Anti-hepatitis C virus compounds obtained from Glycyrrhiza uralensis and other Glycyrrhiza species

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

Licochalcone A regulates viral IRES activity to inhibit enterovirus replication

Enterovirus D68 (EV-D68), belonging to the genus Enterovirus of the Picornavirus family, is an emerging pathogen that can cause neurological and respiratory diseases in children. However, there is little understanding of the pathogenesis of EV-D68, and no effective vaccine or drug for the prevention or treatment of the diseases caused by this virus is available. Autophagy is a cellular process that targets cytoplasmic proteins or organelles to the lysosomes for degradation. Enteroviruses strategically harness the host autophagy pathway to facilitate the completion of their life cycle. Therefore, we selected an autophagy compound library to screen for autophagy-related compounds that may affect viral growth. By using the neutralization screening assay, we identified a compound, 'licochalcone A' that significantly inhibited EV-D68 replication. To investigate the mechanism by which licochalcone A inhibits EV-D68 replication and to identify the viral life cycle stage it inhibits, the time-of-addition, viral attachment, viral entry, and dual-luciferase reporter assays were performed. The results of the time-of-addition assay showed that licochalcone A, a characteristic chalcone found in liquorice roots and widely used in traditional Chinese medicine, inhibits EV-D68 replication during the early stages of the viral life cycle, while those of the dual-luciferase reporter assay showed that licochalcone A does not regulate viral attachment and entry, but inhibits EV-D68 IRES-dependent translation. Licochalcone A also inhibited enterovirus A71 and coxsackievirus B3 but did not significantly inhibit dengue virus 2 or human coronavirus 229E replication. Licochalcone A regulates IRES translation to inhibit EV-D68 viral replication.

Glycyrol Prevents the Progression of Psoriasis-like Skin Inflammation via Immunosuppressive and Anti-Inflammatory Actions

Glycyrol (GC) is one natural active product. Imiquimod-induced psoriasis-like Balb/c mouse models were established. The model mice were intraperitoneally injected with cyclosporine A (CsA) and GC for 8 days followed by a series of biological detections. GC had little toxicity according to the levels of peripheral blood cells, hemoglobin, blood urea nitrogen (BUN), and serum creatinine (CRE), while CsA significantly increased the levels of BUN and CRE. GC decreased the splenic index and reduced the expressions of IL-6, IL-23, and CXCL-3 in the model mice and IL-6, CXCL-1, and CXCL-2 in the inflammatory HaCaT cells. The half inhibition concentration (IC50) of GC on HaCaT cells was 29.72 μmol/L, resulting in improved apoptosis, enhanced expressions of p21, BAX, and BIK, and reduced expressions of BCL-2. GC is an immunosuppressive agent against psoriasis-like symptoms by anti-inflammatory effects, which provides a strategy for the discovery of anti-psoriatic natural products.

Antiviral and antimicrobial applications of chalcones and their derivatives: From nature to greener synthesis

Chalcones and their derivatives have been widely studied due to their versatile pharmacological and biological activities, such as anti-inflammatory, antibacterial, antiviral, and antitumor effects. These compounds have shown suitable antiviral effects through the selective targeting of a variety of viral enzymes, including lactate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fumarate reductase, protein tyrosine phosphatase, topoisomerase-II, protein kinases, integrase/protease, and lactate/isocitrate dehydrogenase, among others. Chalcones and their derivatives have displayed excellent potential for combating pathogenic bacteria and fungi (especially, multidrug-resistant bacteria). However, relevant mechanisms should be further explored, focusing on inhibitory effects against DNA gyrase B, UDP-N-acetylglucosamine enolpyruvyl transferase (MurA), and efflux pumps (e.g., NorA), among others. In addition, the antifungal and antiparasitic activities of these compounds (e.g., antitrypanosomal and antileishmanial properties) have prompted additional explorations. Nonetheless, systematic analysis of the relevant mechanisms, biosafety issues, and pharmacological properties, as well as clinical translation studies, are vital for practical applications. Herein, recent advancements pertaining to the antibacterial, antiviral, antiparasitic, and antifungal activities of chalcones and their derivatives are deliberated, focusing on the relevant mechanisms of action, crucial challenges, and future prospects. Furthermore, due to the great importance of greener and more sustainable synthesis of these valuable compounds, especially on an industrial scale, the progress made in this field has been briefly discussed. Hopefully, this review can serve as a catalyst for researchers to delve deeper into the exploration and designing of novel chalcone compounds with medicinal properties, especially against pathogenic viruses and multidrug-resistant bacteria as major causes of concern for human health.

Licochalcone Mediates the Pain Relief by Targeting the Voltage-Gated Sodium Channel

Licorice is a traditional Chinese medicine and recorded to have pain relief effects in national pharmacopoeia, but the mechanisms behind these effects have not been fully explored. Among the hundreds of compounds in licorice, licochalcone A (LCA) and licochalcone B (LCB) are two important components belonging to the chalcone family. In this study, we compared the analgesic effects of these two licochalcones and the molecular mechanisms. LCA and LCB were applied in cultured dorsal root ganglion (DRG) neurons, and the voltage-gated sodium (NaV) currents and action potentials were recorded. The electrophysiological experiments showed that LCA can inhibit NaV currents and dampen excitabilities of DRG neurons, whereas LCB did not show inhibition effect on NaV currents. Because the NaV1.7 channel can modulate Subthreshold membrane potential oscillations in DRG neuron, which can palliate neuropathic pain, HEK293T cells were transfected with NaV1.7 channel and recorded with whole-cell patch clamp. LCA can also inhibit NaV1.7 channels exogenously expressed in HEK293T cells. We further explored the analgesic effects of LCA and LCB on formalin-induced pain animal models. The animal behavior tests revealed that LCA can inhibit the pain responses during phase 1 and phase 2 of formalin test, and LCB can inhibit the pain responses during phase 2. The differences of the effects on NaV currents between LCA and LCB provide us with the basis for developing NaV channel inhibitors, and the novel findings of analgesic effects indicate that licochalcones can be developed into effective analgesic medicines. SIGNIFICANCE STATEMENT: This study found that licochalcone A (LCA) can inhibit voltage-gated sodium (NaV) currents, dampen excitabilities of dorsal root ganglion neurons, and inhibit the NaV1.7 channels exogenously expressed in HEK293T cells. Animal behavior tests showed that LCA can inhibit the pain responses during phase 1 and phase 2 of formalin test, whereas licochalcone B can inhibit the pain responses during phase 2. These findings indicate that licochalcones could be the leading compounds for developing NaV channel inhibitors and effective analgesic medicines.

Medicinal plant molecules against hepatitis C virus: Current status and future prospect

Hepatitis C virus (HCV), a global malady, causes acute and chronic hepatitis leading to permanent liver damage, hepatocellular carcinoma, and death. Modern anti-HCV therapies are efficient, but mostly inaccessible for residents of underdeveloped regions. To innovate more effective treatments at affordable cost, medicinal plant-based products need to be explored. The aim of this article is to review plant constituents in the light of putative anti-HCV mechanisms of action, and discuss existing problems, challenges, and future directions for their potential application in therapeutic settings. One hundred sixty literatures were collected by using appropriate search strings via scientific search engines: Google Scholar, PubMed, ScienceDirect, and Scopus. Bibliography was prepared using Mendeley desktop software. We found a substantial number of plants that were reported to inhibit different stages of HCV life cycle. Traditional medicinal plants such as Phyllanthus amarus Schumach. and Thonn., Eclipta alba (L.) Hassk., and Acacia nilotica (L.) Delile exhibited strong anti-HCV activities. Again, several phytochemicals such as epigallocatechin-3-gallate, honokilol, punicalagin, and quercetin have shown broad-spectrum anti-HCV effect. We have presented promising phytochemicals like silymarin, curcumin, glycyrrhizin, and camptothecin for nanoparticle-based hepatocyte-targeted drug delivery. Nevertheless, only a few animal studies have been performed to validate the anti-HCV effect of these plant products. Again, insufficient clinical evaluation of the safety and effectiveness of herbal medications remain a problem. Selected plants products could be developed as novel therapeutics for HCV patients only after scrupulous evaluation of their safety and efficacy in a clinical set-up.

