Anti-HSV-2 activity of Terminalia chebula Retz extract and its constituents, chebulagic and chebulinic acids

Plants used in Ayurveda for Jwara or fever: A review of their antiviral studies

Two of the earliest treatises in Ayurveda, the 'Charaka Samhita' and the 'Sushruta Samhita', describe numerous medicinal plants used in the treatment of Jwara (fever). Systematic studies carried out on these plants registered for 'Jwara' are of high significance in antiviral drug development. This article is a comprehensive review of the antiviral studies on medicinal plants listed for 'Jwara' in 'Charaka-Sushruta Samhitas', their antiviral entities and modes of action. The botanical names of the medicinal plants used for 'Jwara' were elucidated from their Sanskrit names in 'Charaka-Sushruta Samhitas' and their subsequent interpretations. Antiviral studies on these plant species and their constituents were compiled from the literature retrieved from Scopus, PubMed, Google Scholar and other databases. Antiviral activities against various viruses were evaluated based on EC50/IC50/LC50 values, high percent inhibitions and molecular docking parameters displayed by their extracts, secondary metabolites, short peptides, polyphenols, anthocyanins and polysaccharides. Their modes of action were also evaluated. Strikingly, in antiviral studies very low EC50/IC50/LC50 and high percent inhibitions were demonstrated by medicinal plants widely used as traditional medicines, vegetables, foods and flavours. Secondary metabolites (including essential oils), anthocyanins, polyphenols, short peptides and polysaccharides in these plants illustrated antiviral activities by hampering membrane permeability, cellular functions and replication cycle of harmful viruses. Medicinal plants used for fever in Ayurveda could be used as natural sources of lead molecules for antiviral drug development. Antiviral activities displayed by these plants are justifying the ancient wisdom traditionally demonstrated over centuries.

Natural compounds target the M23B zinc metallopeptidase Mpg to modulate Neisseria gonorrhoeae Type IV pilus expression

Neisseria gonorrhoeae uses the Type IV pilus (T4p) to colonize several sites within humans by adhering to host cells and tissues. Previously, we identified a periplasmic M23B zinc metallopeptidase, Mpg, that is necessary to protect from oxidative and nonoxidative killing and these phenotypes are mediated by Mpg activities on T4p expression. Here, we use a high-throughput, target-based screening approach to identify novel inhibitors of Mpg's enzymatic activity. We identified two natural compounds, punicalagin and chebulinic acid, which inhibit the peptidoglycan-hydrolyzing activity of Mpg in a dose-dependent manner. Moreover, treatment of N. gonorrhoeae with these compounds leads to a concomitant decrease in the number of T4p, similar to an mpg mutant. However, these compounds are not toxic to N. gonorrhoeae. These compounds exhibit activity against Mpg orthologs from other bacterial species. Notably, these natural compounds inhibit N. gonorrhoeae colonization and survival in cell culture models of infection. This work provides the characterization of two natural compounds with activity against N. gonorrhoeae T4p through the Mpg M23B class zinc metallopeptidase.

IMPORTANCE

Neisseria gonorrhoeae is a global health burden with high transmission rates and multidrug resistance. N. gonorrhoeae encodes a Type IV pilus (T4p), which is a major colonization and virulence factor. The importance of the T4p in multiple stages of infection makes it an attractive drug target. Previously, we identified an M23B zinc metallopeptidase, Mpg, important for T4p production and T4p-mediated resistance to neutrophil killing. In this study, we identified two natural compounds, punicalagin and chebulinic acid, as novel inhibitors of Mpg's enzymatic activity that thus inhibit T4p expression. These findings identify two potential anti-colonization and anti-virulence compounds and provide a framework to target T4p components for future screens, poising the field to potentially discover additional compounds to combat N. gonorrhoeae infection.

Chebulinic acid suppresses porcine epidemic diarrhea virus infection by inhibiting viral entry and viral main protease

Porcine epidemic diarrhea virus (PEDV) has resulted in significant economic losses in the global swine industry, making the development of effective therapeutic approaches a pressing need. In this study, we found that chebulinic acid significantly restrained PEDV replication in CCL-81 and LLC-PK1 cells, demonstrated by reductions in viral genome, viral protein, and titer. Molecular docking analysis made it clear that chebulinic acid might bind the key amino acids of binding pocket and the active center of PEDV main protease. Subsequent in vitro experiments confirmed the inhibitory effects of chebulinic acid on PEDV main protease, with an IC50 value of 61.53 ± 2.12 μM determined through a fluorescence resonance energy transfer (FRET) assay. Additional investigations demonstrated that chebulinic acid could inhibit the attachment and penetration processes of PEDV infection. Overall, our results provide experimental evidence supporting the inhibitory effects of chebulinic acid on PEDV infection by targeting viral entry and the inhibitory effects on main protease. The results of this study offer potential for creating new treatments for porcine epidemic diarrhea.

Antiparasitic Activities of Plants From the Traditional Senegalese Pharmacopoeia: Isolation of Antitrypanosomal and Antileishmanial Ellagic Acid Derivatives From Terminalia Avicennioides

Parasitic diseases such as trypanosomiasis and leishmaniasis pose significant health challenges in Africa. The Senegalese Pharmacopoeia, known for its many medicinal plants with anti-infectious properties, can be a source of antiparasitic natural products. This study aimed to evaluate the in vitro antiparasitic activities of 33 methanolic extracts from 24 ethnopharmacologically selected plants against Trypanosoma brucei brucei (Tbb) and Leishmania mexicana mexicana (Lmm), as well as their cytotoxic activities on WI-38 cells. The most promising plant species were Balanites aegyptiaca, Eucalyptus camaldulensis, Vachellia nilotica and four Combretaceae species. In a second step, antitrypanosomal and antileishmanial compounds were isolated by preparative high-performance liquid chromatography from one of the most active plant extracts, Terminalia avicennioides leaves. Four ellagic acid derivatives were identified by nuclear magnetic resonance (1D & 2D) and high-resolution electrospray ionization-tandem mass spectrometry (HR-ESI-MS/MS) as 3,4,3-tri-O-methylellagic acid (2), 3,4,5-O-trimethyl-3',4'-O,O-methylideneflavellagic acid (3), hexamethylcoruleoellagic acid (4) and pentamethylflavellagic acid (5). In addition, HR-ESI-MS/MS-based dereplication analysis was performed to putatively identify compounds in active cyclohexane and dichloromethane sub-extracts. Pentamethylflavellagic acid (5) showed the most promising activity against Tbb (half-maximal inhibitory concentration = 6.20 µM). This is the first time that these compounds have been isolated from T. avicennioides and evaluated for their antitrypanosomal and antileishmanial activities.

Comprehensive Review on Fruit of Terminalia chebula: Traditional Uses, Phytochemistry, Pharmacology, Toxicity, and Pharmacokinetics

Terminalia chebula Retz., known for its dried fruit, namely Chebulae Fructus, is a medicinal plant with a long-standing global reputation, which was initially recognized for its therapeutic properties during the Jin Dynasty. This review consolidates current knowledge on the traditional uses, phytochemistry, pharmacological properties, toxicity, and pharmacokinetics of Chebulae Fructus, highlighting its clinical significance and the promising therapeutic potential of its compounds. To date, studies have identified approximately 149 compounds within the plant, including tannins, phenolic acids, lignans, triterpenes, flavonoids, and volatiles. These compounds confer a broad spectrum of biological activities in vitro and in vivo, such as antioxidant, anti-inflammatory, antiviral, anticancer, antibacterial, hepatoprotective, nephroprotective, neuroprotective, and anti-diabetic, some of which are already integrated into clinical practice. However, despite substantial advancements, considerable gaps remain in understanding the complete mechanisms of action, pharmacokinetics, and safety profiles of its extracts and compounds. This paper advocates for enhanced focus on these areas to fully elucidate the therapeutic capacities and facilitate the clinical application of Chebulae Fructus. This comprehensive analysis not only reinforces the ethnopharmacological significance of Chebulae Fructus but also lays a foundation for future pharmacological explorations.

