Natural Products as a Potential Source of Promising Therapeutics for COVID-19 and Viral Diseases

Antileishmanial, antitrypanosomal and anti-coronavirus activities of benzophenanthridine alkaloids and other specialized metabolites isolated from the root bark of Zanthoxylum zanthoxyloides (Lam.) B.Zepernick & Timler

Strong antileishmanial and antitrypanosomal activities were highlighted for the crude methanolic extract (IC50 = 0.61 and 2.15 μg/mL, respectively) of Zanthoxylum zanthoxyloides (Lam.) B.Zepernick & Timler root bark, as well as for its apolar partitions (cyclohexane: IC50 = 0.66 and 5.17 μg/mL, respectively and dichloromethane: IC50 = 0.07 and 0.22 μg/mL, respectively), with a good selectivity index (SI) towards WI-38 cells. In addition, cyclohexane and dichloromethane extracts exhibited a dose-dependent inhibition of human coronavirus HCoV-229E infection in hepatoma Huh-7 cells expressing or not the cellular protease TMPRSS2 (IC50 values of 5.29 μg/mL and 4.87 μg/mL, respectively). Fractionation of these active extracts led to the isolation of a new racemic benzophenanthridine alkaloid named zanthoxyloithrine (1), together with 13 known compounds. Their structures were elucidated by spectroscopic techniques including IR, UV, HR-MS, 1D and 2D NMR and electronic circular dichroism. In parallel, HR-ESI-MS/MS based dereplication and molecular networking analysis were performed to identify unpurified compounds in cyclohexane and dichloromethane extracts. Zanthoxyloithrine (1) showed strong antileishmanial (IC50 = 0.14 μM, SI = 52.0) and antitrypanosomal (IC50 = 0.36 μM, SI = 20.8) activities. In addition, compound (1) demonstrated a high antiviral activity against HCoV-229E with IC50 value of 6.70 μM in presence of TMPRRS2 and without significant toxicity on Huh-7 cells. Other purified benzo[c]phenanthridine alkaloids also showed anti-coronavirus and antiparasitic activities.

Antibacterial and anti-coronavirus investigation of selected Senegalese plant species according to an ethnobotanical survey

ETHNOPHARMACOLOGICAL RELEVANCE

In Senegal, upper and lower respiratory tract infections constitute a real health problem. To manage these disorders, most people rely on the use of local medicinal plants. This is particularly the case for species belonging to the botanical families, Combretaceae, Fabaceae, Myrtaceae and Rubiaceae, which are widely used to treat various respiratory problems such as colds, flu, rhinitis, sinusitis, otitis, angina, bronchitis, bronchiolitis and also pneumonia.

AIM OF THE STUDY

The aim of this study was to identify medicinal plants traditionally used for the management of infectious diseases, in particular those of the respiratory tract. On the basis of these ethnopharmacological uses, this study made it possible to highlight the antibacterial, antiviral and cytotoxic activities of selected plant species.

MATERIALS AND METHODS

An ethnobotanical survey was conducted in Senegal among informants, including herbalists, traditional healers, and households, using medicinal plants in the management of infectious diseases, with a focus on respiratory tract infections. The most cited plant species were evaluated in vitro on a panel of 18 human pathogenic bacteria may be involved in respiratory infections and against the human coronavirus HCoV-229E in Huh-7 cells. The antiviral activity of the most active extracts against HCoV-229E was also evaluated on COVID-19 causing agent, SARS-CoV-2 in Vero-81 cells. In parallel, cytotoxic activities were evaluated on Huh-7 cells.

