The sesquiterpenes with the COVID-19 Mpro inhibitory activity from the Carpesium abrotanoides L

The extract of the whole plant of Carpesium abrotanoides L. yielded four new sesquiterpenes including a novel skeleton (claroguaiane A, 1), two guaianolides (claroguaianes B-C, 2-3), and one eudesmanolide (claroeudesmane A, 4), together with three known sesquiterpenoids (5-7). The structures of the new compounds were elucidated by spectroscopic analysis especially 1D and 2D NMR spectroscopy and HRESIMS data. Additionally, all the isolated compounds were preliminarily evaluated for the inhibitive activity of COVID-19 Mpro. As a result, compound 5 showed moderate activity with an IC50 value of 36.81 μM and compound 6 exhibited a potent inhibitory effect with an IC50 value of 16.58 µM, while other compounds were devoid of noticeable activity (IC50 > 50 μM).

In-Silico approach for identification of effective and stable inhibitors for COVID-19 main protease (Mpro) from flavonoid based phytochemical constituents of Calendula officinalis

The recent outbreak of the coronavirus disease COVID-19 is putting the world towards a great threat. A recent study revealed COVID-19 main protease (Mpro) is responsible for the proteolytic mutation of this virus and is essential for its life cycle. Thus inhibition of this protease will eventually lead to the destruction of this virus. In-Silico Molecular docking was performed with the Native ligand and the 15 flavonoid based phytochemicals of Calendula officinals to check their binding affinity towards the COVID-19 main protease. Finally, the top 3 compounds with the highest affinity have been chosen for molecular dynamics simulation to analyses their dynamic properties and conformational flexibility or stability. In-Silico Docking showed that major phytochemicals of Calendula officinals i.e. rutin, isorhamnetin-3-O-β-D, calendoflaside, narcissin, calendulaglycoside B, calenduloside, calendoflavoside have better binding energy than the native ligand (inhibitor N3). MD simulation of 100 ns revealed that all the protease-ligand docked complexes are overall stable as compare to Mpro-native ligand (inhibitor N3) complex. Overall, rutin and caledoflaside showed better stability, compactness, and flexibility. Our in silico (Virtual molecular docking and Molecular dynamics simulation) studies pointed out that flavonoid based phytochemicals of calendula (rutin, isorhamnetin-3-O-β-D, calendoflaside) may be highly effective for inhibiting Mpro which is the main protease for SARS-CoV-2 causing the deadly disease COVID-19. Rutin is already used as a drug and the other two compounds can be made available for future use. Thus the study points a way to combat COVID-19 by the use of major flavonoid based phytochemicals of Calendula officinals. Communicated by Ramaswamy H. Sarma.

Anti-Inflammatory, Antiallergic, and COVID-19 Main Protease (Mpro) Inhibitory Activities of Butenolides from a Marine-Derived Fungus Aspergillus terreus

In December 2020, the U.K. authorities reported to the World Health Organization (WHO) that a new COVID-19 variant, considered to be a variant under investigation from December 2020 (VUI-202012/01), was identified through viral genomic sequencing. Although several other mutants were previously reported, VUI-202012/01 proved to be about 70% more transmissible. Hence, the usefulness and effectiveness of the newly U.S. Food and Drug Administration (FDA)-approved COVID-19 vaccines against these new variants are doubtfully questioned. As a result of these unexpected mutants from COVID-19 and due to lack of time, much research interest is directed toward assessing secondary metabolites as potential candidates for developing lead pharmaceuticals. In this study, a marine-derived fungus Aspergillus terreus was investigated, affording two butenolide derivatives, butyrolactones I (1) and III (2), a meroterpenoid, terretonin (3), and 4-hydroxy-3-(3-methylbut-2-enyl)benzaldehyde (4). Chemical structures were unambiguously determined based on mass spectrometry and extensive 1D/2D NMR analyses experiments. Compounds (1-4) were assessed for their in vitro anti-inflammatory, antiallergic, and in silico COVID-19 main protease (Mpro) and elastase inhibitory activities. Among the tested compounds, only 1 revealed significant activities comparable to or even more potent than respective standard drugs, which makes butyrolactone I (1) a potential lead entity for developing a new remedy to treat and/or control the currently devastating and deadly effects of COVID-19 pandemic and elastase-related inflammatory complications.

In silico approach: docking study of oxindole derivatives against the main protease of COVID-19 and its comparison with existing therapeutic agents

OBJECTIVES

Presently, the pandemic of COVID-19 has worsened the situation worldwide and received global attention. The United States of America have the highest numbers of a patient infected by this disease followed by Brazil, Russia, India and many other countries. Moreover, lots of research is going on to find out effective vaccines or medicine, but still, no potent vaccine or drug is discovered to cure COVID-19. As a consequence, many types of research have designated that computer-based studies, such as protein-ligand interactions, structural dynamics, and chembio modeling are the finest choice due to its low cost and time-saving features. Here, oxindole derivatives have been chosen for docking because of their immense pharmacological applications like antiviral, antidiabetic, anti-inflammatory, and so on. Molecular docking of 30 oxindole derivatives done on the crystallized structure of the protein (COVID-19 Mpro).

METHODS

The process of docking, interaction, and binding the structure of ligand with protein has executed using Molegro Virtual Docker v.7.0.0 (MVD) and visualized the usage by Molegro Molecular Viewer v.7.0.0 (MMV).

RESULTS

Among the 30 derivatives, the outcomes depicted better steric interaction and hydrogen bonding amongst OD-22 ligand, OD-16 ligand, OD-4 ligand, and OD-9 ligand (oxindole derivatives) with COVID-19. In addition to this, the comparative study of these four compounds with existing drugs that are under clinical trials shows comparatively good results in terms of its MolDock scores, H-bonding and steric interactions.

CONCLUSIONS

Hence, It is proposed that these four oxindole derivatives have good potential as a new drug against coronavirus as possible therapeutic agents.