Phytochemicals as Antiviral Agents: Recent Updates. In: Swamy MK, editor. Plant-derived Bioactives. Singapore: Springer; 2020. pp. 279-95. [DOI: 10.1007/978-981-15-1761-7_12]

Metabolites profiling and cheminformatics bioprospection of selected medicinal plants against the main protease and RNA-dependent RNA polymerase of SARS-CoV-2

Despite the existence of some vaccines, SARS-CoV-2 (S-2) infections persist for various reasons relating to vaccine reluctance, rapid mutation rate, and an absence of specific treatments targeted to the infection. Due to their availability, low cost and low toxicity, research into potentially repurposing phytometabolites as therapeutic alternatives has gained attention. Therefore, this study explored the antiviral potential of metabolites of some medicinal plants [Spondias mombin, Macaranga barteri and Dicerocaryum eriocarpum (Sesame plant)] identified using liquid chromatography-mass spectrometry (LCMS) as possible inhibitory agents against the S-2 main protease (S-2 MP) and RNA-dependent RNA polymerase (RP) using computational approaches. Molecular docking was used to identify the compounds with the best affinities for the selected therapeutics targets. Afterwards, compounds with poor physicochemical characteristics, pharmacokinetics, and drug-likeness were screened out. The top-ranked compounds were further subjected to a 120-ns molecular dynamics (MD) simulation. Only quercetin 3-O-rhamnoside (-48.77 kcal/mol) had higher binding free energy than the reference standard (zafirlukast) (-44.99 kcal/mol) against S-2 MP. Conversely, all the top-ranked compounds (ellagic acid hexoside, spiraeoside, apigenin-4'-glucoside and chrysoeriol 7-glucuronide) except gnetin L (-24.24 kcal/mol) had higher binding free energy (-55.19 kcal/mol, -52.75 kcal/mol, -47.22 kcal/mol and -43.35 kcal/mol) respectively, against S-2 RP relative to the reference standard (-34.79 kcal/mol). The MD simulations study further revealed that the investigated inhibitors are thermodynamically stable and form structurally compatible complexes that impede the regular operation of the respective S-2 therapeutic targets. Although, these S-2 therapeutic candidates are promising, further in vitro and in vivo evaluation is required and highly recommended.Communicated by Ramaswamy H. Sarma.

Exploiting new strategies in combating head and neck carcinoma: A comprehensive review on phytochemical approaches passing through PI3K/Akt/mTOR signaling pathway

Recently, malignant neoplasms have growingly caused human morbidity and mortality. Head and neck cancer (HNC) constitutes a substantial group of malignancies occurring in various anatomical regions of the head and neck, including lips, mouth, throat, larynx, nose, sinuses, oropharynx, hypopharynx, nasopharynx, and salivary glands. The present study addresses the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway as a possible therapeutic target in cancer therapy. Finding new multitargeting agents capable of modulating PI3K/Akt/mTOR and cross-linked mediators could be viewed as an effective strategy in combating HNC. Recent studies have introduced phytochemicals as multitargeting agents and rich sources for finding and developing new therapeutic agents. Phytochemicals have exhibited immense anticancer effects, including targeting different stages of HNC through the modulation of several signaling pathways. Moreover, phenolic/polyphenolic compounds, alkaloids, terpenes/terpenoids, and other secondary metabolites have demonstrated promising anticancer activities because of their diverse pharmacological and biological properties like antiproliferative, antineoplastic, antioxidant, and anti-inflammatory activities. The current review is mainly focused on new therapeutic strategies for HNC passing through the PI3K/Akt/mTOR pathway as new strategies in combating HNC.

Discovery of azaleatin as a potential allosteric inhibitor for dengue NS2B-NS3 protease using in vitro and in silico studies

The rise in dengue cases in tropical and sub-tropical areas has become a significant health concern. At present, there is no definitive cure for dengue fever, which underscores the importance of identifying potent inhibitors. Dengue NS2B-NS3 protease is the prime drug target due to its vital function for replication. Quercetin, a flavone, has anti-dengue virus properties but is limited by low bioavailability. Previous studies have shown that methoxy substitution in flavones improves bioavailability and metabolic stability. Azaleatin is a derivative of quercetin with a methoxy substitution at the C5 position, however its ability to inhibit dengue is unknown. In this study, azaleatin was investigated for its inhibition against dengue NS2B-NS3 protease using in vitro and in silico techniques. The fluorescence assay was used to determine the IC50 value and inhibition kinetics. The molecular interaction between azaleatin and NS2B-NS3 was studied using CB-Dock2 and AutoDock Vina. The complex's stability was then analysed using GROMACS. Besides, the ADMETlab 2.0 was utilized to predict pharmacokinetic of the azaleatin. Results showed that azaleatin inhibits dengue NS2B-NS3 protease non-competitively with a Ki of 26.82 µg/ml and an IC50 of 38 µg/ml. Molecular docking indicated binding of the azaleatin to the allosteric pocket of NS2B-NS3 with a docking score of -8.2 kcal/mol. Azaleatin was found stable in the pocket along 100 ns, supporting its inhibitory mode. The compound has favourable pharmacokinetic profiles and conformed to Lipinski's Rule of Five. Taken together, azaleatin inhibits NS2B-NS3 protease in a non-competitive mode, suggesting its potential as safer anti-dengue compound.Communicated by Ramaswamy H. Sarma.

Fighting nature with nature: antiviral compounds that target retroviruses

The human immunodeficiency virus (HIV) is a type of lentivirus that targets the human immune system and leads to acquired immunodeficiency syndrome (AIDS) at a later stage. Up to 2021, there are millions still living with HIV and many have lost their lives. To date, many anti-HIV compounds have been discovered in living organisms, especially plants and marine sponges. However, no treatment can offer a complete cure, but only suppressing it with a life-long medication, known as combined antiretroviral therapy (cART) or highly active antiretroviral therapy (HAART) which are often associated with various adverse effects. Also, it takes many years for a discovered compound to be approved for clinical use. Thus, by employing advanced technologies such as automation, conducting systematic screening and testing protocols may boost the discovery and development of potent and curative therapeutics for HIV infection/AIDS. In this review, we aim to summarize the antiretroviral therapies/compounds and their associated drawbacks since the discovery of azidothymidine. Additionally, we aim to provide an updated analysis of the most recent discoveries of promising antiretroviral candidates, along with an exploration of the current limitations within antiretroviral research. Finally, we intend to glean insightful perspectives and propose future research directions in this crucial area of study.

A novel film spray containing curcumin inhibits SARS-CoV-2 and influenza virus infection and enhances mucosal immunity

BACKGROUND

Infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and influenza virus is still a major worldwide health concern. Plants are a good source of bioactive compounds to be used as preventive measures for both inhibiting the virus binding and enhancing mucosal innate immunity. Curcumin has been shown to possess antiviral activity and modulate innate immunity. Therefore, the purpose of this study was to develop an oro-nasal film spray containing curcumin and determine its antiviral activity against SARS-CoV-2 and influenza virus infection, as well as its effects on mucosal innate immunity and inflammatory cytokines in vitro.

METHODS

The antiviral activity of the film spray against SARS-CoV-2, influenza A/H1N1, A/H3N2, and influenza B was assessed in vitro by plaque reduction assay. Cytotoxicity of the film spray to oral keratinocytes and nasal epithelial cells was assessed by MTT assay, and cytotoxicity to Vero and MDCK cells was assessed by an MTS-based cytotoxicity assay. Oral and nasal innate immune markers in response to the film spray were determined by ELISA and by a commercial Milliplex Map Kit, respectively.

RESULTS

Our data show that the film spray containing curcumin can inhibit both SARS-CoV-2 and influenza virus infections while maintaining cell viability. Results obtained among 4 viruses revealed that curcumin film spray demonstrated the highest inhibitory activity against SARS-CoV-2 with the lowest EC50 of 3.15 µg/ml and the highest SI value of 4.62, followed by influenza B (EC50 = 6.32 µg/ml, SI = 2.04), influenza A/H1N1 (EC50 = 7.24 µg/ml, SI = 1.78), and influenza A/H3N2 (EC50 > 12.5 µg/ml, SI < 1.03), respectively. Antimicrobial peptides LL-37 and HD-5, IL-6 and TNF-α produced by oral keratinocytes were significantly induced by the film spray, while hBD2 was significantly reduced.

CONCLUSION

Film spray containing curcumin possesses multiple actions against SARS-CoV-2 infection by inhibiting ACE-2 binding in target cells and enhancing mucosal innate immunity. The film spray can also inhibit influenza virus infection. Therefore, the curcumin film spray may be effective in preventing the viral infection of both SARS-CoV-2 and influenza.

Caesalpinia pulcherrima lowered serum carcinoembryonic antigen and antigen 125 in 7,12-Dimethylbenz[a]anthracene-induced Mammary Carcinogenesis in Female Albino Rats

Aim

This study is aimed at evaluating the anticancer effect of the aqueous extract of Caesalpinia pulcherrima (L.) Sw in 7,12-Dimethlbenz[a]anthracene (DMBA) - induced mammary cancer.

