A Review of Medicinal Plants with Antiviral Activity Available in Bangladesh and Mechanistic Insight Into Their Bioactive Metabolites on SARS-CoV-2, HIV and HBV

Curcumin and quercetin co-encapsulated in nanoemulsions for nasal administration: A promising therapeutic and prophylactic treatment for viral respiratory infections

One of the most frequent causes of respiratory infections are viruses. Viruses reaching the airways can be absorbed by the human body through the respiratory mucosa and mainly infect lung cells. Several viral infections are not yet curable, such as coronavirus-2 (SARS-CoV-2). Furthermore, the side effect of synthetic antiviral drugs and reduced efficacy against resistant variants have reinforced the search for alternative and effective treatment options, such as plant-derived antiviral molecules. Curcumin (CUR) and quercetin (QUE) are two natural compounds that have been widely studied for their health benefits, such as antiviral and anti-inflammatory activity. However, poor oral bioavailability limits the clinical applications of these natural compounds. In this work, nanoemulsions (NE) co-encapsulating CUR and QUE designed for nasal administration were developed as promising prophylactic and therapeutic treatments for viral respiratory infections. The NEs were prepared by high-pressure homogenization combined with the phase inversion temperature technique and evaluated for their physical and chemical characteristics. In vitro assays were performed to evaluate the nanoemulsion retention into the porcine nasal mucosa. In addition, the CUR and QUE-loaded NE antiviral activity was tested against a murine β-COV, namely MHV-3. The results evidenced that CUR and QUE loaded NE had a particle size of 400 nm and retention in the porcine nasal mucosa. The antiviral activity of the NEs showed a percentage of inhibition of around 99 %, indicating that the developed NEs has interesting properties as a therapeutic and prophylactic treatment against viral respiratory infections.

Two new and effective food-extracted immunomodulatory agents exhibit anti-inflammatory response activity in the hACE2 acute lung injury murine model of COVID-19

Objective

The coronavirus disease 2019 (COVID-19) spread rapidly and claimed millions of lives worldwide. Acute respiratory distress syndrome (ARDS) is the major cause of COVID-19-associated deaths. Due to the limitations of current drugs, developing effective therapeutic options that can be used rapidly and safely in clinics for treating severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections is necessary. This study aims to investigate the effects of two food-extracted immunomodulatory agents, ajoene-enriched garlic extract (AGE) and cruciferous vegetables-extracted sulforaphane (SFN), on anti-inflammatory and immune responses in a SARS-CoV-2 acute lung injury mouse model.

Methods

In this study, we established a mouse model to mimic the SARS-CoV-2 infection acute lung injury model via intratracheal injection of polyinosinic:polycytidylic acid (poly[I:C]) and SARS-CoV-2 recombinant spike protein (SP). After the different agents treatment, lung sections, bronchoalveolar lavage fluid (BALF) and fresh faeces were harvested. Then, H&E staining was used to examine symptoms of interstitial pneumonia. Flow cytometry was used to examine the change of immune cell populations. Multiplex cytokines assay was used to examine the inflammatory cytokines.16S rDNA high-throughput sequencing was used to examine the change of gut microbiome.

Results

Our results showed that AGE and SFN significantly suppressed the symptoms of interstitial pneumonia, effectively inhibited the production of inflammatory cytokines, decreased the percentage of inflammatory cell populations, and elevated T cell populations in the mouse model. Furthermore, we also observed that the gut microbiome of genus Paramuribaculum were enriched in the AGE-treated group.

Conclusion

Here, for the first time, we observed that these two novel, safe, and relatively inexpensive immunomodulatory agents exhibited the same effects on anti-inflammatory and immune responses as neutralizing monoclonal antibodies (mAbs) against interleukin 6 receptor (IL-6R), which have been suggested for treating COVID-19 patients. Our results revealed the therapeutic ability of these two immunomodulatory agents in a mouse model of SARS-CoV-2 acute lung injury by promoting anti-inflammatory and immune responses. These results suggest that AGE and SFN are promising candidates for the COVID-19 treatment.

Precision nutrition to reset virus-induced human metabolic reprogramming and dysregulation (HMRD) in long-COVID

SARS-CoV-2, the etiological agent of COVID-19, is devoid of any metabolic capacity; therefore, it is critical for the viral pathogen to hijack host cellular metabolic machinery for its replication and propagation. This single-stranded RNA virus with a 29.9 kb genome encodes 14 open reading frames (ORFs) and initiates a plethora of virus-host protein-protein interactions in the human body. These extensive viral protein interactions with host-specific cellular targets could trigger severe human metabolic reprogramming/dysregulation (HMRD), a rewiring of sugar-, amino acid-, lipid-, and nucleotide-metabolism(s), as well as altered or impaired bioenergetics, immune dysfunction, and redox imbalance in the body. In the infectious process, the viral pathogen hijacks two major human receptors, angiotensin-converting enzyme (ACE)-2 and/or neuropilin (NRP)-1, for initial adhesion to cell surface; then utilizes two major host proteases, TMPRSS2 and/or furin, to gain cellular entry; and finally employs an endosomal enzyme, cathepsin L (CTSL) for fusogenic release of its viral genome. The virus-induced HMRD results in 5 possible infectious outcomes: asymptomatic, mild, moderate, severe to fatal episodes; while the symptomatic acute COVID-19 condition could manifest into 3 clinical phases: (i) hypoxia and hypoxemia (Warburg effect), (ii) hyperferritinemia ('cytokine storm'), and (iii) thrombocytosis (coagulopathy). The mean incubation period for COVID-19 onset was estimated to be 5.1 days, and most cases develop symptoms after 14 days. The mean viral clearance times were 24, 30, and 39 days for acute, severe, and ICU-admitted COVID-19 patients, respectively. However, about 25-70% of virus-free COVID-19 survivors continue to sustain virus-induced HMRD and exhibit a wide range of symptoms that are persistent, exacerbated, or new 'onset' clinical incidents, collectively termed as post-acute sequelae of COVID-19 (PASC) or long COVID. PASC patients experience several debilitating clinical condition(s) with >200 different and overlapping symptoms that may last for weeks to months. Chronic PASC is a cumulative outcome of at least 10 different HMRD-related pathophysiological mechanisms involving both virus-derived virulence factors and a multitude of innate host responses. Based on HMRD and virus-free clinical impairments of different human organs/systems, PASC patients can be categorized into 4 different clusters or sub-phenotypes: sub-phenotype-1 (33.8%) with cardiac and renal manifestations; sub-phenotype-2 (32.8%) with respiratory, sleep and anxiety disorders; sub-phenotype-3 (23.4%) with skeleto-muscular and nervous disorders; and sub-phenotype-4 (10.1%) with digestive and pulmonary dysfunctions. This narrative review elucidates the effects of viral hijack on host cellular machinery during SARS-CoV-2 infection, ensuing detrimental effect(s) of virus-induced HMRD on human metabolism, consequential symptomatic clinical implications, and damage to multiple organ systems; as well as chronic pathophysiological sequelae in virus-free PASC patients. We have also provided a few evidence-based, human randomized controlled trial (RCT)-tested, precision nutrients to reset HMRD for health recovery of PASC patients.