Acacia mangium: A promising plant for isolating anti-hepatitis C virus agents

Background: Medicinal plants are potential resources for isolating drug candidates. Various plants have been reported to possess pharmacological effects including anti-hepatitis C activities. The current study examined the anti-hepatitis C virus (HCV) activities of Acacia mangium extracts in solvents with various polarities and further evaluated the mechanism of action of the extracts using Western blotting and combination treatment models. Methods: The leaves of A. mangium were extracted in two phases, first in ethanol and then in solvents with different polarities (n-hexane, dichloromethane, and methanol). HCV-infected Huh7it-1 cells were treated with the extracts at concentrations of 0.01, 0.1, 1, 10, 50, and 100 µg/mL. Results: The results revealed the strong anti-HCV activities of the extracts. The 50% inhibition concentrations (IC 50s) of the ethanol, n-hexane, dichloromethane and methanol extracts were of 4.6 ± 0.3, 2.9 ± 0.2, 0.2 ± 0.3, and 2.8 ± 0.2 μg/mL, respectively, and no cytotoxic effect was detected. These extracts displayed stronger effects than the positive control ribavirin. The mode of action of the ethanol extract was evaluated at 30 µg/mL, revealing that the inhibitory effect was stronger on the post-entry step than on the entry step. Western blotting revealed that the extracts decreased NS3 protein expression, indicating that virus replication was suppressed. Further evaluation illustrated that combined treatment with the ethanol extract enhanced the anti-viral activity of simeprevir. Conclusions: These results indicated that A. mangium leaves could represent sources of anti-HCV agents.

Metabolic bioprofiling of different Glycyrrhiza glabra solvent fractions for the identification of anti-adenoviral compounds using LC-HRMS/MS and in-vitro cytopathic assay coupled with chemometry

Human adenovirus type-7 (HAdV-7) is a common pathogen that may cause significant morbidity as well as severe complications. Currently, there is no approved drug for the treatment of HAdV-7 infections and the contemporary strategy mainly rely on nonspecific antivirals. Glycyrrhiza glabra; (licorice), is a well-recognized edible plant used in food and beverages. The plant is renowned for its pharmacological and biological activities including antiviral activities against wide range of viruses. The following study reported for the first time the anti-adenoviral activity of licorice extract using in-vitro cytopathic inhibitory assay. Different solvent fractions showed promising activity with IC₅₀ reaching 1.431 μg/ml. Certain fractions had selectivity index (SI) greater than 10 indicating their efficacy together with relatively low cytotoxic effect. Metabolic profiling using LC-HRMS/MS resulted in identification of 41 compounds from licorice fractions. Chemometric modeling using Orthogonal Projections to Latent Structures (OPLS) suggested the compounds; kaempferol-3-O-rutinoside, violanthin, rhamnoliquiritin, isoliquiritigenin isomer, licoagroside B and liquiritin apioside as potential markers against (HAdV-7). Finally, kaempferol-3-O-rutinoside was further confirmed via in-vitro adenovirus inhibitory assay to possess strong antiviral activity with IC₅₀ and CC₅₀ of 54.7 ± 1.93 μM and 655.7 ± 2.22 μM, respectively.

Short communication: Antibacterial effects of essential oils from Cinnamomum cassia bark and Eucalyptus globulus leaves-The involvements of major constituents

Essential oils from Cinnamomum cassia bark and Eucalyptus globulus leaves have been traditionally applied for bacterial infections, through both of aromatherapy and oral application. (E)-cinnamaldehyde and 1,8 cineole have been identified as their major secondary metabolites, and are also generally considered as the main active ingredients responsible for their medicinal applications. However, ethnobotanical doctors still prefer to use whole essentials oils over purified compounds in bacterial infections. We therefore hypothesized that multi-compound extracts might exert better effects than isolated ingredients. In order to verify the hypothesis about advantages of whole materials, we examined antibacterial properties of the 2 plant essential oils in the comparison with their isolated major compounds, such as (E)-cinnamaldehyde and 1,8 cineole. Effects of liquid- and vapor-phase were examined on a set of 6 gram-positive and -negative bacteria, applying broth dilution, agar well diffusion and disc volatilization methods. In all 3 investigations, we observed that whole cinnamon and eucalyptus oils, with the lower concentrations of (E)-cinnamaldehyde (89.1%) and 1,8 cineole (61.2%), were able to induce better effects than the purified active compounds (≥ 99%). These results partly explain the advantages of using whole essential oils over isolated ingredients, and therefore support the application of traditional dosage forms for bacterial infections in ethnomedicine.

Absorption, tissue distribution, and excretion of glycycoumarin, a major bioactive coumarin from Chinese licorice (Glycyrrhiza uralensis Fisch)

Licorice (Glycyrrhiza uralensis Fisch) is a natural plant resource widely used as a food and herbal medication in China. Glycycoumarin (GCM) is a major coumarin in licorice that possesses several biological activities. However, little is known about its pharmacokinetic profile. The present study aimed to describe the oral absorption, tissue distribution, and excretion of GCM in rats. Free (parent drug) and/or total (parent drug plus the glucuronidated metabolite) GCM in biological samples was quantified before and after the hydrolysis reaction with β-glucuronidase using a reliable LC-MS/MS method. The results indicated that GCM was rapidly absorbed and transformed into its conjugated metabolites after administration. Free GCM plasma concentrations after i. v. (10 mg/kg) administration quickly decreased with an average t_1/2,λz of 0.71 h, whereas the total GCM concentration reduced slowly with a t_{1/2, λz} of 2.46 h. The area under the curve of glucuronidated metabolites was approximately four-times higher than that of free GCM. Presumably, because of hepatic and/or intestinal tract first-pass metabolism, GCM exhibited a poor bioavailability of 9.22%, as estimated from its total plasma concentration. Additionally, GCM was distributed rapidly and widely in various tissues except the brain. The liver had the highest concentration; further, GCM was promptly eliminated from test tissues after intraperitoneal (20 mg/kg) administration, but only a small amount of GCM was excreted via bile and urine. Overall, GCM is absorbed and rapidly transformed into its conjugated metabolites with low bioavailability; further, it is distributed in various tissues, except the brain. These pharmacokinetic results are helpful for better understanding the characteristics and pharmacological effects of GCM.

Effects of Varying Ratios of Glycyrrhiza uralensis and Donkey Hide Gelatin Water Extracts on Dinitrochlorobenzene-Induced Atopic Dermatitis in NC/Nga Mice

Atopic dermatitis is a chronic skin disease that affects millions of people all over the world. The objective of this study was to evaluate the inhibitory effects of the roots of Glycyrrhiza uralensis (GU) and Donkey Hide Gelatin (DHG) water extracts on DNCB-induced NC/Nga mice and TNF-α/IFN-γ treated keratinocytes or LPS-stimulated macrophages. The combined treatment using the water extracts of GU and DHG improved the skin symptom evaluation score and skin histology, with increased expression of the skin barrier proteins Claudin 1 and Sirt 1 in lesion areas. The IFN-γ activity was promoted in PBMCs, ALN, and dorsal skin tissue, while the absolute cell number was reduced for T cells so that the production and expression of serum IgE and cytokines were suppressed. In TNF-α/IFN-γ induced HaCaT cells, IL-6, IL-8, MDC, and RANTES were all inhibited by GU and DHG water extracts, while ICAM-1 and COX-2 levels were similarly downregulated. In addition, GU and DHG water extracts decreased LPS-mediated nitric oxide, IL-6, TNF-α, and PGE₂ in RAW 264.7 cells, and the expression of iNOS and COX-2 also decreased. Notably, the DHG:GU ratio of 4:1 was shown to have the best effects of all ratios. In conclusion, GU and DHG have anti-skin inflammatory potentials that can be used as alternative ingredients in the formula of functional foods for people with atopic dermatitis.

