The Natural Products Withaferin A and Withanone from the Medicinal Herb Withania somnifera Are Covalent Inhibitors of the SARS-CoV-2 Main Protease

Chemoproteomics reveals proteome-wide covalent and non-covalent targets of withaferin A

Withaferin A (WA), a natural product used in traditional medicine, has recently garnered attention because of its diverse pharmacological effects. However, the direct targets responsible for these effects remain elusive. The discovery of targets is usually serendipitous and research has predominantly concentrated on covalent interactions, overlooking non-covalent targets. The unbiased and proteome-wide mapping of WA-interacting proteins in living cells remains largely unexplored. We have developed a chemical proteomics platform that enabled profiling of the covalent/non-covalent interactome and target occupancy in disease-related cells, which was used to reveal the landscape of the targets of WA in triple-negative breast cancer (TNBC) cells. Analysis of the discovered high-occupancy targets suggested that WA was substantially involved in the RNA metabolism pathway, in addition to other biological processes. Moreover, we biochemically validated a selection of previously unknown high-occupancy targets from various important biological pathways, including the non-covalent target MVK and covalent targets HNRNPF and CKAP4, which all play critical roles in TNBC. Collectively, these findings provided a target map for comprehensive understanding of the anti-TNBC activity of WA, and present WA-targetable proteins as new avenues for pharmacological intervention in TNBC. We anticipate that this platform will be applicable for the unbiased profiling of the targets of WA in various other disease-related cell models, as well as for other bioactive electrophilic natural products in different pathophysiological systems.

Bioactive withanolides from the leaves of Athenaea velutina (Sendtn.) D'Arcy

Withanolides are a substantial bio-diverse group of naturally occurring steroidal lactones. Herein, ten still undescribed withanolides (1-10), along with the knowns withaferin A (11), 2,3-dihidrowithaferin A (12), and two other non-withanolides, vomifoliol (13) and the N-trans-p-coumaroyltyramine (14), were isolated from the hexane/EtOAc 1:1 leaf extract of Athenaea velutina (Sendtn.) D'Arcy (Solanaceae). The structures of the undescribed withanolides were elucidated by an extensive analysis of their spectroscopic data: 1D and 2D NMR, HRESIMS, single-crystal X-ray diffraction, and ECD calculations. The antiproliferative properties of the withanolides were evaluated against the human cancer cell lines: central nervous system (SNB-19), prostate (PC-3), colon (HCT-116), and leukemia (HL-60), and a murine fibroblast-like cell (L-929). Withanolides 15-17, isolated from the same plant in a previous work, were included for the pharmacological tests. Compounds 15 and 16 exhibited cytotoxic activity for all cancer cells, while 2 was selectively more cytotoxic to HL-60 cells. In addition, the withanolides were evaluated in guinea pig cardiac tissues. Compounds 15 and 16 showed cardiotonic activity, devoid of a positive chronotropic effect which is a good pharmacological profile for an inotrope agent.

Preclinical pharmacokinetics, absolute bioavailability and dose proportionality evaluation of bioactive phytochemical Withanone in rats

Withanone (WN), a bioactive phytochemical isolated from the medicinal herb Withania somnifera, has shown multiple pharmacological and therapeutic successes, including neuroprotective and anti-cancer activities. However, detailed pharmacokinetic (PK) properties of pure WN were not well defined. Pharmacokinetic (PK) characteristics, dose proportionality, and absolute bioavailability of pure WN were explored in rats using an efficient, reliable, and sensitive LC-MS/MS assay to address this gap. The method shows excellent linearity over 0.5-500 ng/mL (r2 ≥ 0.99), is accurate, and requires less analysis time. A dose proportionality and absolute bioavailability of pure WN were determined in Sprague-Dawley (SD) rats through three ascending oral (10, 20, and 40 mg/kg) and single intravenous (5 mg/kg) PK studies. The peak concentration (Cmax) of WN was 60.53 ± 20.33, 116.30 ± 16.89, and 91.62 ± 6.20 ng/mL, corresponding to oral dosage of 10, 20, and 40 mg/kg, respectively. WN shows poor systemic exposure upon oral administration, leading to low oral bioavailability (<15 %). Additionally, the dose proportionality studies of WN revealed its saturable bioavailability and non-proportional systemic exposure over the dosage range of 10-40 mg/kg in rats. The obtained PK findings of this study would be valuable for better understanding the pharmacological effects of WN, dose regimen optimization for future studies, and relevance for clinical reference to support its future development as a potential therapeutic molecule.