[3-O-β-chacotriosyl glycyrrhetinic acid derivatives as potential small-molecule SARS-CoV-2 fusion inhibitors against SARS-CoV-2 entry into host cells]

OBJECTIVE

To study the inhibitory activities of 3-O-β-chacotriosyl glycyrrhetinic acid derivatives against the entry of SARS-CoV-2 into host cells.

METHODS

With pentacyclic triterpene saponin glycyrrhizic acid (a natural SARS-CoV-2 entry inhibitor) as the lead compound, a series of 3-O-β-chacotriosyl glycyrrhetinic acid derivatives were designed and synthesized based on hypridization principle, and their inhibitory activities against virus entry were tested in SARS-CoV-2 pseudovirusinfected cells. The antiviral targets of the lead compound 1b was identified by pseudotyped SARS-CoV-2 infection assay and surface plasmon resonance (SPR) assay, and the S protein-mediated cell-cell fusion assay was used to evaluate the effect of 1b on virus-cell membrane fusion. Molecular docking and single amino acid mutagenesis were carried out to analyze the effect of 1b on binding activitiy of S protein.

RESULTS

The lead compound 1b showed significant inhibitory effect against Omicron pseudovirus with an EC50 value of 3.28 μmol/L (P < 0.05), and had broad-spectrum antiviral activity against other SARS-CoV-2 pseudovirus. Spike-dependent cell-cell fusion assay demonstrated an inhibitory effect of 1b against SARS-CoV-2 S proteinmediated cell-cell fusion. Molecular docking analysis predicted that the lead compound 1b could be well fitted into a cavity between the attachment (S1) and fusion (S2) subunits at the 3-fold axis, where it formed multiple hydrophobic interactions with Glu309, Ser305, Arg765 and Lys964 residues with a KD value of -8.6 kcal/mol. The compound 1b at 10, 5, 2.5 and 1.25 μmol/L showed a significantly reduced inhibitory activity against the pseudovirus with mutated Arg765, Lys964, Glu309 and Leu303 (P < 0.01).

CONCLUSION

3-O-β-chacotriosyl glycyrrhetinic acid derivatives are capable of stabilizing spike protein in the pre-fusion step to interfere with the fusion of SARS-CoV-2 with host cell membrane, and can thus serve as potential novel small-molecule SARS-CoV-2 fusion inhibitors.

Insights of phytoremediation mechanisms for viruses based on in-vitro, in-vivo and in-silico assessments of selected herbal plants

Waterborne pathogenic viruses present unrelenting challenges to the global health and wastewater treatment industry. Phytoremediation offers promising solutions for wastewater treatment through plant-based technologies. This study investigated antiviral mechanisms in-vivo using bacteriophages MS2 and T4 as surrogates for effective herbs screened in-vitro from three embryophytes (Ocimum basilicum, Mentha sp., Plectranthus amboinicus), two macrophytes (Eichhornia crassipes, Pistia stratiotes) and a perennial grass (Cyperus rotundas). In-silico virtual screening predicted antiviral phytochemicals for further antiviral potency assessment. Results suggested in-vitro antiviral activities of embryophytes and macrophytes were higher (43-62%) than grass (21-26%). O. basilicum (OB, 57-62%) and P. stratiotes (PS, 59-60%) exhibited the highest antiviral activities. In-vivo tests showed notable virus reduction (>60%) in culture solution, attributed to rhizofiltration (66-74%) and phytoinactivation/phytodegradation (63-84%). In-silico analysis identified rutin as a primary antiviral phytochemical for MS2 (-9.7 kcal/mol) and T4 (-10.9 kcal/mol), correlating with dose-response inactivation (∼58-62%). In-vivo tests suggested additional phytocompounds may contribute to viral inactivation, presenting new opportunities for herb-based wastewater treatment solutions. Consequently, this study not only demonstrates the antiviral capabilities of OB and PS but also introduces an innovative approach for addressing viral contaminants in water.

