The comprehensive study on the therapeutic effects of baicalein for the treatment of COVID-19 in vivo and in vitro

Cotton flower metabolites inhibit SARS-CoV-2 main protease

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading globally for over 2 years, causing serious contagious disease and incalculable damage. The introduction of vaccines has slowed the spread of SARS-CoV-2 to some extent, but there remains a need for specific and effective treatment. The high chemical diversity and safety profiles of natural products make them a potential source of effective anti-SARS-CoV-2 drugs. Cotton plant is one of the most important economic and medical crops and is the source of a large number of antiviral phytochemicals. In this work, we used SARS-CoV-2 main protein (M^pro ) as the target to identify potential anti-SARS-CoV-2 natural products in cotton. An in vitro assay showed that of all cotton tissues examined, cotton flower extracts (CFs) exhibited optimal inhibitory effects against M^pro . We proceeded to use the CF metabolite database to screen natural M^pro inhibitors by combining virtual screening and biochemical assays. We identified that several CF natural products, including astragalin, myricitrin, and astilbin, significantly inhibited M^pro with half-maximal inhibitory concentrations (IC50s) of 0.13, 10.73, and 7.92 μm, respectively. These findings may serve as a basis for further studies into the suitability of cotton as a source of potential therapeutics for SARS-CoV-2.

Integrated network pharmacology analysis, molecular docking, LC-MS analysis and bioassays revealed the potential active ingredients and underlying mechanism of Scutellariae radix for COVID-19

Scutellariae radix ("Huang-Qin" in Chinese) is a well-known traditional herbal medicine and popular dietary supplement in the world, extensively used in prescriptions of TCMs as adjuvant treatments for coronavirus pneumonia 2019 (COVID-19) patients in China. According to the differences in its appearance, Scutellariae radix can be classified into two kinds: ZiQin (1∼3 year-old Scutellariae baicalensis with hard roots) and KuQin (more than 3 year-old S. baicalensis with withered pithy roots). In accordance with the clinical theory of TCM, KuQin is superior to ZiQin in cooling down the heat in the lung. However, the potential active ingredients and underlying mechanisms of Scutellariae radix for the treatment of COVID-19 remain largely unexplored. It is still not clear whether there is a difference in the curative effect of ZiQin and KuQin for the treatment of COVID-19. In this research, network pharmacology, LC-MS based plant metabolomics, and in vitro bioassays were integrated to explore both the potential active components and mechanism of Scutellariae radix for the treatment of COVID-19. As the results, network pharmacology combined with molecular docking analysis indicated that Scutellariae radix primarily regulates the MAPK and NF-κB signaling pathways via active components such as baicalein and scutellarin, and blocks SARS-CoV-2 spike binding to human ACE2 receptors. In vitro bioassays showed that baicalein and scutellarein exhibited more potent anti-inflammatory and anti-infectious effects than baicalin, the component with the highest content in Scutellariae radix. Moreover, baicalein inhibited SARS-CoV-2's entry into Vero E6 cells with an IC₅₀ value of 142.50 μM in a plaque formation assay. Taken together, baicalein was considered to be the most crucial active component of Scutellariae radix for the treatment of COVID-19 by integrative analysis. In addition, our bioassay study revealed that KuQin outperforms ZiQin in the treatment of COVID-19. Meanwhile, plant metabolomics revealed that baicalein was the compound with the most significant increase in KuQin compared to ZiQin, implying the primary reason for the superiority of KuQin over ZiQin in the treatment of COVID-19.

Pharmacological Potential of Flavonoids against Neurotropic Viruses

Flavonoids are a group of natural compounds that have been described in the literature as having anti-inflammatory, antioxidant, and neuroprotective compounds. Although they are considered versatile molecules, little has been discussed about their antiviral activities for neurotropic viruses. Hence, the present study aimed to investigate the pharmacological potential of flavonoids in the face of viruses that can affect the central nervous system (CNS). We carried out research from 2011 to 2021 using the Pubmed platform. The following were excluded: articles not in the English language, letters to editors, review articles and papers that did not include any experimental or clinical tests, and papers that showed antiviral activities against viruses that do not infect human beings. The inclusion criteria were in silico predictions and preclinical pharmacological studies, in vitro, in vivo and ex vivo, and clinical studies with flavonoids, flavonoid fractions and extracts that were active against neurotropic viruses. The search resulted in 205 articles that were sorted per virus type and discussed, considering the most cited antiviral activities. Our investigation shows the latest relevant data about flavonoids that have presented a wide range of actions against viruses that affect the CNS, mainly influenza, hepatitis C and others, such as the coronavirus, enterovirus, and arbovirus. Considering that these molecules present well-known anti-inflammatory and neuroprotective activities, using flavonoids that have demonstrated both neuroprotective and antiviral effects could be viewed as an alternative for therapy in the course of CNS infections.

Baicalein Induces Apoptosis of Rheumatoid Arthritis Synovial Fibroblasts through Inactivation of the PI3K/Akt/mTOR Pathway

Purpose

Rheumatoid arthritis (RA) shows abnormal proliferation, apoptosis, and invasion in fibroblast-like synoviocytes (FLSs). Baicalein (BAI), extracted from Scutellaria baicalensis, is used as an anticancer drug through inducing cancer cells apoptosis. However, the mechanism of BAI in RA progression still remains unknown. Here, we demonstrated that BAI inhibited FLS proliferation and migration, whereas it enhanced apoptosis via the PI3K/Akt/mTOR pathway in vitro.

Methods

Cell viability and colony formation were analyzed by MTT and plate colony formation assays in SW982 cells, respectively. Apoptosis was detected by flow cytometry and western blotting. Epithelial-mesenchymal transition (EMT), MMP family proteins (MMP2/9), and the PI3K/Akt/mTOR pathway were detected by western blot. Cell migration was detected by scratch healing assay under BAI treatment in SW982 cells.

Results

BAI dose-dependently inhibited cell viability and colony forming in SW982 cells. BAI upregulated apoptotic proteins and downregulated EMT-related proteins, resulting in enhanced cell apoptosis and inhibited cell migration in SW982 cells. BAI also dose-dependently inhibited the phosphorylation of PI3K, Akt, and mTOR.

Conclusions

These results indicated that BAI inhibited FLSs proliferation and EMT, whereas induced cell apoptosis through blocking the PI3K/Akt/mTOR pathway, supporting clinical application for RA progression.

HPLC method for simultaneous estimation of paclitaxel and baicalein: pharmaceutical and pharmacokinetic applications

Aim: A novel HPLC method was developed and validated for the simultaneous estimation of paclitaxel (PTX) and baicalein (BAC). Materials & methods: The analytes were resolved in a C18 column using the aqueous solution of formic acid (0.10% v/v) and MeOH (30:70 v/v). Results: The developed method was found to be linear over the concentration ranges 0.039-10 μg/ml and 0.019-10 μg/ml for PTX and BAC, respectively. The lower limits of quantification obtained were 0.042 μg/ml and 0.361 μg/ml for PTX and BAC, respectively. Conclusion: The developed method was found to be precise and accurate as per the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines, for simultaneous estimation of PTX and BAC, having an application in formulation development and bioanalytical studies.