Withaferin A inhibits Chikungunya virus nsP2 protease and shows antiviral activity in the cell culture and mouse model of virus infection

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus causing fever, myalgia, and debilitating joint swelling and pain, which in many patients becomes chronic. The frequent epidemics of CHIKV across the world pose a significant public health burden necessitating the development of effective antiviral therapeutics. A cellular imaging-based high-content screening of natural compounds identified withaferin A (WFA), a steroidal lactone isolated from the plant Withania somnifera, as a potent antiviral against CHIKV. In the ERMS cells, WFA inhibited CHIKV replication early during the life cycle by binding the CHIKV non-structural protein nsP2 and inhibiting its protease activity. This inhibited the viral polyprotein processing and the minus-sense viral RNA synthesis. WFA mounted the nsP2 protease inhibitory activity through its oxidising property as the reducing agents N-acetylcysteine and Glutathione-monoethyl ester effectively reversed the WFA-mediated protease inhibition in vitro and abolished the WFA-mediated antiviral activity in cultured cells. WFA inhibited CHIKV replication in the C57BL/6 mouse model of chikungunya disease, resulting in significantly lower viremia. Importantly, CHIKV-infected mice showed significant joint swelling which was not seen in WFA-treated mice. These data demonstrate the potential of WFA as a novel CHIKV antiviral.

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.

How many organic small molecules might be used to treat COVID-19? From natural products to synthetic agents

A large scale of pandemic coronavirus disease (COVID-19) in the past five years motivates a great deal of endeavors donating to the exploration on therapeutic drugs against COVID-19 as well as other diseases caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein is an overview on the organic small molecules that are potentially employed to treat COVID-19 and other SARS-CoV-2-related diseases. These organic small molecules are accessed from both natural resources and synthetic strategies. Notably, typical natural products presented herein consist of polyphenols, lignans, alkaloids, terpenoids, and peptides, which exert an advantage for the further discovery of novel anti-COVID-19 drugs from plant herbs. On the other hand, synthetic prodrugs are composed of a series of inhibitors towards RNA-dependent RNA polymerase (RdRp), main protease (Mpro), 3-chymotrypsin-like cysteine protease (3CLpro), spike protein, papain-like protease (PLpro) of the SARS-CoV-2 as well as the angiotensin-converting enzyme 2 (ACE2) in the host cells. Synthetic strategies are worth taken into consideration because they are beneficial for designing novel anti-COVID-19 drugs in the coming investigations. Although examples collected herein are just a drop in the bucket, developments of organic small molecules against coronavirus infections are believed to pave a promising way for the discovery of multi-targeted therapeutic drugs against not only COVID-19 but also other virus-mediated diseases.

Progress in Research on Inhibitors Targeting SARS-CoV-2 Main Protease (Mpro)

Since 2019, the novel coronavirus (SARS-CoV-2) has caused significant morbidity and millions of deaths worldwide. The Coronavirus Disease 2019 (COVID-19), caused by SARS-CoV-2 and its variants, has further highlighted the urgent need for the development of effective therapeutic agents. Currently, the highly conserved and broad-spectrum nature of main proteases (Mpro) renders them of great importance in the field of inhibitor study. In this study, we categorize inhibitors targeting Mpro into three major groups: mimetic, nonmimetic, and natural inhibitors. We then present the research progress of these inhibitors in detail, including their mechanism of action, antiviral activity, pharmacokinetic properties, animal experiments, and clinical studies. This review aims to provide valuable insights and potential avenues for the development of more effective antiviral drugs against SARS-CoV-2.