Informatics and Computational Approaches for the Discovery and Optimization of Natural Product-Inspired Inhibitors of the SARS-CoV-2 2'-O-Methyltransferase

The urgent need for new classes of orally available, safe, and effective antivirals─covering a breadth of emerging viruses─is evidenced by the loss of life and economic challenges created by the HIV-1 and SARS-CoV-2 pandemics. As frontline interventions, small-molecule antivirals can be deployed prophylactically or postinfection to control the initial spread of outbreaks by reducing transmissibility and symptom severity. Natural products have an impressive track record of success as prototypic antivirals and continue to provide new drugs through synthesis, medicinal chemistry, and optimization decades after discovery. Here, we demonstrate an approach using computational analysis typically used for rational drug design to identify and develop natural product-inspired antivirals. This was done with the goal of identifying natural product prototypes to aid the effort of progressing toward safe, effective, and affordable broad-spectrum inhibitors of Betacoronavirus replication by targeting the highly conserved RNA 2'-O-methyltransferase (2'-O-MTase). Machaeriols RS-1 (7) and RS-2 (8) were identified using a previously outlined informatics approach to first screen for natural product prototypes, followed by in silico-guided synthesis. Both molecules are based on a rare natural product group. The machaeriols (3-6), isolated from the genus Machaerium, endemic to Amazonia, inhibited the SARS-CoV-2 2'-O-MTase more potently than the positive control, Sinefungin (2), and in silico modeling suggests distinct molecular interactions. This report highlights the potential of computationally driven screening to leverage natural product libraries and improve the efficiency of isolation or synthetic analog development.

Medicinal Plants against Viral Infections: A Review of Metabolomics Evidence for the Antiviral Properties and Potentials in Plant Sources

Most plants have developed unique mechanisms to cope with harsh environmental conditions to compensate for their lack of mobility. A key part of their coping mechanisms is the synthesis of secondary metabolites. In addition to their role in plants' defense against pathogens, they also possess therapeutic properties against diseases, and their use by humans predates written history. Viruses are a unique class of submicroscopic agents, incapable of independent existence outside a living host. Pathogenic viruses continue to pose a significant threat to global health, leading to innumerable fatalities on a yearly basis. The use of medicinal plants as a natural source of antiviral agents has been widely reported in literature in the past decades. Metabolomics is a powerful research tool for the identification of plant metabolites with antiviral potentials. It can be used to isolate compounds with antiviral capacities in plants and study the biosynthetic pathways involved in viral disease progression. This review discusses the use of medicinal plants as antiviral agents, with a special focus on the metabolomics evidence supporting their efficacy. Suggestions are made for the optimization of various metabolomics methods of characterizing the bioactive compounds in plants and subsequently understanding the mechanisms of their operation.

Inhibition by components of Glycyrrhiza uralensis of 3CLpro and HCoV-OC43 proliferation

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). 3CLpro is a key enzyme in coronavirus proliferation and a treatment target for COVID-19. In vitro and in silico, compounds 1-3 from Glycyrrhiza uralensis had inhibitory activity and binding affinity for 3CLpro. These compounds decreased HCoV-OC43 cytotoxicity in RD cells. Moreover, they inhibited viral growth by reducing the amounts of the necessary proteins (M, N, and RDRP). Therefore, compounds 1-3 are inhibitors of 3CLpro and HCoV-OC43 proliferation.

Untargeted-based metabolomics analysis and in vitro/in silico antiviral activity of extracts from Phyllanthus brasiliensis (Aubl.) Poir

INTRODUCTION

This study describes the molecular profile and the potential antiviral activity of extracts from Phyllanthus brasiliensis, a plant widely found in the Brazilian Amazon. The research aims to shed light on the potential use of this species as a natural antiviral agent.

METHODS

The extracts were analysed using liquid chromatography-mass spectrometry (LC-MS) system, a potent analytical technique to discover drug candidates. In the meantime, in vitro antiviral assays were performed against Mayaro, Oropouche, Chikungunya, and Zika viruses. In addition, the antiviral activity of annotated compounds was predicted by in silico methods.

RESULTS

Overall, 44 compounds were annotated in this study. The results revealed that P. brasiliensis has a high content of fatty acids, flavones, flavan-3-ols, and lignans. Furthermore, in vitro assays revealed potent antiviral activity against different arboviruses, especially lignan-rich extracts against Zika virus (ZIKV), as follows: methanolic extract from bark (MEB) [effective concentration for 50% of the cells (EC50 ) = 0.80 μg/mL, selectivity index (SI) = 377.59], methanolic extract from the leaf (MEL) (EC50  = 0.84 μg/mL, SI = 297.62), and hydroalcoholic extract from the leaf (HEL) (EC50  = 1.36 μg/mL, SI = 735.29). These results were supported by interesting in silico prediction, where tuberculatin (a lignan) showed a high antiviral activity score.

CONCLUSIONS

Phyllanthus brasiliensis extracts contain metabolites that could be a new kick-off point for the discovery of candidates for antiviral drug development, with lignans becoming a promising trend for further virology research.

Saudi date cultivars' seed extracts inhibit developing hepatic steatosis in rats fed a high-fat diet

This research aim was to assess the impact of the seed extracts of the date cultivars (Qatara, Barhi, and Ruthana) on rat's liver steatosis, oxidative stress, and inflammation triggered by feeding a high-fat diet (HFD). The experimental design was based on random partitioning into two groups; one that received the standard diet and another that received the HFD diet. The HFD rats were orally administered Lipitor or date seed extracts at 300 or 600 mg/kg/day for 4 weeks. Accordingly, feeding rats HFD significantly increased body and liver weights, hepatic and serum lipid levels, glucose, insulin, HOMA-IR, liver function enzymes, and inflammation markers, and decreased oxidative stress enzymes. Oral administration of Barhi and Ruthana date seed extracts significantly decreased body and liver weights. Serum and liver total cholesterol TC, Triglycerides TGs, and free fatty acids FFAs were also decreased as were AST, ALT, MAD, leptin, and CRP, with a concomitant increase in SOD, GSH, and CAT. Furthermore, similar to Lipitor, oral administration of the extracts reduced inflammation markers such as TNF-α, serum CRP, IL-6, IL-1β, and leptin while increasing IL-10 and adiponectin levels. Histological observation revealed that extract administration improved hepatocyte and parenchymal structures and decreased lipid deposition. In conclusion, both Barhi and Ruthana seed extracts showed strong hepatoprotective, anti-inflammatory, and antioxidant effects against HFD-induced liver steatosis. And date seeds have other beneficial potential for prevention and treatment of various diseases, which can be studied in the future.