Diterpenes of Scutellaria spp.: Phytochemistry and pharmacology

Scutellaria genus, a member of the Lamiaceae family, distributed worldwide and known as skullcaps, contains a wide range of pharmacologically active constituents including flavonoids and diterpenes. There are different classes of diterpenes in the plant kingdom, of which many have medicinal applications. Scutellaria spp. contain neo-clerodane diterpenes, a large group of naturally occurring specialized metabolites found in both plant species and in organisms from other taxonomic groups, such as fungi, bacteria, and marine sponges. Although many phytochemical studies have been established reporting interesting specialized diterpene structures from Scutellaria spp., there has not been a comprehensive study reviewing these compounds. Hence, the present review reports on natural diterpenoids from the Scutellaria genus and their pharmacological activities. For this purpose, the scientific databases including Scopus, PubMed, and Google Scholar were searched using the keywords "Scutellaria" and "Diterpenes" or "Diterpenoids". The literature review showed that up to now, more than 300 diterpenes have been isolated and reported from the Scutellaria genus, belonging to neo-clerodane scaffolds. Anticancer, antifeedant, phytotoxic, antimicrobial, and nitric oxide production inhibitory activities are the most reported properties for the diterpenoids from the Scutellaria genus. Diterpenes of Scutellaria spp. have therapeutic potentials to be used for the treatment of different diseases. Further phytochemical, pharmacological, and clinical studies are required in this regard.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia-reperfusion (I-R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I-R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

Investigation of Major Flavonoids from Artemisia argyi as a Potential COVID-19 Drug: Molecular Docking and DFT Calculations

Flavonoids from natural products are well-identified as potential antiviral agents in the treatment of SARS-CoV-2 (COVID-19) infection and related diseases. However, some major species of flavonoids from Chinese traditional folk medicine, such as of Artemisia argyi (A. argyi), have not been evaluated yet. Here, we choose five major flavonoids obtained from A. argyi, namely, Jaceosidin (1), Eupatilin (2), Apigenin (3), Eupafolin (4), and 5,6-Dihydroxy-7,3′,4′-trimethoxyflavone (5), compared to the well-studied Baicalein (6), as potential inhibitors analogs for COVID-19 by computational modeling strategies. The frontier molecular orbitals (FMOs), chemical reactivity descriptors, and electrostatic surface potential (ESP) were performed by density functional theory (DFT) calculations. Additionally, these flavonoids were docked on the main protease (PDB: 6LU7) of SARS-CoV-2 to evaluate the binding affinities. Computational analysis predicted that all of these compounds show a high affinity and might serve as potential inhibitors to SARS-CoV-2, among which compound (5) exhibits the least binding energy (−155.226 kcal/mol). The high binding affinity could be enhanced by increasing the electron repulsion due to the valence shell electron pair repulsion model (VSEPR). Consequently, the major flavonoids in Artemisia argyi have a significant ability to reduce the deterioration of COVID-19 in the terms of DFT calculations and molecular docking.

Mechanistic and therapeutic perspectives of baicalin and baicalein on pulmonary hypertension: A comprehensive review

Pulmonary hypertension (PH) is a chronic and fatal disease, for which new therapeutic drugs and approaches are needed urgently. Baicalein and baicalin, the active compounds of the traditional Chinese medicine, Scutellaria baicalensis Georgi, exhibit a wide range of pharmacological activities. Numerous studies involving in vitro and in vivo models of PH have revealed that the treatment with baicalin and baicalein may be effective. This review summarizes the potential mechanisms driving the beneficial effects of baicalin and baicalein treatment on PH, including anti-inflammatory response, inhibition of pulmonary smooth muscle cell proliferation and endothelial-to-mesenchymal transformation, stabilization of the extracellular matrix, and mitigation of oxidative stress. The pharmacokinetics of these compounds have also been reviewed. The therapeutic potential of baicalin and baicalein warrants their continued study as natural treatments for PH.

Heterologous Biosynthesis of Health-Promoting Baicalein in Lycopersicon esculentum

Baicalein is a valuable flavonoid isolated from the medicinal plant Scutellaria baicalensis Georgi, which exhibits intensive biological activities, such as anticancer and antiviral activities. However, its production is limited in the root with low yield. In this study, In-Fusion and 2A peptide linker were developed to assemble SbCLL-7, SbCHI, SbCHS-2, SbFNSII-2 and SbCYP82D1.1 genes driven by the AtPD7, CaMV 35S and AtUBQ10 promoters with HSP, E9 and NOS terminators, and were used to engineer baicalein biosynthesis in transgenic tomato plants. The genetically modified tomato plants with this construct synthesized baicalein, ranging from 150 ng/g to 558 ng/g FW (fresh weight). Baicalein-fortified tomatoes have the potential to be health-promoting fresh vegetables and provide an alternative source of baicalein production, with great prospects for market application.

Kampo Medicine Promotes Early Recovery From Coronavirus Disease 2019-Related Olfactory Dysfunction: A Retrospective Observational Study

Background: Olfactory dysfunction is a common symptom in patients with coronavirus disease 2019, and it significantly deteriorates patients’ quality of life. Effective treatments remain unknown.

Purpose: To assess the effect of Japanese traditional (Kampo) medicine on coronavirus disease 2019-related olfactory dysfunction.

Study Design: Retrospective observational study.

Methods: In total, 87 patients aged ≥18 years with coronavirus disease 2019 and severe dysosmia or anosmia (Numeric Rating Scale, ≥7) at isolation facilities in Miyagi Prefecture, Japan, were enrolled from October 2020 to March 2021. Patients were divided into the Kampo group (N = 52) and the control group (N = 35) based on the treatment received. Changes in Numeric Rating Scale scores were evaluated at the first visit and 2 weeks after.

Results: The median reduction in the olfactory dysfunction score at both 1 and 2 weeks after the first visit was significantly greater in the Kampo group (6 and 8, respectively; p = 0.03) than in the control group (3 and 7, respectively; p = 0.04). We defined improvement in olfactory dysfunction as a median reduction in the olfactory dysfunction score of ≥5. Multiple logistic regression analysis demonstrated that only Kampo treatment was significantly associated with improvement in olfactory dysfunction.

Conclusion: This study suggests that Kampo medication promotes early recovery from coronavirus disease 2019-related olfactory dysfunction.

In vitro Suppression of SARS-CoV-2 Infection by Existing Kampo Formulas and Crude Constituent Drugs Used for Treatment of Common Cold Respiratory Symptoms

Several traditional Japanese Kampo formulas are known to have inhibitory effects on infections with viruses that cause respiratory symptoms. Although some herbs and their components have been reported to suppress SARS-CoV-2 replication in vitro, it is difficult to compare effective Kampo formulas because of the different methods used in studies. Thus, we carried out in vitro experiments on the suppression of SARS-CoV-2 infection by Kampo formulas and crude drugs used for the common cold to compare their suppressive effects on virus infection. After infecting VeroE6/TMPRSS2 cells with SARS-CoV-2, lysates of the Kampo formulas and crude drugs were added, and after 24 h, the infectious titer in the medium was measured by the TCID₅₀ method. Maoto was the most effective among the Kampo formulas, and Ephedrae herba was the most effective among the constituent crude drugs. However, a comparison of the suppressive effects of Ephedrae herba and Kampo formulas containing Ephedrae herba showed that the suppressive effect on virus infection did not depend on the content of Ephedrae herba. Based on the results, we believe that the use of Maoto among Kampo formulas is suitable as a countermeasure against COVID-19.

De Novo Production of Plant 4'-Deoxyflavones Baicalein and Oroxylin A from Ethanol in Crabtree-Negative Yeast

Baicalein and oroxylin A are well-known medicinal 4'-deoxyflavones found mainly in the roots of traditional medicinal plant Scutellaria baicalensis Georgi. However, extraction from plants is time-consuming, environmentally unfriendly, and insufficient. Although microbial synthesis of flavonoids has been extensively reported, synthesis of downstream modified 4'-deoxyflavones has not, and their yields are extremely low. Here, we reassembled the S. baicalensis 4'-deoxyflavone biosynthetic pathway in a Crabtree-negative yeast, Pichia pastoris, with activity analysis and combinatorial expression of eight biosynthetic genes, allowing production of 4'-deoxyflavones like baicalein, oroxylin A, wogonin, norwogonin, 6-methoxywogonin, and the novel 6-methoxynorwogonin. De novo baicalein synthesis was then achieved by complete pathway assembly. Toxic intermediates highly impaired the cell production capacity; hence, we alleviated cinnamic acid growth inhibition by culturing the cells at near-neutral pH and using alcoholic carbon sources. To achieve pathway balance and improve baicalein and oroxylin A synthesis, we further divided the pathway into five modules. A series of ethanol-induced and constitutive transcriptional amplification devices were constructed to adapt to the modules. This fine-tuning pathway control considerably reduced byproduct and intermediate accumulation and achieved high-level de novo baicalein (401.9 mg/L with a total increase of 1182-fold, the highest titer reported) and oroxylin A (339.5 mg/L, for the first time) production from ethanol. This study provides new strategies for the microbial synthesis of 4'-deoxyflavones and other flavonoids.

