Synthesis of arctigenin derivatives against infectious hematopoietic necrosis virus

A systematic review on botany, ethnopharmacology, quality control, phytochemistry, pharmacology and toxicity of Arctium lappa L. fruit

ETHNOPHARMACOLOGICAL RELEVANCE

Arctium lappa L., is a biennial plant that grows around the Eurasia. Many parts of Arctium lappa L. (roots, leaves and fruits, etc.) are medically used in different countries. Arctium lappa L. fruit, also called Arctii Fructus, is traditionally applied to dispel wind-heat, ventilate lung to promote eruption, remove toxicity substance and relieve sore throat.

THE AIM OF THE REVIEW

The review aims to integrate the botany, ethnopharmacology, quality control, phytochemistry, pharmacology, derivatives and toxicity information of Arctii Fructus, so as to facilitate future research and explore the potential of Arctii Fructus as an agent for treating diseases.

MATERIALS AND METHODS

Related knowledge about Arctii Fructus were acquired from Science Direct, GeenMedical, PubMed, China National Knowledge Infrastructure (CNKI), Web of Science, Pharmacopoeia of the People's Republic of China, Doctoral and Master's thesis, ancient books, etc. RESULTS: Arctii Fructus as an herb used for medicine and food was pervasively distributed and applicated around the world. It was traditionally used to treat anemopyretic cold, dyspnea and cough, sore throat, etc. To date, more than 200 compounds have been isolated and identified from Arctii Fructus. It contained lignans, phenolic acids and fatty acids, terpenoids, volatile oils and others. Lignans, especially arctigenin and arctiin, had the extensive pharmacological effects such as anti-cancer, antiviral, anti-inflammatory activities. The ester derivatives of arctigenin had the anti-cancer, anti-Alzheimer's disease and immunity enhancing effects. Although Arctii Fructus extract had no toxicity, arctigenin was toxic at a certain dose. The alleviating effects of Arctii Fructus on chronic inflammation and ageing have been demonstrated by clinical studies.

CONCLUSION

Arctii Fructus is regarded as a worthy herb with many chemical components and various pharmacological effects. Several traditional applications have been supported by modern pharmacological research. However, their action mechanisms need to be further studied. Although many chemical components were isolated from Arctii Fructus, the current research mainly focused on lignans, especially arctiin and arctigenin. Therefore, it is very important to deeply clarify the pharmacological activities and action mechanism of the compounds and make full medicinal use of the resources of Arctii Fructus.

Inhibition of the largemouth bass virus replication by piperine demonstrates potential application in aquaculture

Largemouth bass virus (LMBV) is a systemic viral pathogen that can cause high mortality rates in cultivated largemouth bass. However, no treatment is currently approved. Therapeutic strategies against LMBV infection are urgently needed. In this study, we investigated the antiviral activity of piperine against LMBV in vitro and in vivo. In vitro antiviral activity assay showed that 210.28 μM piperine significantly decreased LMBV major capsid protein (MCP) gene expression in epithelioma papulosum cyprinid (EPC) cells by a maximum inhibitory rate of >95%. Piperine treatment inhibited LMBV replication in a dose-dependent manner, with the half-maximal activity (IC₅₀ ) of 34.61 μM. Moreover, piperine significantly decreased the viral titers and cytopathic effects (CPE), contributing to the protection of infected cells. With regard to the steps of piperine affecting the life cycle of viruses, piperine had a direct inactivating effect on LMBV. During the virus adsorption phase, piperine prevented the adsorption of LMBV to EPC cells. Furthermore, piperine played an antiviral role mainly in the later stages of viral infection (4-8 h). To further evaluate the antiviral activity of piperine against LMBV in vivo, largemouth bass as a model organism was carried out in relevant experiments. Intraperitoneal injection of piperine (25 mg/kg) effectively improved the survival rate of LMBV-infected largemouth bass by 20%. In addition, RT-qPCR results of viral replication in liver, spleen, kidney, gill and swim bladder tissues showed that piperine significantly inhibited LMBV replication in vivo, thus protecting largemouth bass from LMBV-induced death. Together, our results suggested that piperine is a therapeutic and preventative agent against LMBV infection.

