Anti-TMV activity and mode of action of three alkaloids isolated from Chelidonium majus

The effect and mechanism of sanguinarine against PCV2 based on the analysis of network pharmacology and TMT quantitative proteomics

Porcine circovirus type 2 (PCV2) is highly prevalent in nature and serves as the primary pathogen responsible for porcine circovirus-associated disease (PCVD/PCVAD), posing a significant threat to pig production. Currently, vaccination alone could not provide the complete protection for PCV2 infection. The active ingredients of traditional Chinese medicine have shown a positive effect in combating viral infections. This study employed tandem mass tag (TMT) labeled proteomic analyses and network pharmacology to examine the effect and mechanism of sanguinarine against PCV2. IFIH1, IFITM1, p38α, and JNK were identified as the key targets of sanguinarine against PCV2 based on proteomics and network pharmacology. Using PCV2-infected PK-15 cells, it was discovered that sanguinarine inhibited the expression of the PCV2 CAP gene by upregulating IFIH1, thereby promoting STAT1 phosphorylation and activating MAVS expression. This, in turn, facilitated IRF3 phosphorylation, leading to increase IFITM1 expression. Simultaneously, sanguinarine suppressed the expression of the PCV2 CAP gene by inhibiting the expression of p38α, JNK, and p-JNK protein. In conclusion, the results of this study suggest that sanguinarine exerts anti-PCV2 effects through different targets and pathways, which lays the foundation for the subsequent development of new anti-PCV2 veterinary drugs.

Chemical and Biological Investigations of Antiviral Agents Against Plant Viruses Conducted in China in the 21st Century

Research into the biology of plant viruses, their mechanisms of pathogenicity, and the induction of host resistance has laid a solid foundation for the discovery of antiviral agents and their targets and the development of effective control technologies. Additionally, recent advancements in fields such as chemical biology, cheminformatics, bioinformatics, and synthetic biology have provided valuable methods and tools for the design of antiviral drugs, the synthesis of drug molecules, assessment of their activity, and investigation of their modes of action. Compared with drug development for human viral diseases, the control of plant viral diseases presents greater challenges, including the cost-benefit of agents, simplification of control technologies, and the effectiveness of treatments. Therefore, in the current context of complex outbreaks and severe damage caused by plant viral diseases, it is crucial to delve deeper into the research and development of antiviral agents. This review provides a detailed overview of the biological characteristics of current targets for antiviral agents, the mode of interaction between plant virus targets and antivirals, and insights for future drug development. We believe this review will not only facilitate the in-depth analysis of the development of antivirals for crops but also offer valuable perspectives for the development of antiviral agents for use in human and veterinary medicine.

Discovery of New 1,2,4-Triazole/1,3,4-Oxadiazole-Decorated Quinolinones as Agrochemical Alternatives for Controlling Viral Infection by Inhibiting the Viral Replication and Self-Assembly Process

Tobacco mosaic virus (TMV), a representative plant virus, is widely known and causes severe crop losses worldwide. In order to ensure the demand for crop and food security, the exploration of novel antiviral agents with outstanding activity and unique mechanisms of action is necessary. Herein, 40 new azole-quinolinone molecules were elaborately designed and systematically evaluated for their anti-TMV activity. Notably, compound A21 had significant therapeutic activity against TMV (EC50 value = 200 μg/mL), which was superior to commercial ningnanmycin (280 μg/mL). Studies on the anti-TMV mechanism showed that compound A21 could suppress the expression level of important TMV genes and affect the assembly of TMV viral particles by disrupting the self-assembly process of TMV coat protein (TMV-CP). In-depth antiviral behaviors were verified by molecular docking, fluorescence titration analysis, and TMV assembly assays, suggesting that compound A21 strongly interacted with TMV coat protein through various interactions. Overall, this promising work discloses a new paradigm for the exploitation of 2-quinolinone-based virucidal agents for hindering plant viral infection through triggering versatile antiviral behavior.