Exploring the Potential Pharmacological Mechanism of Hesperidin and Glucosyl Hesperidin against COVID-19 Based on Bioinformatics Analyses and Antiviral Assays

The development of anti-COVID-19 drugs has become the top priority since the outbreak of the epidemic, and Traditional Chinese medicine plays an important role in reducing mortality. Here, hesperidin and its glycosylation product, glucosyl hesperidin were selected to determine their antiviral activity against SARS-CoV-2 due to their structural specificity as reported. To be specific, their binding ability with ACE2, M, S, RBD and N proteins were verified with both in silico and wet lab methods, i.e., molecular docking and binding affinity tests, including biolayer interferometry assay (BLI) and isothermal titration calorimetry assay (ITC). Moreover, systematic pharmacological analysis was conducted to reveal their pharmacological mechanism in treating COVID-19. Finally, their antiviral activity against SARS-CoV-2 was determined in vitro in a biosafety level 3 (BSL3) laboratory. The results demonstrated their outstanding binding affinity with ACE2, M, S and RBD proteins, while showed barely unobserved binding with N protein, indicating their key roles in influencing the invasion and early replication phase of SARS-CoV-2. In addition, both hesperidin and glucosyl hesperidin were shown to have a great impact on immune, inflammation and virus infection induced by COVID-19 according to the systematic pharmacological analysis. Moreover, the IC50s of hesperidin and glucosyl hesperidin against SARS-CoV-2 were further determined (51.5 [Formula: see text]M and 5.5 mM, respectively) with cell-based in vitro assay, suggesting their great anti-SARS-CoV-2 activity. All in all, present research was the first to verify the binding ability of hesperidin and glucosyl hesperidin with SARS-CoV-2 proteins with both in silico and wet-lab methods and proposed the possibility of applying hesperidin and glucosyl hesperidin to treat COVID-19.

Herbal Remedies, Nutraceuticals, and Dietary Supplements for COVID-19 Management: An Update

Currently, the world is facing a Coronavirus pandemic with a grave deficiency of specific therapy for Coronavirus Disease (COVID-19). Moreover, scientists attempt to discover the most refined approach to prevent this condition. Regarding COVID-19 infection, herbal medicines with immunomodulatory effects may offer patients a promising preventive treatment option. Several ayurvedic and Traditional Chinese Medicine (TCM) are effective during this worrisome Coronavirus pandemic i.e. Tinospora cordifolia (Willd.) Miers, Withania somnifera (L.) Dunal, Scutellaria baicalensis Georgi, Curcuma longa L. etc. TCM was shown to be utilized with over 90% efficacy when the COVID-19 pandemic broke out in early 2020. In addition to herbal treatments and nutraceutical drugs, dietary supplements such as vitamins and amino acid derivatives also play a significant part in COVID-19 management. Diet can assist in regulating inflammation, while nutraceuticals can aid in the prevention of viral invasion. Functional amino acids (e.g., arginine, cysteine, glutamate, glutamine, glycine, taurine, and tryptophan) and glutathione, which are all abundant in animal-sourced foodstuffs, are crucial for optimum immunity and health in humans and animals. The goal of this article is to thoroughly evaluate recent statistics on the effectiveness of herbal medicines in COVID-19, the antiviral activity of nutraceuticals, and the significance of these results in creating dietary supplements that would enhance innate immunity and contribute as preventive measures against severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2).

Baicalein—A Potent Pro-Homeostatic Regulator of Microglia in Retinal Ischemic Injury

Retinal ischemia is a common cause of many retinal diseases, leading to irreversible vision impairment and blindness. Excessive neuroinflammation, including microglial activation and T-cell responses, has been identified as a critical factor associated with neurodegeneration in retinal ischemia. Baicalein is a natural flavonoid reported to have broad anti-inflammatory and neuroprotective bioactivities. Herein, the effects of baicalein on microglia activation in vitro and in vivo were investigated. We found that baicalein exhibited robust anti-inflammatory effect on cultured human and mouse microglia, as demonstrated by decreased induction of pro-inflammatory cytokines and the phosphorylation of phosphoinositide 3-kinase (PI3K) and nuclear factor kappa B (NFκB). Proteomic analysis further unraveled baicalein’s effect on modulating IL-17 signaling pathways and its upstream regulator IL-1β. Intravitreal administration of baicalein in the mouse model of retinal ischemia/reperfusion (I/R) injury attenuated microglial activation and retinal T-cell infiltration, particularly the T helper 17 cells. Additionally, baicalein was shown to exert neuroprotective effects by significantly reducing the retinal ganglion cell (RGC) loss after I/R injury, leading to an improved retinal function and spatial vision. These results suggest that baicalein, a natural flavonoid, acts as a negative regulator of activated microglia and immune responses both in vitro and in vivo, effectively alleviating neurodegeneration in retinal I/R injury. This finding indicates that baicalein could be a potential therapeutic agent against currently incurable degenerative retinal diseases.

Oral Chinese Herbal Medicine on Immune Responses During Coronavirus Disease 2019: A Systematic Review and Meta-Analysis

BACKGROUND

Cellular immune responses including lymphocyte functions and immune effector cells are critical for the control of coronavirus infection. Chinese herbal medicine (CHM) potentially has a therapeutic effect for treatment of coronavirus disease 2019 (COVID-19). Nevertheless, there are limited clinical practice suggestions on immunogenicity of the CHM against SARS-CoV-2. To assess the effect of oral CHM on immunogenicity and whether oral CHM improves the clinical parameters through the immunity profile during COVID-19, we performed the present study.

METHODS

For this systematic review and meta-analysis, 11 databases were searched for relevant studies assessing oral CHM for COVID-19 on November 20, 2020 (updated March 9, 2021). Primary outcomes mainly included immunity profiles. Secondary outcomes included all-cause mortality; the remission time of fever, cough, chest tightness, and fatigue. The random effect was used to estimate the heterogeneity of the studies. Summary relative risks, weight mean difference and standardized mean difference were measured with 95% confidence intervals. Modified Jadad scale and Newcastle-Ottawa Scale were used to assess the risk of bias of randomized controlled trials (RCTs) and observational studies, respectively. The certainty of evidence was evaluated using the GRADE approach.

RESULTS

We analyzed findings from 3,145 patients in 30 eligible studies. Compared with routine treatment, oral CHM, as an adjuvant medicine, improved lymphocyte counts, CD4+, and CD4+/CD8+ ratio with low quality of evidence; improved CD3+ with moderate quality of evidence; and reduced TNF-α with low certainty of evidence. Besides, oral CHM, as an adjuvant medicine reduced the time to clinical symptoms remission with a lower risk of all-cause mortality, compared with routine treatment alone.

CONCLUSION

CHM may be recommended as an adjuvant immunotherapy for disease modification and symptom relief in COVID-19 treatment. However, large RCTs objectively assessing the efficacy of CHM on immune responses in COVID-19 are needed to confirm our findings.