Synthesis of esters and amides of 2-aryl-1-hydroxy-4-methyl-1H-imidazole-5-carboxylic acids and study of their antiviral activity against orthopoxviruses

Smallpox was eradicated >40 years ago but it is not a reason to forget forever about orthopoxviruses pathogenic to humans. Though in 1980 the decision of WHO to cease vaccination against smallpox had seemed logical, it led to the decrease of cross immunity against other infections caused by orthopoxviruses. As a result, in 2022 the multi-country monkeypox outbreak becomes a topic of great concern. In spite of existing FDA-approved drugs for the treatment of such diseases, the search for new small-molecule orthopoxvirus inhibitors continues. In the course of this search a series of novel 2-aryl-1-hydroxyimidazole derivatives containing ester or carboxamide moieties in position 5 of heterocycle has been synthesized and tested for activity against Vaccinia virus in Vero cell culture. Some of the compounds under consideration revealed a selectivity index higher than that of the reference drug Cidofovir. The highest selectivity index SI = 919 was exhibited by ethyl 1-hydroxy-4-methyl-2-[4-(trifluoromethyl)phenyl]-1H-imidazole-5-carboxylate 1f. The most active compound also demonstrated inhibitory activity against the cowpox virus (SI = 20) and the ectromelia virus (SI = 46).

Arctigenin: pharmacology, total synthesis, and progress in structure modification

Arctium lappa L. is a prevalent medicinal herb and a health supplement that is commonly used in Asia. Over the last few decades, the bioactive component arctigenin has attracted the attention of researchers because of its anti-inflammatory, antioxidant, immunomodulatory, multiple sclerosis fighting, antitumor, and anti-leukemia properties. After summarising the research and literature on arctigenin, this study outlines the current status of research on pharmacological activity, total synthesis, and structural modification of arctigenin. The purpose of this study is to assist academics in obtaining a more comprehensive understanding of the research progress on arctigenin and to provide constructive suggestions for further investigation of this useful molecule.

Taxifolin Inhibits WSSV Infection and Transmission by Increasing the Innate Immune Response in Litopenaeus vannamei

An outbreak of white spot syndrome virus (WSSV) can hit shrimp culture with a devastating blow, and there are no suitable measures to prevent infection with the virus. In this study, the activity of active molecules from Chinese herbs against WSSV was evaluated and screened. Taxifolin had the highest rate (84%) of inhibition of the WSSV infection. The viral infectivity and genome copy number were reduced by 41% when WSSV virion was pretreated with taxifolin prior to shrimp infection. A continuous exchange of taxifolin significantly reduced the mortality of shrimp infected with WSSV. Due to the WSSV virion infectivity being affected by taxifolin, the horizontal transmission of the virus was blocked with an inhibition rate of up to 30%, which would further reduce the cost of a viral outbreak. Additionally, the viral genome copy number was also reduced by up to 63% in shrimp preincubated in taxifolin for 8 h. There may be a connection to the enhancement of innate immunity in shrimp that resulted in a 15% reduction in mortality for taxifolin-fed shrimp after the WSSV challenge. After dietary supplementation with taxifolin, the resistance of larvae to WSSV was improved, indicating that taxifolin may be a potential immunostimulant for shrimp to prevent WSD. Therefore, the results indicate that taxifolin has application potential for blocking a WSSV outbreak and reducing the loss of shrimp culture.

First Discovery of Beta-Sitosterol as a Novel Antiviral Agent against White Spot Syndrome Virus