Methods

Tumors were induced via a single intraperitoneal injection of DMBA (dissolved in olive oil) at a dose of 80 mg/kg body weight to the test rats and allowed to develop for about four months. They were treated with cyclophosphamide and an aqueous extract of Caesalpinia pulcherrima at doses of 10 and 250 mg/kg body weight, respectively, for 28 days. Serum levels of cancer antigen 125 (CA125), carcinoembryonic antigen (CEA) activity, cyclooxygenase-2 (COX-2), and cytochrome p450 oxidase (cytp450) activity, as well as other diagnostic enzymes, were estimated.

Results

The result revealed that DMBA is associated with a significant (p < 0.05) increase in the serum levels of CA125, CEA, COX-2, cytp450, lactate dehydrogenase (LDH), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) of the rats, thus suggesting tumor-promoting and hepatotoxic effects of DMBA. There was also a significant (p < 0.05) reduction of serum levels of these cancer and liver biomarker enzymes in the groups treated with cyclophosphamide and Caesalpinia pulcherrima compared to the untreated group, thus suggesting anticancer activity of Caesalpinia pulcherrima. The anticancer effect of Caesalpinia pulcherrima was further confirmed by the disappearance of infiltrative fibrous cells and the absence of inflammatory cells from the photomicrographs of the rats treated with Caesalpinia pulcherrima.

Conclusion

Our findings show that Caesalpinia pulcherrima possesses anticancer activity, and could protect against mammary cancer.

Repurposing of Plant-based Antiviral Molecules for the Treatment of COVID-19

COVID-19, stemming from SARS-CoV-2, poses a formidable threat to global healthcare, with a staggering 77 million confirmed cases and 690,067 deaths recorded till December 24, 2023. Given the absence of specific drugs for this viral infection, the exploration of novel antiviral compounds becomes imperative. High-throughput technologies are actively engaged in drug discovery, and there is a parallel effort to repurpose plant-based molecules with established antiviral properties. In this context, the review meticulously delves into the potential of plant-based folk remedies and existing molecules. These substances have showcased substantial viral inhibition in diverse in vivo, in silico, and in vitro studies, particularly against critical viral protein targets, including SARS-CoV-2. The findings position these plant-based molecules as promising antiviral drug candidates for the swift advancement of treatments for COVID-19. It is noteworthy that the inherent attributes of these plant-based molecules, such as their natural origin, potency, safety, and cost-effectiveness, contribute to their appeal as lead candidates. The review advocates for further exploration through comprehensive in vivo studies conducted on animal models, emphasizing the potential of plant-based compounds to help in the ongoing quest to develop effective antivirals against COVID-19.

Systematic Review on Major Antiviral Phytocompounds from Common Medicinal Plants against SARS-CoV-2

BACKGROUND

Viral infections are rising around the globe and with evolving virus types and increasing varieties of viral invasions; the human body is developing antimicrobial resistance continuously. This is making the fight of mankind against viruses weak and unsecured. On the other hand, changing lifestyle, globalization and human activities adversely affecting the environment are opening up risks for new viral predominance on human race. In this context the world has witnessed the pandemic of the human Coronavirus disease (COVID-19) recently. The disease is caused by the Coronavirus namely Severe Acute Respiratory Syndrome Coronavirus 2 (SARSCoV- 2).

METHODS AND MATERIALS

Developing potential and effective vaccine is also time consuming and challenging. The huge resource of plants around us has rich source of potent antiviral compounds. Some of these molecules may serve as tremendously potent lead molecules whose slight structural modifications may give us highly bioactive antiviral derivatives of phytocompounds. Every geographical region is rich in unique plant biodiversity and hence every corner of the world with rich plant biodiversity can serve as abode for potential magical phytocompounds most of which have not been extensively explored for development of antiviral drug formulations against various viruses like the HIV, HPV etc., and the Coronavirus, also known as SARS-CoV-2 which causes the disease COVID-19.

RESULTS

Several phytocompounds from various medicinal plants have already been screened using in silico tools and some of them have yielded promising results establishing themselves as potent lead molecules for development of drugs against the highly mutating SARS-CoV-2 virus and thus these phytocompounds may be beneficial in treating COVID-19 and help human to win the life threatening battle against the deadly virus.

CONCLUSION

The best advantage is that these phytocompounds being derived from nature in most of the cases, come with minimum or no side effects compared to that of chemically synthesized conventional bioactive compounds and are indigenously available hence are the source of cost effective drug formulations with strong therapeutic potentials.

Molecular docking and dynamics studies for the identification of Nipah virus glycoprotein inhibitors from Indian medicinal plants

The infection by Nipah Virus (NiV), a zoonotic paramyxovirus, is fatal and several outbreaks have been reported in humans in various countries. No effective vaccines or drugs are developed till date to control this infection. The NiV-Glycoprotein (NiV-G) is one of the essential proteins for viral entry by binding to the Ephrin-B receptors. The present study screens the potential phytocompounds that can target NiV-G and thereby inhibit the viral entry to human. Computer-aided virtual screening of 1426 phytocompounds from various medicinal plants was carried out to investigate their efficacy as potential therapeutics. Ribavirin, the currently used drug, was also docked to compare the docking score and intermolecular interactions between ligand and target protein. Further, molecular dynamics simulations and MM-PBSA binding free energy calculations were performed to understand the stability of the docked complexes. Radius of gyrations and Solvent Accessible Surface Area were also performed to evaluate the compactness and solvent behaviour of ligand-receptor complexes during the 100 ns simulation. Our analysis revealed that the alkaloid, Serpentinine, has the highest potency to block NiV-G with favourable binding.Communicated by Ramaswamy H. Sarma.

In silico screening of herbal phytochemicals to develop a Rasayana for immunity against Nipah virus

BACKGROUND

The first emergence of the Nipah virus (NiV) in 1998 from Malaysia became a major concern when it came to light and resurfaced on different occasions thereafter. NiV is a bat-borne zoonotic and pleomorphic virus that causes severe infection in human and animal hosts. Studies revealed fruit bats are the major reservoirs as natural hosts and pigs as intermediate hosts for the spread of this infection. This became a major concern as the disease was characterized by high pathogenicity varying from 40% to 80% depending on its acuteness. Moreover, the solemnity lies in the fact that the infection transcends from being a mere mild illness to an acute respiratory infection leading to fatal encephalitis with a reportedly high mortality rate. Currently, there is no treatment or vaccine available against the NiV. Many antiviral drugs have been explored and developed but with limited efficacy.

METHODOLOGY

In search of high-affinity ayurvedic alternatives, we conducted a pan-proteome in silico exploration of the NiV proteins for their interaction with the best-suited phytoconstituents. The toxicity prediction of thirty phytochemicals based on their LD50 value identified thirteen potential candidates. Molecular docking studies of those thirteen phytochemicals with five important NiV proteins identified Tanshinone I as the potential compound with a high binding affinity.

RESULTS

The pharmacokinetics and pharmacodynamics studies also aided in determining the absorption, distribution, metabolism, excretion, and toxicity of the selected phytoconstituent. Interestingly, docking studies also revealed Rosmariquinone as a potent alternative to the antiviral drug Remdesivir binding the same pocket of RNA-dependent RNA polymerase of the NiV. A molecular dynamics simulation study of the surface glycoprotein of NiV against Tanshinone I showed a stable complex formation and significant allosteric changes in the protein structure, implying that these phytochemicals could be a natural alternative to synthetic drugs against NiV.

CONCLUSION

This study provides preliminary evidence based on in silico analysis that the herbal molecules showed an effect against NiV. However, it is essential to further evaluate the efficacy of this approach through cell-based experiments, organoid models, and eventually clinical trials.

Porphyrin-derived carbon dots for an enhanced antiviral activity targeting the CTD of SARS-CoV-2 nucleocapsid

BACKGROUND

Since effective antiviral drugs for COVID-19 are still limited in number, the exploration of compounds that have antiviral activity against SARS-CoV-2 is in high demand. Porphyrin is potentially developed as a COVID-19 antiviral drug. However, its low solubility in water restricts its clinical application. Reconstruction of porphyrin into carbon dots is expected to possess better solubility and bioavailability as well as lower biotoxicity.

METHODS AND RESULTS

In this study, we investigated the antiviral activity of porphyrin and porphyrin-derived carbon dots against SARS-CoV-2. Through the in silico analysis and assessment using a novel drug screening platform, namely dimer-based screening system, we demonstrated the capability of the antivirus candidates in inhibiting the dimerization of the C-terminal domain of SARS-CoV-2 Nucleocapsid. It was shown that porphyrin-derived carbon dots possessed lower cytotoxicity on Vero E6 cells than porphyrin. Furthermore, we also assessed their antiviral activity on the SARS-CoV-2-infected Vero E6 cells. The transformation of porphyrin into carbon dots substantially augmented its performance in disrupting SARS-CoV-2 propagation in vitro.

CONCLUSIONS

Therefore, this study comprehensively demonstrated the potential of porphyrin-derived carbon dots to be developed further as a promisingly safe and effective COVID-19 antiviral drug.

