Hippomanin A from acetone extract of Phyllanthus urinaria inhibited HSV-2 but not HSV-1 infection in vitro

Herbal Substances with Antiviral Effects: Features and Prospects for the Treatment of Viral Diseases with Emphasis on Pro-Inflammatory Cytokines

Viral diseases have a significant impact on human health, and three novel coronaviruses (CoV) have emerged during the 21st century. In this review, we have emphasized the potential of herbal substances with antiviral effects. Our investigation focused on the features and prospects of viral disease treatment, with a particular emphasis on proinflammatory cytokines. We conducted comprehensive searches of various databases, including Science Direct, CABI Direct, Web of Science, PubMed, and Scopus. Cytokine storm mechanisms play a crucial role in inducing a pro-inflammatory response by triggering the expression of cytokines and chemokines. This response leads to the recruitment of leukocytes and promotes antiviral effects, forming the first line of defense against viruses. Numerous studies have investigated the use of herbal medicine candidates as immunomodulators or antivirals. However, cytokine-storm-targeted therapy is recommended for patients with acute respiratory distress syndrome caused by SARS-CoV to survive severe pulmonary failure. Our reviews have demonstrated that herbal formulations could serve as alternative medicines and significantly reduce complicated viral infections. Furthermore, they hold promising potential as specific antiviral agents in experimental animal models.

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.

Upper Airways Spray for Viral Infections Prevention

Aim

Several studies emphasized the antiviral properties of many natural compounds enclosed in nutraceuticals formulas and quite effective to prevent the respiratory infections. The rationale of our investigation has been to achieve protection from common cold viruses' infection of the upper airways pooling together and dispensing different active principles on a multistep defense basis. Material and Methods. 30 patients affected by sudden aspecific viral-induced sore throat rhinitis were divided in two groups: (1) the first group included 15 patients which were administered with our spray formula and (2) the second group included 15 patients with the commercial nasal lavage kit. The mucous smear was stained with May Grunwald-Giemsa to exclude eosinophilic infiltrate and confirm the prevalence of granulocytes and lympho-monocytes typical of viral seasonal inflammatory upper airways conditions.

Results

The symptomatic relieve is remarkedly evident in the treated group with our spray compared to the second group treated with commercial nasal lavage kit.

Conclusions

The open case-control retrospective observational study showed a definite benefit of the spray based on natural herbal extracts to take control of the upper airways respiratory distress due to viral infections.

Medicinal plants: Treasure for antiviral drug discovery

The pandemic of viral diseases like novel coronavirus (2019-nCoV) prompted the scientific world to examine antiviral bioactive compounds rather than nucleic acid analogous, protease inhibitors, or other toxic synthetic molecules. The emerging viral infections significantly associated with 2019-nCoV have challenged humanity's survival. Further, there is a constant emergence of new resistant viral strains that demand novel antiviral agents with fewer side effects and cell toxicity. Despite significant progress made in immunization and regenerative medicine, numerous viruses still lack prophylactic vaccines and specific antiviral treatments that are so often influenced by the generation of viral escape mutants. Of importance, medicinal herbs offer a wide variety of therapeutic antiviral chemotypes that can inhibit viral replication by preventing viral adsorption, adhering to cell receptors, inhibiting virus penetration in the host cell, and competing for pathways of activation of intracellular signals. The present review will comprehensively summarize the promising antiviral activities of medicinal plants and their bioactive molecules. Furthermore, it will elucidate their mechanism of action and possible implications in the treatment/prevention of viral diseases even when their mechanism of action is not fully understood, which could serve as the base for the future development of novel or complementary antiviral treatments.

Effective Antiviral Medicinal Plants and Biological Compounds Against Central Nervous System Infections: A Mechanistic Review

BACKGROUND AND OBJECTIVE

Infectious diseases are amongst the leading causes of death in the world and central nervous system infections produced by viruses may either be fatal or generate a wide range of symptoms that affect global human health. Most antiviral plants contain active phytoconstituents such as alkaloids, flavonoids, and polyphenols, some of which play an important antiviral role. Herein, we present a background to viral central nervous system (CNS) infections, followed by a review of medicinal plants and bioactive compounds that are effective against viral pathogens in CNS infections.