The outbreak of white spot syndrome (WSS) is a looming challenge, due to dramatic losses to the crustacean aquaculture industry. However, at present, there are no prophylactic or therapeutic means to control this infectious viral disease. Here, we screened fifteen medicinal plants for their inhibitory activity on the white spot syndrome virus (WSSV), using red swamp crayfish (Procambarus clarkii) as a model species. The results showed that the crude extracts of Pinellia ternata (Thunb.) Breit. had the highest inhibitory effect (91.59%, 100 mg/kg) on WSSV proliferation, and its main component, beta-sitosterol, showed a much higher activity (95.79%, 50 mg/kg). Further, beta-sitosterol potently reduced (p < 0.01) viral loads and viral gene transcription levels in a concentration-dependent fashion, and significantly promoted the survival rate of WSSV-challenged crayfish (57.14%, 50 mg/kg). The co-incubation assay indicated that beta-sitosterol did not influence the infectivity of WSSV particles. Both pre- and post-treatment of beta-sitosterol exerted a significant inhibitory effect (p < 0.01) on the viral load in vivo. Mechanistically, beta-sitosterol not only interfered with the expression of viral genes (immediate early gene 1, ie1; DNA polymerase, DNApol) that are important in initiating WSSV transcription, but it also attenuated the hijacking of innate immune signaling pathways (Toll, IMD, and JAK/STAT pathways) by viral genes to block WSSV replication. Moreover, the expression of several antiviral immune, antioxidant, pro-inflammatory, and apoptosis-related genes changed significantly in beta-sitosterol-treated crayfish. Beta-sitosterol is a potent WSSV inhibitor and has the potential to be developed as an effective anti-WSSV agent against a WSS outbreak in crustacean aquaculture.

Research Progress on Improving the Efficiency of CDT by Exacerbating Tumor Acidification

In recent years, chemodynamic therapy (CDT) has received extensive attention as a novel means of cancer treatment. The CDT agents can exert Fenton and Fenton-like reactions in the acidic tumor microenvironment (TME), converting hydrogen peroxide (H₂O₂) into highly toxic hydroxyl radicals (·OH). However, the pH of TME, as an essential factor in the Fenton reaction, does not catalyze the reaction effectively, hindering its efficiency, which poses a significant challenge for the future clinical application of CDT. Therefore, this paper reviews various strategies to enhance the antitumor properties of nanomaterials by modulating tumor acidity. Ultimately, the performance of CDT can be further improved by inducing strong oxidative stress to produce sufficient ·OH. In this paper, the various acidification pathways and proton pumps with potential acidification functions are mainly discussed, such as catalytic enzymes, exogenous acids, CAIX, MCT, NHE, NBCn1, etc. The problems, opportunities, and challenges of CDT in the cancer field are also discussed, thereby providing new insights for the design of nanomaterials and laying the foundation for their future clinical applications.

Quinoline, with the active site of 8-hydroxyl, efficiently inhibits Micropterus salmoides rhabdovirus (MSRV) infection in vitro and in vivo

Micropterus salmoides rhabdovirus (MSRV) is an significant pathogen that causes high mortality and related economic losses in bass aquaculture. There is no effective or approved therapy to date. In this study, we evaluated the anti-MSRV effects of 22 quinoline derivatives in grass carp ovary (GCO) cells. Among these compounds, 8-hydroxyquinoline exhibited valid inhibition in decreasing MSRV nucleoprotein gene expression levels of 99.3% with a half-maximal inhibitory concentrations (IC₅₀ ) value of 4.66 μM at 48 h. Moreover, 8-hydroxyquinoline significantly enhanced a protective effect in GCO cells by reducing the cytopathic effect (CPE). By comparing the anti-MSRV activity of 22 quinoline derivatives, we found that 8-hydroxyquinoline possessed the efficient active site of 8-hydroxyl and inhibited MSRV infection in vitro. For in vivo studies, 8-hydroxyquinoline via intraperitoneal injection exhibited an antiviral effect in MSRV-infected largemouth bass by substantially enhancing the survival rate by 15.0%. Importantly, the viral loads in the infected largemouth bass notably reduced in the spleen on the third days post-infection. Overall, 8-hydroxyquinoline was considered to be an efficient agent against MSRV in aquaculture.

In vitro and in vivo inhibition of a novel arctigenin derivative on aquatic rhabdovirus

Spring viraemia of carp virus (SVCV) poses a serious threat to aquaculture industry due to the lack of approved antiviral treatments. Therefore, a novel arctigenin derivative, 4-(2-methylimidazole) octanoxy-arctigenin (MON), was synthesized to assess the antiviral activity against SVCV in vitro and in vivo. The results indicated MON decreased the SVCV glycoprotein (G) gene expression in vitro by a maximum inhibitory rate of > 99% at 3.5 μM. Furthermore, MON showed the protective effect on epithelioma papulosum cyprinid (EPC) cells and considerably decreased the cytopathic effect (CPE). More importantly, MON inhibited SVCV G gene expression levels in vitro at the half-maximal activity (IC₅₀) of 0.18 μM at 48 h. For in vivo studies, MON demonstrated anti-SVCV activity by enhancing the survival rate of zebrafish (Danio rerio) after infection via pelvic fin base injection. These results tended to be consistent with MON decreasing the SVCV titer of infected zebrafish. During this time, viral loads of the spleen and kidney have declined in SVSV-infected zebrafish. Based on the histopathological assay, MON exhibited the high protective effect in the spleen and kidney of SVCV-infected fish. Combined, MON is on track to become a novel agent to address SVCV infection in aquaculture.