The discovery of herbal drugs and natural compounds as inhibitors of SARS-CoV-2 infection in vitro

The emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in 2019 has led to a global health crisis. Mutations of the SARS-CoV-2 genome have impeded the development of effective therapeutics and vaccines against SARS-CoV-2. Natural products are important for discovering therapeutics to treat the 2019 coronavirus disease (COVID-19). In the present study, we investigated the antiviral activity of herbal drug extracts from Polygala Root, Areca, and Quercus Bark and natural compounds derived from herbal drug such as baicalin and glabridin, with IC₅₀ values of 9.5 µg/ml, 1.2 µg/ml, 5.4 µg/ml, 8.8 µM, and 2.5 µM, respectively, against SARS CoV-2 infection in vitro. Certain herbal drug extracts and natural compounds were found to inhibit viral RNA levels and infectious titers of SARS-CoV-2 in a dose-dependent manner. Furthermore, viral protein analyses showed that herbal drug extracts and natural compounds effectively inhibited SARS-CoV-2 in the various entry treatments. Our study revealed that three herbal drugs are good candidates for further in vivo and clinical studies.

Artemisinins in Combating Viral Infections Like SARS-CoV-2, Inflammation and Cancers and Options to Meet Increased Global Demand

Artemisinin is a natural bioactive sesquiterpene lactone containing an unusual endoperoxide 1, 2, 4-trioxane ring. It is derived from the herbal medicinal plant Artemisia annua and is best known for its use in treatment of malaria. However, recent studies also indicate the potential for artemisinin and related compounds, commonly referred to as artemisinins, in combating viral infections, inflammation and certain cancers. Moreover, the different potential modes of action of artemisinins make these compounds also potentially relevant to the challenges the world faces in the COVID-19 pandemic. Initial studies indicate positive effects of artemisinin or Artemisia spp. extracts to combat SARS-CoV-2 infection or COVID-19 related symptoms and WHO-supervised clinical studies on the potential of artemisinins to combat COVID-19 are now in progress. However, implementing multiple potential new uses of artemisinins will require effective solutions to boost production, either by enhancing synthesis in A. annua itself or through biotechnological engineering in alternative biosynthesis platforms. Because of this renewed interest in artemisinin and its derivatives, here we review its modes of action, its potential application in different diseases including COVID-19, its biosynthesis and future options to boost production.

Exploring the Potential Targets and Mechanisms of Huang Lian Jie Du Decoction in the Treatment of Coronavirus Disease 2019 Based on Network Pharmacology

Background

In December 2019, coronavirus disease 2019 (COVID-19) caused by a novel coronavirus (severe acute respiratory syndrome coronavirus 2, SARS-CoV-2; previously known as 2019-nCoV) emerged in Wuhan, China, and caused many infections and deaths. At present, there are no specific drugs for the etiology and treatment of COVID-19. A combination of traditional Chinese and western medicine is proposed to treat COVID-19, in which Huang Lian Jie Du decoction (HLJDD) is recommended for the treatment of COVID-19 in many provinces in China and has been widely used in the clinic. This study explored the potential targets of HLJDD in the treatment of COVID-19 based on network pharmacology.

Methods

First, the chemical composition and targets of HLJDD and COVID-19-related targets were obtained through the TCMSP, UniProt, GeneCards and OMIM databases. Second, HLJDD target and HLJDD-COVID-19 target networks were constructed via the STRING database and Cytoscape software. Finally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the HLJDD-COVID-19 targets was applied via the DAVID database.

Results

Our study identified a total of 67 active ingredients of HLJDD and 204 targets of HLJDD. A total of 502 COVID-19-related targets were obtained, of which 47 were intersecting targets of HLJDD and COVID-19. A total of 179 GO terms and 77 KEGG terms, including the TNF signaling pathway, NF-κB signaling pathway and HIF-1 signaling pathway, were identified.

Conclusion

The present study explored the potential targets and signaling pathways of HLJDD during the treatment of COVID-19, which may provide a basis for the research and development of drugs for the treatment of COVID-19.

Optimization of ultrasound-assisted enzymatic pretreatment for enhanced extraction of baicalein and wogonin from Scutellaria baicalensis roots

It is of great theoretical interest and industrial significance to improve the extraction efficiency of baicalein and wogonin from Scutellaria baicalensis roots because of their high pharmacological activities. The present study was aimed to establish the optimized ultrasound-assisted enzymatic pretreatment (UAEP) process by which ultrasound irradiation and the exogenous enzyme were simultaneously applied to efficiently transform baicalin and wogonoside into baicalein and wogonin, enhancing their extraction efficiency. Single-factor experiment and Box-Behnken design were used to optimize the main UAEP conditions to maximize the total extraction yield of baicalein and wogonin. The optimized UAEP conditions were cellulase concentration of 1.1%, pH of 5.5, UAEP temperature of 56.5 °C, UAEP time of 39.4 min, and ultrasonic power of 200 W with the total extraction yield of 82.51 ± 0.85 mg/g DW. The comparison of the established technique with the reference method based on the enzymatic pretreatment revealed that the productive efficiency was significantly improved with the transformation rates nearly doubled. These results suggest that the optimized UAEP process has the potential to be applied for the green, simple, and efficient extraction of baicalein and wogonin in the pharmaceutical and food industry.

SARS-CoV-2: Current trends in emerging variants, pathogenesis, immune responses, potential therapeutic, and vaccine development strategies

More than a year after the SARS-CoV-2 pandemic, the Coronavirus disease 19 (COVID-19) is still a major global challenge for scientists to understand the different dimensions of infection and find ways to prevent, treat, and develop a vaccine. On January 30, 2020, the world health organization (WHO) officially announced this new virus as an international health emergency. While many biological and mechanisms of pathogenicity of this virus are still unclear, it seems that cytokine storm resulting from an immune response against the virus is considered the main culprit of the severity of the disease. Despite many global efforts to control the SARS-CoV-2, several problems and challenges have been posed in controlling the COVID-19 infection. These problems include the various mutations, the emergence of variants with high transmissibility, the short period of immunity against the virus, the possibility of reinfection in people improved, lack of specific drugs, and problems in the development of highly sensitive and specific vaccines. In this review, we summarized the results of the current trend and the latest research studies on the characteristics of the structure and genome of the SARS-CoV- 2, new mutations and variants of SARS-CoV-2, pathogenicity, immune response, virus diagnostic tests, potential treatment, and vaccine candidate.

Natural Bioactive Molecules: An Alternative Approach to the Treatment and Control of COVID-19

Several coronaviruses (CoVs) have been associated with serious health hazards in recent decades, resulting in the deaths of thousands around the globe. The recent coronavirus pandemic has emphasized the importance of discovering novel and effective antiviral medicines as quickly as possible to prevent more loss of human lives. Positive-sense RNA viruses with group spikes protruding from their surfaces and an abnormally large RNA genome enclose CoVs. CoVs have already been related to a range of respiratory infectious diseases possibly fatal to humans, such as MERS, SARS, and the current COVID-19 outbreak. As a result, effective prevention, treatment, and medications against human coronavirus (HCoV) is urgently needed. In recent years, many natural substances have been discovered with a variety of biological significance, including antiviral properties. Throughout this work, we reviewed a wide range of natural substances that interrupt the life cycles for MERS and SARS, as well as their potential application in the treatment of COVID-19.

Phytochemicals for the treatment of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has underscored the lack of approved drugs against acute viral diseases. Plants are considered inexhaustible sources of drugs for several diseases and clinical conditions, but plant-derived compounds have seen little success in the field of antivirals. Here, we present the case for the use of compounds from vascular plants, including alkaloids, flavonoids, polyphenols, and tannins, as antivirals, particularly for the treatment of COVID-19. We review current evidence for the use of these phytochemicals against SARS-CoV-2 infection and present their potential targets in the SARS-CoV-2 replication cycle.