Covalent binding of withanolides to cysteines of protein targets

Withanolides represent an important category of natural products with a steroidal lactone core. Many of them contain an α,β-unsaturated carbonyl moiety with a high reactivity toward sulfhydryl groups, including protein cysteine thiols. Different withanolides endowed with marked antitumor and anti-inflammatory have been shown to form stable covalent complexes with exposed cysteines present in the active site of oncogenic kinases (BTK, IKKβ, Zap70), metabolism enzymes (Prdx-1/6, Pin1, PHGDH), transcription factors (Nrf2, NFκB, C/EBPβ) and other structural and signaling molecules (GFAP, β-tubulin, p97, Hsp90, vimentin, Mpro, IPO5, NEMO, …). The present review analyzed the covalent complexes formed through Michael addition alkylation reactions between six major withanolides (withaferin A, physalin A, withangulatin A, 4β-hydroxywithanolide E, withanone and tubocapsanolide A) and key cysteine residues of about 20 proteins and the resulting biological effects. The covalent conjugation of the α,β-unsaturated carbonyl system of withanolides with reactive protein thiols can occur with a large set of soluble and membrane proteins. It points to a general mechanism, well described with the leading natural product withaferin A, but likely valid for most withanolides harboring a reactive (electrophilic) enone moiety susceptible to react covalently with cysteinyl residues of proteins. The multiplicity of reactive proteins should be taken into account when studying the mechanism of action of new withanolides. Proteomic and network analyses shall be implemented to capture and compare the cysteine covalent-binding map for the major withanolides, so as to identify the protein targets at the origin of their activity and/or unwanted effects. Screening of the cysteinome will help understanding the mechanism of action and designing cysteine-reactive electrophilic drug candidates.

Divergent synthesis of complex withanolides enabled by a scalable route and late-stage functionalization

Withanolides are a group of naturally occurring C28 steroids based on an ergostane skeleton. They have a high degree of polyoxygenation, and the abundance of O-functional groups has enabled various natural alterations to both the carbocyclic skeleton and the side chain. Consequently, these molecules have intricate structural features that lead to their highly varied display of biological activities including anticancer, anti-inflammatory, and immunomodulating properties. Despite being intriguing leads for further discovery research, synthetic access to the withanolides remains highly challenging-compounds for current biological research are mainly isolated from plants, often inefficiently. Here, we report the divergent synthesis of 11 withanolides in 12 to 20 steps, enabled by a gram-scale route and a series of late-stage functionalizations, most notably a bioinspired photooxygenation-allylic hydroperoxide rearrangement sequence. This approach enables further biological research disconnected from a reliance on minute quantities of the parent natural products or their simple derivatives.

Unraveling antiviral efficacy of multifunctional immunomodulatory triterpenoids against SARS-COV-2 targeting main protease and papain-like protease

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be over, but its variants continue to emerge, and patients with mild symptoms having long COVID is still under investigation. SARS-CoV-2 infection leading to elevated cytokine levels and suppressed immune responses set off cytokine storm, fatal systemic inflammation, tissue damage, and multi-organ failure. Thus, drug molecules targeting the SARS-CoV-2 virus-specific proteins or capable of suppressing the host inflammatory responses to viral infection would provide an effective antiviral therapy against emerging variants of concern. Evolutionarily conserved papain-like protease (PLpro) and main protease (Mpro) play an indispensable role in the virus life cycle and immune evasion. Direct-acting antivirals targeting both these viral proteases represent an attractive antiviral strategy that is also expected to reduce viral inflammation. The present study has evaluated the antiviral and anti-inflammatory potential of natural triterpenoids: azadirachtin, withanolide_A, and isoginkgetin. These molecules inhibit the Mpro and PLpro proteolytic activities with half-maximal inhibitory concentrations (IC50) values ranging from 1.42 to 32.7 μM. Isothermal titration calorimetry (ITC) analysis validated the binding of these compounds to Mpro and PLpro. As expected, the two compounds, withanolide_A and azadirachtin, exhibit potent anti-SARS-CoV-2 activity in cell-based assays, with half-maximum effective concentration (EC50) values of 21.73 and 31.19 μM, respectively. The anti-inflammatory roles of azadirachtin and withanolide_A when assessed using HEK293T cells, were found to significantly reduce the levels of CXCL10, TNFα, IL6, and IL8 cytokines, which are elevated in severe cases of COVID-19. Interestingly, azadirachtin and withanolide_A were also found to rescue the decreased type-I interferon response (IFN-α1). The results of this study clearly highlight the role of triterpenoids as effective antiviral molecules that target SARS-CoV-2-specific enzymes and also host immune pathways involved in virus-mediated inflammation.