Potential application of antiviral coumarin in aquaculture against IHNV infection by reducing viral adhesion to the epithelial cell surface

Due to the lack of relevant therapies for infectious haematopoietic necrosis virus (IHNV) infection, the viral outbreak invariably causes serious economic losses in salmonid species. In this study, we evaluated the anti-IHNV effects of 7-(6-benzimidazole) coumarin (C10) and 4-phenyl-2-thioxo-1,2,3,4-tetrahydro-5H-chromeno[4,3-d]pyrimidin-5-one (S5) in vitro and in vivo. The results revealed that C10 at 12.5 mg/L and S5 at 25 mg/L significantly inhibited IHNV replication in epithelioma papulosum cyprini (EPC) cells with a maximum inhibitory rate >90%, showing that IHNV-induced cytopathic effect (CPE) was alleviated by C10 and S5. There are two complementary effects on antiviral mechanism: 1. C10 completely inhibited IHNV infectivity when the virus was preincubated with C10 at 12.5 mg/L, determining that C10 may have a negative impact on IHNV binding to the cell; 2. C10 also up-regulated the gene expression of extracellular proto type galectin-1 (Gal1-L2) and a chimera galectin-3 (Gal3-L1) of EPC cells to inhibit IHNV adhesion. For the in vivo study, injection and immersion of the coumarins enhanced the survival rate of rainbow trout (Oncorhynchus mykiss) juveniles by 25% (at least) at 12 dpi. IHNV loads in the kidney and spleen were also obviously decreased at 96 h, and thus we considered that they had a delaying effect on IHNV replication in vivo. Meanwhile, C10 with a high stability in aquacultural water in immersion suppressed IHNV horizontal transmission by decreasing the viral loads in recipient fish. Overall, our data suggest that there is a positive effect of C10 and S5 against IHNV infection in aquaculture, and C10 had the potential to be a broad-spectrum antiviral against fish rhabdoviruses.

Synthesis and biological evaluation of novel coumarin derivatives in rhabdoviral clearance

Diseases caused by rhabdoviruses have had a huge impact on the productive lives of the entire human population. The main problem is the lack of drugs for the treatment of this family of viruses. Infectious hematopoietic necrosis virus (IHNV), the causative agent of IHN, is a typical rhabdovirus which has caused huge losses to the salmonid industry. Therefore, in this study, IHNV was studied as a model to evaluate the antiviral activity of 35 novel coumarin derivatives. Coumarin A9 was specifically selected for further validation studies upon comparing the half maximum inhibitory concentration (IC₅₀) of four screened candidate derivatives in epithelioma papulosum cyprinid (EPC) cells, as it exhibited an IC₅₀ value of 2.96 μM against IHNV. The data revealed that A9 treatment significantly suppressed the virus-induced cytopathic effect (CPE) in EPC cells. In addition, A9 showed IC₅₀ values of 1.68 and 2.12 μM for two other rhabdoviruses, spring viremia of carp virus and micropterus salmoides rhabdovirus, respectively. Furthermore, our results suggest that A9 exerts antiviral activity, but not by destroying the virus particles and interfering with the adsorption of IHNV. Moreover, we found that A9 had an inhibitory effect on IHNV-induced apoptosis in EPC cells, as reflected by the protection against cell swelling, formation of apoptotic bodies, and loss of cell morphology and nuclear division. There was a 19.05 % reduction in the number of apoptotic cells in the A9 treatment group compared with that in the IHNV group. In addition, enzyme activity assays proved that A9 suppressed the expression of caspase 3, 8 and 9. These results suggested that A9 inhibit viral replication, to some extent, by blocking IHNV-induced apoptosis. In an in vivo study, A9 exhibited an anti-rhabdovirus effect in virus-infected fish by substantially enhancing the survival rate. Consistent with the above results, A9 repressed IHNV gene expression in virus-sensitive tissues (brain, kidney and spleen) in the early stages of virus infection. Importantly, the data showed that horizontal transmission of IHNV was reduced by A9 in a static cohabitation challenge model, especially in fish that underwent bath treatment, suggesting that A9 might be a suitable therapeutic agent for IHNV in aquaculture. Therefore, coumarin derivatives can be developed as antiviral agents against rhabdoviruses.