Phytochemical profiling, antiviral activities, molecular docking, and dynamic simulations of selected Ruellia species extracts

The antiviral properties of the flowering aerial extracts of Ruellia tuberosa and Ruellia patula were investigated through phytochemical profiling via LC-MS/MS and HPLC techniques. Qualitative LC-MS/MS analyses identified seventy-seven metabolites from both Ruellia species. R. tuberosa had the highest phenolic content (49.3%), whereas R. patula had the highest flavonoid content (57.8%). Additionally, quantitative HPLC investigations of the compounds identified by LC-MS/MS were performed using the available standard compounds. The main constituents in the R. tuberosa extract was found to be catechin (5321.63 µg/g), gallic acid (2878.71 µg/g), and ellagic acid (2530.79 µg/g), whereas the major compounds in the R. patula extract was found to be rutin (11,074.19 µg/g) and chlorogenic acid (3157.35 µg/g). Furthermore, the antiviral activities of both Ruellia species against HAdV-40, herpes simplex type 2 and H1N1 were evaluated. These findings demonstrated that R. tuberosa was more active than R. patula against all tested viruses, except for the HSV-2 virus, against which R. patula showed greater activity than R. tuberosa, with IC50 values of 20, 65, 22.59, and 13.13 µg/ml for R. tuberosa flowering aerial parts and 32.26, 11.66, and 23.03 µg/ml for R. patula flowering aerial parts, respectively for HAdV-40, herpes simplex type 2, and H1N1. Additionally, computational docking and molecular dynamics simulations were used to assess the molecular interactions between the bioactive compounds and specific viral targets. The combined findings from the in-vitro and in-silico experiments comprehensively evaluated the antiviral activities of both Ruellia species extracts.

The Role of Traditional Chinese Medicine and Chinese Pharmacopoeia in the Evaluation and Treatment of COVID-19

The epidemic prompted by COVID-19 continues to spread, causing a great risk to the general population's safety and health. There are still no drugs capable of curing it. Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) are the two other diseases caused by coronaviruses. Traditional Chinese Medicine (TCM) showed benefits in treating SARS and MERS by preventing the disease early, substantially mitigating symptoms, shortening the treatment period, and minimizing risks and adverse reactions caused by hormone therapy. Although several vaccines have been developed and are being used for the treatment of COVID-19, existing vaccines cannot provide complete protection against the virus due to the rapid evolution and mutation of the virus, as mutated viral epitopes evade the vaccine's target and decrease the efficacy of vaccines. Thus, there is a need to develop alternative options. TCM has demonstrated positive effects in the treatment of COVID-19. Previous research studies on TCM showed broad-spectrum antiviral activity, offering a range of possibilities for their potential use against COVID-19. This study shed some light on common TCM used for SARS and MERS outbreaks and their effective use for COVID-19 management. This study provides new insights into COVID-19 drug discovery.

Strictinin: A Key Ingredient of Tea

Strictinin is a relatively tiny ellagitannin, which is found in many plants as a minor constituent. Catechins are known as the major constituents in the young leaves of most tea plants, while strictinin was found as a major constituent in the Pu'er tea plant. In some Pu'er tea varieties, strictinin was identified as the most abundant phenolic compound rather than catechins. In the past decade, strictinin was demonstrated to possess several functional activities, including antiviral, antibacterial, anti-obesity, laxative, anticaries, anti-allergic, antipsoriatic, antihyperuricemia, antidiabetic, and anticancer effects. These functional activities were in accordance with the therapeutic effects empirically perceived for Pu'er tea. Evidently, strictinin is the key ingredient in Pu'er tea that acts as a herbal medicine. In functionally-based applications, an instant powder of Pu'er tea infusion was formulated as an active raw material to be supplemented in food, cosmetics, and beverages; a new type of tea named Bitter Citrus Tzen Tea was developed by combining three teas empirically consumed to expel the cold, and new edible oral care products were designed for caries prevention by supplementation with Pu'er tea extract. More functional activities and practical applications of strictinin are scientifically anticipated in follow-up research.

Food Plant Secondary Metabolites Antiviral Activity and Their Possible Roles in SARS-CoV-2 Treatment: An Overview

Natural products and plant extracts exhibit many biological activities, including that related to the defense mechanisms against parasites. Many studies have investigated the biological functions of secondary metabolites and reported evidence of antiviral activities. The pandemic emergencies have further increased the interest in finding antiviral agents, and efforts are oriented to investigate possible activities of secondary plant metabolites against human viruses and their potential application in treating or preventing SARS-CoV-2 infection. In this review, we performed a comprehensive analysis of studies through in silico and in vitro investigations, also including in vivo applications and clinical trials, to evaluate the state of knowledge on the antiviral activities of secondary metabolites against human viruses and their potential application in treating or preventing SARS-CoV-2 infection, with a particular focus on natural compounds present in food plants. Although some of the food plant secondary metabolites seem to be useful in the prevention and as a possible therapeutic management against SARS-CoV-2, up to now, no molecules can be used as a potential treatment for COVID-19; however, more research is needed.

Insights into Antiviral Properties and Molecular Mechanisms of Non-Flavonoid Polyphenols against Human Herpesviruses

Herpesviruses are one of the most contagious DNA viruses that threaten human health, causing severe diseases, including, but not limited to, certain types of cancer and neurological complications. The overuse and misuse of anti-herpesvirus drugs are key factors leading to drug resistance. Therefore, targeting human herpesviruses with natural products is an attractive form of therapy, as it might improve treatment efficacy in therapy-resistant herpesviruses. Plant polyphenols are major players in the health arena as they possess diverse bioactivities. Hence, in this article, we comprehensively summarize the recent advances that have been attained in employing plant non-flavonoid polyphenols, such as phenolic acids, tannins and their derivatives, stilbenes and their derivatives, lignans, neolignans, xanthones, anthraquinones and their derivatives, curcuminoids, coumarins, furanocoumarins, and other polyphenols (phloroglucinol) as promising anti-herpesvirus drugs against various types of herpesvirus such as alpha-herpesviruses (herpes simplex virus type 1 and 2 and varicella-zoster virus), beta-herpesviruses (human cytomegalovirus), and gamma-herpesviruses (Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus). The molecular mechanisms of non-flavonoid polyphenols against the reviewed herpesviruses are also documented.

Discovery and structural characterization of chicoric acid as a SARS-CoV-2 nucleocapsid protein ligand and RNA binding disruptor

The nucleocapsid (N) protein plays critical roles in coronavirus genome transcription and packaging, representing a key target for the development of novel antivirals, and for which structural information on ligand binding is scarce. We used a novel fluorescence polarization assay to identify small molecules that disrupt the binding of the N protein to a target RNA derived from the SARS-CoV-2 genome packaging signal. Several phenolic compounds, including L-chicoric acid (CA), were identified as high-affinity N-protein ligands. The binding of CA to the N protein was confirmed by isothermal titration calorimetry, ¹H-STD and ¹⁵N-HSQC NMR, and by the crystal structure of CA bound to the N protein C-terminal domain (CTD), further revealing a new modulatory site in the SARS-CoV-2 N protein. Moreover, CA reduced SARS-CoV-2 replication in cell cultures. These data thus open venues for the development of new antivirals targeting the N protein, an essential and yet underexplored coronavirus target.