New chalcone derivatives containing morpholine-thiadiazole: Design, synthesis and evaluation of against tobacco mosaic virus

Twenty chalcone derivatives containing morpholine-thiadiazole were designed and synthesized from the natural product chalcone. The bioactivity test results indicate that some compounds exhibit good antiviral activity against tobacco mosaic virus (TMV). In particular, the EC50 values for the curative and protective activity of S14 against TMV were 91.8 and 130.6 μg/mL, which was better than that of the antiviral agent ningnanmycin (NNM, 237.8, 220.6 μg/mL). The results of preliminary mechanism study indicated that S14 had strong binding capacity and affinity to tobacco mosaic virus coat protein (TMV-CP). In the chlorophyll content assay, the chlorophyll content of tobacco leaves increased significantly after the action of S14, so that it can enhance the photosynthetic capacity of plants. In addition, the results of malondialdehyde (MDA) content assay also indicated that S14 could improve the disease resistance of tobacco.

Enhancing Wound Healing: A Comprehensive Review of Sericin and Chelidonium majus L. as Potential Dressings

Wound healing, a complex physiological process orchestrating intricate cellular and molecular events, seeks to restore tissue integrity. The burgeoning interest in leveraging the therapeutic potential of natural substances for advanced wound dressings is a recent phenomenon. Notably, Sericin, a silk-derived protein, and Chelidonium majus L. (C. majus), a botanical agent, have emerged as compelling candidates, providing a unique combination of natural elements that may revolutionize conventional wound care approaches. Sericin, renowned for its diverse properties, displays unique properties that accelerate the wound healing process. Simultaneously, C. majus, with its diverse pharmacological compounds, shows promise in reducing inflammation and promoting tissue regeneration. As the demand for innovative wound care solutions increases, understanding the therapeutic potential of natural products becomes imperative. This review synthesizes current knowledge on Sericin and C. majus, envisioning their future roles in advancing wound management strategies. The exploration of these natural substances as constituents of wound dressings provides a promising avenue for developing sustainable, effective, and biocompatible materials that could significantly impact the field of wound healing.

Alkaloids in Chelidonium majus L: a review of its phytochemistry, pharmacology and toxicology

Chelidonium majus L. (C. majus), commonly known as "Bai Qu Cai" in China, belongs to the genus Chelidonium of the Papaveraceae family. It has rich medicinal value, such as alleviating coughs, asthma, spasms and pain. Recent studies have demonstrated that C. majus is abundant in various alkaloids, which are the primary components of C. majus and have a range of pharmacological effects, including anti-microbial, anti-inflammatory, anti-viral, and anti-tumor effects. So far, 94 alkaloids have been isolated from C. majus, including benzophenanthridine, protoberberine, aporphine, protopine and other types of alkaloids. This paper aims to review the research progress in phytochemistry, pharmacology and toxicology of C. majus alkaloids, in order to provide a theoretical basis for the application of C. majus in the field of medicinal chemistry and to afford reference for further research and development efforts.

Identification of natural Rutaecarpine as a potent tobacco mosaic virus (TMV) helicase candidate for managing intractable plant viral diseases

BACKGROUND

Naturally occurring alkaloids are particularly suitable for use as pesticide precursors and further modifications due to their cost-effectiveness, unique mechanism of action, tolerable degradation, and environmental friendliness. The famous tobacco mosaic virus (TMV) is a persistent plant pathogenic virus that can parasitize many plants and severely reduce crop production. To treat TMV disease, TMV helicase acts as a crucial target by hydrolyzing adenosine triphosphate (ATP) to provide energy for double-stranded RNA unwinding.

RESULTS

To seek novel framework alkaloid leads targeting TMV helicase, this work successfully established an efficient screening platform for TMV helicase inhibitors based on natural alkaloids. In vivo activity screening, enzyme activity detection, and binding assays showed that Rutaecarpine from Evodia rutaecarpa (Juss.) Benth exhibited excellent TMV helicase inhibitory properties [dissociation constant (Kd ) = 1.1 μm, half maximal inhibitory concentration (IC50 ) = 227.24 μm] and excellent anti-TMV ability. Molecular docking and dynamic simulations depicted that Rutaecarpine could stably bind in active pockets of helicase with low binding energy (ΔGbind  = -17.8 kcal/mol) driven by hydrogen bonding and hydrophobic interactions.