Challenges and Solutions to Viral Diseases of Finfish in Marine Aquaculture

Aquaculture is the fastest food-producing sector in the world, accounting for one-third of global food production. As is the case with all intensive farming systems, increase in infectious diseases has adversely impacted the growth of marine fish farming worldwide. Viral diseases cause high economic losses in marine aquaculture. We provide an overview of the major challenges limiting the control and prevention of viral diseases in marine fish farming, as well as highlight potential solutions. The major challenges include increase in the number of emerging viral diseases, wild reservoirs, migratory species, anthropogenic activities, limitations in diagnostic tools and expertise, transportation of virus contaminated ballast water, and international trade. The proposed solutions to these problems include developing biosecurity policies at global and national levels, implementation of biosecurity measures, vaccine development, use of antiviral drugs and probiotics to combat viral infections, selective breeding of disease-resistant fish, use of improved diagnostic tools, disease surveillance, as well as promoting the use of good husbandry and management practices. A multifaceted approach combining several control strategies would provide more effective long-lasting solutions to reduction in viral infections in marine aquaculture than using a single disease control approach like vaccination alone.

Small Molecule Inhibitors of White Spot Syndrome Virus: Promise in Shrimp Seedling Culture

Rapid production of prawn (Litopenaeus vannamei) under artificial pressure can result in a series of obvious challenges and is vulnerable to serious losses related to aquatic environmental issues and the unrestrained outbreak of white spot syndrome (WSS). However, to date, there are no therapeutic strategies to contain the spread of the virus. Here, we synthesized 27 coumarin derivatives and evaluated their anti-white spot syndrome virus (WSSV) activity in L. vannamei larvae. We demonstrated that electron-withdrawing and electron-giving substituent groups play an important role in reducing toxicity and WSSV replication, respectively. Two coumarin C2 (2-amino-5-oxo-4-(p-tolyl)-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile) and C7 (2-amino-4-(4-chlorophenyl)-5-oxo-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile) were regarded as the most promising anti-WSSV compounds with maximum antiviral response <5% and median effective concentration <10 mg/L. The mortality of WSSV-infected larvae decreased by more than 60% after exposure to C2 and C7. With continuous immersion of C2 and C7 exchange, the mortality further decreased to 40% at 120 h. Additionally, C2 and C7 are the relatively stable in aquacultural water, making these agents suitable for use in inhibiting WSSV horizontal transmission in static aquaculture systems. These results showed the marked advantages of using C2 and C7 in the shrimp industry, and suggest that they hold potential for the treatment and prevention of WSSV infection in shrimp seedling culture.

A preliminary investigation on the mechanism of action of 4-(8-(2-ethylimidazole)octyloxy)-arctigenin against IHNV

Arctigenin derivatives form an elite class of naturally occurring compounds that possess promising antiviral therapeutic perspectives. In a previous study, we design and synthesize a arctigenin derivative, 4-(8-(2-ethylimidazole)octyloxy)-arctigenin (EOA), to evaluate its antiviral activity on infectious hematopoietic necrosis virus (IHNV). In this study, we find that the half maximal inhibitory concentrations (IC₅₀) of EOA on IHNV nucleoprotein (N), phosphoprotein (P), matrix protein (M), nonvirion protein (NV) and polymerase (L) mRNA expression is 0.92, 0.80, 0.98, 0.89 and 0.87 μM, respectively. Mechanistically, our results show that EOA do not damage the viral particles directly, indicating EOA does not possess antiviral activity by destroying virions. Viral binding assays reveal that EOA do not interfere with IHNV adsorption. Because rapamycin has been shown to exhibit anti-IHNV activity by inducing autophagy of epithelioma papulosum cyprini (EPC) cells, we further investigate the relationship between EOA and autophagy in EPC cells. Autophagy fluorescence detection shows that EPC cells have a strong autophagy body after being treated with derivative EOA. The electron microscopy results show that EOA could induce typical autophagosomes which are representative structures of autophagy activation. Moreover, the punctate accumulation of green fluorescence-tagged microtubule-associate protein 1 light chain 3 (LC3) and the protein conversion from LC3-I to LC3-II are respectively confirmed by confocal fluorescence microscopy and western blotting. Overall, these findings demonstrate that EOA plays an anti-IHNV role via inducing autophagy in EPC cells.