Lavandula austroapennina: Assessment of the Antiviral Activity of Lipophilic Extracts from Its Organs

In a framework aimed at the recovery and enhancement of medicinal plants endemic to the territory of the Cilento and Vallo di Diano National Park, Lavandula austroapennina N.G. Passal., Tundis and Upson has aroused interest. An insight into the chemical composition of the corolla, calyx, leaf, stem, and root organs was carried out following ultrasound-assisted maceration in n-hexane. The obtained lipophilic extracts were explored using ultra-high-performance chromatography coupled to high-resolution mass spectrometry (UHPLC-ESI-QqTOF-MS/MS). The extracts from the different organs varied in their relative content of fatty acids, ursanes, and oleanane-type triterpenes. In particular, the oleanolic acid content appeared to increase in the order of corolla < leaf < stem. An MTT assay was performed to verify the possible cytotoxicity of the organ extracts of L. austroapennina at a concentration ranging from 12.5 to 400 µg/mL on the Vero CCL-81 cell line. Antiviral activity against herpes simplex virus type 1 (HSV-1), alpha human coronavirus 229E (HCoV-229E), and poliovirus type 1 (PV-1) was evaluated via a plaque reduction assay in the same cellular model. All the extracts did not show cytotoxic effects after 2 and 24 h exposure times, and the antiviral efficacy was particularly important for the stem extract, capable of completely inhibiting the tested viruses at low doses. The antiviral activity in a non-enveloped virus PV-1 allowed the assertion that the extracts from the organs of L. austroapennina, and especially the stem extract, interfered directly with the viral envelope. This study underlines how much knowledge of a territory's medicinal plant heritage is a harbinger of promising discoveries in the health field.

New Insights into the Role and Therapeutic Potential of Heat Shock Protein 70 in Bovine Viral Diarrhea Virus Infection

Bovine viral diarrhea virus (BVDV), a positive-strand RNA virus of the genus Pestivirus in the Flaviviridae family, is the causative agent of bovine viral diarrhea-mucosal disease (BVD-MD). BVDV's unique virion structure, genome, and replication mechanism in the Flaviviridae family render it a useful alternative model for evaluating the effectiveness of antiviral drugs used against the hepatitis C virus (HCV). As one of the most abundant and typical heat shock proteins, HSP70 plays an important role in viral infection caused by the family Flaviviridae and is considered a logical target of viral regulation in the context of immune escape. However, the mechanism of HSP70 in BVDV infection and the latest insights have not been reported in sufficient detail. In this review, we focus on the role and mechanisms of HSP70 in BVDV-infected animals/cells to further explore the possibility of targeting this protein for antiviral therapy during viral infection.

Strategies for the Management of Spike Protein-Related Pathology

In the wake of the COVID-19 crisis, a need has arisen to prevent and treat two related conditions, COVID-19 vaccine injury and long COVID-19, both of which can trace at least part of their aetiology to the spike protein, which can cause harm through several mechanisms. One significant mechanism of harm is vascular, and it is mediated by the spike protein, a common element of the COVID-19 illness, and it is related to receiving a COVID-19 vaccine. Given the significant number of people experiencing these two related conditions, it is imperative to develop treatment protocols, as well as to consider the diversity of people experiencing long COVID-19 and vaccine injury. This review summarizes the known treatment options for long COVID-19 and vaccine injury, their mechanisms, and their evidentiary basis.

Anti-BVDV Activity of Traditional Chinese Medicine Monomers Targeting NS5B (RNA-Dependent RNA Polymerase) In Vitro and In Vivo

Natural products have emerged as "rising stars" for treating viral diseases and useful chemical scaffolds for developing effective therapeutic agents. The nonstructural protein NS5B (RNA-dependent RNA polymerase) of NADL strain BVDV was used as the action target based on a molecular docking technique to screen herbal monomers for anti-BVDV viral activity. The in vivo and in vitro anti-BVDV virus activity studies screened the Chinese herbal monomers with significant anti-BVDV virus effects, and their antiviral mechanisms were initially explored. The molecular docking screening showed that daidzein, curcumin, artemisinine, and apigenin could interact with BVDV-NADL-NS5B with the best binding energy fraction. In vitro and in vivo tests demonstrated that none of the four herbal monomers significantly affected MDBK cell activity. Daidzein and apigenin affected BVDV virus replication mainly in the attachment and internalization phases, artemisinine mainly in the replication phase, and curcumin was active in the attachment, internalization, replication, and release phases. In vivo tests demonstrated that daidzein was the most effective in preventing and protecting BALB/C mice from BVDV infection, and artemisinine was the most effective in treating BVDV infection. This study lays the foundation for developing targeted Chinese pharmaceutical formulations against the BVDV virus.

Protective Potential of Saussurea costus (Falc.) Lipsch. Roots against Cyclophosphamide-Induced Pulmonary Injury in Rats and Its In Vitro Antiviral Effect

Diseases and infections of the respiratory tract are common global causes of morbidity and mortality. Our study attempts to elucidate a novel remedy for respiratory ailments, in addition to identifying and quantifying the metabolites of Saussurea costus root extract (SCRE) using HPLC. Then, in vitro antiviral and in vivo lung protective effects were elucidated. The in vitro antiviral potential of SCRE was analyzed via plaque assay against the low pathogenic human coronavirus (HCoV-229E) and human influenza virus (H1N1). The value of the half maximal inhibitory concentrations (IC50) of SCRE against HCoV-229E and H1N1 influenza virus were 23.21 ± 1.1 and 47.6 ± 2.3 µg/mL, respectively. SCRE showed a histological improvement, namely a decrease in inducible nitric oxide synthase (iNOS) and caspase-3 immunoexpression in in vivo cyclophosphamide (CP)-induced acute lung injury (ALI). Moreover, there was a considerable decline in microRNA-let-7a gene expression and a significant rise in heme oxygenase-1 (HO-1) gene expression, with a marked decrease in the malondialdehyde (MDA) level. Molecular docking studies revealed that the major constituents of SCRE have a good affinity for caspase-3, HO-1, and iNOS proteins. In conclusion, a traditional plant SCRE could be a promising source of novel therapeutic agents for treating and protecting respiratory tract diseases. More future investigations should be carried out to reveal its efficacy clinically.