Antiviral Potentialities of Chemical Characterized Essential Oils of Acacia nilotica Bark and Fruits against Hepatitis A and Herpes Simplex Viruses: In Vitro, In Silico, and Molecular Dynamics Studies

Acacia nilotica (synonym: Vachellia nilotica (L.) P.J.H.Hurter and Mabb.) is considered an important plant of the family Fabaceae that is used in traditional medicine in many countries all over the world. In this work, the antiviral potentialities of the chemically characterized essential oils (EOs) obtained from the bark and fruits of A. nilotica were assessed in vitro against HAV, HSV1, and HSV2. Additionally, the in silico evaluation of the main compounds in both EOs was carried out against the two proteins, 3C protease of HAV and thymidine kinase (TK) of HSV. The chemical profiling of the bark EOs revealed the identification of 32 compounds with an abundance of di- (54.60%) and sesquiterpenes (39.81%). Stachene (48.34%), caryophyllene oxide (19.11%), and spathulenol (4.74%) represented the main identified constituents of bark EO. However, 26 components from fruit EO were assigned, with the majority of mono- (63.32%) and sesquiterpenes (34.91%), where trans-caryophyllene (36.95%), Z-anethole (22.87%), and γ-terpinene (7.35%) represented the majors. The maximum non-toxic concentration (MNTC) of the bark and fruits EOs was found at 500 and 1000 µg/mL, respectively. Using the MTT assay, the bark EO exhibited moderate antiviral activity with effects of 47.26% and 35.98% and a selectivity index (SI) of 2.3 and 1.6 against HAV and HSV1, respectively. However, weak activity was observed via the fruits EO with respective SI values of 3.8, 5.7, and 1.6 against HAV, HSV1, and HSV2. The in silico results exhibited that caryophyllene oxide and spathulenol (the main bark EO constituents) showed the best affinities (ΔG = -5.62, -5.33, -6.90, and -6.76 kcal/mol) for 3C protease and TK, respectively. While caryophyllene (the major fruit EO component) revealed promising binding capabilities against both proteins (ΔG = -5.31, -6.58 kcal/mol, respectively). The molecular dynamics simulation results revealed that caryophyllene oxide has the most positive van der Waals energy interaction with 3C protease and TK with significant binding free energies. Although these findings supported the antiviral potentialities of the EOs, especially bark EO, the in vivo assessment should be tested in the intraoral examination for these EOs and/or their main constituents.

Combined -omics framework reveals how ant symbionts benefit the Neotropical ant-plant Tococa quadrialata at different levels

Ant-plant defensive mutualism is a widely studied phenomenon, where ants protect their host plants (myrmecophytes) against herbivores in return for the provision of nesting sites and food. However, few studies addressed the influence of ant colonization and herbivory on the plant's metabolism. We chose the Amazonian plant Tococa quadrialata, living in association with Azteca cf. tonduzi ants for an ant-exclusion study to reveal the chemistry behind this symbiosis. We found that colonized plants did not only benefit from protection but also from increased amino acid and nitrogen content, enabling better performance even in an herbivore-free environment. In contrast, ant-deprived T. quadrialata plants accumulated more ellagitannins, a major class of constitutive defense compounds. Moreover, herbivory-induced jasmonate-mediated defense responses, including the upregulation of signaling and defense genes and the emission of volatiles irrespective of colonization status. Altogether, we show how ant-colonization can influence the general and defense-related metabolism and performance of myrmecophytes.

Antiviral perspectives of economically important Indian medicinal plants and spices

Human respiratory diseases caused by viral infections leads to morbidity. Among infectious diseases, viral infections associated with the respiratory tract remain the primary reason for global deaths due to their transmissibility. Since immemorial, traditional Indian medicinal plants, their extracts, and several phytochemicals can treat various diseases. Sources for this review paper are data derived from a peer-reviewed journal that emphasizes the economic importance of medicinal plants. Several plant-based medicines have been reported to be effective against multiple viral infections, including the Human Adenovirus, Enterovirus, Influenza virus, Hepatitis virus, etc. This review emphasizes use of the Indian medicinal plants like as Withania somnifera (Ashwagandha, Winter Cherry), Moringa oleifera (Drumstick), Ocimum tenuiflorum (Tulsi), Azadirachta indica (Neem), Curcuma longa (Turmeric), Terminalia chebula (Chebulic Myrobalan), Punica granatum (Pomegranate) and the Indian household spices (ginger, garlic and black pepper). It further describes their secondary phytoconstituents extraction procedure, mode of action and the potential application to improve clinical outcomes of neutraceuticals against various viral infections.

A comprehensive review on the diverse pharmacological perspectives of Terminalia chebula Retz

Terminalia chebula Retz, commonly known as 'Haritaki/Myrobalan,' has been utilised as a traditional medicine for a long time. It has been extensively exercised in various indigenous medicine practices like Unani, Tibb, Ayurveda, and Siddha to remedy human ailments such as bleeding, carminative, dysentery, liver tonic, digestive, antidiarrheal, analgesic, anthelmintic, antibacterial and helpful in skin disorders. Studies on the pharmacological effects of T. chebula and its phytoconstituents documented between January, 1996 and December, 2021 were explored using various electronic databases. During the time mentioned above, several laboratory approaches revealed the biological properties of T. chebula, including antioxidative, antiproliferative, anti-microbial, proapoptotic, anti-diabetic, anti-ageing, hepatoprotective, anti-inflammatory, and antiepileptic. It is also beneficial in glucose and lipid metabolism and prevents atherogenesis and endothelial dysfunction. Different parts of T. chebula such as fruits, seeds, galls, barks extracted with various solvent systems (aqueous, ethanol, methanol, chloroform, ethyl-acetate) revealed major bioactive compounds like chebulic acid, chebulinic acid, and chebulaginic acid, which in turn proved to have valuable pharmacological properties through broad scientific investigations. There is a common link between chebulagic acid and chebulanin with its antioxidant property, antiaging activity, antiinflammatory, antidiabetic activity, and cardioprotective activity. The actions may be through neutralizing the free radicals responsible for producing tissue damage alongside interconnecting many other diseases. The current review summarises the scientifically documented literature on pharmacological potentials and chemical compositions of T. chebula, which is expected to investigate further studies on this subject.

Ayurvedic formulations: Potential COVID-19 therapeutics?

BACKGROUND

While Molnupiravir and Paxlovid have recently been approved for use in some countries, there are no widely available treatments for COVID-19, the disease caused by SARS-CoV-2 infection. Herbal extracts have been used to treat respiratory clinical indications by Ayurvedic medicine practitioners with minimal adverse reactions and intense research efforts are currently under way to develop some of these formulations for COVID-19 treatment.

METHODS

Literature search for in silico, in vitro, in vivo, and clinical studies on the topic of Ayurvedic formulations for potential COVID-19 treatment, in order to present the current state of current knowledge by integrating information across all systems.

RESULTS

The search yielded 20 peer reviewed articles on in silico studies examining the interaction of phytoconstituents of popular Ayurvedic formulations with SARS-CoV-2 components and its receptors; five articles on preclinical investigations of the ability of selected Ayurvedic formulations to inhibit functions of SARS-CoV-2 proteins; and 51 completed clinical trials on the efficacy of using Ayurvedic formulations for treatment of mild to moderate COVID-19. Clinical data was available from 17 of the 51 trials. There was a considerable overlap between formulations used in the in silico studies and the clinical trials. This finding was unexpected as there is no clearly stated alignment between studies and the traditional pathway to drug discovery- basic discovery leading to in vitro and in vivo proof of concept, followed by validation in clinical trials. This was further demonstrated in the majority of the in silico studies where focus was on potential antiviral mechanisms, while the clinical trials were focused on patient recovery using oral treatments. In all 17 clinical trials where data was available, Ayurvedic treatments lead to a shorter period to recovery in participants with COVID-19.

CONCLUSION

The most commonly used Ayurvedic treatments for management of respiratory symptoms associated with SARS-CoV-2 infection appear to have prophylactic and/or therapeutic properties. It would be of particular interest to assess synergistic and concomitant systemic effects and antiviral activities of individual phytoconstituents and their combinations in the Ayurvedic treatments.

Studies on the antiviral activity of chebulinic acid against dengue and chikungunya viruses and in silico investigation of its mechanism of inhibition

Chebulinic acid (CA), originally isolated from the flower extract of the plant Terminalia chebula, has been shown to inhibit infection of herpes simplex virus-2 (HSV-2), suggestively by inhibiting the host entry step of viral infection. Like HSV-2, the dengue virus (DENV) and chikungunya virus (CHIKV) also use receptor glycosaminoglycans (GAG) to gain host entry, therefore, the activity of CA was tested against these viruses. Co-treatment of 8 µM CA with DENV-2 caused 2 log decrease in the virus titer (4.0 log₁₀FFU/mL) at 120 h post infection, compared to virus control (5.95 log₁₀FFU/mL). In contrast, no inhibitory effect of CA was observed against CHIKV infection under any condition. The mechanism of action of CA was investigated in silico by employing DENV-2 and CHIKV envelope glycoproteins. During docking, CA demonstrated equivalent binding at multiple sites on DENV-2 envelope protein, including GAG binding site, which have previously been reported to play a crucial role in host attachment and fusion, indicating blocking of these sites. However, CA did not show binding to the GAG binding site on envelope protein-2 of CHIKV. The in vitro and in silico findings suggest that CA possesses the ability to inhibit DENV-2 infection at the entry stage of its infection cycle and may be developed as a potential therapeutic agent against it.