Computational approaches for innovative anti-viral drug discovery using Orthosiphon aristatus blume miq against dengue virus

Dengue virus has emerged as infectious mosquito borne disease involved in lowering platelets and white blood cells (WBC) count particularly. The genome structure is based on several structural and non-structural proteins essential for viral replication and progeny. One of the major proteins of replication is non-structural protein 3 (NS3) that transforms polyproteins into functional proteins with a cofactor non-structural protein (NS2B). Heat Shock Protein 70 (HSP70), is a human protein that assists in replication, viral entry and virion synthesis. Therefore, to inhibit the spread of dengue infection, there is a need of antivirals targeting replication proteins and other human proteins that help in dengue virus multiplication. By systemic approach based on molecular docking, ADMET (absorption, distribution, metabolism, excretion and toxicity) properties and molecular dynamic simulation (MD), potent inhibitors can be predicted. Inhibition of NS2B/NS3 dengue and HSP70 proteins involved in multiple steps in dengue virus progression can be prevented by using different phytochemicals. Molecular docking was performed using AutoDock Vina, PatchDock, and SwissDock. Interactions of obtained complex were observed in PyMOL and PLIP. Validation was checked by PROCHEK, simulation was performed using iMODS followed by preclinical testing by admetSAR. Ladanein, a flavonoid of Orthosiphon aristatus, was obtained as the lead compound to inhibit major replication protein of dengue virus with inhibitory potential against HSP70 protein. In summary, various in silico approaches were used to obtain the best phytochemical having anti-dengue potential.Communicated by Ramaswamy H. Sarma.

Role of phytocompounds as the potential anti-viral agent: an overview

Viral diseases are the most notorious infective agent(s) causing morbidity and mortality in every nook and corner for ages; viruses are active in host cells, and specific anti-virus medicines' developments remain uncanny. In this century of the biological era, human viruses act predominantly as versatile spreaders. The infection of the present COVID-19 virus is up in the air; blithely, the integument of medicinal chemistry approaches, particularly bioactive derived phytocompounds could be helpful to control those human viruses, recognized in the last 100 years. Indeed, natural products are being used for various therapeutic purposes. The major bioactive phytocompounds are chemically containing coumarin, thiosulfonate, steroid, polysaccharide, tannin, lignin, proanthocyanidin, terpene, quinone, saponin, flavonoid, alkaloid, and polyphenol, that are documented for inhibitory action against several viral infections. Mostly, about 20-30% of plants from tropical or temperate regions are known to have some antiviral activity. This comprehensive analysis of bioactive-derived phytocompounds would represent a significant impact and might be helpful for antiviral research and the current state of viral treatments.

Effect of Extraction Methods on the Antioxidant Potential and Cytotoxicity of the Combined Ethanolic Extracts of Daucus carota L., Beta vulgaris L., Phyllanthus emblica L. and Lycopersicon esculentum against Gastric Adenocarcinoma Cells

Frequent consumption of fruits and vegetables in the daily diet may alleviate the risk of developing chronic diseases. Daucus carota L. (carrot), Beta vulgaris L. (beetroot) Phyllanthus emblica L. (amla), and Lycopersicon esculentum M (tomatoes) are traditionally consumed functional foods that contain a high concentration of antioxidants, ascorbic acid, polyphenols, and numerous phytochemicals. This study assessed how three distinct preparation methods affect the phenolic, flavonoid, carotenoid, and ascorbic acid contents, antioxidant level, and cytotoxicity of the combined fruit extract. The fruit samples were taken in the ratio of carrot (6): beetroot (2): tomato (1.5): amla (0.5) and processed into a lyophilized slurry (LS) extract, lyophilized juice (LJ) extract, and hot-air oven-dried (HAO) extract samples. The sample extracts were assessed for their phytoconstituent concentrations and antioxidant and cytotoxic potential. The total phenolic content in LS, LJ, and HAO extracts was 171.20 ± 0.02, 120.73 ± 0.02, and 72.05 ± 0.01 mg gallic acid equivalent/100 g, respectively and the total flavonoid content was 23.635 ± 0.003, 20.754 ± 0.005, and 18.635 ± 0.005 mg quercetin equivalent/100 g, respectively. Similarly, total ascorbic acid content, carotenoids, and antioxidant potential were higher in the LS and LJ extracts than in HAO. Overall, the LS extract had a substantially higher concentration of phytochemicals and antioxidants, as well as higher cytotoxic potential, compared to the LJ and HAO extracts. The LS extract was tested in the MKN-45 human gastric cancer cell line to demonstrate its effective antioxidant potential and cytotoxicity. Hence, lyophilization (freezing) based techniques are more effective than heat-based techniques in preserving the phytoconstituents and their antioxidant and cytotoxic potential.

AVPCD: a plant-derived medicine database of antiviral phytochemicals for cancer, Covid-19, malaria and HIV

Serious illnesses caused by viruses are becoming the world's most critical public health issues and lead millions of deaths each year in the world. Thousands of studies confirmed that the plant-derived medicines could play positive therapeutic effects on the patients with viral diseases. Since thousands of antiviral phytochemicals have been identified as lifesaving drugs in medical research, a comprehensive database is highly desirable to integrate the medicinal plants with their different medicinal properties. Therefore, we provided a friendly antiviral phytochemical database AVPCD covering 2537 antiviral phytochemicals from 383 medicinal compounds and 319 different families with annotation of their scientific, family and common names, along with the parts used, disease information, active compounds, links of relevant articles for COVID-19, cancer, HIV and malaria. Furthermore, each compound in AVPCD was annotated with its 2D and 3D structure, molecular formula, molecular weight, isomeric SMILES, InChI, InChI Key and IUPAC name and 21 other properties. Each compound was annotated with more than 20 properties. Specifically, a scoring method was designed to measure the confidence of each phytochemical for the viral diseases. In addition, we constructed a user-friendly platform with several powerful modules for searching and browsing the details of all phytochemicals. We believe this database will facilitate global researchers, drug developers and health practitioners in obtaining useful information against viral diseases.

Target specific inhibition of West Nile virus envelope glycoprotein and methyltransferase using phytocompounds: an in silico strategy leveraging molecular docking and dynamics simulation

Mosquitoes are the primary vector for West Nile virus, a flavivirus. The virus's ability to infiltrate and establish itself in increasing numbers of nations has made it a persistent threat to public health worldwide. Despite the widespread occurrence of this potentially fatal disease, no effective treatment options are currently on the market. As a result, there is an immediate need for the research and development of novel pharmaceuticals. To begin, molecular docking was performed on two possible West Nile virus target proteins using a panel of twelve natural chemicals, including Apigenin, Resveratrol, Hesperetin, Fungisterol, Lucidone, Ganoderic acid, Curcumin, Kaempferol, Cholic acid, Chlorogenic acid, Pinocembrin, and Sanguinarine. West Nile virus methyltransferase (PDB ID: 2OY0) binding affinities varied from -7.4 to -8.3 kcal/mol, whereas West Nile virus envelope glycoprotein affinities ranged from -6.2 to -8.1 kcal/mol (PDB ID: 2I69). Second, substances with larger molecular weights are less likely to be unhappy with the Lipinski rule. Hence, additional research was carried out without regard to molecular weight. In addition, compounds 01, 02, 03, 05, 06, 07, 08, 09, 10 and 11 are more soluble in water than compound 04 is. Besides, based on maximum binding affinity, best three compounds (Apigenin, Curcumin, and Ganoderic Acid) has been carried out molecular dynamic simulation (MDs) at 100 ns to determine their stability. The MDs data is also reported that these mentioned molecules are highly stable. Finally, advanced principal component analysis (PCA), dynamics cross-correlation matrices (DCCM) analysis, binding free energy and dynamic cross correlation matrix (DCCM) theoretical study is also included to established mentioned phytochemical as a potential drug candidate. Research has indicated that the aforementioned natural substances may be an effective tool in the battle against the dangerous West Nile virus. This study aims to locate a bioactive natural component that might be used as a pharmaceutical.

Exploring the inhibitory potential of Nigella sativa against dengue virus NS2B/NS3 protease and NS5 polymerase using computational approaches

Dengue fever, a highly infectious and rapidly spreading vector borne illness, is classified as a Neglected Tropical Disease (NTD) by WHO because they generally afflict the world's poor and historically have not received as much attention as other diseases. DENV NS2B/NS3 protease and NS5 polymerase are regarded as significant prospective therapeutic targets because of their critical involvement in the viral replication cycle. To date, no specific antiviral agents exist for dengue. The commonly used herbal plant Nigella sativa is known for its antibacterial, antiviral, anti-inflammatory, wound-healing, and dermatological properties. Nevertheless, not enough studies on the antiviral effects of Nigella sativa against DENV are reported. The current study used several prediction techniques to anticipate the oral bioavailability of substances, druglikeness, and non-toxic and non-mutagenic effects which could lead to the development of novel, safer medications. Therefore, the current study was conducted to explore the inhibitory potential of 18 phytochemicals from Nigella sativa against two important enzymes of dengue virus i.e., NS2B/NS3 and NS5. Promising results have been observed for NS2B/NS3 with Taraxerol (-9.1 kcal mol^-1), isoquercetin (8.4 kcal mol^-1), apigenin, and stigmasterol (-8.3 kcal mol^-1). Similarly, NS5 has shown favorable outcomes with apigenin (-9.9 kcal mol^-1), rutin (-9.3 kcal mol^-1), nigellicine (-9.1 kcal mol^-1), and stigmasterol (-8.8 kcal mol^-1). MD simulations validated the structural flexibility of the NS2B/NS3-taraxerol and NS5-apigenin docking complexes based on an RMSF value below 5 Å. The study concluded that among the understudied phytocomponents of N. sativa, apigenin, nigellicine, nigellidine, dithymoquinone, taraxerol, campesterol, cycloeucalenol, stigmasterol and beta-sitosterol have been revealed as potential drug candidates, expected to show antiviral activity and promising drug likeliness. Phytochemicals on the short list may serve as inspiration for the creation of new drugs in the future. Further in vitro examination will assist in elucidating the molecular complexity of therapeutic and antiviral capabilities, opening several opportunities for researchers to identify novel medications throughout the drug development process.