Computational Exploration of Licorice for Lead Compounds against Plasmodium vivax Duffy Binding Protein Utilizing Molecular Docking and Molecular Dynamic Simulation

Plasmodium vivax (P. vivax) is one of the human's most common malaria parasites. P. vivax is exceedingly difficult to control and eliminate due to the existence of extravascular reservoirs and recurring infections from latent liver stages. Traditionally, licorice compounds have been widely investigated against viral and infectious diseases and exhibit some promising results to combat these diseases. In the present study, computational approaches are utilized to study the effect of licorice compounds against P. vivax Duffy binding protein (DBP) to inhibit the malarial invasion to human red blood cells (RBCs). The main focus is to block the DBP binding site to Duffy antigen receptor chemokines (DARC) of RBC to restrict the formation of the DBP-DARC complex. A molecular docking study was performed to analyze the interaction of licorice compounds with the DARC binding site of DBP. Furthermore, the triplicates of molecular dynamic simulation studies for 100 ns were carried out to study the stability of representative docked complexes. The leading compounds such as licochalcone A, echinatin, and licochalcone B manifest competitive results against DBP. The blockage of the active region of DBP resulting from these compounds was maintained throughout the triplicates of 100 ns molecular dynamic (MD) simulation, maintaining stable hydrogen bond formation with the active site residues of DBP. Therefore, the present study suggests that licorice compounds might be good candidates for novel agents against DBP-mediated RBC invasion of P. vivax.

In Silico Study of Coumarins: Wedelolactone as a Potential Inhibitor of the Spike Protein of the SARS-CoV-2 Variants

Despite the rigorous global efforts to control SARS-CoV-2 transmission, it continues to pose a serious threat to humans with the frequent emergence of new variants. Thus, robust therapeutics to combat the virus are a desperate need. The SARS-CoV-2 spike (S) protein is an important target protein as it mediates the entry of the virus inside the host cells, which is initiated by the binding of the receptor-binding domain (RBD) to its cognate receptor, angiotensin-converting enzyme 2 (ACE-2). Herein, the inhibition potential of several naturally occurring coumarins was investigated against the spike proteins of SARS-CoV-2 variants using computational approaches. Molecular docking studies revealed 26 coumarins with better binding energies than the reference ligands, molnupiravir and ceftazidime, against the S-RBD of the omicron variant. The top 10 best-docked coumarins were further analyzed to understand their binding interactions against the spike proteins of other variants (wild-type, Alpha, Beta, Gamma, and Delta), and these studies also demonstrated decent binding energies. Physicochemical, QSAR, and pharmacokinetics analyses of the coumarins revealed wedelolactone as the best inhibitor of the spike protein with ideal Lipinski’s drug-likeness and optimal ADMET properties. Furthermore, coarse-grained molecular dynamics (MD) simulation studies of spike protein-wedelolactone complexes validated the stable binding of wedelolactone in the respective binding pockets. As an outcome, wedelolactone could be utilized to develop a potent drug candidate against COVID-19 by blocking the viral entry into the host cell.

Plant Coumarins with Anti-HIV Activity: Isolation and Mechanisms of Action

This review summarizes and systematizes the literature on the anti-HIV activity of plant coumarins with emphasis on isolation and the mechanism of their antiviral action. This review summarizes the information on the anti-HIV properties of simple coumarins as well as annulated furano- and pyranocoumarins and shows that coumarins of plant origin can act by several mechanisms: inhibition of HIV reverse transcriptase and integrase, inhibition of cellular factors that regulate HIV-1 replication, and transmission of viral particles from infected macrophages to healthy ones. It is important to note that some pyranocoumarins are able to act through several mechanisms or bind to several sites, which ensures the resistance of these compounds to HIV mutations. Here we review the last two decades of research on the anti-HIV activity of naturally occurring coumarins.

Flavan-based phytoconstituents inhibit Mpro, a SARS-COV-2 molecular target, in silico

A well-validated in-silico approach can provide promising drug candidates for the treatment of the ongoing CoVID19 pandemic. In this study, we have screened 32 phytochemical constituents (PCCs) with Mpro binding site (PDB:6W63) based on which we identified three possible candidates that are likely to be effective against CoVID19-viz., licoleafol (binding energy: -8.1 kcal/mol), epicatechin gallate (-8.5 kcal/mol) and silibinin (-8.4 kcal/mol) that result in higher binding affinity than the known inhibitor, X77 (-7.7 kcal/mol). Molecular dynamics (MD) simulations of PCCs-Mpro complex confirmed molecular docking results with high structural and dynamical stability. The selected compounds were found to exhibit low mean squared displacements (licoleafol: 2.25 ± 0.43 Å, epicatechin gallate: 1.93 ± 0.35 Å, and silibinin: 1.39 ± 0.19 Å) and overall low fluctuations of the binding complexes (root mean squared fluctuations below 2 Å). Visualization of the MD trajectories and structural analyses revealed that they remain confined to the initial binding region, with mean fluctuations lower than 3 Å. To access the collective motion of the atoms, we performed principal component analysis demonstrating that the first 10 principal components are the major contributors (approximate contribution of 80%) and are responsible for the overall PCCs motion. Considering that the three selected PCCs share the same flavan backbone and exhibit antiviral activity against hepatitis C, we opine that licoleafol, epi-catechin gallate, and silibinin can be promising anti-CoVID19 drug candidates. Communicated by Ramaswamy H. Sarma.

Pharmacological Activities and Pharmacokinetics of Glycycoumarin

Glycycoumarin is a representative coumarin compound with significant pharmacological activities isolated from Glycyrrhiza uralensis Fisch., Fabaceae. Studies have shown that glycycoumarin has many biological activities, such as anti-tumor, liver protection, antispasmodic, antibacterial, and antivirus. However, the poor solubility of glycycoumarin in water and the accompanying reactions of the phase I (hydroxylation) and II (glucuronidation) metabolism limit its druggability, which manifests as low absorption in the body after oral administration and low free drug concentration, ultimately leading to low bioavailability. Therefore, a comprehensive review of the pharmacological effects and pharmacokinetics of glycycoumarin is presented to provide a reference for further research and application as a therapeutic agent.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-022-00342-x.

Recruitment of chalcone's potential in drug discovery of anti-SARS-CoV-2 agents

Chalcone is an interesting scaffold found in the structure of many naturally occurring molecules. Medicinal chemists are commonly interested in designing new chalcone-based structures because of having the α, β-unsaturated ketone functional group, which allows these compounds to participate in Michael's reaction and create strong covalent bonds at the active sites of the targets. Some studies have identified several natural chalcone-based compounds with the ability to inhibit the severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus proteases. A few years after the advent of the coronavirus disease 2019 pandemic and the publication of many findings in this regard, there is some evidence that suggests chalcone scaffolding has great potential for use in the design and development of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inhibitors. Artificial placement of this scaffold in the structure of optimized anti-SARS-CoV-2 compounds can potentially provide irreversible inhibition of the viral cysteine proteases 3-chymotrypsin-like protease and papain-like protease by creating Michael interaction. Despite having remarkable capabilities, the use of chalcone scaffold in drug design and discovery of SARS-CoV-2 inhibitors seems to have been largely neglected. This review addresses issues that could lead to further consideration of chalcone scaffolding in the structure of SARS-CoV-2 protease inhibitors in the future.

18β-Glycyrrhetinic acid altered the intestinal permeability in the human Caco-2 monolayer cell model

PURPOSE

Glycyrrhizin (GL) and its metabolites 18α-glycyrrhetinic acid (18α-GA) and 18β-glycyrrhetinic acid (18β-GA) are used as traditional medicine and food sweeteners. As the major rout of their administration is oral way, therefore their impact on intestinal epithelial cells are investigated.

METHODS

The effects of GL and its metabolites on cell viability using MTT assay, on cytotoxicity using LDH release, on integrity of intestinal epithelial cells by measuring the transepithelial electrical resistance (TEER) and Luciferase permeability tests, on the expression of tight junction proteins at mRNA and protein level by qPCR and western blot techniques, and ultimately on the rate of test compounds absorption via Caco-2 cells monolayer were investigated.