CONCLUSION

Given Rutaecarpine's laudable bioactivity and structural modifiability, it can serve as a privileged building block for further pesticide discovery.

The Chemical Ecology of Plant Natural Products

Plants are excellent chemists with an impressive capability of biosynthesizing a large variety of natural products (also known as secondary or specialized metabolites) to resist various biotic and abiotic stresses. In this chapter, 989 plant natural products and their ecological functions in plant-herbivore, plant-microorganism, and plant-plant interactions are reviewed. These compounds include terpenoids, phenols, alkaloids, and other structural types. Terpenoids usually provide direct or indirect defense functions for plants, while phenolic compounds play important roles in regulating the interactions between plants and other organisms. Alkaloids are frequently toxic to herbivores and microorganisms, and can therefore also provide defense functions. The information presented should provide the basis for in-depth research of these plant natural products and their natural functions, and also for their further development and utilization.

Discovery of novel phenothiazine derivatives as new agrochemical alternatives for treating plant viral diseases

BACKGROUND

Plant viral diseases, namely 'plant cancer', are extremely difficult to control. Even worse, few antiviral agents can effectively control and totally block viral infection. There is an urgent need to explore and discover novel agrochemicals with high activity and a unique mode of action to manage these refractory diseases.

RESULTS

Forty-one new phenothiazine derivatives were prepared and their inhibitory activity against tobacco mosaic virus (TMV) was assessed. Compound A8 had the highest protective activity against TMV, with a half-maximal effective concentration (EC50 ) of 115.67 μg/mL, which was significantly better than that of the positive controls ningnanmycin (271.28 μg/mL) and ribavirin (557.47 μg/mL). Biochemical assays demonstrated that compound A8 could inhibit TMV replication by disrupting TMV self-assembly, but also enabled the tobacco plant to enhance its defense potency by increasing the activities of various defense enzymes.

CONCLUSION

In this study, novel phenothiazine derivatives were elaborately fabricated and showed remarkable anti-TMV behavior that possessed the dual-action mechanisms of inhibiting TMV assembly and invoking the defense responses of tobacco plants. Moreover, new agrochemical alternatives based on phenothiazine were assessed for their antiviral activities and showed extended agricultural application. © 2023 Society of Chemical Industry.

Insights into a class of natural eugenol and its optimized derivatives as potential tobacco mosaic virus helicase inhibitors by structure-based virtual screening

Plant diseases caused by malignant and refractory phytopathogenic viruses have considerably restricted crop yields and quality. To date, drug design targeting functional proteins or enzymes of viruses is an efficient and viable strategy to guide the development of new pesticides. Herein, a series of novel eugenol derivatives targeting the tobacco mosaic virus (TMV) helicase have been designed using structure-based virtual screening (SBVS). Structure-activity relationship indicated that 2 t displayed the most powerful bonding capability (Kd = 0.2 μM) along with brilliant TMV helicase ATPase inhibitory potency (IC50 = 141.9 μM) and applausive anti-TMV capability (EC50 = 315.7 μg/mL), ostentatiously outperforming that of commercial Acyclovir (Kd = 23.0 μM, IC50 = 183.7 μM) and Ribavirin (EC50 = 624.3 μg/mL). Molecular dynamics simulations and docking suggested ligand 2 t was stable and bound in the active pocket of the TMV helicase by multiple interactions. Given these superior properties, eugenol-based derivatives could be considered as the novel potential plant viral helicase inhibitors. Furthermore, this effective and feasible SBVS strategy established a valuable screening platform for helicase-targeted drug development.