Anthocyanins in Red Jasmine Rice (Oryza sativa L.) Extracts and Efficacy on Inhibition of Herpes Simplex Virus, Free Radicals and Cancer Cell

Rice is one of the most important food crops in many countries, with nutritional value and health benefits. In this study, the ethanolic and aqueous extracts of red jasmine rice from Chiang Mai, Thailand were examined for their anthocyanins and phenolic contents. The antioxidant and antiviral activity against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), as well as anticancer activity, were investigated. The total anthocyanins content of 708.03 ± 11.56 mg Cy-3-glc equivalent/g extract, determined from the ethanolic extract, was higher than the aqueous extract. However, the aqueous extract showed the highest total phenolic compound of 81.91 ± 0.51 mg GAE/g extract. In addition, the ethanolic extract demonstrated higher antioxidant activity than aqueous extract using DPPH, ABTS, and FRAP assays by 28.91 ± 3.26 mg GAE/g extract, 189.45 ± 11.58 mg 24 TEAC/g extract, and 3292.46 ± 259.64 g FeSO₄/g extract, respectively. In the antiviral assay, it was found that the ethanolic extract of red jasmine rice could inhibit HSV-1 more effectively than HSV-2 when treated before, during, and after the viral attachment on Vero cells, with 50% effective doses of 227.53 ± 2.41, 189.59 ± 7.76, and 192.62 ± 2.40 µg/mL, respectively. The extract also demonstrated the highest reduction of HSV-1 particles at 4 h after treatment and the inhibition of HSV-1 replication. The ethanolic extract exhibited a higher toxicity level than the aqueous extract, as well as the potential to induce DNA fragmentation by intrinsic and extrinsic apoptosis pathways on the Caco-2 cells. These findings suggest that red jasmine rice extract demonstrates nutritional value and biological activity on HSV, free radicals, and cancer cell inhibition.

Hepatitis C Virus NS3/4A Inhibition and Host Immunomodulation by Tannins from Terminalia chebula: A Structural Perspective

Terminalia chebula Retz. forms a key component of traditional folk medicine and is also reported to possess antihepatitis C virus (HCV) and immunomodulatory activities. However, information on the intermolecular interactions of phytochemicals from this plant with HCV and human proteins are yet to be established. Thus, by this current study, we investigated the HCV NS3/4A inhibitory and host immune-modulatory activity of phytocompounds from T. chebula through in silico strategies involving network pharmacology and structural bioinformatics techniques. To start with, the phytochemical dataset of T. chebula was curated from biological databases and the published literature. Further, the target ability of the phytocompounds was predicted using BindingDB for both HCV NS3/4A and other probable host targets involved in the immune system. Further, the identified targets were docked to the phytochemical dataset using AutoDock Vina executed through the POAP pipeline. The resultant docked complexes with significant binding energy were subjected to 50 ns molecular dynamics (MD) simulation in order to infer the stability of complex formation. During network pharmacology analysis, the gene set pathway enrichment of host targets was performed using the STRING and Reactome pathway databases. Further, the biological network among compounds, proteins, and pathways was constructed using Cytoscape 3.6.1. Furthermore, the druglikeness, side effects, and toxicity of the phytocompounds were also predicted using the MolSoft, ADVERpred, and PreADMET methods, respectively. Out of 41 selected compounds, 10 were predicted to target HCV NS3/4A and also to possess druglike and nontoxic properties. Among these 10 molecules, Chebulagic acid and 1,2,3,4,6-Pentagalloyl glucose exhibited potent HCV NS3/4A inhibitory activity, as these scored a lowest binding energy (BE) of −8.6 kcal/mol and −7.7 kcal/mol with 11 and 20 intermolecular interactions with active site residues, respectively. These findings are highly comparable with Asunaprevir (known inhibitor of HCV NS3/4A), which scored a BE of −7.4 kcal/mol with 20 key intermolecular interactions. MD studies also strongly suggest that chebulagic acid and 1,2,3,4,6-Pentagalloyl glucose as promising leads, as these molecules showed stable binding during 50 ns of production run. Further, the gene set enrichment and network analysis of 18 protein targets prioritized 10 compounds and were predicted to potentially modulate the host immune system, hemostasis, cytokine levels, interleukins signaling pathways, and platelet aggregation. On overall analysis, this present study predicts that tannins from T. chebula have a potential HCV NS3/4A inhibitory and host immune-modulatory activity. However, further experimental studies are required to confirm the efficacies.

Molecular Insights on Bioactive Compounds against Covid-19: A Network Pharmacological and Computational Study

BACKGROUND

Network pharmacology based identification of phytochemicals in the form of cocktails against off-targets can play a significant role in the inhibition of SARS_CoV2 viral entry and its propagation. This study includes network pharmacology, virtual screening, docking and molecular dynamics to investigate the distinct antiviral mechanisms of effective phytochemicals against SARS_CoV2.

METHODS

SARS_CoV2 human-protein interaction network was explored from the BioGRID database and analysed using Cytoscape. Further analysis was performed to explore biological function, proteinphytochemical/ drugs network and up-down regulation of pathological host target proteins. This led to understand the antiviral mechanism of phytochemicals against SARS_CoV2. The network was explored through g: Profiler, EnrichR, CTD, SwissTarget, STITCH, DrugBank, BindingDB, STRING and SuperPred. Virtual screening of phytochemicals against potential antiviral targets such as M-Pro, NSP1, Receptor binding domain, RNA binding domain, and ACE2 discloses the effective interaction between them. Further, the binding energy calculations through simulation of the docked complex explain the efficiency and stability of the interactions.

RESULTS

The network analysis identified quercetin, genistein, luteolin, eugenol, berberine, isorhamnetin and cinnamaldehyde to be interacting with host proteins ACE2, DPP4, COMT, TUBGCP3, CENPF, BRD2 and HMOX1 which are involved in antiviral mechanisms such as viral entry, viral replication, host immune response, and antioxidant activity, thus indicating that herbal cocktails can effectively tackle the viral hijacking of the crucial biological functions of a human host. Further exploration through virtual screening, docking and molecular dynamics recognizes the effective interaction of phytochemicals such as punicalagin, scutellarin, and solamargine with their respective potential targets.

CONCLUSION

This work illustrates a probable strategy for the identification of phytochemical-based cocktails and off-targets which are effective against SARS_CoV 2.

Anti-Herpes Simplex Virus Efficacy of Silk Cocoon, Silkworm Pupa and Non-Sericin Extracts

Herpes simplex virus (HSV) infections are prevalent worldwide and are the cause of life- threatening diseases. Standard treatment with antiviral drugs, such as acyclovir, could prevent serious complications; however, resistance has been reported specifically among immunocompromised patients. Therefore, the development of an alternative approach is needed. The silk cocoon derived from silkworm, Bombyx mori, has been recognized for its broad-spectrum biological activity, including antiviral activity; however, its effects against HSV infection are unknown. In this study, we investigated the inhibitory effects of silk extracts derived from the cocoon shell, silk cocoon, silkworm pupa and non-sericin extract, on blocking HSV-1 and HSV-2 binding to host cells, resulting in the inhibition of the virus infection in Vero cells. Non-sericin extract demonstrated the greatest effectiveness on inhibiting HSV-1 and HSV-2 binding activity. Moreover, the virucidal effect to inactivate HSV-1 and HSV-2 was determined and revealed that non-sericin extract also exerted the highest potential activity. Using the treatment of non-sericin extract in HSV-2-infected HeLa cells could significantly lower the HSV-induced cell death and prevent inflammation via lowering the inflammatory cytokine gene expression. The non-sericin extract was analyzed for its bioactive compounds in which gallic acid, flavonoid and xanthophyll were identified, and might have partially contributed to its antiviral activity. The finding in our study suggested the potential of silk extract as an alternative therapeutic treatment for HSV infection.

