Steroidal lactones from Withania somnifera effectively target Beta, Gamma, Delta and Omicron variants of SARS-CoV-2 and reveal a decreased susceptibility to viral infection and perpetuation: a polypharmacology approach.

Prevention from disease is presently the cornerstone of the fight against COVID-19. With the rapid emergence of novel SARS-CoV-2 variants, there is an urgent need for novel or repurposed agents to strengthen and fortify the immune system. Existing vaccines induce several systemic and local side-effects that can lead to severe consequences. Moreover, elevated cytokines in COVID-19 patients with cancer as co-morbidity represent a significant bottleneck in disease prognosis and therapy. Withania somnifera (WS) and its phytoconstituent(s) have immense untapped immunomodulatory and therapeutic potential and the anticancer potential of WS is well documented. To this effect, WS methanolic extract (WSME) was characterized using HPLC. Withanolides were identified as the major phytoconstituents. In vitro cytotoxicity of WSME was determined against human breast MDA-MB-231 and normal Vero cells using MTT assay. WSME displayed potent cytotoxicity against MDA-MB-231 cells (IC50: 66 µg/mL) and no effect on Vero cells in the above range. MD simulations of Withanolide A with SARS-CoV-2 main protease and spike receptor-binding domain as well as Withanolide B with SARS-CoV spike glycoprotein and SARS-CoV-2 papain-like protease were performed using Schrödinger. Stability of complexes followed the order 6M0J-Withanolide A > 6W9C-Withnaolide B > 5WRG-Withanolide B > 6LU7-Withanolide A. Maximum stable interaction(s) were observed between Withanolides A and B with SARS-CoV-2 and SARS-CoV spike glycoproteins, respectively. Withanolides A and B also displayed potent binding to pro-inflammatory markers viz. serum ferritin and IL-6. Thus, WS phytoconstituents have the potential to be tested further in vitro and in vivo as novel antiviral agents against COVID-19 patients having cancer as a co-morbidity. Supplementary Information: The online version contains supplementary material available at 10.1007/s40203-023-00184-y.

Structural interactions of phytoconstituent(s) from cinnamon, bay leaf, oregano, and parsley with SARS-CoV-2 nucleocapsid protein: A comparative assessment for development of potential antiviral nutraceuticals.

SARS-CoV-2 has been responsible for causing 6,218,308 deaths globally till date and has garnered worldwide attention. The lack of effective preventive and therapeutic drugs against SARS-CoV-2 has further worsened the scenario and has bolstered research in the area. The N-terminal and C-terminal RNA binding domains (NTD and CTD) of SARS-CoV-2 nucleocapsid protein represent attractive therapeutic drug targets. Naturally occurring compounds are an excellent source of novel drug candidates due to their structural diversity and safety. Ten major bioactive compounds were identified in ethanolic extract (s) of Cinnamomum zeylanicum, Cinnamomum tamala, Origanum vulgare, and Petroselinum crispum using HPLC and their cytotoxic potential was determined against cancer and normal cell lines by MTT assay to ascertain their biological activity in vitro. To evaluate their antiviral potential, the binding efficacy to NTD and CTD of SARS-CoV-2 nucleocapsid protein was determined using in silico biology tools. In silico assessment of the phytocomponents revealed that most of the phytoconstituents displayed a druglike character with no predicted toxicity. Binding affinities were in the order apigenin > catechin > apiin toward SARS-CoV-2 nucleocapsid NTD. Toward nucleocapsid CTD, the affinity decreased as apigenin > cinnamic acid > catechin. Remdesivir displayed lesser affinity with NTD and CTD of SARS-CoV-2 nucleocapsid proteins than any of the studied phytoconstituents. Molecular dynamics (MD) simulation results revealed that throughout the 100 ns simulation, SARS-CoV-2 nucleocapsid protein NTD-apigenin complex displayed greater stability than SARS-CoV-2 nucleocapsid protein NTD-cinnamic acid complex. Hence, apigenin, catechin, apiin and cinnamic acid might prove as effective prophylactic and therapeutic candidates against SARS-CoV-2, if examined further in vitro and in vivo. PRACTICAL APPLICATIONS: Ten major bioactive compounds were identified in the extract(s) of four medicinally important plants viz. Cinnamomum zeylanicum, Cinnamomum tamala, Origanum vulgare and Petroselinum crispum using HPLC and their biological activity was also evaluated against cancer and normal cell lines. Interestingly, while all extract(s) wielded significant cytotoxicity against cancer cells, no significant toxicity was found against normal cells. The outcome of the results prompted evaluation of the antiviral potential of the ten bioactive compounds using in silico biology tools. The present study emphasizes on the application of computational approaches to understand the binding interaction and efficacy of the ten bioactive compounds from the above plants with SARS-CoV-2 nucleocapsid protein N-terminal and C-terminal RNA binding domains in preventing and/or treating COVID-19 using in silico tools. Druglikeness and toxicity profiles of the compounds were carried out to check the therapeutic application of the components. Additionally, molecular dynamics (MD) simulation was performed to check the stability of ligand-protein complexes. The results provided useful insights into the structural binding interaction(s) that can be exploited for the further development of potential antiviral agents targeting SARS-CoV-2 especially since no specific therapy is still available to combat the rapidly evolving virus and the existing treatment is more or less symptomatic which makes search for novel antiviral agents all the more necessary and crucial.