METHODS

A comprehensive literature search was conducted on scientific databases including: PubMed, Scopus, Google Scholar, and Web of Science. The relevant keywords used as search terms were: "myelitis", "encephalitis", "meningitis", "meningoencephalitis", "encephalomyelitis", "central nervous system", "brain", "spinal cord", "infection", "virus", "medicinal plants", and "biological compounds".

RESULTS

The most significant viruses involved in central nervous system infections are: Herpes Simplex Virus (HSV), Varicella Zoster Virus (VZV), West Nile Virus (WNV), Enterovirus 71 (EV71), Japanese Encephalitis Virus (JEV), and Dengue Virus (DENV). The inhibitory activity of medicinal plants against CNS viruses is mostly active through prevention of viral binding to cell membranes, blocking viral genome replication, prevention of viral protein expression, scavenging reactive Oxygen Species (ROS), and reduction of plaque formation.

CONCLUSION

Due to the increased resistance of microorganisms (bacteria, viruses, and parasites) to antimicrobial therapies, alternative treatments, especially using plant sources and their bioactive constituents, appear to be more fruitful.

The Signaling Pathways, and Therapeutic Targets of Antiviral Agents: Focusing on the Antiviral Approaches and Clinical Perspectives of Anthocyanins in the Management of Viral Diseases

As the leading cause of death worldwide, viruses significantly affect global health. Despite the rapid progress in human healthcare, there are few viricidal and antiviral therapies that are efficient enough. The rapid emergence of resistance, and high costs, as well as the related side effects of synthetic antiviral drugs, raise the need to identify novel, effective, and safe alternatives against viral diseases. Nature has been of the most exceptional help and source of inspiration for developing novel multi-target antiviral compounds, affecting several steps of the viral life cycle and host proteins. For that matter and due to safety and efficacy limitations, as well as high resistance rate of conventional therapies, hundreds of natural molecules are preferred over the synthetic drugs. Besides, natural antiviral agents have shown acceptable antiviral value in both preclinical and clinical trials.This is the first review regarding molecular and cellular pathways of the virus life cycle, treatment strategies, and therapeutic targets of several viral diseases with a particular focus on anthocyanins as promising natural compounds for significant antiviral enhancements. Clinical applications and the need to develop nano-formulation of anthocyanins in drug delivery systems are also considered.

Mitigating Alzheimer’s Disease with Natural Polyphenols: A Review

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According to Alzheimer’s Disease International (ADI), nearly 50 million people worldwide were living with dementia in 2017, and this number is expected to triple by 2050. Despite years of research in this field, the root cause and mechanisms responsible for Alzheimer’s disease (AD) have not been fully elucidated yet. Moreover, promising preclinical results have repeatedly failed to translate into patient treatments. Until now, none of the molecules targeting AD has successfully passed the Phase III trial. Although natural molecules have been extensively studied, they normally require high concentrations to be effective; alternately, they are too large to cross the blood-brain barrier (BBB).

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In this review, we report AD treatment strategies, with a virtually exclusive focus on green chemistry (natural phenolic molecules). These include therapeutic strategies for decreasing amyloid-β (Aβ) production, preventing and/or altering Aβ aggregation, and reducing oligomers cytotoxicity such as curcumin, (-)-epigallocatechin-3-gallate (EGCG), morin, resveratrol, tannic acid, and other natural green molecules. We also examine whether consideration should be given to potential candidates used outside of medicine and nutrition, through a discussion of two intermediate-sized green molecules, with very similar molecular structures and key properties, which exhibit potential in mitigating Alzheimer’s disease.

A Review of the Phytochemistry and Pharmacology of Phyllanthus urinaria L

The genus Phyllanthus (L.) is one of the most important groups of plants belonging to the Phyllantaceae family. Phyllanthus urinaria (L.) is an annual perennial herbal species found in tropical Asia, America, China, and the Indian Ocean islands. P. urinaria is used in folk medicine as a cure to treat jaundice, diabetes, malaria, and liver diseases. This review provides traditional knowledge, phytochemistry, and biological activities of P. urinaria. The literature reviewed for this article was obtained from the Web of Science, SciFinder, PubMed, ScienceDirect, and Google Scholar journal papers published prior to December 2017. Phytochemical investigations reveal that the plant is a rich source of lignans, tannins, flavonoids, phenolics, terpenoids, and other secondary metabolites. Pharmacological activities include anticancer, hepatoprotective, antidiabetic, antimicrobial, and cardioprotective effects. Thus, this present review summarizes the phytochemical constituents and their biological activities including biological studies on various crude extracts and fractions both in vitro and in vivo, and on clinical trial information about P. urinaria. This review compiles 93 naturally occurring compounds from P. urinaria along with their structures and pharmacological activities. The review is expected to stimulate further research on P. urinaria, and its pharmacological potential to yield novel therapeutic agents.