Rapid Virucidal Activity of Japanese Saxifraga Species-Derived Condensed Tannins against SARS-CoV-2, Influenza A Virus, and Human Norovirus Surrogate Viruses

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IAV), and norovirus are global threats to human health. The application of effective virucidal agents, which contribute to the inactivation of viruses on hands and environmental surfaces, is important to facilitate robust virus infection control measures. Naturally derived virucidal disinfectants have attracted attention owing to their safety and eco-friendly properties. In this study, we showed that multiple Japanese Saxifraga species-derived fractions demonstrated rapid, potent virucidal activity against the SARS-CoV-2 ancestral strain and multiple variant strains, IAV, and two human norovirus surrogates: feline calicivirus (FCV) and murine norovirus (MNV). Condensed tannins were identified as active chemical constituents that play a central role in the virucidal activities of these fractions. At a concentration of 25 μg/mL, the purified condensed tannin fraction Sst-2R induced significant reductions in the viral titers of the SARS-CoV-2 ancestral strain, IAV, and FCV (reductions of ≥3.13, ≥3.00, and 2.50 log₁₀ 50% tissue culture infective doses [TCID₅₀]/mL, respectively) within 10 s of reaction time. Furthermore, at a concentration of 100 μg/mL, Sst-2R induced a reduction of 1.75 log₁₀ TCID₅₀/mL in the viral titers of MNV within 1 min. Western blotting and transmission electron microscopy analyses revealed that Sst-2R produced structural abnormalities in viral structural proteins and envelopes, resulting in the destruction of viral particles. Furthermore, Saxifraga species-derived fraction-containing cream showed virucidal activity against multiple viruses within 10 min. Our findings indicate that Saxifraga species-derived fractions containing condensed tannins can be used as disinfectants against multiple viruses on hands and environmental surfaces. IMPORTANCE SARS-CoV-2, IAV, and norovirus are highly contagious pathogens. The use of naturally derived components as novel virucidal/antiviral agents is currently attracting attention. We showed that fractions from extracts of Saxifraga species, in the form of a solution as well as a cream, exerted potent, rapid virucidal activities against SARS-CoV-2, IAV, and surrogates of human norovirus. Condensed tannins were found to play a central role in this activity. The in vitro cytotoxicity of the purified condensed tannin fraction at a concentration that exhibited some extent of virucidal activity was lower than that of 70% ethanol or 2,000 ppm sodium hypochlorite solution, which are popular virucidal disinfectants. Our study suggests that Saxifraga species-derived fractions containing condensed tannins can be used on hands and environmental surfaces as safe virucidal agents against multiple viruses.

Ethnopharmacological Potential of Phytochemicals and Phytogenic Products against Human RNA Viral Diseases as Preventive Therapeutics

RNA viruses have been the most destructive due to their transmissibility and lack of control measures. Developments of vaccines for RNA viruses are very tough or almost impossible as viruses are highly mutable. For the last few decades, most of the epidemic and pandemic viral diseases have wreaked huge devastation with innumerable fatalities. To combat this threat to mankind, plant-derived novel antiviral products may contribute as reliable alternatives. They are assumed to be nontoxic, less hazardous, and safe compounds that have been in uses in the beginning of human civilization. In this growing COVID-19 pandemic, the present review amalgamates and depicts the role of various plant products in curing viral diseases in humans.

In silico identification of novel benzophenone-coumarin derivatives as SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) inhibitors

In this study, we propose our novel benzophenone-coumarin derivatives (BCDs) as potent inhibitors of the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 virus, one of the key targets that are involved in the viral genome replication. We aim to evaluate the in silico antiviral potential of BCDs against this protein target, which involves molecular docking simulations, druglikeliness and pharmacokinetic evaluations, PASS analysis, molecular dynamics simulations, and computing binding free energy. Out of all the BCDs screened through these parameters, BCD-8 was found to be the most efficient and potent inhibitor of SARS-CoV-2 RdRp. During molecular docking simulation, BCD-8 showed an extensive molecular interaction in comparison with that of the standard control used, remdesivir. The druglikeliness and pharmacokinetic analyses also proved the efficiency of BCD-8 as an effective drug without adverse effects. Further, pharmacological potential analysis through PASS depicted the antiviral property of BCD-8. With these findings, we performed molecular dynamics simulations, where BCD-8 edged out remdesivir with its exemplary stable interaction with SARS-CoV-2 RdRp. Furthermore, binding free energy of both BCD-8 and remdesivir was calculated, where BCD-8 showed a lower binding energy and standard deviations in comparison with that of remdesivir. Moreover, being a non-nucleoside analogue, BCD-8 can be used effectively against SARS-CoV-2, whereas nucleoside analogues like remdesivir may become non-functional or less functional due to exonuclease activity of nsp14 of the virus. Therefore, we propose BCD-8 as a SARS-CoV-2 RdRp inhibitor, showing higher predicted efficiency than remdesivir in all the in silico experiments conducted.Communicated by Ramaswamy H. Sarma.

Polypharmacology of some medicinal plant metabolites against SARS-CoV-2 and host targets: Molecular dynamics evaluation of NSP9 RNA binding protein

Medicinal plants as rich sources of bioactive compounds are now being explored for drug development against COVID-19. 19 medicinal plants known to exhibit antiviral and anti-inflammatory effects were manually curated, procuring a library of 521 metabolites; this was virtually screened against NSP9, including some other viral and host targets and were evaluated for polypharmacological indications. Leads were identified via rigorous scoring thresholds and ADMET filtering. MM-GBSA calculation was deployed to select NSP9-Lead complexes and the complexes were evaluated for their stability and protein-ligand communication via MD simulation. We identified 5 phytochemical leads for NSP9, 23 for Furin, 18 for ORF3a, and 19 for IL-6. Ochnaflavone and Licoflavone B, obtained from Lonicera japonica (Japanese Honeysuckle) and Glycyrrhiza glabra (Licorice), respectively, were identified to have the highest potential polypharmacological properties for the aforementioned targets and may act on multiple pathways simultaneously to inhibit viral entry, replication, and disease progression. Additionally, MD simulation supports the robust stability of Ochnaflavone and Licoflavone B against NSP9 at the active sites via hydrophobic interactions, H-bonding, and H-bonding facilitated by water. This study promotes the initiation of further experimental analysis of natural product-based anti-COVID-19 therapeutics.

Secondary metabolites produced by endophytic fungi, Alternaria alternata, as potential inhibitors of the human immunodeficiency virus

Antiretroviral treatment has significantly reduced human immunodeficiency virus infection and mortality. However, the current treatment regimen is limited by adverse side effects, the emergence of drug resistance, and the inability to eliminate viral reservoirs. Here, fifteen endophytic fungi were isolated from Sclerocarya birrea and Hypoxis plants. Crude extracts of Alternaria alternata (strain ID PO4PR1, PO4PR2, and PO2PL1) of the fifteen isolate's crude extracts showed anti-HIV-1 activity in TZM-bl cell line at inhibitory concentration (IC₅₀) values ranging from 0.017 to 1.170 μg/ml. The three crude extracts also maintained the virus replication inhibition profile on PBMCs and CD4⁺ T cells at concentrations ranging from 0.3 to 50.2 ng/ml. Partial purification using the solid phase extraction and analysis with Gas Chromatography-Mass spectrophotometry showed a diverse profile. The bioactive compounds were identified based on peak area, retention time, similarity index. The major compounds from GC-MS analysis of A. Alternata revealed the existence of cyclotrisiloxane octamethyl (22.92%); Propaninitrile (16,67%); Pyrrolol[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methyl propyl) (10.42%); Silane, diethylethoxy(2-ethoxyethyloxy) (4.17%); Coumarin, 3,4-dihydro-4,5,7-trimethyl- 4,5,7-Trimethyl-2-chromanone (13.7%) and 1,2-Cyclobutanedicarbonitrile (2.08%) with previously reported biological activities such as antimicrobial, anti-inflammatory and antioxidant properties. Therefore, these bioactive compounds from A. alternata fungal endophytes could be repurposed as potential anti-HIV agents. This study showed the potential of endophytic fungi, Alternaria alternata from S. birrea, and Hypoxis species as producers of anti-HIV compounds.