Promising Antiviral Activities of Natural Flavonoids against SARS-CoV-2 Targets: Systematic Review

The ongoing COVID-19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a globally leading public health concern over the past two years. Despite the development and administration of multiple vaccines, the mutation of newer strains and challenges to universal immunity has shifted the focus to the lack of efficacious drugs for therapeutic intervention for the disease. As with SARS-CoV, MERS-CoV, and other non-respiratory viruses, flavonoids present themselves as a promising therapeutic intervention given their success in silico, in vitro, in vivo, and more recently, in clinical studies. This review focuses on data from in vitro studies analyzing the effects of flavonoids on various key SARS-CoV-2 targets and presents an analysis of the structure-activity relationships for the same. From 27 primary papers, over 69 flavonoids were investigated for their activities against various SARS-CoV-2 targets, ranging from the promising 3C-like protease (3CLpro) to the less explored nucleocapsid (N) protein; the most promising were quercetin and myricetin derivatives, baicalein, baicalin, EGCG, and tannic acid. We further review promising in silico studies featuring activities of flavonoids against SARS-CoV-2 and list ongoing clinical studies involving the therapeutic potential of flavonoid-rich extracts in combination with synthetic drugs or other polyphenols and suggest prospects for the future of flavonoids against SARS-CoV-2.

Immunostimulant and Antidepressant Effect of Natural Compounds in the Management of Covid-19 Symptoms

In recent years, the use of natural compounds as adjuvant treatments and alternatives to traditional pharmacological therapies has become increasingly popular. These compounds have a wide range of biological effects, such as: antioxidant, anti-aging, hypocholesterolizing, hypoglycemic, antitumoral, antidepressant, anxiolytic activity, etc. Almost all of these compounds are easily available and are contained in different foods. At the end of 2019 the Coronavirus SARS-CoV-2 appeared in China and quickly spread throughout the world, causing a pandemic. The most common symptoms of this infection are dry cough, fever, dyspnea, and in severe cases bilateral interstitial pneumonia, with consequences that can lead to death. The nations, in trying to prevent the spread of infection, have imposed social distancing and lockdown measures on their citizens. This had a strong psychological-social impact, leading to phobic, anxious and depressive states. Pharmacological therapy could be accompanied by treatment with several natural compounds, such as vitamins, baicalein, zinc and essential oils. These compounds possess marked immunostimulant activity, strengthening the immune response and mitigating interactions between the virus and the host cell. They also have an antidepressant effect, acting on certain neurotransmitters.

Progress in Traditional Chinese Medicine Against Respiratory Viruses: A Review

Respiratory viruses, such as severe acute respiratory syndrome coronavirus (SARS-CoV)-1, SARS-CoV-2, influenza A viruses, and respiratory syncytial virus, pose a serious threat to society. Based on the guiding principles of “holism” and “syndrome differentiation and treatment”, traditional Chinese medicine (TCM) has unique advantages in the treatment of respiratory virus diseases owing to the synergistic effect of multiple components and targets, which prevents drug resistance from arising. According to TCM theory, there are two main strategies in antiviral treatments, namely “dispelling evil” and “fu zheng”. Dispelling evil corresponds to the direct inhibition of virus growth and fu zheng corresponds to immune regulation, inflammation control, and tissue protection in the host. In this review, current progress in using TCMs against respiratory viruses is summarized according to modern biological theories. The prospects for developing TCMs against respiratory viruses is discussed to provide a reference for the research and development of innovative TCMs with multiple components, multiple targets, and low toxicity.

An Overview of COVID-19 and the Potential Plant Harboured Secondary Metabolites against SARS-CoV-2: A Review

The SARS-CoV-2 virus causes COVID-19, a pandemic disease, and it is called the novel coronavirus. It belongs to the Coronaviridae family and has been plagued the world since the end of 2019. Viral infection to the lungs causes fluid filling and breathing difficulties, which leads to pneumonia. Pneumonia progresses to ARDS (Acute Respiratory Distress Syndrome), in which fluid fills the air sac and seeps from the pulmonary veins. In the current scenario, several vaccines have been used to control the pandemic worldwide. Even though vaccines are available and their effectiveness is short, it may be helpful to curb the pandemic, but long-term protection is inevitable when we look for other options. Plants have diversified components such as primary and secondary metabolites. These molecules show several activities such as anti-microbial, anti-cancer, anti-helminthic. In addition, these molecules have good binding ability to the SARS-CoV-2 virus proteins such as RdRp (RNA-dependent RNA polymerase), Mpro (Main Protease), etc. Therefore, these herbal molecules could probably be used to control the COVID-19. However, pre-requisite tests, such as cytotoxicity, in vivo, and human experimental studies, are required before plant molecules can be used as potent drugs. Plant metabolites such as alkaloids, isoquinoline ß-carboline, and quinoline alkaloids such as skimmianine, quinine, cinchonine, and dictamine are present in plants and used in a traditional medicinal system.

Network-Based Identification and Experimental Validation of Drug Candidates Toward SARS-CoV-2 via Targeting Virus-Host Interactome

Despite that several therapeutic agents have exhibited promising prevention or treatment on Coronavirus disease-2019 (COVID-19), there is no specific drug discovered for this pandemic. Targeting virus-host interactome provides a more effective strategy for antivirus drug discovery compared with targeting virus proteins. In this study, we developed a network-based infrastructure to prioritize promising drug candidates from natural products and approved drugs via targeting host proteins of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). We firstly measured the network distances between drug targets and COVID-19 disease module utilizing the network proximity approach, and identified 229 approved drugs as well as 432 natural products had significant associations with SARS-CoV-2. After searching for previous literature evidence, we found that 60.7% (139/229) of approved drugs and 39.6% (171/432) of natural products were confirmed with antivirus or anti-inflammation. We further integrated our network-based predictions and validated anti-SARS-CoV-2 activities of some compounds. Four drug candidates, including hesperidin, isorhapontigenin, salmeterol, and gallocatechin-7-gallate, have exhibited activity on SARS-COV-2 virus-infected Vero cells. Finally, we showcased the mechanism of actions of isorhapontigenin and salmeterol via network analysis. Overall, this study offers forceful approaches for in silico identification of drug candidates on COVID-19, which may facilitate the discovery of antiviral drug therapies.

Anti-SARS-CoV-2 activities of tanshinone IIA, carnosic acid, rosmarinic acid, salvianolic acid, baicalein, and glycyrrhetinic acid between computational and in vitro insights

Six compounds namely, tanshinone IIA (1), carnosic acid (2), rosmarinic acid (3), salvianolic acid B (4), baicalein (5), and glycyrrhetinic acid (6) were screened for their anti-SARS-CoV-2 activities against both the spike (S) and main protease (Mpro) receptors using molecular docking studies. Molecular docking recommended the superior affinities of both salvianolic acid B (4) and glycyrrhetinic acid (6) as the common results from the previously published computational articles. On the other hand, their actual anti-SARS-CoV-2 activities were tested in vitro using plaque reduction assay to calculate their IC₅₀ values after measuring their CC₅₀ values using MTT assay on Vero E6 cells. Surprisingly, tanshinone IIA (1) was the most promising member with IC₅₀ equals 4.08 ng μl^-1. Also, both carnosic acid (2) and rosmarinic acid (3) showed promising IC₅₀ values of 15.37 and 25.47 ng μl^-1, respectively. However, salvianolic acid (4) showed a weak anti-SARS-CoV-2 activity with an IC₅₀ value equals 58.29 ng μl^-1. Furthermore, molecular dynamics simulations for 100 ns were performed for the most active compound from the computational point of view (salvianolic acid 4), besides, the most active one biologically (tanshinone IIA 1) on both the S and Mpro complexes of them (four different molecular dynamics processes) to confirm the docking results and give more insights regarding the stability of both compounds inside the SARS-CoV-2 mentioned receptors, respectively. Also, to understand the mechanism of action for the tested compounds towards SARS-CoV-2 inhibition it was necessary to examine the mode of action for the most two promising compounds, tanshinone IIA (1) and carnosic acid (2). Both compounds (1 and 2) showed very promising virucidal activity with a most prominent inhibitory effect on viral adsorption rather than its replication. This recommended the predicted activity of the two compounds against the S protein of SARS-CoV-2 rather than its Mpro protein. Our results could be very promising to rearrange the previously mentioned compounds based on their actual inhibitory activities towards SARS-CoV-2 and to search for the reasons behind the great differences between their in silico and in vitro results against SARS-CoV-2. Finally, we recommend further advanced preclinical and clinical studies especially for tanshinone IIA (1) to be rapidly applied in COVID-19 management either alone or in combination with carnosic acid (2), rosmarinic acid (3), and/or salvianolic acid (4).