Corilagin, a promising medicinal herbal agent

Corilagin, a gallotannin, is one of the major active components of many ethnopharmacological plants. It was isolated from Caesalpinia coriaria (Jacq.) Willd. (dividivi) by Schmidt in 1951 for the first time. In the past few decades, corilagin was reported to exhibit anti-tumor, anti-inflammatory and hepatoprotective activities, etc. However, little attention was paid to its pharmacological properties due to the complicated and inefficient extract method. In recent years, with the development of extraction technology corilagin was much easier to obtain than before. Thus, people return to pay attention to its anti-tumor, hepatoprotective, and anti-inflammatory activities, particularly as an anti-tumor agent candidate. Our research team had focused on the distribution, preparation and anti-tumor activity of corilagin since 2005. We found corilagin showed good anti-tumor activity on hepatocellular carcinoma and ovarian cancer. What's more, corilagin showed a low level of toxicity toward normal cells and tissues. Due to the extensive attention that corilagin has received, we present a systematic review of the pharmacological effects of corilagin. In this review, we summarized all the pharmacological effects of corilagin with a focus on the molecular mechanism of anti-tumor activity and show you how corilagin affected the signaling pathways of tumor cells as well as its physicochemical properties, distribution and preparation methods.

The Genus Phyllanthus: An Ethnopharmacological, Phytochemical, and Pharmacological Review

The plants of the genus Phyllanthus (Euphorbiaceae) have been used as traditional medicinal materials for a long time in China, India, Brazil, and the Southeast Asian countries. They can be used for the treatment of digestive disease, jaundice, and renal calculus. This review discusses the ethnopharmacological, phytochemical, and pharmacological studies of Phyllanthus over the past few decades. More than 510 compounds have been isolated, the majority of which are lignins, triterpenoids, flavonoids, and tannins. The researches of their remarkable antiviral, antioxidant, antidiabetic, and anticancer activities have become hot topics. More pharmacological screenings and phytochemical investigations are required to support the traditional uses and develop leading compounds.

Activity-based and fraction-guided analysis of Phyllanthus urinaria identifies loliolide as a potent inhibitor of hepatitis C virus entry

Without a vaccine, hepatitis C virus (HCV) remains a global medical and socio-economic burden, predisposing about 170 million carriers worldwide to end-stage liver diseases including cirrhosis and hepatocellular carcinoma. Although the recently developed direct-acting antivirals (DAAs) have revolutionized hepatitis C treatment, most of them are unsuitable for monotherapy due to risks of resistance, thus necessitating combination with interferon (IFN)-alpha, ribavirin, or additional DAAs. More importantly, the high cost associated with the DAAs restricts their accessibility to most parts of the world. Developing novel cost-effective anti-HCV therapeutics may help expand the scope of antivirals and treatment strategies against hepatitis C. Herein, we applied an activity-based and fraction-guided analysis of extracts from the medicinal plant Phyllanthus urinaria (P. urinaria), which yielded fraction 13 (F13) as possessing the most potent inhibitory activity against early viral entry of cell-culture HCV infection. Chemical analysis (silica gel chromatography followed by ESI LC-MS plus (1)H and (13)C NMR) of F13 identified loliolide (LOD), a monoterpenoid lactone, as a novel inhibitor of HCV entry. Specifically, LOD could efficiently inactivate HCV free virus particles, abrogate viral attachment, and impede viral entry/fusion, with minimal effect on viral replication/translation, particle production, and induction of type I IFN host antiviral immune response. ELISA-based binding analysis confirmed the monoterpenoid's ability in efficiently blocking HCV particle attachment to the host cell surface. Furthermore, LOD could inhibit infection by several genotypic strains of HCV. This is the first report characterizing P. urinaria and its bioactive compound LOD as potent HCV entry inhibitors, which merit further evaluation for development as candidate antiviral agents against hepatitis C.