Indispensable Biomolecules for Plant Defense Against Pathogens: NBS-LRR and "nitrogen pool" Alkaloids

In a complex natural environment, plants have evolved intricate and subtle defense response regulatory mechanisms for survival. Plant specific defenses, including the disease resistance protein nucleotide-binding site leucine-rich repeat (NBS-LRR) protein and metabolite derived alkaloids, are key components of these complex mechanisms. The NBS-LRR protein can specifically recognize the invasion of pathogenic microorganisms to trigger the immune response mechanism. Alkaloids, synthesized from amino acids or their derivatives, can also inhibit pathogens. This study reviews NBS-LRR protein activation, recognition, and downstream signal transduction in plant protection, as well as the synthetic signaling pathways and regulatory defense mechanisms associated with alkaloids. In addition, we clarify the basic regulation mechanism and summarize their current applications and the development of future applications in biotechnology for these plant defense molecules. Studies on the NBS-LRR protein and alkaloid plant disease resistance molecules may provide a theoretical foundation for the cultivation of disease resistant crops and the development of botanical pesticides.

Sanguinarine Exhibits Antiviral Activity against Porcine Reproductive and Respiratory Syndrome Virus via Multisite Inhibition Mechanisms

Porcine reproductive and respiratory syndrome virus (PRRSV), the etiological agent of PRRS, is prevalent worldwide, causing substantial and immense economic losses to the global swine industry. While current commercial vaccines fail to efficiently control PRRS, the development of safe and effective antiviral drugs against PRRSV is urgently required. Alkaloids are natural products with wide pharmacological and biological activities. Herein, sanguinarine, a benzophenanthridine alkaloid that occurs in many plants such as Macleaya cordata, was demonstrated as a potent antagonist of PRRSV. Sanguinarine attenuated PRRSV proliferation by targeting the internalization, replication, and release stages of the viral life cycle. Furthermore, ALB, AR, MAPK8, MAPK14, IGF1, GSK3B, PTGS2, and NOS2 were found as potential key targets related to the anti-PRRSV effect of sanguinarine as revealed by network pharmacology and molecular docking. Significantly, we demonstrated that the combination of sanguinarine with chelerythrine, another key bioactive alkaloid derived from Macleaya cordata, improved the antiviral activity. In summary, our findings reveal the promising potential of sanguinarine as a novel candidate for the development of anti-PRRSV agents.

Computational investigation of phytoalexins as potential antiviral RAP-1 and RAP-2 (Replication Associated Proteins) inhibitor for the management of cucumber mosaic virus (CMV): a molecular modeling, in silico docking and MM-GBSA study

The Replication Associated Proteins (RAP-1 and RAP-2) encoded by CMV ORF 1a and ORF 2a are required for the different stages of the viral replication cycle; being multi-functional, they are good inhibitory targets for anti-CMV compounds. As a new perspective for sustainable crop improvement, we investigated the natural plant-based antimicrobial phytoalexins for their anti-CMV potential. Here, we modeled and predicted the functional domains of RAP-1 and RAP-2, docked with a ligand library comprising 128 phytoalexins reported with broad-spectrum activity, determined their binding energies (BEs), molecular interactions, and inhibition constant (Ki), and compared with the reference plant antiviral compounds ribavirin, ningnanmycin, and benzothiadiazole (BTH). Further, the change in Gibb's free energy of binding (ΔG) and the per residue contribution of the selected top-scored ligand molecules was assessed by the prime MM-GBSA approach. Our results revealed RAP-1 as a discontinuous two-domain and RAP-2 as a multi-domain protein. The compounds glyceollidin (9.8 kcal/mol) and moracin D (7.8 kcal/mol) topped the list for RAP-1 and RAP-2 protein targets respectively and also, the lead molecules had energetically more favorable and comparative ΔG values than the top-scored plant antiviral agent ningnanmycin. The evaluation of in vitro toxicity and agrochemical-like properties showed the least toxicity of these anti-CMV compounds. Taken together, our results provide new insights in understanding the inhibitory effects of phytoalexins towards the RAP proteins and could be employed as new promising anti-CMV candidate compounds for their application in agriculture as biopesticides to combat the CMV disease incidence.Communicated by Ramaswamy H. Sarma.

