychloroquine, ivermectin, artemisinin, remdesivir, azithromycin considered for clinical trials, there has been an inherent need to find distinctive antiviral mechanisms of these drugs. Curcumin, a natural bioactive molecule has been shown to have therapeutic potential for various diseases, and its effect on COVID-19 is also currently being explored. In this study, we show the binding potential of curcumin targeted to a variety of SARS-CoV-2 proteins, viz. spike glycoproteins (PDB ID: 6VYB), nucleocapsid phosphoprotein (PDB ID: 6VYO), spike protein-ACE2 (PDB ID: 6M17) along with nsp10 (PDB ID: 6W4H) and RNA dependent RNA polymerase (PDB ID: 6M71) structures. Furthermore, representative docking complexes were validated using molecular dynamics simulations and mechanistic studies at 100 ns was carried on nucleocapsid and nsp10 proteins with curcumin complexes which resulted in stable and efficient binding energies and correlated with that of docked binding energies of the complexes. Both the docking and simulation studies indicate that curcumin has the potential as an antiviral against COVID-19.

Rifampicin and Letermovir as potential repurposed drug candidate for COVID-19 treatment: insights from an in-silico study.

INTRODUCTION: Drug repurposing is the need of the hour considering the medical emergency caused by the COVID-19 pandemic. Recently, cytokine storm by the host immune system has been linked with high viral load, loss of lung function, acute respiratory distress syndrome (ARDS), multiple organ failure, and subsequent fatal outcome. OBJECTIVE: This study aimed to identify potential FDA approved drugs that can be repurposed for COVID-19 treatment using an in-silico analysis. METHODS: In this study, virtual screening of selected FDA approved drugs was performed by targeting the main protease (Mpro) of SARS-CoV-2 and the key molecules involved in the 'Cytokine storm' in COVID-19 patients. Based on our preliminary screening supported by extensive literature search, we selected FDA approved drugs to target the SARS-CoV-2 main protease (Mpro) and the key players of cytokine storm, TNF-α, IL-6, and IL-1ß. These compounds were examined based on systematic docking studies and further validated using a combination of molecular dynamics simulations and molecular mechanic/generalized/Born/Poisson-Boltzmann surface area (MM/G/P/BSA) free energy calculations. RESULTS: Based on the findings, Rifampicin and Letermovir appeared as the most promising drug showing a very good binding affinity with the main protease of SARS-CoV-2 and TNF-α, IL-6, and IL-1ß. However, it is pertinent to mention here that our findings need further validation by in vitro analysis and clinical trials. CONCLUSION: This study provides an insight into the drug repurposing approach in which several FDA approved drugs were examined to inhibit COVID-19 infection by targeting the main protease of SARS-COV-2 and the cytokine storm.

Identification of phytochemical inhibitors against main protease of COVID-19 using molecular modeling approaches.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a novel corona virus that causes corona virus disease 2019 (COVID-19). The COVID-19 rapidly spread across the nations with high mortality rate even as very little is known to contain the virus at present. In the current study, we report novel natural metabolites namely, ursolic acid, carvacrol and oleanolic acid as the potential inhibitors against main protease (Mpro) of COVID-19 by using integrated molecular modeling approaches. From a combination of molecular docking and molecular dynamic (MD) simulations, we found three ligands bound to protease during 50 ns of MD simulations. Furthermore, the molecular mechanic/generalized/Born/Poisson-Boltzmann surface area (MM/G/P/BSA) free energy calculations showed that these chemical molecules have stable and favourable energies causing strong binding with binding site of Mpro protein. All these three molecules, namely, ursolic acid, carvacrol and oleanolic acid, have passed the ADME (Absorption, Distribution, Metabolism, and Excretion) property as well as Lipinski's rule of five. The study provides a basic foundation and suggests that the three phytochemicals, viz. ursolic acid, carvacrol and oleanolic acid could serve as potential inhibitors in regulating the Mpro protein's function and controlling viral replication. Communicated by Ramaswamy H. Sarma.

In silico studies evidenced the role of structurally diverse plant secondary metabolites in reducing SARS-CoV-2 pathogenesis.

Plants are endowed with a large pool of structurally diverse small molecules known as secondary metabolites. The present study aims to virtually screen these plant secondary metabolites (PSM) for their possible anti-SARS-CoV-2 properties targeting four proteins/ enzymes which govern viral pathogenesis. Results of molecular docking with 4,704 ligands against four target proteins, and data analysis revealed a unique pattern of structurally similar PSM interacting with the target proteins. Among the top-ranked PSM which recorded lower binding energy (BE), > 50% were triterpenoids which interacted strongly with viral spike protein-receptor binding domain, > 32% molecules which showed better interaction with the active site of human transmembrane serine protease were belongs to flavonoids and their glycosides, > 16% of flavonol glycosides and > 16% anthocyanidins recorded lower BE against active site of viral main protease and > 13% flavonol glycoside strongly interacted with active site of viral RNA-dependent RNA polymerase. The primary concern about these PSM is their bioavailability. However, several PSM recorded higher bioavailability score and found fulfilling most of the drug-likeness characters as per Lipinski's rule (Coagulin K, Kamalachalcone C, Ginkgetin, Isoginkgetin, 3,3'-Biplumbagin, Chrysophanein, Aromoline, etc.). Natural occurrence, bio-transformation, bioavailability of selected PSM and their interaction with the target site of selected proteins were discussed in detail. Present study provides a platform for researchers to explore the possible use of selected PSM to prevent/ cure the COVID-19 by subjecting them for thorough in vitro and in vivo evaluation for the capabilities to interfering with the process of viral host cell recognition, entry and replication.