Quercetin: A Functional Food-Flavonoid Incredibly Attenuates Emerging and Re-Emerging Viral Infections through Immunomodulatory Actions

Many of the medicinally active molecules in the flavonoid class of phytochemicals are being researched for their potential antiviral activity against various DNA and RNA viruses. Quercetin is a flavonoid that can be found in a variety of foods, including fruits and vegetables. It has been reported to be effective against a variety of viruses. This review, therefore, deciphered the mechanistic of how Quercetin works against some of the deadliest viruses, such as influenza A, Hepatitis C, Dengue type 2 and Ebola virus, which cause frequent outbreaks worldwide and result in significant morbidity and mortality in humans through epidemics or pandemics. All those have an alarming impact on both human health and the global and national economies. The review extended computing the Quercetin-contained natural recourse and its modes of action in different experimental approaches leading to antiviral actions. The gap in effective treatment emphasizes the necessity of a search for new effective antiviral compounds. Quercetin shows potential antiviral activity and inhibits it by targeting viral infections at multiple stages. The suppression of viral neuraminidase, proteases and DNA/RNA polymerases and the alteration of many viral proteins as well as their immunomodulation are the main molecular mechanisms of Quercetin's antiviral activities. Nonetheless, the huge potential of Quercetin and its extensive use is inadequately approached as a therapeutic for emerging and re-emerging viral infections. Therefore, this review enumerated the food-functioned Quercetin source, the modes of action of Quercetin for antiviral effects and made insights on the mechanism-based antiviral action of Quercetin.

Antiviral Potential of Traditional Unani Medicine with Special Emphasis on Dengue: A Review

Dengue fever has become a major public health concern. It is usually related to intravascular leaking, bleeding disorders, and thrombocytopenia and is recognized as a potent threat to humans. The scarcity of anti-dengue medication or vaccine for such a serious disease leads to an upsurge in the usage of traditional medicines for its proper management. India has diverse biodiversity and a long history of using plant-based remedies. Several medicinal plant extracts have been studied for producing anti-dengue viral activity. AYUSH traditional systems provide a plethora of plants that have been reported to be useful in the treatment of fever. Single and compound plant- based formulations in natural form have been used in Unani holistic approaches. This review serves as a new approach to illustrate the most recent evidence regarding the antiviral activity of various plants by providing scientific proof and also to validate the traditional formulations as effective treatments in dengue fever for global acceptance.

Ursolic Acid Analogs as Potential Therapeutics for Cancer

Ursolic acid (UA) is a pentacyclic triterpene isolated from a large variety of vegetables, fruits and many traditional medicinal plants. It is a structural isomer of Oleanolic Acid. The medicinal application of UA has been explored extensively over the last two decades. The diverse pharmacological properties of UA include anti-inflammatory, antimicrobial, antiviral, antioxidant, anti-proliferative, etc. Especially, UA holds a promising position, potentially, as a cancer preventive and therapeutic agent due to its relatively non-toxic properties against normal cells but its antioxidant and antiproliferative activities against cancer cells. Cell culture studies have shown interference of UA with multiple pharmacological and molecular targets that play a critical role in many cells signaling pathways. Although UA is considered a privileged natural product, its clinical applications are limited due to its low absorption through the gastro-intestinal track and rapid elimination. The low bioavailability of UA limits its use as a therapeutic drug. To overcome these drawbacks and utilize the importance of the scaffold, many researchers have been engaged in designing and developing synthetic analogs of UA via structural modifications. This present review summarizes the synthetic UA analogs and their cytotoxic antiproliferative properties reported in the last two decades.

Small molecules in the treatment of COVID-19

The outbreak of COVID-19 has become a global crisis, and brought severe disruptions to societies and economies. Until now, effective therapeutics against COVID-19 are in high demand. Along with our improved understanding of the structure, function, and pathogenic process of SARS-CoV-2, many small molecules with potential anti-COVID-19 effects have been developed. So far, several antiviral strategies were explored. Besides directly inhibition of viral proteins such as RdRp and M^pro, interference of host enzymes including ACE2 and proteases, and blocking relevant immunoregulatory pathways represented by JAK/STAT, BTK, NF-κB, and NLRP3 pathways, are regarded feasible in drug development. The development of small molecules to treat COVID-19 has been achieved by several strategies, including computer-aided lead compound design and screening, natural product discovery, drug repurposing, and combination therapy. Several small molecules representative by remdesivir and paxlovid have been proved or authorized emergency use in many countries. And many candidates have entered clinical-trial stage. Nevertheless, due to the epidemiological features and variability issues of SARS-CoV-2, it is necessary to continue exploring novel strategies against COVID-19. This review discusses the current findings in the development of small molecules for COVID-19 treatment. Moreover, their detailed mechanism of action, chemical structures, and preclinical and clinical efficacies are discussed.

Cytotoxicity, acute and sub-chronic toxicities of the fruit extract of Tetrapleura tetraptera (Schumm. & Thonn.) Taub. (Fabaceae)

Background

Tetrapleura tetraptera is a medicinal spice traditionally used to treat cancer, diabetes, and several other ailments. This study analyzed the cytotoxicity of the dichloromethane methanol extract of T. tetraptera fruits (TTF) and its constituents. The toxicity profile of the TTF extract was also evaluated in rats.