Targeting phytoprotection in the COVID-19-induced lung damage and associated systemic effects-the evidence-based 3PM proposition to mitigate individual risks

The risks related to the COVID-19 are multi-faceted including but by far not restricted to the following: direct health risks by poorly understood effects of COVID-19 infection, overloaded capacities of healthcare units, restricted and slowed down care of patients with non-communicable disorders such as cancer, neurologic and cardiovascular pathologies, among others; social risks-restricted and broken social contacts, isolation, professional disruption, explosion of aggression in the society, violence in the familial environment; mental risks-loneliness, helplessness, defenceless, depressions; and economic risks-slowed down industrial productivity, broken delivery chains, unemployment, bankrupted SMEs, inflation, decreased capacity of the state to perform socially important programs and to support socio-economically weak subgroups in the population. Directly or indirectly, the above listed risks will get reflected in a healthcare occupation and workload which is a tremendous long-term challenge for the healthcare capacity and robustness. The article does not pretend to provide solutions for all kind of health risks. However, it aims to present the scientific evidence of great clinical utility for primary, secondary, and tertiary care to protect affected individuals in a cost-effective manner. To this end, due to pronounced antimicrobial, antioxidant, anti-inflammatory, and antiviral properties, naturally occurring plant substances are capable to protect affected individuals against COVID-19-associated life-threatening complications such as lung damage. Furthermore, they can be highly effective, if being applied to secondary and tertiary care of noncommunicable diseases under pandemic condition. Thus, the stratification of patients evaluating specific health conditions such as sleep quality, periodontitis, smoking, chronic inflammation and diseases, metabolic disorders and obesity, vascular dysfunction, and cancers would enable effective managemenet of COVID-19-associated complications in primary, secondary, and tertiary care in the context of predictive, preventive, and personalized medicine (3PM).

Co-crystallization and structure determination: An effective direction for anti-SARS-CoV-2 drug discovery

Safer and more-effective drugs are urgently needed to counter infections with the highly pathogenic SARS-CoV-2, cause of the COVID-19 pandemic. Identification of efficient inhibitors to treat and prevent SARS-CoV-2 infection is a predominant focus. Encouragingly, using X-ray crystal structures of therapeutically relevant drug targets (PLpro, Mpro, RdRp, and S glycoprotein) offers a valuable direction for anti-SARS-CoV-2 drug discovery and lead optimization through direct visualization of interactions. Computational analyses based primarily on MMPBSA calculations have also been proposed for assessing the binding stability of biomolecular structures involving the ligand and receptor. In this study, we focused on state-of-the-art X-ray co-crystal structures of the abovementioned targets complexed with newly identified small-molecule inhibitors (natural products, FDA-approved drugs, candidate drugs, and their analogues) with the assistance of computational analyses to support the precision design and screening of anti-SARS-CoV-2 drugs.

Natural Products with tandem Anti-inflammatory, Immunomodulatory and Anti-SARS-CoV/2 effects: A Drug Discovery Perspective against SARS-CoV-2

BACKGROUND

COVID-19 is still causing victims with long-term health consequences, mass deaths, and collapsing healthcare systems around the world. The disease has no efficient drugs. However, previous studies revealed that SARS-CoV-2 and SARS-CoV have 96% and 86.5% similarities in cysteine proteases (3CL^pro) and papain-like protease (PL^pro) sequences, respectively. This resemblance could be significant in the search for drug candidates with antiviral effects against SARS-CoV-2.

OBJECTIVE

This paper is a compilation of natural products that inhibit SARS-CoV 3CL^pro and PL^pro and, concomitantly, reduce inflammation and/or modulate the immune system as a perspective strategy for COVID-19 drug discovery. It also presents in silico studies performed on these selected natural products using SARS-CoV-2 3CL^pro and PL^pro as targets to propose a list of hit compounds.

METHOD

The plant metabolites were selected in the literature based on their biological activities on SARS-CoV proteins, inflammatory mediators, and immune response. The consensus docking analysis was performed using four different packages.

RESULTS

Seventy-nine compounds reported in the literature with inhibitory effects on SARS-CoV proteins were reported as anti-inflammatory agents. Fourteen of them showed in previous studies immunomodulatory effects. Five and six of these compounds showed significant in silico consensus as drug candidates that can inhibit PL^pro and 3CL^pro, respectively. Our findings corroborated recent results reported on anti-SARS-CoV-2 in the literature.

CONCLUSION

This study revealed that amentoflavone, rubranoside B, savinin, psoralidin, hirsutenone, and papyriflavonol A are good drug candidate for the search of antibiotics against COVID-19.

Hairy Roots of Scutellaria spp. (Lamiaceae) as Promising Producers of Antiviral Flavones

We measured and studied the growth parameters and the qualitative and quantitative composition of the flavones of hairy roots of the Scutellaria genus: S. lateriflora, S. przewalskii and S. pycnoclada. Hairy roots were obtained using wild-type Agrobacterium rhizogenes A4 by co-cultivation of explants (cotyledons) in a suspension of Agrobacterium. The presence of the rol-genes was confirmed by PCR analysis. The hairy roots of the most studied plant from the Scutellaria genus, S. baicalensis, were obtained earlier and used as a reference sample. HPLC-MS showed the predominance of four main flavones (baicalin, baicalein, wogonin and wogonoside) in the methanol extracts of the studied hairy roots. In addition to the four main flavones, the other substances which are typical to the aerial part of plants were found in all the extracts: apigenin, apigetrin, scutellarin and chrysin-7-O-β-d-glucuronide. According to the total content of flavones, the hairy roots of the studied skullcaps form the following series: S. przewalskii (33 mg/g dry weight) > S. baicalensis (17.04 mg/g dry weight) > S. pycnoclada (12.9 mg/g dry weight) > S. lateriflora (4.57 mg/g dry weight). Therefore, the most promising producer of anti-coronavirus flavones is S. przewalskii.

Flavonoids as Promising Antiviral Agents against SARS-CoV-2 Infection: A Mechanistic Review

A newly diagnosed coronavirus in 2019 (COVID-19) has affected all human activities since its discovery. Flavonoids commonly found in the human diet have attracted a lot of attention due to their remarkable biological activities. This paper provides a comprehensive review of the benefits of flavonoids in COVID-19 disease. Previously-reported effects of flavonoids on five RNA viruses with similar clinical manifestations and/or pharmacological treatments, including influenza, human immunodeficiency virus (HIV), severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and Ebola, were considered. Flavonoids act via direct antiviral properties, where they inhibit different stages of the virus infective cycle and indirect effects when they modulate host responses to viral infection and subsequent complications. Flavonoids have shown antiviral activity via inhibition of viral protease, RNA polymerase, and mRNA, virus replication, and infectivity. The compounds were also effective for the regulation of interferons, pro-inflammatory cytokines, and sub-cellular inflammatory pathways such as nuclear factor-κB and Jun N-terminal kinases. Baicalin, quercetin and its derivatives, hesperidin, and catechins are the most studied flavonoids in this regard. In conclusion, dietary flavonoids are promising treatment options against COVID-19 infection; however, future investigations are recommended to assess the antiviral properties of these compounds on this disease.