Acyclovir inhibits channel catfish virus replication and protects channel catfish ovary cells from apoptosis

The channel catfish virus (CCV) can cause lethal hemorrhagic infection in channel catfish, resulting in significant economic losses in the fish industry. Effective drugs for the virus are still lacking. Acyclovir is known as a potent antiviral agent against human herpes viruses and some animal DNA viruses. The present study was undertaken to explore the antiviral response and mechanism of acyclovir against CCV in channel catfish ovary (CCO) cells. Acyclovir was able to significantly inhibit the expression of viral genes related to CCV viral DNA synthesis and suppress viral replication at a safe concentration. Furthermore, acyclovir blocked the cytopathic effects and apoptosis induced by CCV, thereby maintaining the normal cellular morphological structure, as shown by the protection of CCO cells from the formation of apoptotic bodies or nuclear fragmentation. Moreover, reverse transcript quantitative polymerase chain reaction (RT-qPCR) demonstrated that acyclovir suppressed the expression of caspase 3, caspase 8 and caspase 9, while there was no significant impact on the expression of the apoptosis-inhibiting gene bcl-2 in CCV-infected cells. In addition, acyclovir did not promote the expression of immune-related genes such as MyD88, Mx1, IRF3, IRF7, IFN-I, NF-kB and IL-1β, suggesting that the antiviral activity of acyclovir to CCV infection is not achieved by facilitating the expression of immune-related genes in CCO cells. Taken together, the results from this study suggest that acyclovir could effectively regulate CCV-induced infection, and thus is a promising therapeutic agent against CCV. Our results will aid our understanding of the pharmacological mechanisms of antiviral agents.

In vitro and in vivo evaluation of antiviral activity of a phenylpropanoid derivative against spring viraemia of carp virus

Phenylpropanoids, common natural compounds, possess many different biological activities such as antioxidant, anti-inflammatory and antiviral. Spring viraemia of carp virus (SVCV) can cause a high mortality in common carp (Cyprinus carpio). However, there are currently no licenced drugs that effectively cure this disease. In this study, we designed and synthesized a phenylpropanoid derivative 4-(4-methoxyphenyl)-3,4-dihydro-2H-chromeno[4,3-d]pyrimidine-2,5(1 H)-dione (E2), and explored the antiviral effect against SVCV in vitro and in vivo. Up to 25 mg/L of E2 significantly inhibited the expression levels of SVCV protein genes in the epithelioma papulosum cyprini (EPC) cell line by a maximum inhibitory rate of >90%. As expected, E2 remarkably declined the apoptotic of SVCV-infected cells and suppressed potential enhancement of the mitochondrial membrane potential (ΔΨm), these data implied that E2 could protect mitochondria from structural damage in response to SVCV. Meanwhile, E2 was added to EPC cells under four different conditions: time-of-addition, time-of-removal, pre-treatment of viruses and pre-treatment of cells indicated that E2 may block the post-entry transport process of the virus. Additionally, the up-regulation of six interferon (IFN)-related genes also demonstrated that E2 indirectly activated IFNs for the clearance of SVCV in common carp. Drug cure effect showed that treatment with E2 at 0.5 d post infection (dpi) is more effective than at 0, 1 or 2 dpi. Most importantly, intraperitoneal therapy of E2 markedly improved common carp survival rate and reduced virus copies in body. Therefore, the E2 has potential to be developed into a novel anti-SVCV agent.