Plant-Based Natural Products and Extracts: Potential Source to Develop New Antiviral Drug Candidates

Viral infections are among the most complex medical problems and have been a major threat to the economy and global health. Several epidemics and pandemics have occurred due to viruses, which has led to a significant increase in mortality and morbidity rates. Natural products have always been an inspiration and source for new drug development because of their various uses. Among all-natural sources, plant sources are the most dominant for the discovery of new therapeutic agents due to their chemical and structural diversity. Despite the traditional use and potential source for drug development, natural products have gained little attention from large pharmaceutical industries. Several plant extracts and isolated compounds have been extensively studied and explored for antiviral properties against different strains of viruses. In this review, we have compiled antiviral plant extracts and natural products isolated from plants reported since 2015.

Ayurveda Rasayana as antivirals and immunomodulators: potential applications in COVID-19

Coronavirus disease (COVID-19) has been declared as a pandemic by the World Health Organization with rapid spread across 216 countries. COVID-19 pandemic has left its imprints on various health systems globally and caused immense social and economic disruptions. The scientific community across the globe is in a quest for digging the effective treatment for COVID-19 and exploring potential leads from traditional systems of healthcare across the world too. Ayurveda (Indian traditional system of medicine) has a comprehensive aspect of immunity through Rasayana which is a rejuvenation therapy. Here we attempt to generate the potential leads based on the classical text from Ayurveda in general and Rasayana in particular to develop effective antiviral and/or immunomodulator for potential or adjunct therapy in SARS-CoV-2. The Rasayana acts not only by resisting body to restrain or withstand the strength, severity or progression of a disease but also by promoting power of the body to prevent the manifestation of a disease. These Rasayana herbs are common in practice as immunomodulator, antiviral and protectives. The studies on Rasayana can provide an insight into the future course of research for the plausible development of effective management of COVID-19 by the utilization and development of various traditional systems of healthcare. Keeping in view the current pandemic situation, there is an urgent need of developing potential medicines. This study proposes certain prominent medicinal plants which may be further studied for drug development process and also in clinical setup under repurposing of these herbs.

Drug Design Strategies for the Treatment of Viral Disease. Plant Phenolic Compounds and Their Derivatives

The coronavirus pandemic (SARS CoV-2) that has existed for over a year, constantly forces scientists to search for drugs against this virus. In silico research and selected experimental data have shown that compounds of natural origin such as phenolic acids and flavonoids have promising antiviral potential. Phenolic compounds inhibit multiplication of viruses at various stages of the viral life cycle, e.g., attachment (disturbance of the interaction between cellular and viral receptors), penetration (inhibition of viral pseudo-particle fusion to the host membrane), replication (inhibition of integrase and 3C-like protease), assembly and maturation (inhibition of microsomal triglyceride transfer protein (MTP) activity hydrolysis) and release (inhibition of secretion of apolipoprotein B (apoB) from infected cells). Phenolic compounds also indirectly influence on the viral life cycle by affecting the host cell's biochemical processes that viruses use for their own benefit. Phenolic compounds may inhibit the proteasomes and cellular deubiquitinating activity that causes an increase in the ubiquitinated proteins level in host cells. This, in turn, contributes to the lowering the available ubiquitin molecules that viruses could use for their own replication. One of the drug design strategy for the treatment of viral diseases may be an enhancement of the antiviral properties of phenolic compounds by metal complexation. Many studies have shown that the presence of a metal ion in the structure can significantly affect the affinity of the compound to key structural elements of the SARS CoV-2, such as Mpro protease, RNA-dependent RNA polymerase (RdRp) and spike protein. We believe that in the era of coronavirus pandemic, it is necessary to reconsider the search for therapeutics among well-known compounds of plant origin and their metal complexes.

Antiviral Active Compounds Derived from Natural Sources against Herpes Simplex Viruses

Herpes simplex viruses (HSV) are ubiquitously distributed with a seroprevalence ranging up to 95% in the adult population. Refractory viral infections with herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) represent a major global health issue. In particular, the increasing occurrence of resistance to conventional antiviral drugs make the therapy of such infections even more challenging. For instance, the frequent and long-term use of acyclovir and other nucleoside analogues targeting the viral DNA-polymerase enhance the development of resistant viruses. Particularly, the incidental increase of those strains in immunocompromised patients is alarming and represent a major health concern. Alternative treatment concepts are clearly needed. Natural products such as herbal medicines showed antiherpetic activity in vitro and in vivo and proved to be an excellent source for the discovery and isolation of novel antivirals. By this means, numerous plant-derived compounds with antiviral or antimicrobial activity could be isolated. Natural medicines and their ingredients are well-tolerated and could be a good alternative for treating herpes simplex virus infections. This review provides an overview of the recent status of natural sources such as plants, bacteria, fungi, and their ingredients with antiviral activity against herpes simplex viruses. Furthermore, we highlight the most potent herbal medicines and ingredients as promising candidates for clinical investigation and give an overview about the most important drug classes along with their potential antiviral mechanisms. The content of this review is based on articles that were published between 1996 and 2021.

Ferroptosis-Inhibitory Difference between Chebulagic Acid and Chebulinic Acid Indicates Beneficial Role of HHDP

The search for a safe and effective inhibitor of ferroptosis, a recently described cell death pathway, has attracted increasing interest from scientists. Two hydrolyzable tannins, chebulagic acid and chebulinic acid, were selected for the study. Their optimized conformations were calculated using computational chemistry at the B3LYP-D3(BJ)/6-31G and B3LYP-D3(BJ)/6-311 + G(d,p) levels. The results suggested that (1) chebulagic acid presented a chair conformation, while chebulinic acid presented a skew-boat conformation; (2) the formation of chebulagic acid requires 762.1729 kcal/mol more molecular energy than chebulinic acid; and (3) the 3,6-HHDP (hexahydroxydiphenoyl) moiety was shown to be in an (R)- absolute stereoconfiguration. Subsequently, the ferroptosis inhibition of both tannins was determined using a erastin-treated bone marrow-derived mesenchymal stem cells (bmMSCs) model and compared to that of ferrostatin-1 (Fer-1). The relative inhibitory levels decreased in the following order: Fer-1 > chebulagic acid > chebulinic acid, as also revealed by the in vitro antioxidant assays. The UHPLC-ESI-Q-TOF-MS analysis suggested that, when treated with 16-(2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxy free radicals, Fer-1 generated dimeric products, whereas the two acids did not. In conclusion, two hydrolyzable tannins, chebulagic acid and chebulinic acid, can act as natural ferroptosis inhibitors. Their ferroptosis inhibition is mediated by regular antioxidant pathways (ROS scavenging and iron chelation), rather than the redox-based catalytic recycling pathway exhibited by Fer-1. Through antioxidant pathways, the HHDP moiety in chebulagic acid enables ferroptosis-inhibitory action of hydrolyzable tannins.

Binding Insight of Anti-HIV Phytocompounds with Prime Targets of HIV: A Molecular Dynamics Simulation Analysis

BACKGROUND

Despite intense efforts, AIDS is difficult to tackle by current anti-retroviral therapy (ART) due to its side effects; therefore, there is an urgent need to discover potential, multitarget and low-cost anti-HIV compounds.

OBJECTIVE

We have shown that few phytocompounds can potentially inhibit the prime targets of HIV namely GP120 envelope protein, reverse transcriptase, protease, integrase and ribonulcease. In this study, top ranked prioritized compounds were subjected to Molecular Dynamics (MD) simulation in order to study the conformational dynamics and integrity of crucial interaction in the receptor sites.

METHODS

The system was built for selected protein-ligand complex using TIP3P water model and OPLS_2005 force field. Trajectories were recorded up to 20 ns simulation time in Desmond module of Schrödinger software.