Natural Products, Alone or in Combination with FDA-Approved Drugs, to Treat COVID-19 and Lung Cancer

As a public health emergency of international concern, the highly contagious coronavirus disease 2019 (COVID-19) pandemic has been identified as a severe threat to the lives of billions of individuals. Lung cancer, a malignant tumor with the highest mortality rate, has brought significant challenges to both human health and economic development. Natural products may play a pivotal role in treating lung diseases. We reviewed published studies relating to natural products, used alone or in combination with US Food and Drug Administration-approved drugs, active against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and lung cancer from 1 January 2020 to 31 May 2021. A wide range of natural products can be considered promising anti-COVID-19 or anti-lung cancer agents have gained widespread attention, including natural products as monotherapy for the treatment of SARS-CoV-2 (ginkgolic acid, shiraiachrome A, resveratrol, and baicalein) or lung cancer (daurisoline, graveospene A, deguelin, and erianin) or in combination with FDA-approved anti-SARS-CoV-2 agents (cepharanthine plus nelfinavir, linoleic acid plus remdesivir) and anti-lung cancer agents (curcumin and cisplatin, celastrol and gefitinib). Natural products have demonstrated potential value and with the assistance of nanotechnology, combination drug therapies, and the codrug strategy, this "natural remedy" could serve as a starting point for further drug development in treating these lung diseases.

Green Tea Polyphenol Catechins Inhibit Coronavirus Replication and Potentiate the Adaptive Immunity and Autophagy-Dependent Protective Mechanism to Improve Acute Lung Injury in Mice

Effective antiviral therapeutics are urgently required to fight severe acute respiratory syndrome (SARS) caused by a SARS coronavirus (SARS-CoV). Because polyphenol catechins could confer antioxidative, anti-inflammatory, antiviral, and antimicrobial activities, we assessed the therapeutic effects of catechins against SARS-CoV replication in Vero E6 cells, the preventive effect of catechins on CD25/CD69/CD94/CD8⁺ cytotoxic T lymphocytes-mediated adaptive immunity, and the protective effect on lipopolysaccharide-induced acute lung injury (ALI) in mice. We found that catechins containing 32.8% epigallocatechin gallate, 15.2% epicatechin gallate, 13.2 epicatechin, 10.8% epigallocatechin, 10.4% gallocatechin, and 4.4% catechin directly inhibited SARS-CoV replication at sub-micromolecular concentrations. Four-week catechins ingestion increased CD8⁺ T cell percentage, upregulated CD69⁺/CD25⁺/CD94-NKG2A/CD8⁺ T lymphocytes-mediated adaptive immunity, and increased type I cytokines release responding to ovalbumin/alum. Catechins significantly reduced lipopolysaccharide-induced cytokine storm and oxidative stress and ALI by inhibiting PI3K/AKT/mTOR signaling to upregulate Beclin-1/Atg5-Atg12/LC3-II-mediated autophagy mechanism. Pretreatment of autophagy inhibitor 3-Methyladenine reversed the inhibiting effects of catechins on the cytokines and oxidative stress levels and ALI. In conclusion, our data indicated that catechins directly inhibited SARS-CoV replication, potentiated the CD25/CD69/CD94/CD8⁺ T lymphocytes-mediated adaptive immunity and attenuated lipopolysaccharide-induced ALI and cytokine storm by PI3K/AKT/mTOR-signaling-mediated autophagy, which may be applied to prevent and/or treat SARS-CoV infection.

Baicalein Protects Against Aspergillus fumigatus Keratitis by Reducing Fungal Load and Inhibiting TSLP-Induced Inflammatory Response

Purpose

To investigate the antifungal and anti-inflammatory effects of baicalein on Aspergillus fumigatus (A. fumigatus) keratitis and the underlying mechanisms.

Methods

The noncytotoxic antifungal concentration of baicalein was determined using CCK8, cell scratch assay, minimum inhibitory concentration, biofilm formation, scanning electron microscopy, propidium iodide uptake test and adherence assay in vitro and Draize test in vivo. In fungal keratitis (FK) mouse models, clinical score and plate count were used to evaluate FK severity, and myeloperoxidase assay and immunofluorescence staining were performed to examine neutrophil infiltration and activity. Real-time PCR, ELISA, and Western blot were performed to explore the anti-inflammatory activity of baicalein and the underlying mechanisms in vivo and in vitro.

Results

Baicalein at 0.25 mM (noncytotoxic) significantly inhibited A. fumigatus growth, biofilm formation, and adhesion in vitro. In A. fumigatus keratitis mice, baicalein mitigated FK severity, reduced fungal load, and inhibited neutrophil infiltration and activity. Baicalein not only suppressed mRNA and protein levels of proinflammatory factors IL-1β, IL-6, and TNF-α, but also inhibited the expression of thymic stromal lymphopoietin (TSLP) and TSLP receptor (TSLPR) in vivo and in vitro. In HCECs, mRNA and protein levels of IL-1β, IL-6, and TNF-α were significantly lower in the TSLP siRNA–treated group, while higher in the rTSLP-treated group than in the corresponding control. Baicalein treatment significantly inhibited rTSLP induced the expression of IL-1β, IL-6, and TNF-α.

Conclusions

Baicalein plays a protective role in mouse A. fumigatus keratitis by inhibiting fungal growth, biofilm formation, and adhesion, and suppressing inflammatory response via downregulation of the TSLP/TSLPR pathway.

A Review on the Medicinal and Pharmacological Properties of Traditional Ethnomedicinal Plant Sonapatha, Oroxylum indicum

Oroxylum indicum, Sonapatha is traditionally used to treat asthma, biliousness, bronchitis, diarrhea, dysentery, fevers, vomiting, inflammation, leukoderma, skin diseases, rheumatoid arthritis, wound injury, and deworm intestine. This review has been written by collecting the relevant information from published material on various ethnomedicinal and pharmacological aspects of Sonapatha by making an internet, PubMed, SciFinder, Science direct, and Google Scholar search. Various experimental studies have shown that Sonapatha scavenges different free radicals and possesses alkaloids, flavonoids, cardio glycosides, tannins, sterols, phenols, saponins, and other phytochemicals. Numerous active principles including oroxylin A, chrysin, scutellarin, baicalein, and many more have been isolated from the different parts of Sonapatha. Sonapatha acts against microbial infection, cancer, hepatic, gastrointestinal, cardiac, and diabetic disorders. It is useful in the treatment of obesity and wound healing in in vitro and in vivo preclinical models. Sonapatha elevates glutathione, glutathione-s-transferase, glutathione peroxidase, catalase, and superoxide dismutase levels and reduces aspartate transaminase alanine aminotransaminase, alkaline phosphatase, lactate dehydrogenase, and lipid peroxidation levels in various tissues. Sonapatha activates the expression of p53, pRb, Fas, FasL, IL-12, and caspases and inhibited nuclear factor kappa (NF-κB), cyclooxygenase (COX-2), tumor necrosis factor (TNFα), interleukin (IL6), P38 activated mitogen-activated protein kinases (MAPK), fatty acid synthetase (FAS), sterol regulatory element-binding proteins 1c (SREBP-1c), proliferator-activated receptor γ2 (PPARγ2), glucose transporter (GLUT4), leptin, and HPV18 oncoproteins E6 and E7 at the molecular level, which may be responsible for its medicinal properties. The phytoconstituents of Sonapatha including oroxylin A, chrysin, and baicalein inhibit the replication of SARS-CoV-2 (COVID-19) in in vitro and in vivo experimental models, indicating its potential to contain COVID-19 infection in humans. The experimental studies in various preclinical models validate the use of Sonapatha in ethnomedicine and Ayurveda.