Interaction of Bioactive Compounds of Moringa oleifera Leaves with SARS-CoV-2 Proteins to Combat COVID-19 Pathogenesis: a Phytochemical and In Silico Analysis.

Novel SARS-CoV-2 claimed a large number of human lives. The main proteins for viral entry into host cells are SARS-CoV-2 spike glycoprotein (PDB ID: 6VYB) and spike receptor-binding domain bound with ACE2 (spike RBD-ACE2; PDB ID: 6M0J). Currently, specific therapies are lacking globally. This study was designed to investigate the bioactive components from Moringa oleifera leaf (MOL) extract by gas chromatography-mass spectroscopy (GC-MS) and their binding interactions with spike glycoprotein and spike RBD-ACE2 protein through computational analysis. GC-MS-based analysis unveiled the presence of thirty-seven bioactive components in MOL extract, viz. polyphenols, fatty acids, terpenes/triterpenes, phytosterols/steroids, and aliphatic hydrocarbons. These bioactive phytoconstituents showed potential binding with SARS-CoV-2 spike glycoprotein and spike RBD-ACE2 protein through the AutoDock 4.2 tool. Further by using AutoDock 4.2 and AutoDock Vina, the top sixteen hits (binding energy ≥ - 6.0 kcal/mol) were selected, and these might be considered as active biomolecules. Moreover, molecular dynamics simulation was determined by the Desmond module. Interestingly two biomolecules, namely ß-tocopherol with spike glycoprotein and ß-sitosterol with spike RBD-ACE2, displayed the best interacting complexes and low deviations during 100-ns simulation, implying their strong stability and compactness. Remarkably, both ß-tocopherol and ß-sitosterol also showed the drug- likeness with no predicted toxicity. In conclusion, these findings suggested that both compounds ß-tocopherol and ß-sitosterol may be developed as anti-SARS-CoV-2 drugs. The current findings of in silico approach need to be optimized using in vitro and clinical studies to prove the effectiveness of phytomolecules against SARS-CoV-2.

Unmodified household coffee maker assisted extraction and purification of anticancer agents from Dillenia indica fruits.

Bioassay targeted, 80% aqueous ethanol crude extract of the fruits of Dillenia indica Linn, using the unmodified household coffee maker, afforded five compounds, namely betulinic acid (1), rhamnazin (2), dillenetin (3), luteolin-7-O-ß-D-glucoside (4) and hypolaetin-8-O-ß-D-glucoside (5). The crude extract, fractions and purified compounds were tested against MDA MB-231, A549 and HeLa cancer cell lines by MTT assay, using betulinic acid 1, as a positive control. Compound 3 showed the best activity against A549 (IC50 = 26.60 ± 2.5 µM) and HeLa cancer cell lines (IC50 =19.35 ± 0.9 µM), whereas compound 5 was found to show the best activity against MDA MB-231 (IC50 = 34.62 ± 5.2µM) cancer cell line. These highly potent anticancer compounds obtained from the fruits of D. indica may be suitable for herbal drug development and formulations.