C60 fullerene against SARS-CoV-2 coronavirus: an in silico insight

Click synthesis of dendronized malonates for the preparation of amphiphilic dendro[60]fullerenes

Fullerene C60 and its malonate derivatives, produced via the Bingel-Hirsch reaction, have displayed promising properties against various diseases. These molecules have great therapeutic potential, but their broad use has been limited due to poor aqueous solubility and toxicity caused by accumulation. In this study, we synthesized new malonates and malonamides attached to first- and second-generation polyester dendrons using click chemistry (CuAAC). These dendrons were then linked at C60 through the Bingel-Hirsch reaction, resulting in an amphiphilic system that retains the hydrophobic nature of C60. The dendronized malonate derivatives showed good reaction yields for the Bingel-Hirsch mono-adducts and were easier to work with than the corresponding malonamides. However, the malonamide derivatives, which were obtained through a multistep reaction sequence, showed moderate yields in the Bingel-Hirsch reaction. Surprisingly, removing acetonide protecting groups from dendritic architectures was more challenging than anticipated, likely due to product decomposition. Only the corresponding free malonate derivatives 25 and 26 were obtained, but in a low yield due to decomposition under the reaction conditions. Meanwhile, it was not possible to obtain the corresponding malonamide derivatives 27 and 28. Currently, efforts are being made to improve the production of the desired molecules and to design new synthesis routes that allow direct access to the desired poly-hydroxylated derivatives. These derivatives will be evaluated as multitarget ligands against Alzheimer's disease, through their use as inhibitors of amyloid β-peptide aggregation, acetylcholinesterase modulators, and antioxidants.

The Functional Implications of Broad Spectrum Bioactive Compounds Targeting RNA-Dependent RNA Polymerase (RdRp) in the Context of the COVID-19 Pandemic

BACKGROUND

As long as COVID-19 endures, viral surface proteins will keep changing and new viral strains will emerge, rendering prior vaccines and treatments decreasingly effective. To provide durable targets for preventive and therapeutic agents, there is increasing interest in slowly mutating viral proteins, including non-surface proteins like RdRp.

METHODS

A scoping review of studies was conducted describing RdRp in the context of COVID-19 through MEDLINE/PubMed and EMBASE. An iterative approach was used with input from content experts and three independent reviewers, focused on studies related to either RdRp activity inhibition or RdRp mechanisms against SARS-CoV-2.

RESULTS

Of the 205 records screened, 43 studies were included in the review. Twenty-five evaluated RdRp activity inhibition, and eighteen described RdRp mechanisms of existing drugs or compounds against SARS-CoV-2. In silico experiments suggested that RdRp inhibitors developed for other RNA viruses may be effective in disrupting SARS-CoV-2 replication, indicating a possible reduction of disease progression from current and future variants. In vitro, in vivo, and human clinical trial studies were largely consistent with these findings.

CONCLUSIONS

Future risk mitigation and treatment strategies against forthcoming SARS-CoV-2 variants should consider targeting RdRp proteins instead of surface proteins.

The Emergence of Carbon Nanomaterials as Effective Nano-Avenues to Fight against COVID-19

COVID-19 (Coronavirus Disease 2019), a viral respiratory ailment that was first identified in Wuhan, China, in 2019, and then expanded globally, was caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The severity of the illness necessitated quick action to cease the virus's spread. The best practices to avert the infection include early detection, the use of protective clothing, the consumption of antiviral medicines, and finally the immunization of the patients through vaccination. The family of carbon nanomaterials, which includes graphene, fullerene, carbon nanotube (CNT), and carbon dot (CD), has a great deal of potential to effectively contribute to each of the main trails in the battle against the coronavirus. Consequently, the recent advances in the application of carbon nanomaterials for containing and combating the SARS-CoV-2 virus are discussed herein, along with their associated challenges and futuristic applicability.