Methods

The Cytotoxicity of this extract was evaluated using the resazurin reduction assay (RRA). Acute and sub-chronic toxicity studies were performed according to the protocol described by the Organisation for Economic Cooperation, and Development (OECD). Hematological, serum, and urine biochemical parameters, as well as histological sections of the liver and kidney, were also evaluated based on standard methods.

Results

The TTF extract, compound 5, and the reference drug doxorubicin were active in all 9 tested cancer cell lines. The recorded IC₅₀ ranged from 18.32 μM (against B16-F1 murine melanoma cells) to 36.18 μM (against SKMel-505 BRAF wildtype melanoma cells) for TTF, from 10.02 μM (towards MaMel-80a BRAF-V600E homozygous mutant melanoma cells) to 31.73 μM (against SKMel-28 BRAF-V600E homozygous mutant melanoma cells) for compound 5, and from 0.22 μM (against B16-F1 cells) to 9.39 μM (against SKMel-505 cells) for doxorubicin. The study of acute toxicity test showed that the lethal dose (LD₅₀) of this extract was greater than 5000 mg/kg body weight. In the sub-chronic toxicity studies, variations were observed in some biochemical parameters, especially at higher doses.

Conclusion

TTF and its most active compound (5) are found to be potential cytotoxic agents, meanwhile, TTF was safe when given a single oral dose of 5000 mg/kg. However, caution is necessary in case of prolonged oral administration due to potential alterations of renal function at high doses (> 1000 mg/kg).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03659-1.

Quercetin Inhibits Hsp70 Blocking of Bovine Viral Diarrhea Virus Infection and Replication in the Early Stage of Virus Infection

Bovine viral diarrhea virus (BVDV), a positive-strand RNA virus of the genus Pestivirus in the Flaviviridae family, is the causative agent of viral diarrheal disease in bovine. BVDV has been used as a surrogate model for the hepatitis C virus (HCV) to evaluate the efficacy of antiviral drugs. The plant flavonol quercetin causes multiple health-promoting effects in humans and animals. It can be made into a variety of additives, and it exerts a variety of immunomodulatory effects with the potential to be used as an antiviral agent. However, quercetin's antiviral effect and mechanism of action on BVDV are still unclear. Therefore, this study was designed to evaluate quercetin's effect on BVDV virus replication in vitro and in vivo and elucidate its mechanism of action. A CCK-8 kit was used to analyze the toxicity of the quercetin to the MDBK cells. Western blot, qRT-PCR, TCID₅₀, and histological analysis were used to determine the mechanism of quercetin's anti-BVDV activity. An oxidative stress kit was used to evaluate the effects of quercetin on ROS, antioxidant enzymes, and MDA indexes. The effect of quercetin on IL-2 and IFN-γ in the serum of mice was determined by using an ELISA kit. The results showed that quercetin inhibits Hsp70, blocks BVDV infection in the early stage of virus infection and inhibits BVDV replication by inhibiting oxidative stress or ERK phosphorylation. In addition, quercetin alleviated the decrease in IFN-γ and IL-2 in the serum of BVDV-infected mice. Quercetin ameliorated BVDV-induced histopathological changes. In summary, this study demonstrated for the first time the role of Hsp70 in BVDV infection and the potential application of quercetin in treating BVDV infection.

Antiviral Activity of Ficus rubiginosa Leaf Extracts against HSV-1, HCoV-229E and PV-1

Ficus rubiginosa plant extract showed antimicrobial activity, but no evidence concerning its antiviral properties was reported. The antiviral activity of the methanolic extract (MeOH) and its n-hexane (H) and ethyl acetate (EA) fractions against Herpes simplex virus-1 (HSV-1), Human coronavirus (HCoV) -229E, and Poliovirus-1 (PV-1) was investigated in the different phases of viral infection in the VERO CCL-81 cell line. To confirm the antiviral efficacy, a qPCR was conducted. The recorded cytotoxic concentration 50% was 513.1, 298.6, and 56.45 µg/mL for MeOH, H, and EA, respectively, assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay after 72 h of treatment. The Ficus rubiginosa leaf extract inhibited the replication of HSV-1 in the early stages of infection, showing a complete inhibition up to 0.62, 0.31, and 1.25 µg/mL. Against HCoV-229E, a total inhibition up to 1.25 µg/mL for MeOH and H as well as 5 µg/mL for EA was observed. Otherwise, no activity was recorded against PV-1. The leaf extract could act directly on the viral envelope, destructuring the lipid membrane and/or directly blocking the enriched proteins on the viral surface. The verified gene inhibition suggested that the treatments with M, H, and EA impaired HSV-1 and HCoV-229E replication, with a greater antiviral efficiency against HSV-1 compared to HCoV-229E, possibly due to a greater affinity of Ficus rubiginosa towards membrane glycoproteins and/or the different lipid envelopes.

Reducing Virus Infection Risk in Space Environments through Nutrient Supplementation

Space exploration has brought many challenges to human physiology. In order to evaluate and reduce possible pathological reactions triggered by space environments, we conducted bioinformatics analyses on the methylation data of the Mars 520 mission and human transcriptome data in the experiment simulating gravity changes. The results suggest that gene expression levels and DNA methylation levels were changed under the conditions of isolation and gravity changes, and multiple viral infection-related pathways were found in the enrichment analysis results of changed genes including Epstein Barr virus (EBV) infection, Hepatitis B virus (HBV) infection, Herpes simplex virus (HSV) infection and Kaposi’s sarcoma-associated herpesvirus (KHSV) infection. In this study, we found that Epigallocatechin-3-gallate (EGCG) and vitamin D are helpful in reducing viral infection risk. In addition, the causal associations between nutrients and viral infections were calculated using Two sample Mendelian Randomization (2SMR) method, the results indicated that vitamin D can reduce EBV infection and HBV infection risk. In summary, our study suggests that space environments increase the risk of human viral infection, which may be reduced by supplementing EGCG and vitamin D. These results can be used to formulate medical plans for astronauts, which have practical application value for future space exploration.