The Allium triquetrum L. Leaves Mitigated Hepatotoxicity and Nephrotoxicity Induced by Lead Acetate in Wistar Rats

The aim of this study was to scrutinize the possible mitigating role of leaves' Allium triquetrum L. against the toxicity of lead acetate on liver and kidney markers of Wistar rat. Lead acetate (Pb) and leaves' aqueous extracts (L) were orally administrated for 3 weeks. Rats were divided into the control, Pb group (500 mg/kg body weight/day), positive controls L (2g, 3g, 4g/kg BW/day), along with three combined groups of the same doses (Pb-L1, Pb-L2, Pb-L3). The levels of plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total proteins (TP), albumin (ALB), urea, creatinine (Cr), and uric acid (UA), as well as the hepatic and the renal malondialdehyde (MDA), glutathione (GSH), and glutathione peroxidase (GPx), were estimated. Results exhibited a significant increase in plasma AST, ALT, ALP, urea, creatinine, uric acid, and MDA levels of the Pb group compared to the control, with the exception of TP, ALB, GSH levels, and GPx activities that were significantly diminished, though the co-administration of garlic extracts (Pb-L) revealed a significant decrease in all mentioned markers, excluding the TP, ALB, GSH, and GPx levels. Likewise, Pb caused histological injuries in the hepatic and renal tissues of rats, while the co-administration of leaves' wild garlic has reduced such effect. Thought, the Pb-L has attenuated the Pb-induced toxicity in a dose-dependent manner. In conclusion, the aqueous extracts of A. triquetrum have the potential to alleviate Pb hepatotoxicity and nephrotoxicity through the modulation of most biomarkers in Wistar rat.

Molecular Docking and In-Silico Analysis of Natural Biomolecules against Dengue, Ebola, Zika, SARS-CoV-2 Variants of Concern and Monkeypox Virus

The emergence and rapid evolution of human pathogenic viruses, combined with the difficulties in developing effective vaccines, underline the need to develop innovative broad-spectrum antiviral therapeutic agents. The present study aims to determine the in silico antiviral potential of six bacterial antimicrobial peptides (AMPs), two phytochemicals (silvestrol, andrographolide), and two bacterial secondary metabolites (lyngbyabellin A, hapalindole H) against dengue virus, Zika virus, Ebola virus, the major variants of SARS-CoV-2 and monkeypox virus. The comparison of docking scores obtained with natural biomolecules was performed with specific neutralizing antibodies (positive controls for ClusPro) and antiviral drugs (negative controls for Autodock Vina). Glycocin F was the only natural biomolecule tested to show high binding energies to all viral surface proteins and the corresponding viral cell receptors. Lactococcin G and plantaricin ASM1 also achieved high docking scores with all viral surface proteins and most corresponding cell surface receptors. Silvestrol, andrographolide, hapalindole H, and lyngbyabellin A showed variable docking scores depending on the viral surface proteins and cell receptors tested. Three glycocin F mutants with amino acid modifications showed an increase in their docking energy to the spike proteins of SARS-CoV-2 B.1.617.2 Indian variant, and of the SARS-CoV-2 P.1 Japan/Brazil variant, and the dengue DENV envelope protein. All mutant AMPs indicated a frequent occurrence of valine and proline amino acid rotamers. AMPs and glycocin F in particular are the most promising biomolecules for the development of broad-spectrum antiviral treatments targeting the attachment and entry of viruses into their target cell.

Quercetin, a flavonoid, combats rotavirus infection by deactivating rotavirus-induced pro-survival NF-κB pathway

Rotavirus (RV) is the leading cause of acute gastroenteritis and watery diarrhea in children under 5 years accounting for high morbidity and mortality in countries with poor socioeconomic status. Although vaccination against RV has been implemented in more than 100 countries, the efficacy of vaccine has been challenged in low-income settings. The lack of any FDA-approved drug against RV is an additional concern regarding the treatment associated with rotavirus-induced infantile death. With the purpose for the discovery of anti-RV therapeutics, we assessed anti-rotaviral potential of quercetin, a well-characterized antioxidant flavonoid. In vitro study revealed that quercetin treatment resulted in diminished production of RV-SA11 (simian strain) viral particles in a concentration-dependent manner as estimated by the plaque assay. Consistent with this result, Western blot analysis also revealed reduced synthesis of viral protein in quercetin-treated RV-SA11-infected MA104 cells compared to vehicle (DMSO) treated controls. Not surprisingly, infection of other RV strains A5-13 (bovine strain) and Wa (Human strain) was also found to be abridged in the presence of quercetin compared to DMSO. The IC₅₀ of quercetin against three RV strains ranges between 2.79 and 4.36 Mm, and S.I. index is greater than 45. Concurrent to the in vitro results, in vivo study in mice model also demonstrated reduced expression of viral proteins and viral titer in the small intestine of quercetin-treated infected mice compared to vehicle-treated infected mice. Furthermore, the result suggested anti-rotaviral activity of quercetin to be interferon-independent. Mechanistic study revealed that the antiviral action of quercetin is co-related with the inhibition of RV-induced early activation of NF-κB pathway. Overall, this study delineates the strong anti-RV potential of quercetin and also proposes it as future therapeutics against rotaviral diarrhea.

In Silico Analysis Using SARS-CoV-2 Main Protease and a Set of Phytocompounds to Accelerate the Development of Therapeutic Components against COVID-19

SARS-CoV-2, the virus that caused the widespread COVID-19 pandemic, is homologous to SARS-CoV. It would be ideal to develop antivirals effective against SARS-CoV-2. In this study, we chose one therapeutic target known as the main protease (Mpro) of SARS-CoV-2. A crystal structure (Id: 6LU7) from the protein data bank (PDB) was used to accomplish the screening and docking studies. A set of phytocompounds was used for the docking investigation. The nature of the interaction and the interacting residues indicated the molecular properties that are essential for significant affinity. Six compounds were selected, based on the docking as well as the MM-GBSA score. Pentagalloylglucose, Shephagenin, Isoacteoside, Isoquercitrin, Kappa-Carrageenan, and Dolabellin are the six compounds with the lowest binding energies (−12 to −8 kcal/mol) and show significant interactions with the target Mpro protein. The MMGBSA scores of these compounds are highly promising, and they should be investigated to determine their potential as Mpro inhibitors, beneficial for COVID-19 treatment. In this study, we highlight the crucial role of in silico technologies in the search for novel therapeutic components. Computational biology, combined with structural biology, makes drug discovery studies more rigorous and reliable, and it creates a scenario where researchers can use existing drug components to discover new roles as modulators or inhibitors for various therapeutic targets. This study demonstrated that computational analyses can yield promising findings in the search for potential drug components. This work demonstrated the significance of increasing in silico and wetlab research to generate improved structure-based medicines.

Andrographolide induces anti-SARS-CoV-2 response through host-directed mechanism: an in silico study

Aim: Considering the present alarming situation of COVID-19 pandemic, we concentrated on evaluating the efficacy of a novel natural antiviral drug-candidate andrographolide against SARS-CoV-2 through an in silico model of study. Materials & methods: Interaction of andrographolide against the major host molecules that are responsible for SARS-CoV-2 pathogenesis were determined using bio-computational tools, in other words, molecular docking, molecular dynamics simulation and pharmacodynamics–pharmacokinetics analysis. Result: Computational findings represent that andrographolide efficiently interacts with the major human–host-associated putative drug-targets of viral-entry points like furin (-10.54 kcal/mol), TMPRSS-2 (-9.50 kcal/mol), ACE2 (-8.99 kcal/mol) and Cathepsin L (-8.98 kcal/mol). Moreover, it also blocks the inflammatory regulators including TLR4-MD2 and IL-6, which promote virus-induced inflammation leading to cytokine storm in the host body. Conclusion: This work elucidates that, the candidature of andrographolide can be utilized as a potent natural agent for the therapeutic intervention of SARS-CoV-2 through host-directed treatment.

LOW PREVALENCE OF COVID-19 IN LAOS AND CAMBODIA: DOES DIET PLAY A ROLE?

The study aims to review the involvement of different dietary habits in Laotian, Cambodian, and Vietnamese populations in reducing COVID19 impact. Materials and Methods. The methods of collection, systematization, analysis and generalization of information data have been used. The analysis of literature in scientific databases and analytical platforms by the listed keywords has been performed; all relevant references in the found sources have also been reviewed. Results and Discussion. Coronavirus disease (COVID-19) outbreak is an ongoing pandemic caused by a highly pathogenic human coronavirus known as SARS-CoV2. Current epidemiology reported that more than 500 million cases of COVID-19 occurred in more than 180 countries worldwide. When the upper respiratory tract gets infected by low pathogenetic HCoVs, it typically triggers a mild respiratory disease. In contrast, when the lower airways get infected by highly pathogenic HCoVs, such as SARS-CoV2, acute respiratory distress syndrome (ARDS) may occur and even fatal pneumonia. Such a situation causes the need for an urgent search of effective treatment measures. A very low incidence of SARS-CoV-2 in Laos and Cambodia, as well as low mortality rate due to COVID-19 in Vietnam and Laos, are extremely interesting, especially because of their early exposure to the virus, continuing ties to China, relative poverty, and high population density. The use of several spices and aromatic herbs as natural treatments for several illnesses, including viral infections, has been reported since a long time ago. The research reviewed three integral elements of Laotian, Cambodian, and Vietnamese diets, such as special culinary spices and herbs, coconut oil, and palm oil-rich for saturated fatty acids as well as fermented shrimp paste. Environmental and population genetic causes may be forwarded but moreover local dietary habits may have even a role in this evidence. Therefore, all these items highlight the possibility of a significant contribution of local cuisine and diet into the impact on appropriate anti-inflammatory and immune-resistant mechanisms of the human population. Conclusions. The review on Vietnam, Cambodia, and Laos inhabitants' diet helped to suggest the dietary factors having the contributing potential of reducing the severity of SARS-CoV-2 symptoms.