Synthesis of [60]Fullerene Hybrids Endowed with Steroids and Monosaccharides: Theoretical Underpinning as Promising anti-SARS-CoV-2 Agents

Cyclopropanation reactions between C60 and different malonates decorated with monosaccharides and steroids using the Bingel-Hirsch methodology have allowed the obtention of a new family of hybrid compounds in good yields. A complete set of instrumental techniques has allowed us to fully characterize the hybrid derivatives and to determine the chemical structure of monocycloadducts. Besides, the proposed structures were investigated by cyclic voltammetry, which evidenced the exclusive reductive pattern of fullerene Bingel-type monoadducts. Theoretical calculations at the DFT-D3(BJ)/PBE 6-311G(d,p) level of the synthesized conjugates predict the most stable conformation and determine the factors that control the hybrid molecules' geometry. Some parameters such as polarity, lipophilicity, polar surface area, hydrophilicity index, and solvent-accessible surface area were also estimated, predicting its potential permeability and capability as cell membrane penetrators. Additionally, a molecular docking simulation has been carried out using the main protease of SARS-CoV-2 (Mpro) as the receptor, thus paving the way to study the potential application of these hybrids in biomedicine.

Fullerene derivatives as inhibitors of the SARS-CoV-2 main protease

COVID-19 is an ongoing worldwide pandemic. Even today, there is a need for the development of effective therapeutic agents. SARS-CoV-2 is known as the causative virus of COVID-19, and its main protease is one of the enzymes essential for its growth and is considered a drug discovery target. In this study, we evaluated the inhibitory activities of a variety of fullerene derivatives, including newly synthesized derivatives, against the main protease of SARS-CoV-2. As a result, the malonic acid-type fullerene derivatives showed the strongest inhibitory activity.

State-of-the-Art Smart and Intelligent Nanobiosensors for SARS-CoV-2 Diagnosis

The novel coronavirus appeared to be a milder infection initially, but the unexpected outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), commonly called COVID-19, was transmitted all over the world in late 2019 and caused a pandemic. Human health has been disastrously affected by SARS-CoV-2, which is still evolving and causing more serious concerns, leading to the innumerable loss of lives. Thus, this review provides an outline of SARS-CoV-2, of the traditional tools to diagnose SARS-CoV-2, and of the role of emerging nanomaterials with unique properties for fabricating biosensor devices to diagnose SARS-CoV-2. Smart and intelligent nanomaterial-enabled biosensors (nanobiosensors) have already proven their utility for the diagnosis of several viral infections, as various detection strategies based on nanobiosensor devices are already present, and several other methods are also being investigated by researchers for the determination of SARS-CoV-2 disease; however, considerably more is undetermined and yet to be explored. Hence, this review highlights the utility of various nanobiosensor devices for SARS-CoV-2 determination. Further, it also emphasizes the future outlook of nanobiosensing technologies for SARS-CoV-2 diagnosis.

Fullerene Derivatives for Drug Delivery against COVID-19: A Molecular Dynamics Investigation of Dendro[60]fullerene as Nanocarrier of Molnupiravir

In this paper, a theoretical investigation is made regarding the possibility of using a water-soluble derivative of C₆₀ as a drug delivery agent for treating Coronavirus disease 2019 (COVID-19). Molnupiravir is chosen as the transporting pharmaceutical compound since it has already proved to be very helpful in saving lives in case of hospitalization. According to the proposed formulation, a carboxyfullerene known as dendro[60]fullerene is externally connected with two molnupiravir molecules. Two properly formed nitrogen single bonds (N-N) are used as linkers between the dendro[60]fullerene and the two molnupiravir molecules to create the final form of the C₆₀ derivate/molnupiravir conjugate. The energetics of the developed molecular system and its interaction with water and n-octanol are extensively studied via classical molecular dynamics (MD) using the COMPASS II force field. To study the interactions with water and n-octanol, an appropriate periodic amorphous unit cell is created that contains a single C₆₀ derivative/molnupiravir system surrounded by numerous solvent molecules and simulated via MD in room conditions. In addition, the corresponding solvation-free energies of the investigated drug delivery system are computed and set in contrast with the corresponding properties of the water-soluble dendro[60]fullerene, to test its solubility capabilities.