Mining Therapeutic Efficacy from Treasure Chest of Biodiversity and Chemodiversity: Pharmacophylogeny of Ranunculales Medicinal Plants

Ranunculales, comprising of 7 families that are rich in medicinal species frequently utilized by traditional medicine and ethnomedicine, represents a treasure chest of biodiversity and chemodiversity. The phylogenetically related species often have similar chemical profile, which makes them often possess similar therapeutic spectrum. This has been validated by both ethnomedicinal experiences and pharmacological investigations. This paper summarizes molecular phylogeny, chemical constituents, and therapeutic applications of Ranunculales, i.e., a pharmacophylogeny study of this representative medicinal order. The phytochemistry/metabolome, ethnomedicine and bioactivity/pharmacology data are incorporated within the phylogenetic framework of Ranunculales. The most studied compounds of this order include benzylisoquinoline alkaloid, flavonoid, terpenoid, saponin and lignan, etc. Bisbenzylisoquinoline alkaloids are especially abundant in Berberidaceae and Menispermaceae. The most frequent ethnomedicinal uses are arthritis, heat-clearing and detoxification, carbuncle-abscess and sore-toxin. The most studied bioactivities are anticancer/cytotoxic, antimicrobial, and anti-inflammatory activities, etc. The pharmacophylogeny analysis, integrated with both traditional and modern medicinal uses, agrees with the molecular phylogeny based on chloroplast and nuclear DNA sequences, in which Ranunculales is divided into Ranunculaceae, Berberidaceae, Menispermaceae, Lardizabalaceae, Circaeasteraceae, Papaveraceae, and Eupteleaceae families. Chemical constituents and therapeutic efficacy of each taxonomic group are reviewed and the underlying connection between phylogeny, chemodiversity and clinical uses is revealed, which facilitate the conservation and sustainable utilization of Ranunculales pharmaceutical resources, as well as developing novel plant-based pharmacotherapy.

Fluorescence, Absorption, Chromatography and Structural Transformation of Chelerythrine and Ethoxychelerythrine in Protic Solvents: A Comparative Study

Chelerythrine (CH) and ethoxychelerythrine (ECH) are chemical reference substances for quality control of Chinese herbal medicines, and ECH is the dihydrogen derivative of CH. In this study, their fluorescence and absorption spectra, as well as their structural changes in different protic solvents were compared. It was observed that their emission fluorescence spectra in methanol were almost the same (both emitted at 400 nm), which may be attributed to the nucleophilic and exchange reactions of CH and ECH with methanol molecules with the common product of 6-methoxy-5,6-dihydrochelerythrine (MCH). When diluted with water, MCH was converted into CH, which mainly existed in the form of positively charged CH⁺ under acidic and near-neutral conditions with the fluorescence emission at 550 nm. With the increase of pH value of the aqueous solution, CH⁺ converted to 6-hydroxy-5,6-dihydrochelerythrine (CHOH) with the fluorescence emission at 410 nm. The fluorescence quantum yields of MCH and CHOH were 0.13 and 0.15, respectively, and both the fluorescence intensities were much stronger than that of CH⁺. It is concluded that CH and ECH can substitute each other in the same protic solvent, which was further verified by high-performance liquid chromatography. This study will help in the investigation of structural changes of benzophenanthridine alkaloids and will provide the possibility for the mutual substitution of standard substances in relevant drug testing.

Recent Research Progress: Discovery of Anti-Plant Virus Agents Based on Natural Scaffold

Plant virus diseases, also known as “plant cancers”, cause serious harm to the agriculture of the world and huge economic losses every year. Antiviral agents are one of the most effective ways to control plant virus diseases. Ningnanmycin is currently the most successful anti-plant virus agent, but its field control effect is not ideal due to its instability. In recent years, great progress has been made in the research and development of antiviral agents, the mainstream research direction is to obtain antiviral agents or lead compounds based on structural modification of natural products. However, no antiviral agent has been able to completely inhibit plant viruses. Therefore, the development of highly effective antiviral agents still faces enormous challenges. Therefore, we reviewed the recent research progress of anti-plant virus agents based on natural products in the past decade, and discussed their structure-activity relationship (SAR) and mechanism of action. It is hoped that this review can provide new inspiration for the discovery and mechanism of action of novel antiviral agents.