Plant-derived active compounds as a potential nucleocapsid protein inhibitor of SARS-CoV-2: an in-silico study

The coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2. This virus has a high mismatch repair proofreading ability due to its unique exonuclease activity, making it knotty to treat. The nucleocapsid protein can serve as a potential antiviral drug target, as this protein is responsible for multiple captious functions during the viral life cycle. Herein, we have investigated the potential to repurpose active antiviral compounds of plant origins for treating the SARS-CoV-2 infection. In the present study, we followed the molecular docking methodology to screen druggable natural plants' active compounds against the nucleocapsid protein of SARS-CoV-2. The virtual screening of all 68 compounds revealed that the top seven active compounds, such as withanolide D, hypericin, silymarin, oxyacanthine, withaferin A, Acetyl aleuritolic acid, and rhein, exhibit good binding affinity with druggable ADME properties, toxicity, and Pass prediction. The stability of the docked complexes was studied by conducting molecular simulations of 100 ns. MM-GBSA calculated the binding free energy uncovered that withanolide D, hypericin, and silymarin result in highly stable binding conformations in three different sites of the nucleocapsid protein. However, further investigation is needed in order to validate the candidacy of these inhibitors for clinical trials. HighlightsNatural plants' active compounds may aid in the inhibition of SARS-CoV-2 replication and COVID-19 therapeutics.Hypericin, silymarin, withanolide D, oxyacanthine, withaferin A, Acetyl aleuritolic acid, and rhein are effective against SARS-CoV-2 N protein.Studied natural plants' active compounds could be useful against COVID-19 and its associated organs comorbidities.ADMET properties of selected compounds favor these compounds as druggable candidates.Communicated by Ramaswamy H. Sarma.

The Traditional Chinese Medicine Formula Jing Guan Fang for Preventing SARS-CoV-2 Infection: From Clinical Observation to Basic Research

COVID-19 is a global epidemic. Developing adjuvant therapies which could prevent the virus from binding to cells may impair viral infection. This study produces a traditional Chinese medicine formula, Jing Guan Fang (JGF), based on ancient medical texts, and examines the efficacy and the mechanism by which JGF prevents viral infections. JGF reduces COVID-19 like symptoms. Functional studies show that JGF inhibits the formation of syncytium and reduces the formation of viral plaque. JGF is not toxic in vitro and in vivo. Mechanistically, JGF induces lysosomal-dependent ACE2 degradation and suppresses mRNA and the protein levels of TMPRSS2 in human lung WI-38 and MRC-5 cells. Mice that inhale JGF exhibit reduced ACE2 and TMPRSS2 protein levels in lung tissues. Together, these findings suggest that JGF may improve the COVID-19 like symptoms and inhibit viral infection. Moreover, JGF may be applicable as an adjuvant preventive strategy against SARS-CoV-2 infection in addition to the use of vaccines.

Therapeutic benefits of Salvia species: A focus on cancer and viral infection

Man is increasingly being faced with many health conditions, including viral infection, some of which increases the risk to cancer. These infectious agents contribute to the large number of persons with cancer and the worrisome number that die from the diseases. A good range of drugs are currently in place for treating patients infected with viruses, however, some of the drugs' effectiveness are limited by the emergence of drug-resistant strains of the viruses, as well as adverse effects of the drugs. Similarly, the inability of many anticancer drugs to selectively kill cancer cells while sparing hosts' normal cells limit their use. This warrants more research for newer drugs, especially from chemicals naturally encrypted in plants with anticancer and antiviral activities. In response to infection with cancer-inducing viruses, plants such as Salvia species synthesize and store secondary metabolites to protect themselves and kill these viruses as well as inhibit their ability to induce carcinogenesis. Hence, this review presented a discussion on the potential application of Salvia species in the prevention and management of cancer and viral infection. The study also discusses the cellular mechanisms of action of these herbal products against cancer cells and viruses, where available and provided suggestions on future research directions. The study is believed to spur more research on how to exploit Salvia phytochemicals as candidates for the development of nutraceuticals and drugs for managing cancers and viral infection.

Licorice (Glycyrrhiza glabra) Extracts-Suitable Pharmacological Interventions for COVID-19? A Review

Even though vaccination has started against COVID-19, people should continue maintaining personal and social caution as it takes months or years to get everyone vaccinated, and we are not sure how long the vaccine remains efficacious. In order to contribute to the mitigation of COVID-19 symptoms, the pharmaceutical industry aims to develop antiviral drugs to inhibit the SARS-CoV-2 replication and produce anti-inflammatory medications that will inhibit the acute respiratory distress syndrome (ARDS), which is the primary cause of mortality among the COVID-19 patients. In reference to these tasks, this article considers the properties of a medicinal plant named licorice (Glycyrrhiza glabra), whose phytochemicals have shown both antiviral and anti-inflammatory tendencies through previous studies. All the literature was selected through extensive search in various databases such as google scholar, Scopus, the Web of Science, and PubMed. In addition to the antiviral and anti-inflammatory properties, one of the licorice components has an autophagy-enhancing mechanism that studies have suggested to be necessary for COVID-19 treatment. Based on reviewing relevant professional and historical literature regarding the medicinal properties of licorice, it is suggested that it may be worthwhile to conduct in vitro and in vivo studies, including clinical trials with glycyrrhizic and glycyrrhetinic acids together with other flavonoids found in licorice, as there is the potentiality to provide natural interventions against COVID-19 symptoms.

In Vitro Anti-Epstein Barr Virus Activity of Olea europaea L. Leaf Extracts

Olea europaea L. var. sativa (OESA) preparations are widely used in traditional medicine in the Mediterranean region to prevent and treat different diseases. In this research, olive extracts derived from the leaves of the OESA tree have been screened for antioxidant activity by two methods: the DPPH free radical scavenging assay (DPPH) and the Ferric reducing antioxidant power (FRAP) assay. The DPPH assay showed that OESA possesses a stronger antioxidant activity (84%) at 1 mg/mL while the FRAP method showed a strong metal ion chelating activity (90%) at 1 mg/mL. The low IC₅₀ values, obtained by two different methods, implies that OESA has a noticeable effect on scavenging free radicals comparable to standards. During EBV infection, the free radicals increased triggering lipid oxidation. Therefore, the monitoring of the secondary lipid peroxidation products was done by measuring malonaldehyde (MDA) and conjugated dienes (DC). The simultaneous treatment of Raji cells with OESA and TPA, as an inductorof the lytic cycle, generated a significant decrease in MDA levels and DC (p < 0.05). Besides, Raji cells simultaneously exposed to TPA and OESA exhibited a percentage of EBV-positive fluorescence cells lower than TPA treated cells (**** p < 0.0001). This suggests that OESA treatment has a protective effect against EBV lytic cycle induction.

Evaluation of secondary metabolites of herbal plant extracts as an antiviral effect on infectious bursal disease virus isolates in embryonated chicken eggs

BACKGROUND AND AIM

Infectious bursal disease attacks the poultry industry, mainly young chickens, causing immunosuppression, and death with high economic losses. This study aimed to evaluate the effects of the monoextract, diextracts, and triextracts of Quercus infectoria (QI), Citrus aurantifolia (CiA), and Coffea arabica (CoA) on infectious bursal disease virus (IBDV) in embryonated chicken eggs (ECEs).

MATERIALS AND METHODS

The experimental design consisted of three sets of ECEs at 11 days of age, and each set included seven groups (G1-G7). The extracts of QI, CiA, and CoA were inoculated to ECEs by the chorioallantoic membrane method before, in concomitant (mixed) with, and after IBDV infection to the first, second, and third sets, respectively. The monoextract, diextracts, and triextracts of QI, CiA, and CoA were given at 1%, 2%, 5%, and 10% concentrations to G1-G3, G4-G6, and G7, respectively. Real-time polymerase chain reaction identified and confirmed the virus in accordance with the pathological changes.

RESULTS

The monoextract (5-10% concentrations) inhibited IBDV and had no effect on viral infection preinoculation, whereas the monoextract (10% concentration) inhibited IBDV during mixed inoculation and post-inoculation. Diextracts (2-10% concentrations) inhibited IBDV and had no effect on viral infection preinoculation, whereas diextracts (5-10% concentrations) inhibited IBDV during mixed inoculation and post-inoculation. Triextracts (1%, 2%, 5%, and 10% concentrations) inhibited IBDV by ameliorating the pathological changes of the virus and preventing the death of ECEs.

CONCLUSION

The inoculation of herbal extracts, particularly triextracts, alleviates the pathological changes in ECEs infected with IBDV. This study recommends the oral route in evaluating plant extracts against IBDV in poultry.

Enhanced Accumulation of Betulinic Acid in Transgenic Hairy Roots of Senna obtusifolia Growing in the Sprinkle Bioreactor and Evaluation of Their Biological Properties in Various Biological Models

Betulinic acid, which is found in transgenic roots of Senna obtusifolia (L.) H.S.Irwin & Barneby, is a pentacyclic triterpene with distinctive pharmacological activities. In this study, we report the differences in the content of betulinic acid and selected anthraquinones in transgenic S. obtusifolia hairy roots with overexpression of the PgSS1 gene (SOPSS2 line) and in transformed hairy roots without this genetic construct (SOA41 line). Both hairy root lines grew in 10 L sprinkle bioreactor. Additionally, the extracts obtained from this plant material were used for biological tests. Our results demonstrated that the SOPSS2 hairy root cultures from the bioreactor showed an increase in the content of betulinic acid (38.125 mg/g DW), compared to the SOA41 hairy root line (4.213 mg/g DW). Biological studies have shown a cytotoxic and antiproliferative effect on U-87MG glioblastoma cells, and altering the level of apoptotic proteins (Bax, p53, Puma and Noxa). Antimicrobial properties were demonstrated for both tested extracts, with a stronger effect of SOPSS2 extract. Moreover, both extracts showed moderate antiviral properties on norovirus surrogates.