RESULTS

MTT assay showed a concentration- and time-dependent decrease in metabolic activity of Caco-2 cells induced by GL, 18α-GA, and 18β-GA, while only 18β-GA increased the LDH leakage. The monolayer integrity of Caco-2 cells in TEER assay only was affected by 18β-GA. The permeability of paracellular transport marker was increased by 18α-GA and 18β-GA and not GL. In transport studies, only metabolites were able to cross from Caco-2 cells monolayer. qPCR analyses revealed that 18β-GA upregulated the expression of claudin-1 and -4, occludin, junctional adhesion molecules and zonula occludens-1, while 18α-GA upregulated only claudin-4. The expression of claudin-4 at protein level was downregulated non-significantly at 50 μM concentration of 18β-GA.

CONCLUSION

Our results suggest that 18β-GA may cause cellular damages at higher concentrations on gastrointestinal cells and requires a remarkable attention of the nutraceutical and pharmaceutical industries.

Coumarins as Fungal Metabolites with Potential Medicinal Properties

Coumarins are a structurally varied set of 2H-chromen-2-one compounds categorized also as members of the benzopyrone group of secondary metabolites. Coumarin derivatives attract interest owing to their wide practical application and the unique reactivity of fused benzene and pyrone ring systems in molecular structure. Coumarins have their own specific fingerprints as antiviral, antimicrobial, antioxidant, anti-inflammatory, antiadipogenic, cytotoxic, apoptosis, antitumor, antitubercular, and cytotoxicity agents. Natural products have played an essential role in filling the pharmaceutical pipeline for thousands of years. Biological effects of natural coumarins have laid the basis of low-toxic and highly effective drugs. Presently, more than 1300 coumarins have been identified in plants, bacteria, and fungi. Fungi as cultivated microbes have provided many of the nature-inspired syntheses of chemically diverse drugs. Endophytic fungi bioactivities attract interest, with applications in fields as diverse as cancer and neuronal injury or degeneration, microbial and parasitic infections, and others. Fungal mycelia produce several classes of bioactive molecules, including a wide group of coumarins. Of promise are further studies of conditions and products of the natural and synthetic coumarins’ biotransformation by the fungal cultures, aimed at solving the urgent problem of searching for materials for biomedical engineering. The present review evaluates the fungal coumarins, their structure-related peculiarities, and their future therapeutic potential. Special emphasis has been placed on the coumarins successfully bioprospected from fungi, whereas an industry demand for the same coumarins earlier found in plants has faced hurdles. Considerable attention has also been paid to some aspects of the molecular mechanisms underlying the coumarins’ biological activity. The compounds are selected and grouped according to their cytotoxic, anticancer, antibacterial, antifungal, and miscellaneous effects.

Virtual screening reveals liquiritigenin as a broad-spectrum inhibitor of SARS-CoV-2 variants of concern: an in silico study

The SARS-CoV-2 has severely impacted the lives of people worldwide. Global concern is on the rise due to a large number of unexpected mutations in the viral genome, resulting in new variants. Nature-based bioactive phytochemicals hold great promise as inhibitors against pathogenic viruses. The current study was aimed at evaluating some bioactive antiviral phytochemicals against SARS-CoV-2 variants of concern. A total of 46 phytochemicals were screened against the pathogenic spike protein of Alpha, Beta, Delta, Gamma, and Omicron variants. In addition to molecular docking, screening for favorable pharmacokinetic and pharmacodynamic properties such as absorption, distribution, metabolism, excretion, and toxicity was undertaken. For each of the aforementioned five SARS-CoV-2 variants of concern, a 100 ns molecular dynamics simulation was run to assess the stability of the complexes between their respective spike protein receptor-binding domain and the best-selected compound. From our current investigation, the natural compound liquiritigenin turned out to be the most promising potential lead compound against almost all the variants. These findings could pave the way for the development of effective medications against SARS-CoV-2 variants. However, in vivo trials in future studies are necessary for further validation of our results.Communicated by Ramaswamy H. Sarma.

The long and stumble way to find potential active compounds from plants for defeating hepatitis B and C: review

Hepatitis is a liver illness caused by virus such as hepatitis A virus, hepatitis B virus and hepatitis C virus. Hepatitis B and C are considerably more usual and induce more cirrhosis and dead worldwide than hepatitis A. Although drugs that are currently often used in the medication of hepatitis B and C, the finding of recent drug from various resources including herbal has been intensively developed. Therefore, the purpose of this review is to consider the possibility of plant’s compounds as anti-HBV and anti-HCV. From the results of a review of several articles, several plant’s compound have shown effectiveness againts HBV and HCV by in silico, in vitro and in vivo studies. In conclusion, several plant’s active compounds are possibility to be developed as anti-hepatitis B and C.

Therapeutic Intervention in Cancer by Isoliquiritigenin from Licorice: A Natural Antioxidant and Redox Regulator

Oxidative stress could lead to a variety of body dysfunctions, including neurodegeneration and cancer, which are closely associated with intracellular signal transducers such as reactive oxygen species (ROS). It has been suggested that ROS is the upstream regulator of autophagy, and that it provides a negative feedback regulation to remove oxidative damage. Defects in the ROS-autophagic redox homeostasis could lead to the increased production of ROS and the accumulation of damaged organelles that in turn promote metabolic reprogramming and induce tumorigenesis. One significant characteristic of pancreatic cancer is the reprogramming of cellular energy metabolism, which facilitates the rapid growth, invasiveness, and the survival of cancer cells. Thus, the rectification of metabolic dysfunction is essential in therapeutic cancer targeting. Isoliquiritigenin (ISL) is a chalcone obtained from the plant Glycyrrhiza glabra, which is a powdered root licorice that has been consumed for centuries in different regions of the world. ISL is known to be a natural antioxidant that possesses diversified functions, including redox regulation in cells. This review contains discussions on the herbal source, biological properties, and anticancer potential of ISL. This is the first time that the anticancer activities of ISL in pancreatic cancer has been elucidated, with a coverage of the involvement of antioxidation, metabolic redox regulation, and autophagy in pancreatic cancer development. Furthermore, some remarks on related compounds of the isoflavonoid biosynthetic pathway of ISL will also be discussed.

Formulation Design and Cell Cytotoxicity of Curcumin-Loaded Liposomal Solid Gels for Anti-Hepatitis C Virus

Backgrounds. Curcumin (CUR) is a low-molecular-weight polyphenolic substance obtained from the tuber part of Curcuma species. Anti-inflammatory and anti-hepatitis C virus (HCV) activities have been associated with CUR. However, its poor aqueous solubility and low systemic bioavailability have been the challenges in improving the therapeutic efficacy of curcumin. Aim. The study aimed to produce CUR-loaded liposomal solid gels as anti-HCV delivery systems. Parameters including the physical characteristics and the cell cytotoxicity properties were evaluated. Methods. The freeze-drying technique was applied to manufacture the CUR-loaded liposomal solid gels. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), and differential thermal analysis (DTA) were involved to reveal the characteristics of the solid gels. Such characteristics were as follows: the morphology and the microscopic structure of the solid gels, the crystallinity structure of the curcumin, and the thermal properties of the mixtures. Furthermore, their cell cytotoxicity was investigated using a Huh7it cell line. Results. The SEM images confirmed that curcumin liposomes were intact and trapped in the solid gel matrix. The XRD data showed flat patterns diffractograms of the formulations, confirming the transformation of CUR from crystalline to amorphous form. The DTA thermograms showed a single melting endothermic peak at a higher temperature around 200°C, indicating a single-phase transition of the mixtures. The XRD and DTA data revealed the molecular dispersion of CUR in the developed formulations. The cytotoxicity data provided as cell cytotoxicity 50 (CC50) for all formulations were ≥25 mg. These data confirmed that the developed liposomal solid gels were not cytotoxic to Huh7it cell line, indicating that the anti-HCV activity would be through a specific pathway and not by its toxicity. Conclusion. The CUR-loaded liposomal solid gels exhibited the potential and offered an alternative dosage form to improve the therapeutic efficacy of curcumin as an anti-HCV.