RESULTS

A total of 127 informants, including 100 men (78.74%) and 27 women (21.26%) participated in this study. The ethnobotanical survey led to the inventory of 41 plant species belonging to 19 botanical families used by herbalists and/or traditional healers and some households to treat infectious diseases, with a specific focus on upper respiratory tract disorders. Among the 41 plant species, the most frequently mentioned in the survey were Guiera senegalensis J.F. Gmel. (95.2%), Combretum glutinosum Perr. Ex DC. (93.9%) and Eucalyptus spp. (82.8%). Combretaceae (30.2%) represented the most cited botanical family with six species, followed by Fabaceae (29.3%, 12 species). A total of 33 crude methanolic extracts of the 24 plant species selected for their number of citations were evaluated in vitro for their antimicrobial and cytotoxic activities. Guiera senegalensis, Combretum glutinosum, Vachellia nilotica subsp. tomentosa (Benth.) Kyal. & Boatwr, Eucalyptus camaldulensis Dehnh., and Terminalia avicennioides Guill. & Perr., showed antibacterial activities. The most active plants against HCoV-229E were: Ficus sycomorus L., Mitragyna inermis (Willd.) Kuntze, Pterocarpus erinaceus Poir., and Spermacoce verticillata L. One of these plants, Mitragyna inermis, was also active against SARS-CoV-2.

CONCLUSION

This work confirmed the anti-infective properties of plant species traditionally used in Senegal. Overall, the most frequently cited plant species showed the best antibacterial activities. Moreover, some of the selected plant species could be considered as a potential source for the management of coronavirus infections. This new scientific data justified the use of these plants in the management of some infectious pathologies, especially those of the respiratory tract.

Herbal-based therapeutics for diabetic patients with SARS-Cov-2 infection

Human SARS Coronavirus-2 (SARS-CoV-2) has infected more than 170 million people worldwide, being responsible for about 3.5 million deaths so far. Despite ongoing investigations, there is still more to understand the mechanism of COVID-19 infection completely. However, it has been evidenced that SARS-CoV-2 can cause Coronavirus disease (COVID-19) notably in diabetic people. Approximately 35% of the patients who died of this disease had diabetes. A growing number of studies have evidenced that hyperglycemia is a significant risk factor for severe SARS-CoV-2 infection and plays a key role in COVID-19 mortality and diabetes comorbidity. The uncontrolled hyperglycemia can produce low-grade inflammation and impaired immunity-mediated cytokine storm that fail multiple organs and sudden death in diabetic patients with SARS-CoV-2 infection. More importantly, SARS-CoV-2 infection and interaction with ACE2 receptors also contribute to pancreatic and metabolic impairment. Thus, using of diabetes medications has been suggested to be beneficial in the better management of diabetic COVID-19 patients. Herbal treatments, as safe and affordable therapeutic agents, have recently attracted a lot of attention in this field. Accordingly, in this review, we intend to have a deep look into the molecular mechanisms of diabetic complications in SARS-CoV-2 infection and explore the therapeutic potentials of herbal medications and natural products in the management of diabetic COVID-19 patients based on recent studies and the existing clinical evidence.

Phytoconstituents as potential therapeutic agents against COVID-19: a computational study on inhibition of SARS-CoV-2 main protease

The Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) has become a global health crisis, and the urgent need for effective treatments is evident. One potential target for COVID-19 therapeutics is the main protease (Mpro) of SARS‑CoV‑2, an essential enzyme for viral replication. Natural compounds have been explored as a source of potential inhibitors for Mpro due to their safety and availability. In this study, we employed a computational approach to screen a library of phytoconstituents and identified potential Mpro inhibitors based on their binding affinities and molecular interactions. The top-ranking compounds were further validated through molecular dynamics simulations (MDS) and free energy calculations. As a result of the above procedures, we identified two phytoconstituents, Khelmarin B and Neogitogenin, with appreciable binding affinity and specificity towards the Mpro binding pocket. Our results suggest that Khelmarin B and Neogitogenin could potentially serve as Mpro inhibitors and have the potential to be developed as COVID-19 therapeutics. Further experimental studies are required to confirm the efficacy and safety of these compounds.Communicated by Ramaswamy H. Sarma.