Ferulic acid derivatives with piperazine moiety as potential antiviral agents

BACKGROUND

Plant virus diseases are difficult to control and severely threaten the productivity of crops, which leads to huge financial losses. To discover the new antiviral drugs, 34 novel ferulic acid derivatives with piperazine moiety were synthesized, and the antiviral activities were systematically screened as well.

RESULTS

Bioassay results indicated that most of the target compounds had outstanding antiviral activities against tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV) in vivo. In particular, compound E2 exhibited remarkable curative activities to TMV and CMV with EC₅₀ values of 189.0 and 401.7 μg/mL compared to those for ningnanmycin (387.0, 519.3 μg/mL) and ribavirin (542.1, 721.5 μg/mL). And then the mechanisms of compound E2 were studied by chlorophyll content, differentially expressed proteins and genes tests.

CONCLUSION

The excellent antiviral activity of compound E2 was closely associated with the increase in host photosynthesis, which was confirmed by chlorophyll content, differentially expressed proteins and genes assays. Compound E2 can be considered as a lead structure for the discovery of new antiviral agents. © 2022 Society of Chemical Industry.

In Silico Pesticide Discovery for New Anti-Tobacco Mosaic Virus Agents: Reactivity, Molecular Docking, and Molecular Dynamics Simulations

Considerable data are available regarding the molecular genetics of the tobacco mosaic virus. The disease caused by the tobacco mosaic virus is still out of control due to the lack of an efficient functional antagonist chemical molecule. Extensive research was carried out to try to find effective new anti-tobacco mosaic virus agents, however no study could find an effective agent which could completely inhibit the disease caused by the virus. In recent years, molecular docking, combined with molecular dynamics, which is considered to be one of the most important methods of drug discovery and design, were used to evaluate the type of binding between the ligand and its protein enzyme. The aim of the current work was to assess the in silico anti-tobacco mosaic virus activity for a selection of 41 new and 2 reference standard compounds. These compounds were chosen to examine their reactivity and binding efficiency with the tobacco mosaic virus coat protein (PDB ID: 2OM3). A comparison was made between the activity of the selected compounds and that for ningnanmycin and ribavirin, which are common inhibitors of plant viruses. The simulation results obtained from the molecular docking and molecular dynamics showed that two compounds of the antofine analogues could bind with the tobacco mosaic virus coat protein receptor better than ningnanmycin and ribavirin.

Scopolia mild mottle virus: a new tobamovirus isolated from a Scopolia japonica plant in Japan

A tobamovirus was isolated from leaves of a Scopolia japonica plant showing mild yellowing. Back-inoculation of healthy Scopolia japonica with the isolated virus induced mild mottle on upper leaves. Phylogenetic analysis based on coat protein and replicase protein sequences revealed that the newly isolated tobamovirus was most closely related to yellow tailflower mild mottle virus (YTMMV). The newly isolated tobamovirus shared the highest nucleotide sequence identity (71%) with YTMMV, which is lower than the cutoff (90%) set for species demarcation in the genus Tobamovirus. Thus, our result suggested that scopolia mild mottle virus (SMMoV) is a new tobamovirus that infects Scopolia japonica plants in Japan.

Autoxidation Products of the Methanolic Extract of the Leaves of Combretum micranthum Exert Antiviral Activity against Tomato Brown Rugose Fruit Virus (ToBRFV)