Computational and synthetic biology approaches for the biosynthesis of antiviral and anticancer terpenoids from Bacillus subtilis

Recent advancements in medicinal research have identified several antiviral and anticancer terpenoids that are usually deployed as a source of flavor, fragrances and pharmaceuticals. Under the current COVID-19 pandemic conditions, natural therapeutics with least side effects are the need of the hour to save the patients, especially, which are pre-affected with other medical complications. Although, plants are the major sources of terpenoids; however, for the environmental concerns, the global interest has shifted to the biocatalytic production of molecules from microbial sources. The gram-positive bacterium Bacillus subtilis is a suitable host in this regard due to its GRAS (generally regarded as safe) status, ease in genetic manipulations and wide industrial acceptability. The B. subtilis synthesizes its terpenoid molecules from 1-deoxy-d-xylulose-5-phosphate (DXP) pathway, a common route in almost all microbial strains. Here, we summarize the computational and synthetic biology approaches to improve the production of terpenoid-based therapeutics from B. subtilis by utilizing DXP pathway. We focus on the in-silico approaches for screening the functionally improved enzyme-variants of the two crucial enzymes namely, the DXP synthase (DXS) and farnesyl pyrophosphate synthase (FPPS). The approaches for engineering the active sites are subsequently explained. It will be helpful to construct the functionally improved enzymes for the high-yield production of terpenoid-based anticancer and antiviral metabolites, which would help to reduce the cost and improve the availability of such therapeutics for the humankind.

Therapeutic potential of phytoconstituents of edible fruits in combating emerging viral infections

Plant-derived bioactive molecules display potential antiviral activity against various viral targets including mode of viral entry and its replication in host cells. Considering the challenges and search for antiviral agents, this review provides substantiated data on chemical constituents of edible fruits with promising antiviral activity. The bioactive constituents like naringenin, mangiferin, α-mangostin, geraniin, punicalagin, and lectins of edible fruits exhibit antiviral effect by inhibiting viral replication against IFV, DENV, polio, CHIKV, Zika, HIV, HSV, HBV, HCV, and SARS-CoV. The significance of edible fruit phytochemicals to block the virulence of various deadly viruses through their inhibitory action against the entry and replication of viral genetic makeup and proteins are discussed. In view of the antiviral property of active constituents of edible fruits which can strengthen the immune system and reduce oxidative stress, they are suggested to be diet supplements to combat various viral diseases including COVID-19. PRACTICAL APPLICATIONS: Considering the increasing threat of COVID-19, it is suggested to examine the therapeutic efficacy of existing antiviral molecules of edible fruits which may provide prophylactic and adjuvant therapy with their potential antioxidant, anti-inflammatory, and immune-modulatory effects. Several active molecules like geraniin, naringenin, (2R,4R)-1,2,4-trihydroxyheptadec-16-one, betacyanins, mangiferin, punicalagin, isomangiferin, procyanidin B2, quercetin, marmelide, jacalin lectin, banana lectin, and α-mangostin isolated from various edible fruits have showed promising antiviral properties against different pathogenic viruses. Especially flavonoid compounds extracted from edible fruits possess potential antiviral activity against a wide array of viruses like HIV-1, HSV-1 and 2, HCV, INF, dengue, yellow fever, NSV, and Zika virus infection. Hence taking such fruits or edible fruits and their constituents/compounds as dietary supplements could deliver adequate plasma levels in the body to optimize the cell and tissue levels and could lead to possible benefits for the preventive measures for this pandemic COVID-19 situation.

Icariin, Formononetin and Caffeic Acid Phenethyl Ester Inhibit Feline Calicivirus Replication In Vitro

Cats infected with feline calicivirus (FCV) often display oral ulcers and inflammation of the upper respiratory tract, which can lead to death in severe cases. Antiviral therapy is one of the most effective ways to control FCV infection. Natural compounds in Chinese herbal medicines and medicinal plants provide abundant resources for research on antiviral drugs. In this study, we found that icariin (ICA), formononetin (FMN) and caffeic acid phenethyl ester (CPAE) show low cytotoxicity towards F81 cells, that the three natural compounds have apparent antiviral effects on FCV in vitro, and that they can inhibit different FCV strains. Then, we found that ICA and FMN mainly function in the early stage of FCV infection, while CAPE can function in both the early and late stages of FCV infection. Finally, we found that ICA has an antagonistic effect on FMN and CAPE in FCV infection, and FMN has a synergistic effect with CAPE against FCV infection. Our results showed that ICA, FMN and CAPE may be potential drug candidates for FCV-induced diseases.

Potent phytochemicals against COVID-19 infection from phyto-materials used as antivirals in complementary medicines: a review

Background

Following the outbreak of the COVID-19 pandemic, there was a surge of research activity to find methods/drugs to treat it. There has been drug-repurposing research focusing on traditional medicines. Concomitantly, many researchers tried to find in silico evidence for traditional medicines. There is a great increase in article publication to commensurate the new-found research interests. This situation inspired the authors to have a comprehensive understanding of the multitude of publications related to the COVID-19 pandemic with a wish to get promising drug leads.

Main body

This review article has been conceived and made as a hybrid of the review of the selected papers advertised recently and produced in the interest of the COVID-19 situation, and in silico work done by the authors. The outcome of the present review underscores a recommendation for thorough MDS analyses of the promising drug leads. The inclusion of in silico work as an addition to the review was motivated by a recently published article of Toelzer and colleagues. The in silico investigation of free fatty acids is novel to the field and it buttresses the further MDS analysis of drug leads for managing the COVID-19 pandemic.

Conclusion

The review performed threw light on the need for MDS analyses to be considered together with the application of other in silico methods of prediction of pharmacologic properties directing towards the sites of drug-receptor regulation. Also, the present analysis would help formulate new recipes for complementary medicines.

Bioactive phytocompound mulberroside C and endophytes of Morus alba as potential inhibitors of HIV-1 replication: a mechanistic evaluation

OBJECTIVES

Despite considerable advancement in antiretroviral therapy, development of safe, effective, and multi-targeted drugs for HIV still remains a big challenge. Endophytes are untouched and, hence, an important and novel sources in drug discovery endeavours. The present study was conducted to identify the anti-HIV compounds from Morus alba and endophytes isolated from it.

METHODS

The extracts of isolated endophytes were screened using high-performance liquid chromatography (HPLC). Further, all samples were analysed for their cytotoxicity using a thiazolyl blue tetrazolium bromide assay. Subsequently, anti-HIV activity was performed using cell-based and cell-free assay. At the end, potential endophytes were identified using gene sequencing.

RESULTS

A total of 27 endophytes were isolated from the eight stem bark samples of M. alba. Of the 27 endophytes, extracts of total of four endophytes showed a profile similar to the M. alba plant when analysed by HPLC. Further experimentation with extracts of these four endophytes, along with an extract of M. alba stem bark and its bioactive molecule, mulberroside C, revealed that all these six samples have good inhibitory potential for HIV. Among them, mulberroside C and two endophytic fungal extracts showed very potent anti-HIV activity. Subsequently, mechanistic studies at the molecular level showed that out of six test samples, three acted as protease inhibitors. Further, all four potential endophytes were identified using gene sequencing.

CONCLUSIONS

The overall findings of these studies can help in the development of a novel anti-HIV candidate from mulberroside C, an extract of stem bark of M. alba and extracts of these endophytes. However, further validation and clinical studies are required to develop an anti-HIV drug.

Therapeutic Potentials of Antiviral Plants Used in Traditional African Medicine With COVID-19 in Focus: A Nigerian Perspective

The coronavirus disease 2019 (COVID-19) pandemic is caused by an infectious novel strain of coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which was earlier referred to as 2019-nCoV. The respiratory disease is the most consequential global public health crisis of the 21st century whose level of negative impact increasingly experienced globally has not been recorded since World War II. Up till now, there has been no specific globally authorized antiviral drug, vaccines, supplement or herbal remedy available for the treatment of this lethal disease except preventive measures, supportive care and non-specific treatment options adopted in different countries via divergent approaches to halt the pandemic. However, many of these interventions have been documented to show some level of success particularly the Traditional Chinese Medicine while there is paucity of well reported studies on the impact of the widely embraced Traditional African Medicines (TAM) adopted so far for the prevention, management and treatment of COVID-19. We carried out a detailed review of publicly available data, information and claims on the potentials of indigenous plants used in Sub-Saharan Africa as antiviral remedies with potentials for the prevention and management of COVID-19. In this review, we have provided a holistic report on evidence-based antiviral and promising anti-SARS-CoV-2 properties of African medicinal plants based on in silico evidence, in vitro assays and in vivo experiments alongside the available data on their mechanistic pharmacology. In addition, we have unveiled knowledge gaps, provided an update on the effort of African Scientific community toward demystifying the dreadful SARS-CoV-2 micro-enemy of man and have documented popular anti-COVID-19 herbal claims emanating from the continent for the management of COVID-19 while the risk potentials of herb-drug interaction of antiviral phytomedicines when used in combination with orthodox drugs have also been highlighted. This review exercise may lend enough credence to the potential value of African medicinal plants as possible leads in anti-COVID-19 drug discovery through research and development.