Discovery of stereospecific cytotoxicity of (8R,8'R)-trans-arctigenin against insect cells and structure-activity relationship on aromatic ring

One of the arctigenin stereoisomers, (8R,8'R)-trans-form 1, showed stereospecific cytotoxicity against insect cells, Sf9 and NIAS-AeAl-2 cells. By the comparison with other stereoisomers, the most importance of the 8'R stereochemistry for the higher activities was clarified. On the other hand, the wider range of activity level among stereoisomers against cancer cells, HL-60, was not observed. The structure-activity relationship research using derivatives bearing (8R,8'R)-trans-form was performed to show the same level of activities of 3-iodo, 4-iodo, and 3,4-methylenedioxy derivatives 28, 29, and 36 as (8R,8'R)-trans-arctigenin 1. In the examination of thiono derivatives, 4-iodo thiono and 3,4-methylenedioxy thiono derivatives 66, 67 showed similar level of activities to that of (8R,8'R)-trans-arctigenin 1. The expression of ribosomal 28S rRNA gene of Sf9 cells was increased by (8R,8'R)-trans-arctigenin 1, whereas a degradation of DNA was not observed.

Evaluation on the antiviral effect of a hydroxycoumarin against infectious hematopoietic necrosis virus infection in vitro and in vivo

Infectious hematopoietic necrosis (IHN) caused by the viral pathogen infectious hematopoietic necrosis virus (IHNV) is a highly contagious disease of salmonid species, resulting in significant economic impact. The previous study showed a hydroxycoumarin derivative 7-[6-(2-methylimidazole) hexyloxy] coumarin (D5) significantly inhibited spring viraemia of carp virus (SVCV) infection, suggesting that D5 may be useful as a potential anti-IHNV agent. In this study, D5 at the concentration of up to 10 mg/L significantly inhibited IHNV replication in epithelioma papulosum cyprini (EPC) cells with a maximum inhibitory rate of >90%, maintained mitochondrial membrane potential (ΔΨm) levels, and decreased IHNV-induced apoptosis in virus-infected cells. As the consequence of protection on mitochondria, D5 enhanced antioxidant enzyme activities and decreased reactive oxygen species (ROS) to maintain the antioxidant-oxidant balance of IHNV-infected EPC cells. For in vivo study, D5 via intraperitoneal injection exhibited an anti-IHNV effect in the virus-infected fish by substantially enhancing the survival rate. Meanwhile, up-regulation of six interferon (IFN) related gene expressions demonstrated that D5 may activate IFN-related expressions for inhibiting IHNV replication during the early stage of viral infection, which is beneficial for the continuous antiviral action on controlling low viral loads in rainbow trout juvenile. Thus, D5 effective regulated IHNV-induced undesirable conditions to be an excellent potential therapeutic agent against IHNV infection.

Arctigenin prevents the progression of osteoarthritis by targeting PI3K/Akt/NF-κB axis: In vitro and in vivo studies

Osteoarthritis (OA), which is principally featured by progressive joint metabolic imbalance and subsequent degeneration of articular cartilage, is a common chronic joint disease. Arctigenin (ATG), a dietary phyto-oestrogen, has been described to have potent anti-inflammatory effects. Nevertheless, its protective effects on OA have not been clearly established. The target of our following study is to evaluate the protective effects of ATG on IL-1β-induced human OA chondrocytes and mouse OA model. Our results revealed that the ATG pre-treatment effectively decreases the level of pro-inflammatory mediators, such as prostaglandin E2 (PGE2), nitrous oxide (NO), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-6 and tumour necrosis factor alpha (TNF-α) in IL-1β-induced human chondrocytes. In addition, ATG protects against the degradation of extracellular matrix (ECM) under the stimulation of IL-1β and the possible mechanism might be connected with the inactivation of phosphatidylinositol-3-kinase (PI3K)/Akt/nuclear factor-kappa B (NF-κB) axis. Furthermore, a powerful binding capacity between ATG and PI3K was also uncovered in our molecular docking research. Meanwhile, ATG may act as a protector on the mouse OA model. Collectively, all these findings suggest that ATG could be utilized as a promising therapeutic agent for the treatment of OA.