Isolation and Characterization of Two Chalcone Derivatives with Anti-Hepatitis B Virus Activity from the Endemic Socotraen Dracaena cinnabari (Dragon’s Blood Tree)

Hepatitis B virus (HBV) infection is prevalent and continues to be a global health concern. In this study, we determined the anti-hepatitis B virus (HBV) potential of the Socotra-endemic medicinal plant Dracaena cinnabari and isolated and characterized the responsible constituents. A bioassay-guided fractionation using different chromatographic techniques of the methanolic extract of D. cinnabari led to the isolation of two chalcone derivatives. Using a variety of spectroscopic techniques, including ¹H-, ¹³C-, and 2D-NMR, these derivatives were identified as 2,4’-dihydroxy-4-methoxydihydrochalcone (compound 1) and 2,4’-dihydroxy-4-methoxyhydrochalcone (compound 2). Both compounds were isolated for the first time from the red resin (dragon’s blood) of D. cinnabari. The compounds were first evaluated for cytotoxicity on HepG2.2.15 cells and 50% cytotoxicity concentration (CC50) values were determined. They were then evaluated for anti-HBV activity against HepG2.2.15 cells by assessing the suppression of HBsAg and HBeAg production in the culture supernatants and their half maximum inhibitory concentration (IC₅₀) and therapeutic index (TI) values were determined. Compounds 1 and 2 indicated inhibition of HBsAg production in a dose- and time-dependent manner with IC₅₀ values of 20.56 and 6.36 μg/mL, respectively.

Traditional Uses, Pharmacological Effects, and Molecular Mechanisms of Licorice in Potential Therapy of COVID-19

The current Coronavirus disease 2019 (COVID-19) pandemic has become a global challenge, and although vaccines have been developed, it is expected that mild to moderate patients will control their symptoms, especially in developing countries. Licorice, not only a food additive, but also a common traditional Chinese herbal medicine, which has several pharmacological effects, such as anti-inflammation, detoxification, antibacterial, antitussive, and immunomodulatory effects, especially in respiratory diseases. Since the outbreak of COVID-19, glycyrrhizin, glycyrrhizin diamine and glycyrrhizin extract have been widely studied and used in COVID-19 clinical trials. Therefore, it is a very interesting topic to explore the material basis, pharmacological characteristics and molecular mechanism of licorice in adjuvant treatment of COVID-19. In this paper, the material basis of licorice for the prevention and treatment of COVID-19 is deeply analyzed, and there are significant differences among different components in different pharmacological mechanisms. Glycyrrhizin and glycyrrhetinic acid inhibit the synthesis of inflammatory factors and inflammatory mediators by blocking the binding of ACE 2 to virus spike protein, and exert antiviral and antibacterial effects. Immune cells are stimulated by multiple targets and pathways to interfere with the pathogenesis of COVID-19. Liquiritin can prevent and cure COVID-19 by simulating type I interferon. It is suggested that licorice can exert its therapeutic advantage through multi-components and multi-targets. To sum up, licorice has the potential to adjuvant prevent and treat COVID-19. It not only plays a significant role in anti-inflammation and anti-ACE-2, but also significantly improves the clinical symptoms of fever, dry cough and shortness of breath, suggesting that licorice is expected to be a candidate drug for adjuvant treatment of patients with early / mild COVID-19.

Chalcone Scaffolds, Bioprecursors of Flavonoids: Chemistry, Bioactivities, and Pharmacokinetics

Chalcones are secondary metabolites belonging to the flavonoid (C6-C3-C6 system) family that are ubiquitous in edible and medicinal plants, and they are bioprecursors of plant flavonoids. Chalcones and their natural derivatives are important intermediates of the flavonoid biosynthetic pathway. Plants containing chalcones have been used in traditional medicines since antiquity. Chalcones are basically α,β-unsaturated ketones that exert great diversity in pharmacological activities such as antioxidant, anticancer, antimicrobial, antiviral, antitubercular, antiplasmodial, antileishmanial, immunosuppressive, anti-inflammatory, and so on. This review provides an insight into the chemistry, biosynthesis, and occurrence of chalcones from natural sources, particularly dietary and medicinal plants. Furthermore, the pharmacological, pharmacokinetics, and toxicological aspects of naturally occurring chalcone derivatives are also discussed herein. In view of having tremendous pharmacological potential, chalcone scaffolds/chalcone derivatives and bioflavonoids after subtle chemical modification could serve as a reliable platform for natural products-based drug discovery toward promising drug lead molecules/drug candidates.

The potential of glycyrrhizin and licorice extract in combating COVID-19 and associated conditions

BACKGROUND

Several recent studies have stated that glycyrrhizin and licorice extract are present in most traditional Chinese medicine formulas used against SARS-CoV-2 in China. Significant data are showing that glycyrrhizin and licorice extract have multiple beneficial activities in combating most features of SARS-CoV-2.

PURPOSE

The aim of current review was to highlight recent progresses in research that showed the evidence of the potential use of glycyrrhizin and licorice extract against COVID-19.

METHODOLOGY

We have reviewed the information published from 1979 to October 2020. These studies demonstrated the effects , use and safety of glycyrrhizin and icorice extract against viral infections,bacterial infections, inflammatory disorders of lung ( in vitro and in vivo).  These studies were collated through online electronic databases research (Academic libraries as PubMed, Scopus, Web of Science and Egyptian Knowledge Bank).

RESULTS

Pooled effect size of articles provides information about the rationale for using glycyrrhizin and licorice extract to treat COVID-19. Fifty studies demonstrate antiviral activity of glycyrrhizin and licorice extract. The most frequent mechanism of the antiviral activity is due to disrupting viral uptake into the host cells and disrupting the interaction between receptor- binding domain (RBD) of SARS-COV2 and ACE2 in recent articles. Fifty studies indicate that glycyrrhizin and licorice extract have significant antioxidant, anti-inflammatory and immunomodulatory effects. Twenty five studies provide evidence for the protective effect of glycyrrhizin and licorice extract against inflammation-induced acute lung injury and cardiovascular disorders.

CONCLUSION

The current study showed several evidence regarding the beneficial effects of glycyrrhizin and licorice extract in combating COVID-19. More randomized clinical trials are needed to obtain a precise conclusion.

Glycyrrhiza Genus: Enlightening Phytochemical Components for Pharmacological and Health-Promoting Abilities

The Glycyrrhiza genus, generally well-known as licorice, is broadly used for food and medicinal purposes around the globe. The genus encompasses a rich pool of bioactive molecules including triterpene saponins (e.g., glycyrrhizin) and flavonoids (e.g., liquiritigenin, liquiritin). This genus is being increasingly exploited for its biological effects such as antioxidant, antibacterial, antifungal, anti-inflammatory, antiproliferative, and cytotoxic activities. The species Glycyrrhiza glabra L. and the compound glycyrrhizin (glycyrrhizic acid) have been studied immensely for their effect on humans. The efficacy of the compound has been reported to be significantly higher on viral hepatitis and immune deficiency syndrome. This review provides up-to-date data on the most widely investigated Glycyrrhiza species for food and medicinal purposes, with special emphasis on secondary metabolites' composition and bioactive effects.