A cut above the rest: oxidative stress in chronic wounds and the potential role of polyphenols as therapeutics

OBJECTIVES

The pathophysiology of chronic wounds typically involves redox imbalance and inflammation pathway dysregulation, often with concomitant microbial infection. Endogenous antioxidants such as glutathione and tocopherols are notably reduced or absent, indicative of significant oxidative imbalance. However, emerging evidence suggests that polyphenols could be effective agents for the amelioration of this condition. This review aims to summarise the current state of knowledge surrounding redox imbalance in the chronic wound environment and the potential use of polyphenols for the treatment of chronic wounds.

KEY FINDINGS

Polyphenols provide a multi-faceted approach towards the treatment of chronic wounds. Firstly, their antioxidant activity allows direct neutralisation of harmful free radicals and reactive oxygen species, assisting in restoring redox balance. Upregulation of pro-healing and anti-inflammatory gene pathways and enzymes by specific polyphenols further acts to reduce redox imbalance and promote wound healing actions, such as proliferation, extracellular matrix deposition and tissue remodelling. Finally, many polyphenols possess antimicrobial activity, which can be beneficial for preventing or resolving infection of the wound site.

SUMMARY

Exploration of this diverse group of natural compounds may yield effective and economical options for the prevention or treatment of chronic wounds.

Virtual screening of phytochemical compounds as potential inhibitors against SARS-CoV-2 infection

Background

The present pandemic situation due to coronavirus has led to the search for newer prevention, diagnostic, and treatment methods. The onset of the corona infection in a human results in acute respiratory illness followed by death if not diagnosed and treated with suitable antiretroviral drugs. With the unavailability of the targeted drug treatment, several repurposed drugs are being used for treatment. However, the side-effects of the drugs urges us to move to a search for newer synthetic- or phytochemical-based drugs. The present study investigates the use of various phytochemicals virtually screened from various plant sources in Western Ghats, India, and subsequently molecular docking studies were performed to identify the efficacy of the drug in retroviral infection particularly coronavirus infection.

Results

Out of 57 phytochemicals screened initially based on the structural and physicochemical properties, 39 were effectively used for the docking analysis. Finally, 5 lead compounds with highest hydrophobic interaction and number of H-bonds were screened. Results from the interaction analysis suggest Piperolactam A to be pocketed well with good hydrophobic interaction with the residues in the binding region R1. ADME and toxicity profiling also reveals Piperolactam A with higher LogS values indicating higher permeation and hydrophilicity. Toxicity profiling suggests that the 5 screened compounds to be relatively safe.

Conclusion

The in silico methods used in this study suggests that the compound Piperolactam A to be the most effective inhibitor of S-protein from binding to the GRP78 receptor. By blocking the binding of the S-protein to the CS-GRP78 cell surface receptor, they can inhibit the binding of the virus to the host.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43088-021-00095-x.

Evaluation of certain medicinal plants compounds as new potential inhibitors of novel corona virus (COVID-19) using molecular docking analysis

SARS-CoV-2 is a new strain of coronavirus that appeared in China in December 2019, in recent years, great progress has been made in developing new antiviral drugs, and natural products, are important sources of potential and new antiviral drugs. The present study aimed to assess some biologically active compounds present in medicinal plants as potential COVID-19 inhibitors, using molecular docking methods. The Docking study was performed by Molecular Operating Environment software (MOE). About 20 Compounds were screened in this study; these compounds were selected based on classification of their chemical origin and their antiviral activity from literature. These compounds might be used to inhibit COVID-19 infection. The results demonstrate the effectiveness of this screening strategy, which can lead to rapid drug discovery in response to new infectious diseases. The results showed that many compounds isolated from medicinal plants such as; Gallic acid (- 17.45), Quercetin (- 15.81), Naringin (- 14.50), Capsaicin (- 13.90), and Psychotrine (- 13.5) are important sources for novel antiviral drugs targeting COVID-19.

Phycobilins as Potent Food Bioactive Broad-Spectrum Inhibitors Against Proteases of SARS-CoV-2 and Other Coronaviruses: A Preliminary Study

In the 21st century, we have witnessed three coronavirus outbreaks: SARS in 2003, MERS in 2012, and the ongoing pandemic coronavirus disease 2019 (COVID-19). The search for efficient vaccines and development and repurposing of therapeutic drugs are the major approaches in the COVID-19 pandemic research area. There are concerns about the evolution of mutant strains (e.g., VUI - 202012/01, a mutant coronavirus in the United Kingdom), which can potentially reduce the impact of the current vaccine and therapeutic drug development trials. One promising approach to counter the mutant strains is the "development of effective broad-spectrum antiviral drugs" against coronaviruses. This study scientifically investigates potent food bioactive broad-spectrum antiviral compounds by targeting main protease (M^pro) and papain-like protease (PL^pro) proteases of coronaviruses (CoVs) using in silico and in vitro approaches. The results reveal that phycocyanobilin (PCB) shows potential inhibitor activity against both proteases. PCB had the best binding affinity to Mpro and PLpro with IC₅₀ values of 71 and 62 μm, respectively. Also, in silico studies with M^pro and PL^pro enzymes of other human and animal CoVs indicate broad-spectrum inhibitor activity of the PCB. As with PCB, other phycobilins, such as phycourobilin (PUB), phycoerythrobilin (PEB), and phycoviolobilin (PVB) show similar binding affinity to SARS-CoV-2 M^pro and PL^pro.

Virtual screening of phytoconstituents from miracle herb nigella sativa targeting nucleocapsid protein and papain-like protease of SARS-CoV-2 for COVID-19 treatment

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel etiological agent of coronavirus disease 2019 (COVID-19). Nigella sativa, commonly known as black seed or black cumin, has been a historical and traditional plant since thousands of years. Based on their therapeutic efficacy, the chief components of terpenoids and flavonoids were selected from N. sativa seeds and seed oil. This study was designed to check the antiviral efficacy of N. sativa main phytoconstituents against five potential targets of SARS-CoV-2 using in silico structure-based virtual screening approach. Out of twenty five phytocomponents, ten components showed best binding affinity against two viral proteins viz. N-terminal RNA binding domain (NRBD; PDB ID: 6M3M) of nucleocapsid protein and papain-like protease (PL-_PRO; PDB ID: 6W9C) of SARS-CoV-2 using AutoDock 4.2.6, AutoDock Vina and iGEMDOCK. PASS analyses of all ten phytocomponents using Lipinski's Rule of five showed promising results. Further, druglikeness and toxicity assessment using OSIRIS Data Warrior v5.2.1 software exhibited the feasibility of phytocomponents as drug candidates with no predicted toxicity. Molecular dynamics simulation study of NRBD of SARS-CoV-2 nucleocapsid protein-alpha-spinasterol complex and PL-_PRO-cycloeucalenol complex displayed strong stability at 300 K. Both these complexes exhibited constant root mean square deviation (RMSDs) of protein side chains and Cα atoms throughout the simulation run time. Interestingly, PL-_PRO and NRBD are key proteins in viral replication, host cell immune evasion and viral assembly. Thus, NRBD and PL-_PRO have the potential to serve as therapeutic targets for N. sativa phytoconstituents in drug discovery process against COVID-19.

In Search of Herbal Anti-SARS-Cov2 Compounds

On March 11, 2020, the World Health Organization (WHO) announced that the spread of the new coronavirus had reached the stage of a pandemic. To date (23.10.2020), there are more than 40 million confirmed cases of the disease in the world, at the same time there is still no effective treatment for the disease. For management and treatment of SARS-Cov2, the development of an antiviral drug is needed. Since the representatives of all human cultures have used medicinal plants to treat viral diseases throughout their history, plants can be considered as sources of new antiviral drug compounds against emerging viruses. The huge metabolic potential of plants allows us to expect discovery of plant compounds for the prevention and treatment of coronavirus infection. This idea is supported by number of papers on the anti-SARS-Cov2 activity of plant extracts and specific compounds in the experiments in silico, in vitro, and in vivo. Here, we summarize information on methods and approaches aimed to search for anti-SARS-Cov2 compounds including cheminformatics, bioinformatics, genetic engineering of viral targets, interacting with drugs, biochemical approaches etc. Our mini-review may be useful for better planning future experiments (including rapid methods for screening compounds for antiviral activity, the initial assessment of the antiviral potential of various plant species in relation to certain pathogens, etc.) and giving a hand to those who are making first steps in this field.

Potentials of plant-based substance to inhabit and probable cure for the COVID-19

COVID-19 has been the most devastating pandemic in human history. Despite the highest scientific efforts and investments, a reliable and certified medication has yet to be developed regarding to immune or cure this virus. However, while synthetic medications are gaining the focus of attentions, it appears from a significant number of recent studies that plant-based substances could also be potential candidates for developing effective and secure remedies against this novel disease. Citing such recent works, this review primarily demonstrates the antiviral potentials of medicinal plants for inhibiting human coronaviruses. It also shows the importance of antiviral plants substances, particularly in the development of a broad spectrum medication for coronaviruses including SARS-CoV-2 responsible for COVID-19.