First study on in vitro antiviral and virucidal effects of flavonoids against feline infectious peritonitis virus at the early stage of infection

Isoginkgetin Inhibits RANKL-induced Osteoclastogenesis and Alleviates Bone Loss

Osteoporosis is characterized by excessive osteoclast activity leading to bone loss, decreased bone mineral density, and increased susceptibility to fractures. Through in vivo/vitro experiments, along with network pharmacology analysis, we aimed to explore the underlying mechanisms of Isoginkgetin (IGG) in inhibiting osteoclastogenesis, providing valuable insights for further research in the future. Firstly, we ascertained the safe concentration of IGG stimulation on BMMs, followed by a systematic exploration of the concentration gradient at which IGG inhibited osteoclastogenesis using TRAP analysis. An osteoporosis model was established to further validate the in vitro experimental findings by combining Micro-CT and immunohistochemical analysis. The results show that IGG did not exhibit cytotoxicity or proliferative effects on BMMs at concentrations equal to or less than 10 μM. Additionally, IGG inhibited the activity of osteoclastogenesis and bone resorption function at lower concentrations. RT-PCR and Western Blot results demonstrated that IGG could downregulate genes and proteins associated with osteoclastogenesis. The Western Blot results also showed that IGG inhibited the phosphorylation expression of P38, ERK, and P65 in the MAPK and NF-κB pathways. At the same time, it rescued the degradation of IκB-α at 15 and 60 min. IGG can also impact the relative expression levels of oxidative proteins such as SOD-1, HO-1, and catalase, thereby influencing cellular equilibrium and stress levels, ultimately inhibiting the formation of mature OC. In vivo experiments demonstrated that IGG alleviated bone loss caused by osteoclasts and improved relevant parameters of trabecular bone. So, IGG effectively attenuated osteoclastogenesis, and improved bone density, thereby portraying its role in osteoporosis management.

Antiviral activity of Vigna radiata extract against feline coronavirus in vitro

Feline infectious peritonitis (FIP) is a fatal illness caused by a mutated feline coronavirus (FCoV). This disease is characterized by its complexity, resulting from systemic infection, antibody-dependent enhancement (ADE), and challenges in accessing effective therapeutics. Extract derived from Vigna radiata (L.) R. Wilczek (VRE) exhibits various pharmacological effects, including antiviral activity. This study aimed to investigate the antiviral potential of VRE against FCoV, addressing the urgent need to advance the treatment of FIP. We explored the anti-FCoV activity, antiviral mechanism, and combinational application of VRE by means of in vitro antiviral assays. Our findings reveal that VRE effectively inhibited the cytopathic effect induced by FCoV, reduced viral proliferation, and downregulated spike protein expression. Moreover, VRE blocked FCoV in the early and late infection stages and was effective under in vitro ADE infection. Notably, when combined with VRE, the polymerase inhibitor GS-441524 or protease inhibitor GC376 suppressed FCoV more effectively than monotherapy. In conclusion, this study characterizes the antiviral property of VRE against FCoV in vitro, and VRE possesses therapeutic potential for FCoV treatment.

Dual effects of ipecac alkaloids with potent antiviral activity against foot-and-mouth disease virus as replicase inhibitors and direct virucides