Tomato brown rugose fruit virus (ToBRFV) is a new damaging plant virus of great interest from both an economical and research point of view. ToBRFV is transmitted by contact, remains infective for months, and to-date, no resistant cultivars have been developed. Due to the relevance of this virus, new effective, sustainable, and operator-safe antiviral agents are needed. Thus, 4-hydroxybenzoic acid was identified as the main product of the alkaline autoxidation at high temperature of the methanolic extract of the leaves of C. micranthum, known for antiviral activity. The autoxidized extract and 4-hydroxybenzoic acid were assayed in in vitro experiments, in combination with a mechanical inoculation test of tomato plants. Catechinic acid, a common product of rearrangement of catechins in hot alkaline solution, was also tested. Degradation of the viral particles, evidenced by the absence of detectable ToBRFV RNA and the loss of virus infectivity, as a possible consequence of disassembly of the virus coat protein (CP), were shown. Homology modeling was then applied to prepare the protein model of ToBRFV CP, and its structure was optimized. Molecular docking simulation showed the interactions of the two compounds, with the amino acid residues responsible for CP-CP interactions. Catechinic acid showed the best binding energy value in comparison with ribavirin, an anti-tobamovirus agent.

Identification of anti-TMV active flavonoid glycosides and their mode of action on virus particles from Clematis lasiandra Maxim

BACKGROUND

Tobacco mosaic virus (TMV) is a disreputable plant pathogen that causes a decline in the quality and yield of various economic crops. Natural products are important potential sources of biopesticides to control TMV. This study focuses on the discovery of anti-TMV active flavonoid glycosides and their mode of action on TMV particles from Clematis lasiandra Maxim.

RESULTS

A new benzoyl acylated flavonoid glycoside, kaempferol 3-O-(2''-benzoyl)-β-d-glucopyranosyl-7-O-α-l-rhamnopyranoside (1), and nine known flavonoids (2-10) were identified first from C. lasiandra. The hydroxyl group at C-7, E-p-coumarate at C-6'' in the Glc of C-6, and the glucuronic acid at C-3 were functional groups for the antiviral flavonoid glycosides. Flavonoids 2, 5, and 6 showed higher inactivation efficacies of 64.62% to 82.54% compared with ningnanmycin at 500 μg ml^-1 . The protective and curative efficacies for 2 and 5 were 57.44-59.00% and 41.17-43.92% at 500 μg ml^-1 , respectively. Compound 5 showed higher TMV systemic resistance with control efficacies of 41.64%, 36.56% and 27.62% at concentrations of 500, 250 and 125 μg ml^-1 compared with ningnanmycin in K326 tobaccos, respectively. Compound 5 can directly fracture TMV particles into small fragments combining with the fusion phenomena, and TMV-CP was an important target for 5 to break TMV particles.

CONCLUSION

Flavonoid glycosides from C. lasiandra showed potent antiviral activities against TMV with multiple modes of action including inactivation, protective and curative effects, and inducing systemic resistance. TMV-CP was an important target for active flavonoid glycosides to fracture TMV particles. The results provided evidence that flavonoid glycosides from C. lasiandra have the potential to control TMV.

Therapeutic potential of chelerythrine as a multi-purpose adjuvant for the treatment of COVID-19

Multifunctional nature of phytochemicals and their chemical diversity has attracted attention to develop leads originated from nature to fight COVID-19. Pharmacological activities of chelerythrine and its congeners have been studied and reported in the literature. This compound simultaneously has two key therapeutic effects for the treatment of COVID-19, antiviral and anti-inflammatory activities. Chelerythrine can prevent hyper-inflammatory immune response through regulating critical signaling pathways involved in SARS-CoV-2 infection, such as alteration in Nrf2, NF-κB, and p38 MAPK activities. In addition, chelerythrine has a strong protein kinase C-α/-β inhibitory activity suitable for cerebral vasospasm prevention and eryptosis reduction, as well as beneficial effects in suppressing pulmonary inflammation and fibrosis. In terms of antiviral activity, chelerythrine can fight with SARS-CoV-2 through various mechanisms, such as direct-acting mechanism, viral RNA-intercalation, and regulation of host-based antiviral targets. Although chelerythrine is toxic in vitro, the in vivo toxicity is significantly reduced due to its structural conversion to alkanolamine. Its multifunctional action makes chelerythrine a prominent compound for the treatment of COVID-19. Considering precautions related to the toxicity at higher doses, it is expected that this compound is useful in combination with proper antivirals to reduce the severity of COVID-19 symptoms.