In silico analysis and identification of antiviral coumarin derivatives against 3-chymotrypsin-like main protease of the novel coronavirus SARS-CoV-2

Abstract

Coronavirus disease 2019 (COVID-19) is a pandemic viral disease caused by SARS-CoV-2 that generated serious damages for both the human population and the global economy. Therefore, it is currently considered as one of the most important global health problems of human societies and there is an urgent need for potent drugs or vaccines which can effectively combat this virus. The chymotrypsin-like protease (3CLpro) of SARS-CoV-2 plays a key role in the viral replication inside the host and thus is a promising drug target to design and develop effective antiviral drugs against SARS and other coronaviruses. This study evaluated some antiviral coumarin phytochemicals as potential inhibitors of coronaviruses 3CLpro by in silico approaches such as molecular docking, ADMET prediction, molecular dynamics simulation, and MM-PBSA binding energy calculation. Natural coumarin derivatives were docked to the 3CLpro of SARS-CoV-2 and for further investigation, docked to the 3CLpro of SARS-CoV and MERS-CoV. The docking scores of these natural compounds were compared with 3CLpro referenced inhibitors (ritonavir and lopinavir) and co-crystal inhibitor N3. Molecular docking studies suggested more than half of the coumarin phytochemicals had favorable interaction at the binding pocket of the coronaviruses 3CLpro and exhibited better binding affinities toward 3CLpro than ritonavir and lopinavir. Most antiviral phytochemicals interact strongly with one or both the catalytic dyad residues (His41 and Cys145) and the other key residues of SARS-CoV-2 main protease. Further, MD simulation and binding free energy calculations using MM-PBSA were carried out for three 3CLpro-coumarin complexes and 3CLpro-N3/lopinavir. The results confirmed that the 3CLpro-glycycoumarin, 3CLpro-oxypeucedanin hydrate, and 3CLpro-inophyllum P complexes were highly stable, experience fewer conformation fluctuations and share a similar degree of compactness. Also, the pharmacokinetics and drug-likeness studies showed good results for the selected coumarin phytochemicals.Therefore, the coumarin phytochemicals could be used as antiviral agents in the treatment of COVID-19 after further studies.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11030-021-10230-6.

Licochalcone A inhibits enterovirus A71 replication in vitro and in vivo

Enterovirus A71 (EV-A71) is one of the main causative agents of hand-foot-mouth disease (HFMD) and causes serious neurological complications. However, no effective therapy is currently available for treating these infections. Therefore, effective drugs to prevent and treat EV-A71 infections are urgently needed. Here, we demonstrated that treatment with Licochalcone A (LCA) significantly inhibited EV-A71 replication in a dose-dependent manner, with an EC₅₀ of 9.30 μM in RD cells and 5.73 μM in Vero cells. The preliminary results on the inhibition mechanism showed that LCA exerted antiviral effects by interfering with the early step of viral replication. We further demonstrated that LCA showed potent antiviral activity against many enteroviruses, including EV-A71 (strain C4), EV-A71 (strain H), and coxsackievirus A16 (CV-A16). Furthermore, LCA could effectively prevent the clinical symptoms and death of virus infected mice and decreased viral load in EV-A71-infected mice. Taken together, our studies showed for the first time, that LCA is a promising EV-A71 inhibitor and provide important information for the clinical development of LCA as a potential new anti-EV-A71 agent.

Medicinal plant compounds as promising inhibitors of coronavirus (COVID-19) main protease: an in silico study

The novel Coronavirus (COVID-19) has spread rapidly across the globe and has involved more than 215 countries and territories. Due to a lack of effective therapy or vaccine, urgent and concerted efforts are needed to identify therapeutic targets and medications. COVID-19 main protease represents a major target for drug treatment to inhibit viral function. The present study sought to evaluate medicinal plant compounds as potential inhibitors of the COVID-19 main protease using molecular docking and molecular dynamic analysis. The PDB files of COVID-19 main protease and some medicinal plant compounds were retrieved from the Protein Data Bank (http://www.rcsb.org) and Pubchem server, respectively. The Gromacs software was used for simulation studies, and molecular docking analysis was done using Autodock 4.2. The COVID-19 main protease simulation, compared with some phytochemicals docked to the COVID-19 main protease, were analyzed. Glabridin, catechin, and fisetin had the greatest tendency to interact with the COVID-19 main protease by hydrogen and hydrophobic interactions. Docking of these phytochemicals to COVID-19 main protease led to an increase in the radius of gyration (Rg), decrease in the Root mean square fluctuation (RMSF), and induced variation in COVID-19 main protease secondary structure. The high tendency interaction of glabridin, catechin, and fisetin to COVID-19 main protease induced conformational changes on this enzyme. These interactions can lead to enzyme inhibition. This simulated study indicates that these phytochemicals may be considered as potent inhibitors of the viral protease; however, more investigations are required to explore their potential medicinal use.Communicated by Ramaswamy H. Sarma.

Phytochemicals from Plant Foods as Potential Source of Antiviral Agents: An Overview

To date, the leading causes of mortality and morbidity worldwide include viral infections, such as Ebola, influenza virus, acquired immunodeficiency syndrome (AIDS), severe acute respiratory syndrome (SARS) and recently COVID-19 disease, caused by the SARS-CoV-2 virus. Currently, we can count on a narrow range of antiviral drugs, especially older generation ones like ribavirin and interferon which are effective against viruses in vitro but can often be ineffective in patients. In addition to these, we have antiviral agents for the treatment of herpes virus, influenza virus, HIV and hepatitis virus. Recently, drugs used in the past especially against ebolavirus, such as remdesivir and favipiravir, have been considered for the treatment of COVID-19 disease. However, even if these drugs represent important tools against viral diseases, they are certainly not sufficient to defend us from the multitude of viruses present in the environment. This represents a huge problem, especially considering the unprecedented global threat due to the advancement of COVID-19, which represents a potential risk to the health and life of millions of people. The demand, therefore, for new and effective antiviral drugs is very high. This review focuses on three fundamental points: (1) presents the main threats to human health, reviewing the most widespread viral diseases in the world, thus describing the scenario caused by the disease in question each time and evaluating the specific therapeutic remedies currently available. (2) It comprehensively describes main phytochemical classes, in particular from plant foods, with proven antiviral activities, the viruses potentially treated with the described phytochemicals. (3) Consideration of the various applications of drug delivery systems in order to improve the bioavailability of these compounds or extracts. A PRISMA flow diagram was used for the inclusion of the works. Taking into consideration the recent dramatic events caused by COVID-19 pandemic, the cry of alarm that denounces critical need for new antiviral drugs is extremely strong. For these reasons, a continuous systematic exploration of plant foods and their phytochemicals is necessary for the development of new antiviral agents capable of saving lives and improving their well-being.

Naturally occurring coumestans from plants, their biological activities and therapeutic effects on human diseases

Naturally occurring coumestans are known as a collection of plant-derived polycyclic aromatic secondary metabolites which are characterized by the presence of an oxygen heterocyclic four-ring system comprising a coumarin moiety and a benzofuran moiety sharing a C˭C bond. Recently, there is an increasing attention in excavating the medicinal potential of coumestans, particularly coumestrol, wedelolactone, psoralidin and glycyrol, in a variety of diseases. This review is a comprehensive inventory of the chemical structures of coumestans isolated from various plant sources during the period of 1956-2020, together with their reported biological activities. 120 molecules were collected and further classified as coumestans containing core skeleton, dimethylpyranocoumestans, furanocoumestans, O-glycosylated coumestans and others, which showed a wide range of pharmacological activities including estrogenic, anti-cancer, anti-inflammatory, anti-osteoporotic, organ protective, neuroprotective, anti-diabetic and anti-obesity, antimicrobial, immunosuppressive, antioxidant and skin-protective activities. Furthermore, this review focuses on the counteraction of coumestans against bone diseases and organ damages, and the involved molecular mechanisms, which could provide important information to better understand the medicinal values of these compounds. This review is intended to be instructive for the rational design and development of less toxic and more effective drugs with a coumestan scaffold.

Glycyrrhizin Mediates Downregulation of Notch Pathway Resulting in Initiation of Apoptosis and Disruption in the Cell Cycle Progression in Cervical Cancer Cells

Growing emphasis on exploring the antiproliferative potential of natural compounds has gathered momentum for the formulation of anticancer drugs. In the present study, the anticancer and apoptotic potential of glycyrrhizin (GLY) was studied on HPV^- C33A cervical cancer (CCa) cells. Our results indicated that GLY exerted antiproliferative effects in the C33A cells by inducing significant cytotoxicity. Treatment with GLY substantially increases the apoptosis in a dose-dependent manner via disrupting the mitochondrial membrane potential. GLY induced apoptosis in C33A cells via activation of capsase-9 (intrinsic pathway) and caspase-8 (extrinsic pathway) along with the modulation of pro- and antiapoptotic protein expression. Moreover, GLY also exerted cell cycle arrest in C33A cells at G₀/G₁ phase which was associated with the decreased expression of cyclin D1 and cyclin-dependent kinase 4 (CDK4) along with the increased expression of CDK inhibitor p21^Cip1. Furthermore, GLY treated CCa cells exhibited significant downregulation of Notch signaling pathway which may be associated with increased apoptosis as well as cell cycle arrest in C33A CCa cells. Thus, GLY could be an appendage in the prevention and management of CCa.