Herbal plants and plant preparations as remedial approach for viral diseases

Herbal plants, plant preparations and phytoconstituents have proved useful in attenuating infectious conditions and were the only remedies available, till the advent of antibiotics (many being of plant origin themselves). Among infectious diseases, viral diseases in particular, remain the leading cause of death in humans globally. A variety of phytoconstituents derived from medicinal herbs have been extensively studied for antiviral activity. Based on this rationale, an online search was performed, which helped to identify a large number of plant species harboring antiviral molecules. These herbal sources have been reported individually or in combinations across a large number of citations studied. Activities against rabies virus, Human immunodeficiency virus, Chandipura virus, Japanese Encephalitis Virus, Enterovirus, Influenza A/H1N1 and other influenza viruses were discovered during the literature search. This review includes all such plant species exhibiting antiviral properties. The review also encompasses composition and methodologies of preparing various antiviral formulations around the globe. An elaborate section on the formulations filed for patent registration, along with non-patented formulations, has also been included in this article. To conclude, herbal sources provide researchers enormous scope to explore and bring out viable alternatives against viral diseases, considering non-availability of suitable drug candidates and increasing resistance to existing drug molecules for many emerging and re-emerging viral diseases.

Antiviral natural products and herbal medicines

Viral infections play an important role in human diseases, and recent outbreaks in the advent of globalization and ease of travel have underscored their prevention as a critical issue in safeguarding public health. Despite the progress made in immunization and drug development, many viruses lack preventive vaccines and efficient antiviral therapies, which are often beset by the generation of viral escape mutants. Thus, identifying novel antiviral drugs is of critical importance and natural products are an excellent source for such discoveries. In this mini-review, we summarize the antiviral effects reported for several natural products and herbal medicines.

Antiviral Properties of Phytochemicals

In recent years, significant progress has been achieved for the development of novel anti-viral drugs. These newly developed drugs belong to three groups of compounds, nucleoside analogues, thymidine kinase-dependent nucleotide analogues and specific viral enzyme inhibitors. It has been found that the natural products, like plant-derived compounds (phytochemicals) as well as traditional medicines, like traditional Chinese medicines (TCM), Ayurvedic medicines and so on, are the important sources for potential and novel anti-viral drugs. In this chapter, the history of natural products as antiviral drugs, the approaches to discover potential lead compounds, and the anti-viral properties of phytochemicals with different action mechanisms are discussed. The key conclusion is that natural products are most important sources for novel anti-viral drugs.

Antimetastatic potentials of Phyllanthus urinaria L on A549 and Lewis lung carcinoma cells via repression of matrix-degrading proteases

Tumor metastasis is the most important cause of cancer death and various treatment strategies have targeted at preventing the occurrence of metastasis. Phyllanthus urinaria L is a popular folk medicine and has several proven biological properties, including antioxidant, antihypertension, and anti-inflammatory. This study provides molecular evidence associated with the antimetastatic effects of P urinaria L extracts (PUE), which contained polyphenols including gallic acid, methyl gallate, epicatechin, epigallocatechin-3-gallate, gallocatechin-3-gallate, rutin, epicatechin-3-gallate, and naringin, by showing a marked inhibition on the invasion (P < .001) and migration (P < .001) of highly metastatic A549 and Lewis lung carcinoma (LLC) cells. To further investigate the precise involvement of PUE in tumor metastasis, A549 and LLC cells were treated with PUE at various concentrations and results from zymography and Western blotting showed that a PUE treatment may decrease the expressions of matrix metalloproteinase-2 (MMP-2; P < .001), MMP-9 (P < .001), urokinase plasminogen activator (P < .001), and their endogenous inhibitors, that is, tissue inhibitor of metalloproteinase-2 and plasminogen activator inhibitor-1, in a concentration-dependent manner. Reverse transcription-polymerase chain reaction and MMP-2 promoter luciferase analysis (P < .001) revealed that PUE inhibits the transcription of MMP-2 mRNA. PUE also exerted an inhibitory effect on the DNA-binding activity and the nuclear translocation of NF-κB and AP-1. Furthermore, the inhibitory effects of PUE on the metastasis and growth of LLC cells in vivo were proven. These results indicate that PUE could be applied to be a potential antimetastatic agent.