Inhibition of a novel coumarin on an aquatic rhabdovirus by targeting the early stage of viral infection demonstrates potential application in aquaculture

Spring viremia of carp virus (SVCV) is one of the most serious pathogens in aquaculture, resulting in devastating damage in cyprinid. In this study, we designed and synthesized a novel coumarin derivative (C3007) for evaluating its in vitro and in vivo anti-SVCV effects. Here, we determined that up to 25 mg/L C3007 significantly decreased SVCV protein gene expression levels in EPC cells by a maximum inhibitory rate of >95%. When C3007 was preincubated with SVCV, infectivity was significantly inhibited in vitro in a time-dependent manner, with complete inhibition at 25 mg/L. For in vivo studies, C3007 exhibited an anti-SVCV effect by substantially enhancing the survival rate of virus-infected fish via intraperitoneal injection. Although the horizontal transmission of SVCV was hindered by C3007 in a static cohabitation challenge model, it was not completely blocked, showing that the viral loads in recipient fish were obviously reduced. Thus, C3007 could potentially be used as a therapeutic agent with great potential in aquatic systems and may also be suitable for applications in pond aquaculture settings against viral transmission. Additionally, the C3007-preincubated virus induced an antiviral immune response with high levels of IFN expression, suggesting that C3007 pre-treatment could be used in vaccine development.

Ursolic acid from Prunella vulgaris L. efficiently inhibits IHNV infection in vitro and in vivo

Infectious hematopoietic necrosis virus (IHNV) is a fish viral pathogen that causes severe disease and huge economic losses in the salmonid aquaculture industry. However, anti-IHNV drugs currently are scarce. For the purpose of seeking out anti-IHNV drugs, the anti-IHNV activities of 32 medicinal plants were investigated by using epithelioma papulosum cyprini (EPC) cells. Among these plants, Prunella vulgaris L. (PVL) showed the strongest inhibition on IHNV replication with an inhibitory percentage of 99.3% at the concentration 100 mg/L. Further studies demonstrated that ursolic acid (UA), a major constituent of PVL, also showed a highly effective anti-IHNV activity. The half-maximal inhibitory concentration (IC50) at 72 h of UA on IHNV was 8.0 μM. Besides, UA could significantly decrease cytopathic effect (CPE) and the viral titer induced by IHNV in EPC cells. More importantly, UA also showed a strong anti-IHNV activity in vivo, as indicated by increasing the survival rate of rainbow trout and inhibiting viral gene expression. Intraperitoneal injection of UA increased the relative percentage of survival of rainbow trout by 18.9% and inhibited IHNV glycoprotein mRNA expression by > 90.0% in the spleen at the 1st-day post-infection. Altogether, UA was expected to be a therapeutic agent against IHNV infection in aquaculture.

Synthesis and antiviral activity of a new arctigenin derivative against IHNV in vitro and in vivo

Viral diseases in aquaculture were challenging because there are few preventative measures and/or treatments. Our previous study indicated that imidazole arctigenin derivatives possessed antiviral activities against infectious hematopoietic necrosis virus (IHNV). Based on the structure-activity relationship in that study, a new imidazole arctigenin derivative, 4-(8-(2-ethylimidazole)octyloxy)-arctigenin (EOA), was designed, synthesized and its anti-IHNV activity was evaluated. By comparing inhibitory concentration at half-maximal activity (IC₅₀), we found that EOA (IC₅₀ = 0.56 mg/L) possessed a higher antiviral activity than those imidazole arctigenin derivatives in our previous study. Besides, EOA could significantly decrease cytopathic effect (CPE) and viral titer induced by IHNV in epithelioma papulosum cyprinid (EPC) cells. In addition, EOA significantly inhibited apoptosis induced by IHNV in EPC cells. Further data verified that EOA inhibited IHNV replication in rainbow trout, with reducing 32.0% mortality of IHNV-infected fish. The results suggested that EOA was more stable with a prolonged inhibitory half-life in the early stage of virus infection (1-4 days). Consistent with above results, EOA repressed IHNV glycoprotein gene expression in virus sensitive tissues (kidney and spleen) in the early stage of virus infection. Moreover, histopathological evaluation showed that tissues from the spleen and kidney of fish infected with IHNV exhibited pathological changes. But there were no lesions in any of the tissues from the control group and EOA-treaten group. In accordance with the histopathological assay, EOA could elicited anti-inflammation response in non-viral infected rainbow trout by down-regulating the expression of cytokine genes (IL-8, IL-12p40, and TNF-α). Altogether, EOA was expected to be a therapeutic agent against IHNV infection in the field of aquaculture.