Traditional foods with their constituent's antiviral and immune system modulating properties

Background

Viruses are responsible for several diseases, including severe acute respiratory syndrome, a condition caused by today's pandemic coronavirus disease (COVID-19). A negotiated immune system is a common risk factor for all viral infections, including COVID-19. To date, no specific therapies or vaccines have been approved for coronavirus. In these circumstances, antiviral and immune boosting foods may ensure protection against viral infections, especially SARS-CoV-2 by reducing risk and ensuring fast healing of SARS-CoV-2 illness.

Scope and approach

In this review, we have conducted an online search using several search engines (Google Scholar, PubMed, Web of Science and Science Direct) to find out some traditional foods (plant, animal and fungi species), which have antiviral and immune-boosting properties against numerous viral infections, particularly coronaviruses (CoVs) and others RNA-virus infections. Our review indicated some foods to be considered as potential immune enhancers, which may help individuals to overcome viral infections like COVID-19 by modulating immune systems and reducing respiratory problems. Furthermore, this review will provide information regarding biological properties of conventional foods and their ingredients to uphold general health.

Key Findings and Conclusions

We observed some foods with antiviral and immune-boosting properties, which possess bioactive compounds that showed significant antiviral properties against different viruses, particularly RNA viruses such as CoVs. Interestingly, some antiviral and immune-boosting mechanisms were very much similar to the antiviral drug of COVID-19 homologous SARS (Severe Acute Respiratory Syndrome Coronavirus) and MERS (Middle East Respiratory Syndrome Coronavirus). The transient nature and the devastating spreading capability of COVID-19 lead to ineffectiveness of many curative therapies. Therefore, body shielding and immune-modulating foods, which have previous scientific recognition, have been discussed in this review to discern the efficacy of these foods against viral infections, especially SARS-CoV-2.

A comprehensive review on the antiviral activities of chalcones

Some viral outbreaks have plagued the world since antiquity, including the most recent COVID-19 pandemic. The continuous spread and emergence of new viral diseases have urged the discovery of novel treatment options that can overcome the limitations of currently marketed antiviral drugs. Chalcones are natural open chain flavonoids that are found in various plants and can be synthesised in labs. Several studies have shown that these small organic molecules exert a number of pharmacological activities, including antiviral, anti-inflammatory, antimicrobial and anticancer. The purpose of this review is to provide a summary of the antiviral activities of chalcones and their derivatives on a set of human viral infections and their potential for targeting the most recent COVID-19 disease. Accordingly, we herein review chalcones activities on the following human viruses: Middle East respiratory syndrome coronavirus, severe acute respiratory syndrome coronavirus, human immunodeficiency, influenza, human rhinovirus, herpes simplex, dengue, human cytomegalovirus, hepatitis B and C, Rift Valley fever and Venezuelan equine encephalitis. We hope that this review will pave the way for the design and development of potentially potent and broad-spectrum chalcone based antiviral drugs.

Herb-Drug Interaction Potential of Licorice Extract and Paclitaxel: A Pharmacokinetic Study in Rats

BACKGROUND AND OBJECTIVES

Licorice is the dried roots and rhizomes of Glycyrrhiza uralensis Fisch (Leguminosae), which is often used with paclitaxel to alleviate paclitaxel-induced pain in clinics. However, the herb-drug interaction between licorice and paclitaxel is still unknown. Our study evaluates the effects of oral licorice on the paclitaxel in rats via pharmacokinetic studies.

METHODS

A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to determine paclitaxel in rat. SD rats were randomly divided into 3 groups of 6 animals each as follows: two groups of rats that were pretreated with a daily gavage of licorice (3 g/kg) for 1 or 14 successive days; Control group that was administered distilled water. All rats were then intravenously administered with paclitaxel (3 mg/kg).

RESULTS

The results showed that 14 days pretreatment of licorice could decrease the area under the curve (AUC_0-t) (from 7483.08 ± 528.78 to 6679.12 ± 266.56 mg/L × h) (P < 0.01), and increase the total clearance (CL) (from 0.36 ± 0.02 to 0.39 ± 0.02 L/h/kg) of paclitaxel (P < 0.01). However, a single co-administration of licorice did not significantly alter the pharmacokinetic parameters of paclitaxel, such as AUC_0-t (from 7483.08 ± 528.78 to 7201.24 ± 292.76 mg/L × h) (P > 0.05) and CL (from 0.36 ± 0.02 to 0.36 ± 0.01 L/h/kg) (P > 0.05).

CONCLUSIONS

The results will contribute to better use of licorice in the adjunctive therapy and provide information to study the interaction between herbs and chemotherapy.

An Evaluation of Traditional Persian Medicine for the Management of SARS-CoV-2

A new coronavirus causing severe acute respiratory syndrome (SARS-CoV-2) has emerged and with it, a global investigation of new antiviral treatments and supportive care for organ failure due to this life-threatening viral infection. Traditional Persian Medicine (TPM) is one of the most ancient medical doctrines mostly known with the manuscripts of Avicenna and Rhazes. In this paper, we first introduce a series of medicinal plants that would potentially be beneficial in treating SARS-CoV-2 infection according to TPM textbooks. Then, we review medicinal plants based on the pharmacological studies obtained from electronic databases and discuss their mechanism of action in SARS-CoV-2 infection. There are several medicinal plants in TPM with cardiotonic, kidney tonic, and pulmonary tonic activities, protecting the lung, heart, and kidney, the three main vulnerable organs in SARS-CoV-2 infection. Some medicinal plants can prevent "humor infection", a situation described in TPM which has similar features to SARS-CoV-2 infection. Pharmacological evaluations are in line with the therapeutic activities of several plants mentioned in TPM, mostly through antiviral, cytoprotective, anti-inflammatory, antioxidant, and anti-apoptotic mechanisms. Amongst the primarily-introduced medicinal plants from TPM, rhubarb, licorice, garlic, saffron, galangal, and clove are the most studied plants and represent candidates for clinical studies. The antiviral compounds isolated from these plants provide novel molecular structures to design new semisynthetic antiviral agents. Future clinical studies in healthy volunteers as well as patients suffering from pulmonary infections are necessary to confirm the safety and efficacy of these plants as complementary and integrative interventions in SARS-CoV-2 infection.

Licochalcone A, a licorice flavonoid: antioxidant, cytotoxic, genotoxic, and chemopreventive potential

Licochalcone A (LicoA) is a flavonoid derived from Glycyrrhiza spp. plants. The present study aimed to investigate the antioxidant, cytotoxic, genotoxic, and chemopreventive effects of LicoA in in vitro and in vivo systems. The results showed that LicoA (197.1 μM) scavenged 77.92% of free radicals. Concentrations of 147.75 µM or higher LicoA produced cytotoxicity in Chinese hamster ovary (CHO) fibroblasts. LicoA treatments of 4.43 to 10.34 µM did not exert genotoxic activity, but at 11.8 µM significantly lowered nuclear division indexes, compared to negative control, revealing cytotoxicity. Lower concentrations (1.85 to 7.39 µM) exhibited protective activity against chromosomal damage induced by doxorubicin (DXR) or methyl methanesulfonate (MMS) in CHO cells. LicoA exerted no marked influence on DXR-induced genotoxicity in mouse erythrocytes, but reduced pre-neoplastic lesions induced by 1,2-dimethylhydrazine (DMH) in rat colon at 3.12 to 50 mg/kg b.w. Biochemical markers and body weight indicated no apparent toxicity. These findings contribute to better understanding the mechanisms underlying LicoA-initiated activity as a promising chemopreventive compound.