Excoecarianin, Isolated from Phyllanthus urinaria Linnea, Inhibits Herpes Simplex Virus Type 2 Infection through Inactivation of Viral Particles

Phyllanthus urinaria Linnea (Euphorbiaceae) is one of the traditional medicinal plants widely used by oriental people to treat various diseases. We have previously demonstrated that the acetone extract of P. urinaria inhibits herpes simplex virus type 2 (HSV-2) but not HSV-1 infection. In a continuing effort to clarify the antiviral mechanisms of P. urinaria, we isolated the pure compound excoecarianin from the whole plant of P. urinaria through acetone extraction, and investigated its anti-HSV-1 and HSV-2 activities. Our results indicated that excoecarianin protected Vero cells from HSV-2 but not HSV-1 infection, and its 50% inhibitory concentration (IC₅₀) was 1.4 ± 0.1 μM. The antiviral effective concentration of excoecarianin did not affect the viability or the morphology of Vero cells. Although excoecarianin inhibited HSV-2 infection, the inhibitory effect, however, was most prominent when excoecarianin was concurrently added with the virus. Pretreatment of Vero cells with excoecarianin with removal of the drug prior to infection did not yield any antiviral effects, and the same observation was made for post viral entry treatment. Subsequent studies revealed that excoecarianin inactivated HSV-2 virus particles to prevent viral infection. A synergistic antiviral effect against HSV-2 was also observed when Vero cells were treated with a combination of acyclovir (ACV) and excoecarianin. These results suggested that excoecarianin merits to be further explored as an entry inhibitor against HSV-2 and could potentially be investigated for combinatorial drug treatment with nucleoside analogues such as ACV in therapeutic management of HSV-2 infection.

Hydrolyzable tannins (chebulagic acid and punicalagin) target viral glycoprotein-glycosaminoglycan interactions to inhibit herpes simplex virus 1 entry and cell-to-cell spread

Herpes simplex virus 1 (HSV-1) is a common human pathogen that causes lifelong latent infection of sensory neurons. Non-nucleoside inhibitors that can limit HSV-1 recurrence are particularly useful in treating immunocompromised individuals or cases of emerging acyclovir-resistant strains of herpesvirus. We report that chebulagic acid (CHLA) and punicalagin (PUG), two hydrolyzable tannins isolated from the dried fruits of Terminalia chebula Retz. (Combretaceae), inhibit HSV-1 entry at noncytotoxic doses in A549 human lung cells. Experiments revealed that both tannins targeted and inactivated HSV-1 viral particles and could prevent binding, penetration, and cell-to-cell spread, as well as secondary infection. The antiviral effect from either of the tannins was not associated with induction of type I interferon-mediated responses, nor was pretreatment of the host cell protective against HSV-1. Their inhibitory activities targeted HSV-1 glycoproteins since both natural compounds were able to block polykaryocyte formation mediated by expression of recombinant viral glycoproteins involved in attachment and membrane fusion. Our results indicated that CHLA and PUG blocked interactions between cell surface glycosaminoglycans and HSV-1 glycoproteins. Furthermore, the antiviral activities from the two tannins were significantly diminished in mutant cell lines unable to produce heparan sulfate and chondroitin sulfate and could be rescued upon reconstitution of heparan sulfate biosynthesis. We suggest that the hydrolyzable tannins CHLA and PUG may be useful as competitors for glycosaminoglycans in the management of HSV-1 infections and that they may help reduce the risk for development of viral drug resistance during therapy with nucleoside analogues.

In vitro anti-influenza screening of several Euphorbiaceae species: structure of a bioactive Cyanoglucoside from Codiaeum variegatum

A bio-guided screening against influenza A virus (FLUAV) was carried out with seven Euphorbiaceae species. The results showed that chromatographic fractions from Phyllantus niruri, Euphorbia pulcherrima and Codiaeum variegatum had relevant anti-FLUAV activity, although only chromatographical subfractions from C. variegatum kept the activity. From this plant, the active compound against FLUAV was isolated. Its structure was assigned as 2-(3,4,5)-trihydroxy-6-hydroxymethyltetrahydropyran-2-yloxymethyl)acrylonitrile (1) on the basis of NMR, mass spectrometry and X-ray diffraction analysis. The compound displayed virucidal activity without impairment of haemagglutination properties of the used virus strain. This is the first report indicating antiviral activity of a cyanoglucoside.