RESULTS

As a result of a comprehensive analysis of molecular properties and dynamics of the complexes, it has been concluded that Chebulic acid, Curcumin and Mulberroside C could be developed as envelope glycoprotein GP120 inhibitor, reverse transcriptase inhibitor and protease inhibitor respectively. However, the fluctuation of Chebulic acid with respect to integrase and ribonuclease protein was higher during the simulation.

CONCLUSION

These findings can aid in the designing of the structural properties for more effective anti-HIV compounds against the given targets.

Clinical outcomes among COVID-19 patients managed with modern and traditional Siddha medicine -A retrospective cohort study, Chennai, Tamil Nadu, India, 2020

Background

Kabasura Kudineer (KSK) is a Siddha polyherbal decoction recommended by the Ministry of AYUSH and the Tamil Nadu government to prevent and manage COVID-19 in India.

Objective(s)

We aimed to determine the outcome of integrated therapy for COVID-19 using KSK in virologic clearance and length of hospital stay.

Materials and methods

It was a single-centre, retrospective cohort study. We included the COVID-19 patients admitted to SRM Medical College Hospital and Research Centre, Chennai, during May–June 2020. KSK was administered along with the standard of care for all the patients. We collected data pertaining to demographic, clinical, and laboratory parameters and presented as frequencies and proportions.

Results

We collected 204 COVID-19 positive patients’ data. The mean (SD) age was 39.5 (13.4) years with a range of 13–79. Majority of the patients were male (n = 157; 77%), 28% (n = 58) had any co-morbidities, and 61% (n = 131) had mild symptoms. Fever (n = 57; 27.9%) and cough (n = 53; 25.9%) were the commonly reported symptoms. Paracetamol (n = 135; 66.7%) and Zincovit (n = 197, 96.6%) were the commonly administered medicines along with KSK. About 74% of asymptomatic (n = 54) and 65% of mild symptomatic (n = 85) patients turned negative for COVID-19 in RT-PCR within 4–7 days. There was a significant difference in the blood parameters (p < 0.05) after the integrated treatment.

Conclusion

The use of KSK with standard care of treatment in COVID-19 treatment had notable results in the duration taken for virologic clearance, thereby reducing the length of hospital stay and improvement in laboratory parameters.

Indian Medicinal Plants and Formulations and Their Potential Against COVID-19-Preclinical and Clinical Research

The cases of COVID-19 are still increasing day-by-day worldwide, even after a year of its first occurrence in Wuhan city of China. The spreading of SARS-CoV-2 infection is very fast and different from other SARS-CoV infections possibly due to structural differences in S proteins. The patients with severe diseases may die due to acute respiratory distress syndrome (ARDS) caused by systemic inflammatory reactions due to the excessive release of pro-inflammatory cytokines and chemokines by the immune effector cells. In India too, it is spreading very rapidly, although the case fatality rate is below 1.50% (https://www.statista.com), which is markedly less than in other countries, despite the dense population and minimal health infrastructure in rural areas. This may be due to the routine use of many immunomodulator medicinal plants and traditional AYUSH formulations by the Indian people. This communication reviews the AYUSH recommended formulations and their ingredients, routinely used medicinal plants and formulations by Indian population as well as other promising Indian medicinal plants, which can be tested against COVID-19. Special emphasis is placed on Indian medicinal plants reported for antiviral, immunomodulatory and anti-allergic/anti-inflammatory activities and they are categorized for prioritization in research on the basis of earlier reports. The traditional AYUSH medicines currently under clinical trials against COVID-19 are also discussed as well as furtherance of pre-clinical and clinical testing of the potential traditional medicines against COVID-19 and SARS-CoV-2. The results of the clinical studies on AYUSH drugs will guide the policymakers from the AYUSH systems of medicines to maneuver their policies for public health, provide information to the global scientific community and could form a platform for collaborative studies at national and global levels. It is thereby suggested that promising AYUSH formulations and Indian medicinal plants must be investigated on a priority basis to solve the current crisis.

Review of Whole Plant Extracts With Activity Against Herpes Simplex Viruses In Vitro and In Vivo

Herpes simplex viruses, HSV-1 and HSV-2, are highly contagious and cause lifelong, latent infections with recurrent outbreaks of oral and/or genital lesions. No cure exists for HSV-1 or HSV-2 infections, but antiviral medications are commonly used to prevent and treat outbreaks. Resistance to antivirals has begun to emerge, placing an importance on finding new and effective therapies for prophylaxis and treatment of HSV outbreaks. Botanicals may be effective HSV therapies as the constituents they contain act through a variety of mechanisms, potentially making the development of antiviral resistance more challenging. A wide variety of plants from different regions in the world have been studied for antiviral activity against HSV-1 and/or HSV-2 and showed efficacy of varying degrees. The purpose of this review is to summarize research conducted on whole plant extracts against HSV-1 and/or HSV-2 in vitro and in vivo. The majority of the research reviewed was conducted in vitro using animal cell lines, and some studies used an animal model design. Also summarized are a limited number of human trials conducted using botanical therapies on HSV lesions.

Therapeutic potential of medicinal plants against COVID-19: The role of antiviral medicinal metabolites

There are numerous trials underway to find treatment for the COVID-19 through testing vaccines as well as existing drugs. Apart from the many synthetic chemical compounds, plant-based compounds could provide an array of \suitable candidates for testing against the virus. Studies have confirmed the role of many plants against respiratory viruses when employed either as crude extracts or their active ingredients in pure form. The purpose of this review article is to highlight the importance of phytomedicine against COVID-19. The main aim is to review the mechanistic aspects of most important phytochemical compounds that have showed potential against coronaviruses. Glycyrrhizin from the roots of Glycyrrhiza glabra has shown promising potential against the previously epidemic coronavirus, SARS-CoV. Other important plants such as Artemisia annua, Isatis indigotica, Lindera aggregate, Pelargonium sidoides, and Glychirrhiza spp. have been employed against SARS-CoV. Active ingredients (e.g. emodin, reserpine, aescin, myricetin, scutellarin, apigenin, luteolin, and betulonic acid) have shown promising results against the coronaviruses. Phytochemicals have demonstrated activity against the coronaviruses through mechanisms such as viral entry inhibition, inhibition of replication enzymes and virus release blockage. However, compared to synthetic drugs, phytomedicine are mechanistically less understood and should be properly evaluated before application. Nonetheless, phytochemicals reduce the tedious job of drug discovery and provide a less time-consuming alternative for drug testing. Therefore, along with other drugs currently tested against COVID-19, plant-based drugs should be included for speedy development of COVID-19 treatment.

Integrative role of traditional and modern technologies to combat COVID-19

INTRODUCTION

With the development of various branches of sciences, we will be able to resolve different clinical aspects of various diseases better. The convergence of these sciences can potentially tackle the new corona crisis.

AREAS COVERED

In this review, we attempted to explore and describe various scientific branches studying COVID-19. We have reviewed the literature focusing on the prevention, diagnosis, and treatment of COVID-19. The primary databases targeted were Science Direct, Scopus and PubMed. The most relevant reports from the recent two decades were collected utilizing keywords including SARS-CoV, MERS-CoV, COVID-19, epidemiology, therapeutics and diagnosis.

EXPERT OPINION

Based on this literature review, both traditional and emerging approaches are vital for the prevention, diagnosis and treatment of COVID-19. The traditional sciences play an essential role in the preventive and supportive care of corona infection, and modern technologies appear to be useful in the development of precise diagnosis and powerful treatment approaches for this disease. Indeed, the integration of these sciences will help us to fight COVID-19 disease more efficiently.