Unraveling antiviral efficacy of multifunctional immunomodulatory triterpenoids against SARS‐COV‐2 targeting main protease and papain‐like protease

The coronavirus disease 2019 (COVID‐19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) may be over, but its variants continue to emerge, and patients with mild symptoms having long COVID is still under investigation. SARS‐CoV‐2 infection leading to elevated cytokine levels and suppressed immune responses set off cytokine storm, fatal systemic inflammation, tissue damage, and multi‐organ failure. Thus, drug molecules targeting the SARS‐CoV‐2 virus‐specific proteins or capable of suppressing the host inflammatory responses to viral infection would provide an effective antiviral therapy against emerging variants of concern. Evolutionarily conserved papain‐like protease (PLpro) and main protease (Mpro) play an indispensable role in the virus life cycle and immune evasion. Direct‐acting antivirals targeting both these viral proteases represent an attractive antiviral strategy that is also expected to reduce viral inflammation. The present study has evaluated the antiviral and anti‐inflammatory potential of natural triterpenoids: azadirachtin, withanolide_A, and isoginkgetin. These molecules inhibit the Mpro and PLpro proteolytic activities with half‐maximal inhibitory concentrations (IC50) values ranging from 1.42 to 32.7 μM. Isothermal titration calorimetry (ITC) analysis validated the binding of these compounds to Mpro and PLpro. As expected, the two compounds, withanolide_A and azadirachtin, exhibit potent anti‐SARS‐CoV‐2 activity in cell‐based assays, with half‐maximum effective concentration (EC50) values of 21.73 and 31.19 μM, respectively. The anti‐inflammatory roles of azadirachtin and withanolide_A when assessed using HEK293T cells, were found to significantly reduce the levels of CXCL10, TNFα, IL6, and IL8 cytokines, which are elevated in severe cases of COVID‐19. Interestingly, azadirachtin and withanolide_A were also found to rescue the decreased type‐I interferon response (IFN‐α1). The results of this study clearly highlight the role of triterpenoids as effective antiviral molecules that target SARS‐CoV‐2‐specific enzymes and also host immune pathways involved in virus‐mediated inflammation.

Structure-Based Discovery of the SARS-CoV-2 Main Protease Noncovalent Inhibitors from Traditional Chinese Medicine

Traditional Chinese medicine (TCM) has been extensively employed for the treatment of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, there is demand for discovering more SARS-CoV-2 Mpro inhibitors with diverse scaffolds to optimize anti-SARS-CoV-2 lead compounds. In this study, comprehensive in silico and in vitro assays were utilized to determine the potential inhibitors from TCM compounds against SARS-CoV-2 Mpro, which is an important therapeutic target for SARS-CoV-2. The ensemble docking analysis of 18263 TCM compounds against 15 SARS-CoV-2 Mpro conformations identified 19 TCM compounds as promising candidates. Further in vitro testing validated three compounds as inhibitors of SARS-CoV-2 Mpro and showed IC50 values of 4.64 ± 0.11, 7.56 ± 0.78, and 11.16 ± 0.26 μM, with EC50 values of 12.25 ± 1.68, 15.58 ± 0.77, and 29.32 ± 1.25 μM, respectively. Molecular dynamics (MD) simulations indicated that the three complexes remained stable over the last 100 ns of production run. An analysis of the binding mode revealed that the active compounds occupy different subsites (S1, S2, S3, and S4) of the active site of SARS-CoV-2 Mpro via specific poses through noncovalent interactions with key amino acids (e.g., HIS 41, ASN 142, GLY 143, MET 165, GLU 166, or GLN 189). Overall, this study provides evidence indicating that the three natural products obtained from TCM could be further used for anti-COVID-19 research, justifying the investigation of Chinese herbal medicinal ingredients as bioactive constituents for therapeutic targets.