Topological and Multivalent Effects in Glycofullerene Oligomers as EBOLA Virus Inhibitors

The synthesis of new biocompatible antiviral materials to fight against the development of multidrug resistance is being widely explored. Due to their unique globular structure and excellent properties, [60]fullerene-based antivirals are very promising bioconjugates. In this work, fullerene derivatives with different topologies and number of glycofullerene units were synthesized by using a SPAAC copper free strategy. This procedure allowed the synthesis of compounds 1–3, containing from 20 to 40 mannose units, in a very efficient manner and in short reaction times under MW irradiation. The glycoderivatives were studied in an infection assay by a pseudotyped viral particle with Ebola virus GP1. The results obtained show that these glycofullerene oligomers are efficient inhibitors of EBOV infection with IC₅₀s in the nanomolar range. In particular, compound 3, with four glycofullerene moieties, presents an outstanding relative inhibitory potency (RIP). We propose that this high RIP value stems from the appropriate topological features that efficiently interact with DC-SIGN.

Drummondin E and Flinderole B are potential inhibitors of RNA-dependent RNA polymerase of SARS-CoV-2: an in silico study

Coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected 235.6 million people worldwide. In the present study, RNA-dependent RNA polymerase (RdRp) (PDB Id: 6M71) of SARS-CoV-2, an essential enzyme needed for subgenomic replication and amplification of RNA, was selected. Similar to other RdRps, it is a conserved protein and a popular target for antiviral drug therapy. Based on a computational approach, potential RdRp inhibitors were identified. The absorption, distribution, metabolism, excretion, and toxicity (ADMET) of selected molecules were determined using computation tools. The potential inhibitors were docked to the RdRp and later confirmed by Molecular Dynamics (MD) using the "Flare" module of Cresset software. Drummondin E and Flinderole B had higher drug similarity scores among the compounds selected in this study. Both these compounds are noncarcinogenic, nonirritant, nontumorigenic, and nonmutagenic. Molecular docking studies showed that both compounds can bind to RdRp. The best ligand interaction patterns were validated by MD using the "Flare" module. MD was performed for the period of 100 ns with the time step of 1 fs. The simulation results suggest that Thr-680, Arg-624, Lys-676, and Val-557 are key interacting partners in the Drummondin E-RdRp complex, while Asp-618, Asp-760, Asp-623, Arg-624, and Asp-761 are the interacting partners in the Flinderole B-RdRp complex. Based on the in silico drug-likeness score; ADMET properties; and molecular simulation result, we surmise that Flinderole B and Drummondin E could impede SARS-CoV-2 genome replication and transcription by targeting the RdRp protein.

Fullerenes against COVID-19: Repurposing C60 and C70 to Clog the Active Site of SARS-CoV-2 Protease

The persistency of COVID-19 in the world and the continuous rise of its variants demand new treatments to complement vaccines. Computational chemistry can assist in the identification of moieties able to lead to new drugs to fight the disease. Fullerenes and carbon nanomaterials can interact with proteins and are considered promising antiviral agents. Here, we propose the possibility to repurpose fullerenes to clog the active site of the SARS-CoV-2 protease, M^pro. Through the use of docking, molecular dynamics, and energy decomposition techniques, it is shown that C₆₀ has a substantial binding energy to the main protease of the SARS-CoV-2 virus, M^pro, higher than masitinib, a known inhibitor of the protein. Furthermore, we suggest the use of C₇₀ as an innovative scaffold for the inhibition of SARS-CoV-2 M^pro. At odds with masitinib, both C₆₀ and C₇₀ interact more strongly with SARS-CoV-2 M^pro when different protonation states of the catalytic dyad are considered. The binding of fullerenes to M^pro is due to shape complementarity, i.e., vdW interactions, and is aspecific. As such, it is not sensitive to mutations that can eliminate or invert the charges of the amino acids composing the binding pocket. Fullerenic cages should therefore be more effective against the SARS-CoV-2 virus than the available inhibitors such as masinitib, where the electrostatic term plays a crucial role in the binding.