Anti-respiratory syncytial virus and anti-herpes simplex virus activity of six Tanzanian medicinal plants with extended studies of Erythrina abyssinica stem bark

ETHNOPHARMACOLOGICAL RELEVANCE

Except for few highly pathogenic viruses, no antiviral drug has been approved for treatment of viral infections in humans. Plant extracts, selected based on their ethno-medical use, represent an important source of compounds for the development of novel candidate antiviral drugs. This especially concerns plants with ethnomedical records on their use in treatment of viral infections.

AIM OF THE STUDY

To identify and document medicinal plants used by traditional health practitioners (THPs) for treatment of respiratory infections and muco-cutaneous lesions in order to study their antiviral activity including identification of active components and elucidation of mode of antiviral activity.

MATERIALS AND METHODS

The ethno-medical survey was performed in the Kagera region of Tanzania. The THPs were asked for plants used for treatment of signs and symptoms of respiratory infections and watery muco-cutaneous blisters in oral and genital regions. The plants identified were successively extracted with n-hexane, ethyl acetate and water, and the extracts assayed for anti-respiratory syncytial virus (RSV), anti-herpes simplex virus 2 (HSV-2), and anti-human parainfluenza virus 2 (HPIV-2) activity in cultured cells. Antiviral components were separated by ethanol precipitation and CL-6B chromatography, and the mode of antiviral activity elucidated by the time-of-addition assay and selection for the virus variants resistant to antiviral plant extract.

RESULTS

THPs identified fifteen plants used for treatment of respiratory infections and muco-cutaneous blisters. The water extract, but not n-hexane or ethyl acetate extracts, of six of these plants including Erythrina abyssinica stem bark, inhibited infectivity of two glycosaminoglycan-binding viruses i.e., RSV and HSV-2 but not the sialic acid binding HPIV-2. An activity-guided separation revealed that antiviral component(s) of water extract of E. abyssinica could be precipitated with ethanol. This sample potently and selectively inhibited RSV and HSV-2 infectivity in cultured cells with IC50 values of 2.1 μg/ml (selectivity index >476) and 0.14 μg/ml (selectivity index >7143) respectively. The sample exhibited inhibitory effect on the virus attachment to and entry into the cells by directly targeting the viral particles. Indeed, 10 consecutive virus passages in HEp-2 cells in the presence of this extract selected for a resistant RSV variant lacking the attachment, viral membrane-associated, G protein due to a stop codon at amino acid residue 33 (Leu33stop). Fractionation of the E. abyssinica extract on a CL-6B column revealed that anti-RSV and HSV-2 activity correlated with carbohydrate content. The most pronounced antiviral activity was associated with a carbohydrate containing ingredient of molecular mass of <5 kDa, which may polymerize to antiviral composites of up to 410 kDa.

CONCLUSIONS

Altogether, the water extract of six medicinal plants showed anti-RSV and anti-HSV-2 activities. Extended studies of the stem bark of E. abyssinica identified antiviral components that potently and selectively inhibited infectivity of free RSV and HSV-2 particles, a feature of importance in topical treatment of these infections. This observation confirms ethno-medical information concerning the use of E. abyssinica extract for treatment of respiratory infections and herpetic lesions.

A Comprehensive Update on the Bioactive Compounds from Seagrasses

Marine angiosperms produce a wide variety of secondary metabolites with unique structural features that have the potential to be developed as effective and potent drugs for various diseases. Recently, research trends in secondary metabolites have led to drug discovery with an emphasis on their pharmacological activity. Among marine angiosperms, seagrasses have been utilized for a variety of remedial purposes, such as treating fevers, mental disorders, wounds, skin diseases, muscle pain, and stomach problems. Hence, it is essential to study their bioactive metabolites, medical properties, and underlying mechanisms when considering their pharmacological activity. However, there is a scarcity of studies on the compilation of existing work on their pharmacological uses, pharmacological pathways, and bioactive compounds. This review aims to compile the pharmacological activities of numerous seagrass species, their secondary metabolites, pharmacological properties, and mechanism of action. In conclusion, this review highlights the potency of seagrasses as a promising source of natural therapeutical products for preventing or inhibiting human diseases.

Medicinal Herbs in the Relief of Neurological, Cardiovascular, and Respiratory Symptoms after COVID-19 Infection A Literature Review

COVID-19 infection causes complications, even in people who have had a mild course of the disease. The most dangerous seem to be neurological ailments: anxiety, depression, mixed anxiety–depressive (MAD) syndromes, and irreversible dementia. These conditions can negatively affect the respiratory system, circulatory system, and heart functioning. We believe that phytotherapy can be helpful in all of these conditions. Clinical trials confirm this possibility. The work presents plant materials (Valeriana officinalis, Melissa officinalis, Passiflora incarnata, Piper methysticum, Humulus lupulus, Ballota nigra, Hypericum perforatum, Rhodiola rosea, Lavandula officinalis, Paullinia cupana, Ginkgo biloba, Murraya koenigii, Crataegus monogyna and oxyacantha, Hedera helix, Polygala senega, Pelargonium sidoides, Lichen islandicus, Plantago lanceolata) and their dominant compounds (valeranon, valtrate, apigenin, citronellal, isovitexin, isoorientin, methysticin, humulone, farnesene, acteoside, hypericin, hyperforin, biapigenin, rosavidin, salidroside, linalool acetate, linalool, caffeine, ginkgolide, bilobalide, mihanimbine, epicatechin, hederacoside C,α-hederine, presegenin, umckalin, 6,7,8-trixydroxybenzopyranone disulfate, fumaroprotocetric acid, protolichesteric acid, aucubin, acteoside) responsible for their activity. It also shows the possibility of reducing post-COVID-19 neurological, respiratory, and cardiovascular complications, which can affect the functioning of the nervous system.