Traditional medicinal plants against replication, maturation and transmission targets of SARS-CoV-2: computational investigation

COVID-19 is an infectious pandemic caused by the SARS-CoV-2 virus. The critical components of SARS-CoV-2 are the spike protein (S-protein) and the main protease (M^pro). M^pro is required for the maturation of the various polyproteins involved in replication and transcription. S-protein helps the SARS-CoV-2 to enter the host cells through the angiotensin-converting enzyme 2 (ACE2). Since ACE2 is required for the binding of SARS-CoV-2 on the host cells, ACE2 inhibitors and blockers have got wider attention, in addition to S-protein and M^pro modulators as potential therapeutics for COVID-19. So far, no specific drugs have shown promising therapeutic potential against COVID-19. The current study was undertaken to evaluate the therapeutic potential of traditional medicinal plants against COVID-19. The bioactives from the medicinal plants, along with standard drugs, were screened for their binding against S-protein, M^pro and ACE2 targets using molecular docking followed by molecular dynamics. Based on the higher binding affinity compared with standard drugs, bioactives were selected and further analyzed for their pharmacological properties such as drug-likeness, ADME/T-test, biological activities using in silico tools. The binding energies of several bioactives analyzed with target proteins were relatively comparable and even better than the standard drugs. Based on Lipinski factors and lower binding energies, seven bioactives were further analyzed for their pharmacological and biological characteristics. The selected bioactives were found to have lower toxicity with a higher GI absorption rate and potent anti-inflammatory and anti-viral activities against targets of COVID-19. Therefore, the bioactives from these medicinal plants can be further developed as phytopharmaceuticals for the effective treatment of COVID-19.

Plants-Derived Biomolecules as Potent Antiviral Phytomedicines: New Insights on Ethnobotanical Evidences against Coronaviruses

SARS-CoV-2 infection (COVID-19) is in focus over all known human diseases, because it is destroying the world economy and social life, with increased mortality rate each day. To date, there is no specific medicine or vaccine available against this pandemic disease. However, the presence of medicinal plants and their bioactive molecules with antiviral properties might also be a successful strategy in order to develop therapeutic agents against SARS-CoV-2 infection. Thus, this review will summarize the available literature and other information/data sources related to antiviral medicinal plants, with possible ethnobotanical evidence in correlation with coronaviruses. The identification of novel antiviral compounds is of critical significance, and medicinal plant based natural compounds are a good source for such discoveries. In depth search and analysis revealed several medicinal plants with excellent efficacy against SARS-CoV-1 and MERS-CoV, which are well-known to act on ACE-2 receptor, 3CLpro and other viral protein targets. In this review, we have consolidated the data of several medicinal plants and their natural bioactive metabolites, which have promising antiviral activities against coronaviruses with detailed modes of action/mechanism. It is concluded that this review will be useful for researchers worldwide and highly recommended for the development of naturally safe and effective therapeutic drugs/agents against SARS-CoV-2 infection, which might be used in therapeutic protocols alone or in combination with chemically synthetized drugs.

Evaluation of medicinal herbs as a potential therapeutic option against SARS-CoV-2 targeting its main protease

The COVID‐19 disease caused by the SARS‐CoV‐2 has emerged as a worldwide pandemic and caused huge damage to the lives and economy of more than hundred countries. As on May 10, 2020, more than 4,153,300 people stand infected from the virus due to an unprecedented rate of transmission and 282,700 have lost their lives because of the disease. In this context, medicinal plants may provide a way to treat the disease by targeting specific essential proteins of the virus. We screened about 51 medicinal plants and found that Tea (Camellia sinensis) and Haritaki (Terminalia chebula) has potential against SARS‐COV‐2 3CL^pro, with an IC₅₀ for Green Tea as 8.9 ± 0.5 μg/ml and Haritaki 8.8 ± 0.5 μg/ml. The in‐silico studies suggested that Tea component Thearubigins binds to the cysteine 145 of protease active site and could be a pharmacoactive molecule. We predict that the inhibition in protease activity may be able to halt the SARS‐CoV‐2 replication cycle and therefore, we propose Green Tea, Black Tea, and Haritaki plant extracts as potential therapeutic candidates for SARS‐CoV‐2 infection. Further investigation on role of bioactive constituents of extracts is needed to establish the molecular basis of inhibition and towards expedited drug discovery.

Potential Synergistic Action of Bioactive Compounds from Plant Extracts against Skin Infecting Microorganisms

The skin is an important organ that acts as a physical barrier to the outer environment. It is rich in immune cells such as keratinocytes, Langerhans cells, mast cells, and T cells, which provide the first line of defense mechanisms against numerous pathogens by activating both the innate and adaptive response. Cutaneous immunological processes may be stimulated or suppressed by numerous plant extracts via their immunomodulatory properties. Several plants are rich in bioactive molecules; many of these exert antimicrobial, antiviral, and antifungal effects. The present study describes the impact of plant extracts on the modulation of skin immunity, and their antimicrobial effects against selected skin invaders. Plant products remain valuable counterparts to modern pharmaceuticals and may be used to alleviate numerous skin disorders, including infected wounds, herpes, and tineas.

Virtual Screening Identifies Chebulagic Acid as an Inhibitor of the M2(S31N) Viral Ion Channel and Influenza A Virus

The increasing prevalence of drug-resistant influenza viruses emphasizes the need for new antiviral countermeasures. The M2 protein of influenza A is a proton-gated, proton-selective ion channel, which is essential for influenza replication and an established antiviral target. However, all currently circulating influenza A virus strains are now resistant to licensed M2-targeting adamantane drugs, primarily due to the widespread prevalence of an M2 variant encoding a serine to asparagine 31 mutation (S31N). To identify new chemical leads that may target M2(S31N), we performed a virtual screen of molecules from two natural product libraries and identified chebulagic acid as a candidate M2(S31N) inhibitor and influenza antiviral. Chebulagic acid selectively restores growth of M2(S31N)-expressing yeast. Molecular modeling also suggests that chebulagic acid hydrolysis fragments preferentially interact with the highly-conserved histidine residue within the pore of M2(S31N) but not adamantane-sensitive M2(S31). In contrast, chebulagic acid inhibits in vitro influenza A replication regardless of M2 sequence, suggesting that it also acts on other influenza targets. Taken together, results implicate chebulagic acid and/or its hydrolysis fragments as new chemical leads for M2(S31N) and influenza-directed antiviral development.

Elucidation of the mechanism of anti-herpes action of two novel semisynthetic cardenolide derivatives

Human herpesviruses are among the most prevalent pathogens worldwide and have become an important public health issue. Recurrent infections and the emergence of resistant viral strains reinforce the need of searching new drugs to treat herpes virus infections. Cardiac glycosides are used clinically to treat cardiovascular disturbances, such as congestive heart failure and atrial arrhythmias. In recent years, they have sparked new interest in their potential anti-herpes action. It has been previously reported by our research group that two new semisynthetic cardenolides, namely C10 (3β-[(N-(2-hydroxyethyl)aminoacetyl]amino-3-deoxydigitoxigenin) and C11 (3β-(hydroxyacetyl)amino-3-deoxydigitoxigenin), exhibited potential anti-HSV-1 and anti-HSV-2 with selectivity index values > 1,000, comparable with those of acyclovir. This work reports the mechanism investigation of anti-herpes action of these derivatives. The results demonstrated that C10 and C11 interfere with the intermediate and final steps of HSV replication, but not with the early stages, since they completely abolished the expression of the UL42 (β) and gD (γ) proteins and partially reduced that of ICP27 (α). Additionally, they were not virucidal and had no prophylactic effects. Both compounds inhibited HSV replication at nanomolar concentrations, but cardenolide C10 was more active than C11 and can be considered as an anti-herpes drug candidate including against acyclovir-resistant HSV-1 strains.

Fruits of Terminalia chebula Retz.: A review on traditional uses, bioactive chemical constituents and pharmacological activities

Fruits of Terminalia chebula Retz. (Combretaceae) are widely used as crude drugs in various traditional medicine systems. The aim of this article is to review the available scientific information regarding the traditional uses, bioactive chemical constituents and the pharmacological activities of T. chebula. Numerous researches conducted on T. chebula have confirmed the presence of wide range of the phytochemicals such as flavonoids, tannins, phenolic acids and other bioactive compounds. T. chebula is also widely studied regarding its pharmacological activities such as antioxidant, hepatoprotective, neuroprotective, cytotoxic, antidiabetic, anti-inflammatory activities among others. However, more in vivo and clinical studies for mechanism-based pharmacological evaluation should be conducted in future to provide stronger scientific evidences for their traditional uses.