Molecular networking unveils anti-SARS-CoV-2 constituents from traditionally used remedies

ETHNOPHARMACOLOGICAL RELEVANCE

Plants and fungi have a long tradition in ethnopharmacology for the treatment of infectious diseases including viruses. Many of these natural products have also been used to combat SARS-CoV-2 infections or symptoms of the post- and long-COVID form, owing to the scarcity of clinically approved therapeutics.

AIM OF THE STUDY

The ongoing threat posed by SARS-CoV-2, along with the rapidly evolving new variants, requires the development of new antiviral compounds. The aim of this study was to identify anti-SARS-CoV-2 herbal and fungal extracts used in traditional medicine against acute respiratory infection, inflammation, and related symptoms. Additionally, we sought to characterize their bioactive constituents.

MATERIALS AND METHODS

The antiviral activity and cell cytotoxicity of 179 herbal and fungal extracts were evaluated using two SARS-CoV-2 infection assays in Caco-2 cells. 19 plant extracts with and without anti-SARS-CoV-2 activity underwent detailed dereplication using molecular networking.

RESULTS

Extracts from Angelica sinensis (Oliv.) Diels roots, Annona squamosa L. seeds, Azadirachta indica A. Juss. fruits, Buddleja officinalis Maxim. flowers, Burkea africana Hook. bark and Clinopodium menthifolium (Host) Stace aerial parts showed a potent anti SARS-CoV-2 activity (IC50 < 5 μg/ml) with only moderate cytotoxicity (CC50 > 60 μg/ml, Caco-2). By performing the dereplication with a bioactivity-featured molecular network (MN) on the extract library level, rather than on the level of individual extracts, we could pinpoint compounds characteristic for active extracts. Thus, a straight-forward identification of potential anti-SARS-CoV-2 natural compounds was achieved prior to any fractionation or isolation efforts.

CONCLUSIONS

A sophisticated hyphenation of empirical knowledge with MS-based bioinformatics and automated compound annotation was applied to decipher the chemical space of the investigated extracts. The correlation with experimentally assessed anti-SARS-CoV-2 activities helped in predicting compound classes and structural elements relevant for the antiviral activities. Consequently, this accelerated the identification of constituents from the investigated mixtures with inhibitory effects against SARS-CoV-2.

Withaferin A Inhibits Liver Cancer Tumorigenesis by Suppressing Aerobic Glycolysis through the p53/IDH1/HIF-1α Signaling Axis

BACKGROUND

The energy supply of certain cancer cells depends on aerobic glycolysis rather than oxidative phosphorylation. Our previous studies have shown that withaferin A (WA), a lactone compound derived from Withania somnifera, suppresses skin carcinogenesis at least partially by stabilizing IDH1 and promoting oxidative phosphorylation. Here, we have extended our studies to evaluate the anti-tumor effect of WA in liver cancer.

METHODS

Differential expression of glycolysis-related genes between liver cancer tissues and normal tissues and prognosis were verified using an online database. Glycolysis-related protein expression was detected using western blot after overexpression and knockdown of IDH1 and mitochondrial membrane potential assay based on JC-1, and mitochondrial complex I activity was also detected. The inhibitory effect of WA on the biological functions of HepG2 cells was detected along with cell viability using MTT assay, scratch assay, clone formation assay, glucose consumption and lactate production assay. Western blot and qRT-PCR were used to detect the expression of proteins and genes related to IDH1, p53 and HIF1α signaling pathways.

RESULTS

We first identified that IDH1 expression was downregulated in human liver cancer cells compared to normal liver cells. Next, we found that treatment of HepG2 cells with WA resulted in significantly increased protein levels of IDH1, accompanied by decreased levels of several glycolytic enzymes. Furthermore, we found that WA stabilized IDH1 proteins by inhibiting the degradation by the proteasome. The tumor suppressor p53 was also upregulated by WA treatment, which played a critical role in the upregulation of IDH1 and downregulation of the glycolysis-related genes. Under hypoxic conditions, glycolysis-related genes were induced, which was suppressed by WA treatment, and IDH1 expression was still maintained at higher levels under hypoxia.