Targeting Multiple Signal Transduction Pathways of SARS-CoV-2: Approaches to COVID-19 Therapeutic Candidates

Due to the complicated pathogenic pathways of coronavirus disease 2019 (COVID-19), related medicinal therapies have remained a clinical challenge. COVID-19 highlights the urgent need to develop mechanistic pathogenic pathways and effective agents for preventing/treating future epidemics. As a result, the destructive pathways of COVID-19 are in the line with clinical symptoms induced by severe acute coronary syndrome (SARS), including lung failure and pneumonia. Accordingly, revealing the exact signaling pathways, including inflammation, oxidative stress, apoptosis, and autophagy, as well as relative representative mediators such as tumor necrosis factor-α (TNF-α), nuclear factor erythroid 2-related factor 2 (Nrf2), Bax/caspases, and Beclin/LC3, respectively, will pave the road for combating COVID-19. Prevailing host factors and multiple steps of SARS-CoV-2 attachment/entry, replication, and assembly/release would be hopeful strategies against COVID-19. This is a comprehensive review of the destructive signaling pathways and host-pathogen interaction of SARS-CoV-2, as well as related therapeutic targets and treatment strategies, including potential natural products-based candidates.

Baicalein and Baicalin Inhibit SARS-CoV-2 RNA-Dependent-RNA Polymerase

Coronavirus Disease 2019 (COVID-19) is a deadly emerging infectious disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Because SARS-CoV-2 is easily transmitted through the air and has a relatively long incubation time, COVID-19 has rapidly developed into a global pandemic. As there are no antiviral agents for the prevention and treatment of this severe pathogen except for remdesivir, development of antiviral therapies to treat infected individuals remains highly urgent. Here, we showed that baicalein and baicalin exhibited significant antiviral activity against SARS-CoV-2, the causative agent of COVID-19 through in vitro studies. Our data through cell-based and biochemical studies showed that both compounds act as SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) inhibitors directly and inhibit the activity of the SARS-CoV-2 RdRp, but baicalein was more potent. We also showed specific binding of baicalein to the SARS-CoV-2 RdRp, making it a potential candidate for further studies towards therapeutic development for COVID-19 as a selective non-nucleoside polymerase inhibitor.

The Potential Therapeutic Effect of RNA Interference and Natural Products on COVID-19: A Review of the Coronaviruses Infection

The SARS-CoV-2 virus was reported for the first time in Wuhan, Hubei Province, China, and causes respiratory infection. This pandemic pneumonia killed about 1,437,835 people out of 61,308,161cases up to November 27, 2020. The disease's main clinical complications include fever, recurrent coughing, shortness of breath, acute respiratory syndrome, and failure of vital organs that could lead to death. It has been shown that natural compounds with antioxidant, anticancer, and antiviral activities and RNA interference agents could play an essential role in preventing or treating coronavirus infection by inhibiting the expression of crucial virus genes. This study aims to introduce a summary of coronavirus's genetic and morphological structure and determine the role of miRNAs, siRNAs, chemical drugs, and natural compounds in stimulating the immune system or inhibiting the virus's structural and non-structural genes that are essential for replication and infection of SARS-CoV-2.

Baicalein Inhibits Streptococcus mutans Biofilms and Dental Caries-Related Virulence Phenotypes

Dental caries, the most common oral disease, is a major public healthcare burden and affects more than three billion people worldwide. The contemporary understanding of the need for a healthy microbiome and the emergence of antimicrobial resistance has resulted in an urgent need to identify compounds that curb the virulence of pathobionts without microbial killing. Through this study, we have demonstrated for the first time that 5,6,7-trihydroxyflavone (Baicalein) significantly downregulates crucial caries-related virulence phenotypes in Streptococcus mutans. Baicalein significantly inhibited biofilm formation by Streptococcus mutans UA159 (MBIC50 = 200 μM), without significant growth inhibition. Notably, these concentrations of baicalein did not affect the commensal S. gordonii. Strikingly, baicalein significantly reduced cell surface hydrophobicity, autoaggregation and acid production by S. mutans. Mechanistic studies (qRT-PCR) showed downregulation of various genes regulating biofilm formation, surface attachment, quorum sensing, acid production and competence. Finally, we demonstrate the potential translational value of baicalein by reporting synergistic interaction with fluoride against S. mutans biofilms.

iRGD conjugated nimbolide liposomes protect against endotoxin induced acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a deadly respiratory illness associated with refractory hypoxemia and pulmonary edema. The recent pandemic outbreak of COVID-19 is associated with severe pneumonia and inflammatory cytokine storm in the lungs. The anti-inflammatory phytomedicine nimbolide (NIM) may not be feasible for clinical translation due to poor pharmacokinetic properties and lack of suitable delivery systems. To overcome these barriers, we have developed nimbolide liposomes conjugated with iRGD peptide (iRGD-NIMLip) for targeting lung inflammation. It was observed that iRGD-NIMLip treatment significantly inhibited oxidative stress and cytokine storm compared to nimbolide free-drug (f-NIM), nimbolide liposomes (NIMLip), and exhibited superior activity compared to dexamethasone (DEX). iRGD-NIMLip abrogated the LPS induced p65 NF-κB, Akt, MAPK, Integrin β3 and β5, STAT3, and DNMT1 expression. Collectively, our results demonstrate that iRGD-NIMLip could be a promising novel drug delivery system to target severe pathological consequences observed in ARDS and COVID-19 associated cytokine storm.

Possible Therapeutic Use of Natural Compounds Against COVID-19

The outbreak of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has led to coronavirus disease-19 (COVID-19); a pandemic disease that has resulted in devastating social, economic, morbidity and mortality burdens. SARS-CoV-2 infects cells following receptor-mediated endocytosis and priming by cellular proteases. Following uptake, SARS-CoV-2 replicates in autophagosome-like structures in the cytosol following its escape from endolysosomes. Accordingly, the greater endolysosome pathway including autophagosomes and the mTOR sensor may be targets for therapeutic interventions against SARS-CoV-2 infection and COVID-19 pathogenesis. Naturally existing compounds (phytochemicals) through their actions on endolysosomes and mTOR signaling pathways might provide therapeutic relief against COVID-19. Here, we discuss evidence that some natural compounds through actions on the greater endolysosome system can inhibit SARS-CoV-2 infectivity and thereby might be repurposed for use against COVID-19.

Scutellaria baicalensis Flavones as Potent Drugs against Acute Respiratory Injury during SARS-CoV-2 Infection: Structural Biology Approaches

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can result in severe damage to the respiratory system. With no specific treatment to date, it is crucial to identify potent inhibitors of SARS-CoV-2 Chymotrypsin-like protease (3CLpro) that could also modulate the enzymes involved in the respiratory damage that accompanies SARS-CoV-2 infection. Here, flavones isolated from Scutellaria baicalensis (baicalein, baicalin, wogonin, norwogonin, and oroxylin A) were studied as possible compounds in the treatment of SARS-CoV-2 and SARS-CoV-2-induced acute lung injuries. We used structural bioinformatics and cheminformatics to (i) identify the critical molecular features of flavones for their binding activity at human and SARS-CoV-2 enzymes; (ii) predict their drug-likeness and lead-likeness features; (iii) calculate their pharmacokinetic profile, with an emphasis on toxicology; (iv) predict their pharmacodynamic profiles, with the identification of their human body targets involved in the respiratory system injuries; and (v) dock the ligands to SARS-CoV-2 3CLpro. All flavones presented appropriate drug-like and kinetics features, except for baicalin. Flavones could bind to SARS-CoV-2 3CLpro at a similar site, but interact slightly differently with the protease. Flavones’ pharmacodynamic profiles predict that (i) wogonin strongly binds at the cyclooxygenase2 and nitric oxide synthase; (ii) baicalein and norwogonin could modulate lysine-specific demethylase 4D-like and arachidonate 15-lipoxygenase; and (iii) baicalein, wogonin, norwogonin, and oroxylin A bind to SARS-CoV-2 3CLpro. Our results propose these flavones as possible potent drugs against respiratory damage that occurs during SARS-CoV-2 infections, with a strong recommendation for baicalein.