Medicinal plant sources and traditional healthcare practices of forest-dependent communities in and around Chunati Wildlife Sanctuary in southeastern Bangladesh

Bangladesh's forest-dependent people rely on medicinal plants for traditional healthcare practices, as plant-based medicines are easily available and cost-effective. This study evaluated and documented ethnomedicinal practices for, and traditional knowledge of, utilising plants to cure ailments. Ethnobotanical indices quantified the use value (UV), frequency of citation, relative frequency of citation (RFC) and the informant consensus factor. Using a semi-structured questionnaire, the study interviewed 231 respondents from 18 villages in and around Chunati Wildlife Sanctuary (CWS). The study documented 134 medicinal plant species from 60 families; tree species were dominant (37.31%). Malvaceae (seven species), Rutaceae and Lamiaceae (six species each) families covered more species. Nearly half of the species (46.02%) were collected from CWS. Both above-ground and below-ground plant parts treated 71 types of ailments under 21 categories, with leaves (66 species) being the most widely used plant part. In total 33 species were used to treat dysentery, 25 species each for fever and jaundice, and 24 species for cuts and wounds. The average UV value was 0.24 and RFC value was 0.47%. Communities were found to utilise medicinal plants more at home than to sell at markets, substantially relying on medicinal plants to meet their domestic needs. Plants used for healthcare and cultural and religious beliefs have a strong connection that plays a vital role in plant conservation. This study identified 42 medicinal plant species that could be considered to treat COVID-19 patients in Bangladesh. The findings suggest that community awareness of sustainable harvesting and commercial cultivation could lead to conservation and use of these invaluable plant species for healthcare, new drugs discovery and sustainable forest management.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42398-022-00230-z.

Computational Study of the Phytochemical Constituents from Uncaria tomentosa Stem Bark against SARS-CoV-2 Omicron Spike Protein

The SARS-CoV-2 Omicron variant has spread rapidly and is considered the predominant variant in the world, and its main characteristic is related to evade immunity from natural infection or vaccines, due to its multiple mutations in the spike protein. On the other hand, medicinal plants have been used as alternatives therapies to ameliorate some signs and symptoms in COVID-19, and in our previous work, the cat’s claw (Uncaria tomentosa) stem bark has been studied in vitro and showed antiviral activity on SARS-CoV-2 as well as in silico studies on the 3CLpro protein and as disruptor between the ACE-2 human receptor and the spike protein. The aim in this computational study was to determine the main phytochemical constituents from U. tomentosa stem bark against the SARS-CoV-2 Omicron spike protein based on molecular modeling. A molecular docking was carried out on the isolated phytochemicals in a previous work against the SARS-CoV-2 Omicron spike protein-binding domain (PDB ID: 7T9K). Next, a molecular dynamic study was carried out to monitor the stability during the MD simulations. As results proanthocyanidin-C1 (-10.76 kcal/mol), quinovic acid-type 2 (-9.86 kcal/mol), and proanthocyanidin-B2 (-9.82 kcal/mol) were the constituents with the best binding free energy on the SARS-CoV-2 Omicron spike protein, and the best compound was stable during the dynamic simulation under physiological conditions. It is concluded that the anthocyanidin-based compounds determined in the stem bark ethanol extract could be responsible for the potential antiviral activity on SARS-CoV-2 Omicron variant, and the proanthocyanidin-C1 emerged as a powerful candidate to combat new variants.

A Review on Mechanistic Insight of Plant Derived Anticancer Bioactive Phytocompounds and Their Structure Activity Relationship

Cancer is a disorder that rigorously affects the human population worldwide. There is a steady demand for new remedies to both treat and prevent this life-threatening sickness due to toxicities, drug resistance and therapeutic failures in current conventional therapies. Researchers around the world are drawing their attention towards compounds of natural origin. For decades, human beings have been using the flora of the world as a source of cancer chemotherapeutic agents. Currently, clinically approved anticancer compounds are vincristine, vinblastine, taxanes, and podophyllotoxin, all of which come from natural sources. With the triumph of these compounds that have been developed into staple drug products for most cancer therapies, new technologies are now appearing to search for novel biomolecules with anticancer activities. Ellipticine, camptothecin, combretastatin, curcumin, homoharringtonine and others are plant derived bioactive phytocompounds with potential anticancer properties. Researchers have improved the field further through the use of advanced analytical chemistry and computational tools of analysis. The investigation of new strategies for administration such as nanotechnology may enable the development of the phytocompounds as drug products. These technologies have enhanced the anticancer potential of plant-derived drugs with the aim of site-directed drug delivery, enhanced bioavailability, and reduced toxicity. This review discusses mechanistic insights into anticancer compounds of natural origins and their structural activity relationships that make them targets for anticancer treatments.

Secondary plant metabolites as potent drug candidates against antimicrobial-resistant pathogens

Antibiotic resistance is a major public health threat of the twenty-first century and represents an important risk to the global economy. Healthcare-associated infections mainly caused by drug-resistant bacteria are wreaking havoc in patient care worldwide. The spread of such pathogens limits the utility of available drugs and complicates the treatment of bacterial diseases. As a result, there is an urgent need for new drugs with mechanisms of action capable of curbing resistance. Plants synthesize and utilize various metabolic compounds to deter pathogens and predators. Utilizing these plant-based metabolites is a promising option in identifying novel bioactive compounds that could be harnessed to develop new potent antimicrobial drugs to treat multidrug-resistant pathogens. The purpose of this review is to highlight medicinal plants as important sources of novel antimicrobial agents that could be developed to help combat antimicrobial resistance.