Antiviral effect of Chinese herbal prescription JieZe-1 on adhesion and penetration of VK2/E6E7 with herpes simplex viruses type 2

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese Herbal Prescription JieZe-1(JZ-1), added and subtracted from Yihuang Decoction, a famous formula in the 12th year of Kangxi in Qing Dynasty, has a clear effect on Genital Herpes (GH) and no obvious adverse reactions occur clinically. JZ-1 also has preventive and therapeutic effects on Trichomonas vaginitis, Candida albicans vaginitis and GH in vitro and in vivo experiments.

AIM OF STUDY

The effect and mechanism of JZ-1 on anti-herpes simplex virus type 2(HSV-2) in vitro focusing on adhesion and penetration stages were investigated.

MATERIALS AND METHODS

A model of HSV-2 infection of VK2/E6E7 was developed. In order to explore JZ-1's anti-HSV-2 effect in vitro, cell morphology, ultrastructural pathology, cell viability and expression of viral glycoprotein D (gD) were assessed at 6 h, 12 h, 18 h, and 24 h of JZ-1 treatment. Then we measured the exact time required for adhesion and penetration of HSV-2 into VK2/E6E7 among a series of times at room temperature and under temperature control techniques. We treated VK2/E6E7 with JZ-1, penciclovir, or berberine and explored the mechanism of JZ-1 in blocking HSV-2 adhesion and penetration of host cells by assessing the cell ultrastructural pathology, viability, viral proteins gB, gD, VP16, ICP5, and ICP4 and host cell proteins HVEM, Nectin-1, and Nectin-2.

RESULTS

HSV-2 can fully adhere and penetrate into VK/E6E7 within 5 mins at room temperature while it takes 60mins under temperature control techniques. JZ-1 and penciclovir showed significant anti-HSV-2 effects, with improved host cell morphologies and increased host cell viabilities observed after treatment for 24 h. The anti-HSV-2 effect of JZ-1 can be detected after treatment for 6 h while that of penciclovir was not obvious until treatment for 12 h. JZ-1 showed distinct effect on HSV-2 adhesion and penetration stages by significantly reducing the expression of viral proteins gB, gD, VP16, ICP5, and ICP4, improving cell morphology and increasing cell viability. However, these effects were not exerted via downregulated expression of membrane fusion-related proteins such as HVEM, Nectin-1, or Nectin-2. The specific anti-HSV-2 mechanism of JZ-1 need to be further explored.

CONCLUSION

The anti-HSV-2 effect of JZ-1 was superior to that of penciclovir and berberine in vitro, and was mainly mediated by enhancing host cell defense and blocking adhesion and penetration of HSV-2.

Identification of Chebulinic Acid and Chebulagic Acid as Novel Influenza Viral Neuraminidase Inhibitors

The influenza A virus (IAV) causes seasonal epidemics and occasional but devastating pandemics, which are of a major public health concern. Although several antiviral drugs are currently available, there is an urgent need to develop novel antiviral therapies with different mechanisms of action due to emergence of drug resistance. In this study, two related compounds, chebulagic acid (CHLA) and chebulinic acid (CHLI), were identified as novel inhibitors against IAV replication. A reporter virus-based infection assay demonstrated that CHLA and CHLI exhibit no inhibitory effect on IAV entry or RNA replication during the virus replication cycle. Results of viral release inhibition assay and neuraminidase (NA) inhibition assay indicated that CHLA and CHLI exert their inhibitory effect on the NA-mediated viral release. Moreover, oseltamivir-resistance mutation NA/H274Y of NA is susceptible to CHLA or CHLI, suggesting a different mechanism of action for CHLA and CHLI. In summary, CHLA and CHLI are promising new NA inhibitors that may be further developed as novel antivirals against IAVs.

Natural Products-Derived Chemicals: Breaking Barriers to Novel Anti-HSV Drug Development

Recently, the problem of viral infection, particularly the infection with herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), has dramatically increased and caused a significant challenge to public health due to the rising problem of drug resistance. The antiherpetic drug resistance crisis has been attributed to the overuse of these medications, as well as the lack of new drug development by the pharmaceutical industry due to reduced economic inducements and challenging regulatory requirements. Therefore, the development of novel antiviral drugs against HSV infections would be a step forward in improving global combat against these infections. The incorporation of biologically active natural products into anti-HSV drug development at the clinical level has gained limited attention to date. Thus, the search for new drugs from natural products that could enter clinical practice with lessened resistance, less undesirable effects, and various mechanisms of action is greatly needed to break the barriers to novel antiherpetic drug development, which, in turn, will pave the road towards the efficient and safe treatment of HSV infections. In this review, we aim to provide an up-to-date overview of the recent advances in natural antiherpetic agents. Additionally, this paper covers a large scale of phenolic compounds, alkaloids, terpenoids, polysaccharides, peptides, and other miscellaneous compounds derived from various sources of natural origin (plants, marine organisms, microbial sources, lichen species, insects, and mushrooms) with promising activities against HSV infections; these are in vitro and in vivo studies. This work also highlights bioactive natural products that could be used as templates for the further development of anti-HSV drugs at both animal and clinical levels, along with the potential mechanisms by which these compounds induce anti-HSV properties. Future insights into the development of these molecules as safe and effective natural anti-HSV drugs are also debated.

The Genus Terminalia (Combretaceae): An Ethnopharmacological, Phytochemical and Pharmacological Review

Terminalia Linn, a genus of mostly medium or large trees in the family Combretaceae with about 250 species in the world, is distributed mainly in southern Asia, Himalayas, Madagascar, Australia, and the tropical and subtropical regions of Africa. Many species are used widely in many traditional medicinal systems, e.g., traditional Chinese medicine, Tibetan medicine, and Indian Ayurvedic medicine practices. So far, about 39 species have been phytochemically studied, which led to the identification of 368 compounds, including terpenoids, tannins, flavonoids, phenylpropanoids, simple phenolics and so on. Some of the isolates showed various bioactivities, in vitro or in vivo, such as antitumor, anti HIV-1, antifungal, antimicrobial, antimalarial, antioxidant, diarrhea and analgesic. This review covers research articles from 1934 to 2018, retrieved from SciFinder, Wikipedia, Google Scholar, Chinese Knowledge Network and Baidu Scholar by using "Terminalia" as the search term ("all fields") with no specific time frame setting for the search. Thirty-nine important medicinal and edible Terminalia species were selected and summarized on their geographical distribution, traditional uses, phytochemistry and related pharmacological activities.

Assessment of a new arbidol derivative against herpes simplex virus II in human cervical epithelial cells and in BALB/c mice

As one of the highly contagious forms, herpes simplex virus type 2 (HSV-2) commonly caused severe genital diseases and closely referred to the HIV infection. The lack of effective vaccines and drug-resistance proclaimed the preoccupation for alternative antiviral agents against HSV-2. Molecules bearing indole nucleus presented diverse biological properties involving antiviral and anti-inflammatory activities. In this study, one of the indole molecules, arbidol derivative (ARD) was designed and synthesized prior to the evaluation of its anti-HSV-2 activity. Our data showed that the ARD effectively suppressed HSV-2-induced cytopathic effects and the generation of progeny virus, with 50% effective concentrations of 3.386 and 1.717 μg/mL, respectively. The results of the time-course assay suggested that the ARD operated in a dual antiviral way by interfering virus entry and impairing the earlier period of viral cycle during viral DNA synthesis. The ARD-mediated HSV-2 inhibition was partially attained by blocking NF-κB pathways and down-regulating the expressions of several inflammatory cytokines. Furthermore, in vivo studies showed that oral administration of ARD protected BALB/c mice from intravaginal HSV-2 challenge by alleviating serious vulval lesions and histopathological changes in the target organs. Besides, the treatment with ARD also made the levels of viral protein, NF-κB protein and inflammatory cytokines lower, in consistent with the in-vitro studies. Collectively, ARD unveiled therapeutic potential for the prevention and treatment of HSV-2 infections.