CONCLUSION

Taken together, our results indicated that WA suppresses liver cancer tumorigenesis by p53-mediated IDH1 upregulation, which promotes mitochondrial respiration, thereby inhibiting the HIF-1α pathway and blocking aerobic glycolysis.

Can Ashwagandha Benefit the Endocrine System?-A Review

Withania somnifera, also known as Ashwagandha, has been used in traditional medicine for thousands of years. Due to the wide range of its activities, there has been interest in its possible beneficial effects on the human body. It is proved that, among others, Ashwagandha has anti-stress, anti-inflammatory, antimicrobial, anti-cancer, anti-diabetic, anti-obesity, cardioprotective, and hypolipidemic properties. Particularly interesting are its properties reported in the field of psychiatry and neurology: in Alzheimer's disease, Parkinson's disease, multiple sclerosis, depression, bipolar disorder, insomnia, anxiety disorders and many others. The aim of this review is to find and summarize the effect that Ashwagandha root extract has on the endocrine system and hormones. The multitude of active substances and the wide hormonal problems faced by modern society sparked our interest in the topic of Ashwagandha's impact on this system. In this work, we also attempted to draw conclusions as to whether W. somnifera can help normalize the functions of the human endocrine system in the future. The search mainly included research published in the years 2010-2023. The results of the research show that Ashwagandha can have a positive effect on the functioning of the endocrine system, including improving the secretory function of the thyroid gland, normalizing adrenal activity, and multidirectional improvement on functioning of the reproductive system. The main mechanism of action in the latter appears to be based on the hypothalamus-pituitary-adrenal (HPA) axis, as a decrease in cortisol levels and an increase in hormones such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in men were found, which results in stress level reduction and improvement in fertility. In turn, other studies prove that active substances from W. somnifera, acting on the body, cause an increase in the secretion of triiodothyronine (T3) and thyroxine (T4) by the thyroid gland and a subsequent decrease in the level of thyroid-stimulating hormone (TSH) in accordance with the hypothalamus-pituitary-thyroid (HPT) axis. In light of these findings, it is clear that Ashwagandha holds significant promise as a natural remedy for various health concerns, especially those related to the endocrine system. Future research may provide new insights into its mechanisms of action and expand its applications in both traditional and modern medicine. The safety and toxicity of Ashwagandha also remain important issues, which may affect its potential use in specific patient groups.

Effective inhibition of HCoV-OC43 and SARS-CoV-2 by phytochemicals in vitro and in vivo

OBJECTIVE

Several coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and human coronavirus OC43 (HCoV-OC43), can cause respiratory infections in humans. To address the need for reliable anti-coronavirus therapeutics, we screened 16 active phytochemicals selected from medicinal plants used in traditional applications for respiratory-related illnesses.

METHODS

An initial screen was completed using HCoV-OC43 to identify compounds that inhibit virus-induced cytopathic effect (CPE) and cell death inhibition. Then the top hits were validated in vitro against both HCoV-OC43 and SARS-CoV-2 by determining virus titer in cell supernatant and virus-induced cell death. Finally, the most active phytochemical was validated in vivo in the SARS-CoV-2-infected B6.Cg-Tg(K18-ACE2)2Prlmn/J mouse model.

RESULTS

The phytochemicals lycorine (LYC), capsaicin, rottlerin (RTL), piperine and chebulinic acid (CHU) inhibited HCoV-OC43-induced cytopathic effect and reduced viral titres by up to 4 log. LYC, RTL and CHU also suppressed virus replication and cell death following SARS-CoV-2 infection. In vivo, RTL significantly reduced SARS-CoV-2-induced mortality by ∼40% in human angiotensin-converting enzyme 2 (ACE2)-expressing K18 mice.

CONCLUSION

Collectively, these studies indicate that RTL and other phytochemicals have therapeutic potential to reduce SARS-CoV-2 and HCoV-OC43 infections.