ABBREVIATIONS

AC, aberrant crypts; ACF, aberrant crypt foci; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BOD, biochemical oxygen demand; CHO, Chinese hamster ovary fibroblast; DMH, 1,2-dimethylhydrazine; DMSO, dimethyl sulfoxide; DPPH, 2,2-diphenyl-1-picrylhydrazyl; DXR, doxorubicin hydrochloride; EDTA, ethylenediaminetetraacetic acid; GA, gallic acid; LicoA, licochalcone A; MMS, methyl methanesulfonate; MNBC, micronucleated binucleated cells; MNPCE, micronucleated polychromatic erythrocyte; NCE, normochromatic erythrocyte; NDI, nuclear division index; PBS, phosphate-buffered saline; PCE, polychromatic erythrocyte; XTT, 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide.

Pharmacological Activities of Coumarin Compounds in Licorice: A Review

Licorice is a traditional medicine commonly used in China and many other countries. Over the last 50 years, the structure and pharmacological effects of coumarin compounds in licorice have been investigated. However, a comprehensive review of the literature summarizing current trends is currently lacking. Thus, the aim of the present review is to provide an up-to-date summary of the scientific literature regarding the pharmacological effects of coumarin compounds in licorice, thereby laying the foundation for further research and optimal utilization of licorice. We retrieved 111 articles on the coumarin components of licorice and their potential pharmacological effects, based on titles, keywords, and abstracts from databases (including PubMed and Web of Science). Glycycoumarin, isoglycycoumarin, licoarylcoumarin, licopyranocoumarin, glycyrin, isotrifoliol, glycyrol, and glycyrurol have been investigated for their anticancer, hepatoprotective, antispasmodic, immunosuppressive, anti-inflammatory, and antibacterial properties, and use as therapeutic agents in metabolic syndrome, thereby demonstrating their potential for clinical applications. Future research should further explore the pharmacological mechanisms of action of coumarin compounds, including their antibacterial activities. Investigations into the pharmacological activities of different glycycoumarin isomers might open new research frontiers.

Could herbal medicine (Soshihotang) be a new treatment option for COVID-19?: a narrative review

BACKGROUND

While the world struggles under the coronavirus disease 2019 (COVID-19) pandemic, a variety of antiviral agents and symptomatic treatments are being administered to patients and urgent clinical trials are underway. Under these circumstances, it is important to explore various possibilities for the treatment of COVID-19 including herbal medicines. Among various herbal medicines, Soshihotang (SSHT, Xiao Chai Hu Tang in Chinese) has been prescribed to treat various viral diseases and is used in combination with other herbal medicines depending on the patient's symptoms.

METHODS

For conducting the present review, we searched electronic databases focusing on the antiviral effect of SSHT in experimental and clinical study until April 2020. The search keywords included SSHT, constituents of SSHT, and antiviral effect. We also searched for materials related to topic directly from websites and published books. Based on these search results, we summarized the results of the included materials in the form of a narrative review.

RESULTS

In a number of recent clinical studies, treatment with SSHT improved the infection status of the respiratory and hepatobiliary systems, and experimental studies demonstrated the antiviral effect of SSHT and its components. Furthermore, SSHT are being used in China-where COVID-19 outbreak first took place-and offer a new option to treat COVID-19.

CONCLUSION

Based on the present evidences, it is believed that SSHT is likely to be a new therapeutic option for COVID-19. Conducting further studies might provide improved understanding regarding the use of SSHT in treating COVID-19.

Inhibition of Butyrylcholinesterase and Human Monoamine Oxidase-B by the Coumarin Glycyrol and Liquiritigenin Isolated from Glycyrrhiza uralensis

Eight compounds were isolated from the roots of Glycyrrhiza uralensis and tested for cholinesterase (ChE) and monoamine oxidase (MAO) inhibitory activities. The coumarin glycyrol (GC) effectively inhibited butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) with IC₅₀ values of 7.22 and 14.77 µM, respectively, and also moderately inhibited MAO-B (29.48 µM). Six of the other seven compounds only weakly inhibited AChE and BChE, whereas liquiritin apioside moderately inhibited AChE (IC₅₀ = 36.68 µM). Liquiritigenin (LG) potently inhibited MAO-B (IC₅₀ = 0.098 µM) and MAO-A (IC₅₀ = 0.27 µM), and liquiritin, a glycoside of LG, weakly inhibited MAO-B (>40 µM). GC was a reversible, noncompetitive inhibitor of BChE with a K_i value of 4.47 µM, and LG was a reversible competitive inhibitor of MAO-B with a K_i value of 0.024 µM. Docking simulations showed that the binding affinity of GC for BChE (−7.8 kcal/mol) was greater than its affinity for AChE (−7.1 kcal/mol), and suggested that GC interacted with BChE at Thr284 and Val288 by hydrogen bonds (distances: 2.42 and 1.92 Å, respectively) beyond the ligand binding site of BChE, but that GC did not form hydrogen bond with AChE. The binding affinity of LG for MAO-B (−8.8 kcal/mol) was greater than its affinity for MAO-A (−7.9 kcal/mol). These findings suggest GC and LG should be considered promising compounds for the treatment of Alzheimer’s disease with multi-targeting activities.

Influence of Herbal Medicines on HMGB1 Release, SARS-CoV-2 Viral Attachment, Acute Respiratory Failure, and Sepsis. A Literature Review

By attaching to the angiotensin converting enzyme 2 (ACE2) protein on lung and intestinal cells, Sudden Acute Respiratory Syndrome (SARS-CoV-2) can cause respiratory and homeostatic difficulties leading to sepsis. The progression from acute respiratory failure to sepsis has been correlated with the release of high-mobility group box 1 protein (HMGB1). Lack of effective conventional treatment of this septic state has spiked an interest in alternative medicine. This review of herbal extracts has identified multiple candidates which can target the release of HMGB1 and potentially reduce mortality by preventing progression from respiratory distress to sepsis. Some of the identified mixtures have also been shown to interfere with viral attachment. Due to the wide variability in chemical superstructure of the components of assorted herbal extracts, common motifs have been identified. Looking at the most active compounds in each extract it becomes evident that as a group, phenolic compounds have a broad enzyme inhibiting function. They have been shown to act against the priming of SARS-CoV-2 attachment proteins by host and viral enzymes, and the release of HMGB1 by host immune cells. An argument for the value in a nonspecific inhibitory action has been drawn. Hopefully these findings can drive future drug development and clinical procedures.

Licochalcone A Selectively Resensitizes ABCG2-Overexpressing Multidrug-Resistant Cancer Cells to Chemotherapeutic Drugs

The overexpression of the ATP-binding cassette (ABC) transporter ABCG2 has been linked to clinical multidrug resistance in solid tumors and blood cancers, which remains a significant obstacle to successful cancer chemotherapy. For years, the potential modulatory effect of bioactive compounds derived from natural sources on ABCG2-mediated multidrug resistance has been investigated, as they are inherently well tolerated and offer a broad range of chemical scaffolds. Licochalcone A (LCA), a natural chalcone isolated from the root of Glycyrrhiza inflata, is known to possess a broad spectrum of biological and pharmacological activities, including pro-apoptotic and antiproliferative effects in various cancer cell lines. In this study, the chemosensitization effect of LCA was examined in ABCG2-overexpressing multidrug-resistant cancer cells. Experimental data demonstrated that LCA inhibits the drug transport function of ABCG2 and reverses ABCG2-mediated multidrug resistance in human multidrug-resistant cancer cell lines in a concentration-dependent manner. Results of LCA-stimulated ABCG2 ATPase activity and the in silico docking analysis of LCA to the inward-open conformation of human ABCG2 suggest that LCA binds ABCG2 in the transmembrane substrate-binding pocket. This study provides evidence that LCA should be further evaluated as a modulator of ABCG2 in drug combination therapy trials against ABCG2-expressing drug-resistant tumors.