Foot-and-Mouth Disease (FMD) is a contagious, blistering disease caused by the Foot-and-Mouth Disease virus (FMDV), which affects livestock globally. Currently, no commercial antiviral agent is available for effective disease control. This study investigated the antiviral potential of natural-derived alkaloids against FMDV in BHK-21 cells. Twelve alkaloids were assessed for their antiviral activities at various stages of FMDV infection, including pre-viral entry, post-viral entry, and prophylactic assays, as well as attachment and penetration assays by evaluating cytopathic effect reduction and directed-virucidal effects. The results showed that ipecac alkaloids, cephaeline (CPL) and emetine (EMT), exhibited dual effects with robust antiviral efficacy by reducing cytopathic effect and inhibiting FMDV replication in a dose-dependent manner. Evaluation through immunoperoxidase monolayer assay and RT-PCR indicated effectiveness at post-viral entry stage, with sub-micromolar EC50 values for CPL and EMT at 0.05 and 0.24 µM, respectively, and high selective indices. Prophylactic effects prevented infection with EC50 values of 0.23 and 0.64 µM, respectively. Directed-virucidal effects demonstrated significant reduction of extracellular FMDV, with CPL exhibiting a dose-dependent effect. Furthermore, the replicase (3Dpol) inhibition activity was identified using the FMDV minigenome assay, which revealed strong inhibition with IC50 values of 0.15 µM for CPL and 4.20 µM for EMT, consistent with the decreased negative-stranded RNA production. Molecular docking confirmed the interaction of CPL and EMT with residues in the active site of FMDV 3Dpol. In conclusion, CPL and EMT exhibited promising efficacy through their dual effects and provide an alternative approach for controlling FMD in livestock.

Inhibition of NS2B-NS3 protease from all four serotypes of dengue virus by punicalagin, punicalin and ellagic acid identified from Punica granatum

Despite a major threat to the public health in tropical and subtropical regions, dengue virus (DENV) infections are untreatable. Therefore, efforts are needed to investigate cost-effective therapeutic agents that could cure DENV infections in future. The NS2B-NS3 protease encoded by the genome of DENV is considered a critical target for the development of anti-dengue drugs. The objective of the current study was to find out a specific inhibitor of the NS2B-NS3 proteases from all four serotypes of DENV. To begin with, nine plant extracts with a medicinal history were evaluated for their role in inhibiting the NS2B-NS3 proteases by Fluorescence Resonance Energy Transfer (FRET) assay. Among the tested extracts, Punica granatum was found to be the most effective one. The metabolic profiling of this extract revealed the presence of several active compounds, including ellagic acid, punicalin and punicalagin, which are well-established antiviral agents. Further evaluation of IC50 values of these three antiviral molecules revealed punicalagin as the most potent anti-NS2B-NS3 protease drug with IC50 of 0.91 ± 0.10, 0.75 ± 0.05, 0.42 ± 0.03, 1.80 ± 0.16 µM against proteases from serotypes 1, 2, 3 and 4, respectively. The docking studies demonstrated that these compounds interacted at the active site of the enzyme, mainly with His and Ser residues. Molecular dynamics simulations analysis also showed the structural stability of the NS2B-NS3 proteases in the presence of punicalagin. In summary, this study concludes that the punicalagin can act as an effective inhibitor against NS2B-NS3 proteases from all four serotypes of DENV.

Feline Infectious Peritonitis: European Advisory Board on Cat Diseases Guidelines

Feline coronavirus (FCoV) is a ubiquitous RNA virus of cats, which is transmitted faeco-orally. In these guidelines, the European Advisory Board on Cat Diseases (ABCD) presents a comprehensive review of feline infectious peritonitis (FIP). FCoV is primarily an enteric virus and most infections do not cause clinical signs, or result in only enteritis, but a small proportion of FCoV-infected cats develop FIP. The pathology in FIP comprises a perivascular phlebitis that can affect any organ. Cats under two years old are most frequently affected by FIP. Most cats present with fever, anorexia, and weight loss; many have effusions, and some have ocular and/or neurological signs. Making a diagnosis is complex and ABCD FIP Diagnostic Approach Tools are available to aid veterinarians. Sampling an effusion, when present, for cytology, biochemistry, and FCoV RNA or FCoV antigen detection is very useful diagnostically. In the absence of an effusion, fine-needle aspirates from affected organs for cytology and FCoV RNA or FCoV antigen detection are helpful. Definitive diagnosis usually requires histopathology with FCoV antigen detection. Antiviral treatments now enable recovery in many cases from this previously fatal disease; nucleoside analogues (e.g., oral GS-441524) are very effective, although they are not available in all countries.