The aqueous root extract of Withania somnifera ameliorates LPS-induced inflammatory changes in the in vitro cell-based and mice models of inflammation

Introduction: Most critically ill COVID-19 patients have bronchitis, pneumonia, and acute respiratory distress syndrome (ARDS) due to excessive inflammatory conditions. Corticosteroids have largely been prescribed for the management of inflammation in these patients. However, long-term use of corticosteroids in patients with comorbidities such as metabolic, cardiovascular, and other inflammatory disorders is ideally not recommended due to safety issues. A potential and safer anti-inflammatory therapy is therefore the need of the hour. Withania somnifera (WS), a well-known herbal medicine used during the pandemic in India to prevent SARS-CoV2 infection, also possesses anti-inflammatory properties. Methods: In the present study, we, therefore, evaluated the effect of the aqueous extract of the roots of W. somnifera in the cell-based assays and in the experimental animal models of LPS-induced inflammation. Results: In the NCI-H460, A549 cells and human peripheral blood mononuclear cells (PBMCs) pre-treatment with W. somnifera reduced the LPS-induced expression of the pro-inflammatory cytokines. In addition, W. somnifera extract also showed potent anti-inflammatory activity in the lung tissues of BALB/c mice challenged intranasally with LPS. We observed a marked reduction in the neutrophil counts in the broncho-alveolar lavage (BAL) fluid, inflammatory cytokines, and fibrosis in the mice lungs pre-treated with W. somnifera. Results obtained thus suggest the potential utility of W. somnifera extract in reducing airway inflammation and recommend the clinical evaluation of W. somnifera extract in COVID-19 patients with a high propensity for lung inflammation.

Phytochemicals of Withania somnifera as a Future Promising Drug against SARS-CoV-2: Pharmacological Role, Molecular Mechanism, Molecular Docking Evaluation, and Efficient Delivery

Coronavirus disease (COVID-19) has killed millions of people since first reported in Wuhan, China, in December 2019. Intriguingly, Withania somnifera (WS) has shown promising antiviral effects against numerous viral infections, including SARS-CoV and SARS-CoV-2, which are contributed by its phytochemicals. This review focused on the updated testing of therapeutic efficacy and associated molecular mechanisms of WS extracts and their phytochemicals against SARS-CoV-2 infection in preclinical and clinical studies with the aim to develop a long-term solution against COVID-19. It also deciphered the current use of the in silico molecular docking approach in developing potential inhibitors from WS targeting SARS-CoV-2 and host cell receptors that may aid the development of targeted therapy against SARS-CoV-2 ranging from prior to viral entry until acute respiratory distress syndrome (ARDS). This review also discussed nanoformulations or nanocarriers in achieving effective WS delivery to enhance its bioavailability and therapeutic efficacy, consequently preventing the emergence of drug resistance, and eventually therapeutic failure.

The immunomodulatory role of withania somnifera (L.) dunal in inflammatory diseases

Withania somnifera (L.) Dunal (Solanaceae) (also known as Ashwagandha) is a botanical drug that has been used for centuries to treat many chronic diseases like high blood pressure, arthritis, diabetes, Alzheimer's disease, and depression. As many botanical drugs, w. Somnifera possesses anti-inflammatory, antioxidant, anticarinogenic, anti-diabetic, and anti-asthmatic properties. W. somnifera is often compared to the ginseng plant due to its ability to reduce stress, improve cognitive functions (e.g., memory), and promote a healthy immune system. It promotes immunomodulatory effects whose function is to balance the humoral and cellular responses of the adaptive immune system. The therapeutic effect of w. Somnifera is attributed to active ingredients like alkaloids, steroidal lactones (such as withanolides, withaferins), and steroidal saponins. Although w. Somnifera is safe and highly recommended for treating various diseases, the current knowledge and understanding of its operational mechanisms are limited. One of the proposed mechanisms states that w. Somnifera promotes cellular-mediated immunity or initiates chemical interactions that contribute to therapeutic effects. Withania somnifera has been shown to play a significant role in immunological diseases by modulating several cytokines, increasing T-cell proliferation and enhancing macrophages functions. In this review, we will discuss the latest therapeutic effects of w. Somnifera on a number of diseases through modulating immunological markers and which specific components of w. Somnifera induce these therapeutic activities. We will also focus on the chemical properties in w. Somnifera components and their immunomodulatory role in type 2 allergic diseases where type 2 inflammation is highly imbalanced.